(19)
(11)EP 3 130 173 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
29.07.2020 Bulletin 2020/31

(21)Application number: 15776476.2

(22)Date of filing:  10.04.2015
(51)International Patent Classification (IPC): 
H04W 28/02(2009.01)
H04W 4/00(2018.01)
H04W 72/12(2009.01)
H04W 76/10(2018.01)
H04W 28/08(2009.01)
H04W 74/08(2009.01)
(86)International application number:
PCT/KR2015/003631
(87)International publication number:
WO 2015/156643 (15.10.2015 Gazette  2015/41)

(54)

METHOD AND SYSTEM FOR PROVIDING DATA COMMUNICATION THROUGH A CLUSTER HEAD FOR MACHINE TYPE COMMUNICATION (MTC) BASED GROUP COMMUNICATION

VERFAHREN UND SYSTEM ZUR DATENÜBERTRAGUNG DURCH EINEN CLUSTER-KOPF FÜR AUF MASCHINENKOMMUNIKATION (MTC) BASIERENDE GRUPPENKOMMUNIKATION

PROCÉDÉ ET SYSTÈME DE FOURNITURE D'UNE COMMUNICATION DE DONNÉES PAR L'INTERMÉDIAIRE D'UNE TÊTE DE GRAPPE POUR UNE COMMUNICATION DE GROUPE BASÉE SUR UNE COMMUNICATION DE TYPE MACHINE (MTC)


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 10.04.2014 IN 1894CH2014
16.03.2015 KR 20150036108

(43)Date of publication of application:
15.02.2017 Bulletin 2017/07

(73)Proprietor: Samsung Electronics Co., Ltd.
Gyeonggi-do 16677 (KR)

(72)Inventors:
  • SHARMA, Diwakar
    Bangalore 560037 (IN)
  • RANGARAJ MANAVALAN, Karthik
    Bangalore 560037 (IN)
  • HARIKRISHNAN, Yamini
    Bangalore 560037 (IN)

(74)Representative: Nederlandsch Octrooibureau 
P.O. Box 29720
2502 LS The Hague
2502 LS The Hague (NL)


(56)References cited: : 
US-A1- 2007 058 665
US-A1- 2013 107 797
US-A1- 2013 212 219
US-A1- 2014 094 183
US-A1- 2009 034 432
US-A1- 2013 150 061
US-A1- 2013 336 206
  
  • WANG SEN-HUNG ET AL: "Random access design for clustered wireless machine to machine networks", 2013 FIRST INTERNATIONAL BLACK SEA CONFERENCE ON COMMUNICATIONS AND NETWORKING (BLACKSEACOM), IEEE, 3 July 2013 (2013-07-03), pages 107-111, XP032499181, DOI: 10.1109/BLACKSEACOM.2013.6623391 [retrieved on 2013-10-07]
  • SHIH-EN WEI ET AL: "Enabling dense machine-to-machine communications through interference-controlled clustering", WIRELESS COMMUNICATIONS AND MOBILE COMPUTING CONFERENCE (IWCMC), 2012 8TH INTERNATIONAL, IEEE, 27 August 2012 (2012-08-27), pages 774-779, XP032253396, DOI: 10.1109/IWCMC.2012.6314302 ISBN: 978-1-4577-1378-1
  
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


Description

Technical Field



[0001] The present invention relates to the field of machine type communications (MTC), and more particularly relates to a method and system for enabling data communication through a cluster head via a dedicated connection for MTC based group communications.

Background Art



[0002] Machine-to Machine (M2M)/Machine Type Communications (MTC) applications are applications where machines communicate with each other directly without human intervention. Examples of applications include smart metering, safety applications, health monitoring, fleet management, data applications and remote applications.

[0003] The MTC devices can be embedded in cars, consumer electronic devices, vending devices, etc. These devices are large in number and are wide spread. The applications should communicate through widely deployed networks connecting the MTC devices to the Internet forming Internet of Things (IoT). While some existing MTC deployments use short range communications, it would be ideal to use cellular networks as the infrastructure is established in a stable manner and can support a large number of MTC devices.

[0004] US 2013/0336206 A1 discloses a system in which a cluster of terminals within a wireless communication network comprises a delegate terminal which communicates with a base station on behalf of the rest of the terminals in the cluster, wherein the delegate terminal transmits to the base station information about the terminals in the cluster.

[0005] WANG SEN-HUNG ET AL: "Random access design for clustered wireless machine to machine networks", 2013 FIRST INTERNATIONAL BLACK SEA CONFERENCE ON COMMUNICATIONS AND NETWORKING (BLACKSEACOM), IEEE, 3 July 2013, pages 107-111, discloses an MTC network in which the MTC devices are grouped in clusters including a cluster head, wherein the cluster head aggregates the traffic and relays to the macro base station.

[0006] SHIH-EN WEI ET AL: "Enabling dense machine-to-machine communications through interference-controlled clustering", WIRELESS COMMUNICATIONS AND MOBILE COMPUTING CONFERENCE (IWCMC), 2012 8TH

[0007] INTERNATIONAL, IEEE, 27 August 2012, pages 774-779, discloses clustering of machines for better spatial reuse, proposing a mixed-integer non-linear programming problem to determine the optimal cluster structure and power control, and proposes an algorithm to solve this problem.

[0008] US2013/0212219 A1 discloses an apparatus that facilitates mobile gateway operation for machines, wherein the apparatus provides configuration information to the machines, and allowing connection of the machines with a mobile terminal.

Disclosure of Invention


Technical Problem



[0009] The enormous amount of signaling flow generated by the large number of MTC devices trying to connect to the network at the same time leads to congestion in radio access network (RAN) and the core network (CN). This in turn causes intolerable delays, packet loss and also service unavailability. Also, congestion in MTC would also affect the non MTC devices.

[0010] Generally at the RAN side, the congestion occurs when a large number of MTC devices try to communicate concurrently with the eNodeB. For example, MTC devices which are used for monitoring (bridge monitoring or rainfall/flood monitoring) will transmit the monitored data concurrently. As the devices are connected to the same eNodeB, using the same common channels (Random accesses), can lead to congestion. Consequently the network should be optimized to support these communication requests from the devices simultaneously.

[0011] In Release 11, 3GPP System Architecture working group 1 (SA1) has defined system aspects and technical specifications for MTC device to device communication, group based services and possible enhancements to improve the network for MTC. Various solutions such as Access Class Barring schemes, Separate Random Access Channel (RACH) resources for MTC, Dynamic allocation of RACH resources, MTC Specific Back off scheme, slotted access and the like are proposed by the 3GPP to overcome the problem of congestion. These solutions from 3GPP will distribute the RACH load. However, in case of super dense deployment of Pico cells it will either impair the M2M devices or Human to Human (H2H) users.

[0012] The deployment scenarios herein take into consideration a combination environment where there is constant movement of MTC devices alongside the static MTC devices. This creates congestion at the RAN due to random access contention during uplink transmission where multiple MTC devices try to send data to the network. Further, during downlink transmission and capacity should be improved while supporting large number of MTC devices along with the existing H2H interaction in downlink transmission. Further, the RACH burst from MTC devices will overload the RACH access at eNodeB which deprives the cellular users from normal service due to over loading of RACH by higher density of M2M devices.

[0013] In view of the foregoing, there is a need for an MTC device friendly system and method for minimizing RACH load and provide accesses to MTC devices in MTC based communication.

Solution to Problem



[0014] The various embodiments of the present invention disclose a method according to claim 1 and cluster head according to claim 13 for providing data communication for machine type communication (MTC) devices. The invention is defined by the subject-matter of the independent claims. Particular embodiments of the invention are set out in the dependent claims. Examples and technical descriptions of apparatuses, products and/or methods in the description and/or drawings which are not covered by the claims are presented not as embodiments of the invention but as background art or examples useful for understanding the invention.

[0015] According to an embodiment of the present invention, determining availability of base station resources for transferring data traffic comprises of creating a priority list of active MTC devices based on the delay tolerance, comparing the delay tolerance of the active MTC devices with a time required for establishing a connection with a base station, triggering a connection request with the base station when the delay tolerance for a high priority MTC device is equal to the pre-set time and establishing a dedicated connection with the base station for transferring the data traffic. The delay tolerance herein is defined as a total tolerable time of communication without impacting a quality of service for the MTC member device.

[0016] According to an embodiment of the present invention, the method further comprises of sending, by the cluster head, at least one of an ACK or NACK message from the base station through the dedicated connection established between the cluster head and the base station and relaying at least one of an ACK or NACK message from the base station to a corresponding MTC device.

[0017] According to an embodiment of the present invention, the cluster head establishes and releases the dedicated connection with the base station based on an incoming traffic from the one or more MTC devices.

[0018] According to an embodiment of the present invention, the preset time is the time interval required for the establishment of dedicated connection between the cluster head and the base station.

[0019] According to an embodiment of the present invention, the method further comprises of sub-clustering a plurality of MTC devices within a cluster based on a first set of parameters. The first set of parameters comprises of a congestion level and Signal-to-Noise Ratio (SINR) associated with the plurality of MTC devices.

[0020] According to an embodiment of the present invention, the congestion level based sub-cluster formation is performed based on a load index, wherein the load index is an average of a resource utilization at the base station.

[0021] According to an embodiment of the present invention, the method further comprises of calculating the load index of a selected base station and redirecting one or more MTC devices from a first base station to a second base station if the load index of the second base station is greater than a previous load index and less than a maximum load index, wherein the maximum load index is associated with a maximum availability of network resources.

[0022] According to an embodiment of the present invention, the method further comprises of redirecting one or more MTC devices from the first base station to the second base station having a load index between the maximum load index and a minimum load index, if the load index of the first base station is less than the previous load index and is equal to or less than the minimum load index. The minimum load index is associated with the minimum availability of network resources.

[0023] According to an embodiment of the present invention, the method further comprises of redirecting one or more MTC devices from the first base station to the second base station if the load index of the first base station is greater than the maximum load index and shutting down the primary base station.

[0024] According to an embodiment of the present invention, the SINR based sub-cluster formation comprises of measuring the SINR by each MTC device with respect to each base station, reporting the SINR value to a serving base station, sharing the SINR report with a plurality of neighboring base stations by the serving base station, sorting, by each base station, the reported SINR for the one or more MTC devices with respect to each base station and creating a sub cluster based on the common SINR sequence for the one or more MTC devices with respect to each base station.

[0025] According to an embodiment of the present invention, the cluster head have the highest SINR with serving cell and have decreasing order of SINR for the neighboring base stations or cooperative base stations which are jointly serving cluster head.

[0026] The embodiments herein further disclose a method for providing data communication for machine type communication (MTC) devices for multiple base-stations in a wireless communication. The method comprising steps of informing, by a cluster head, to one or more MTC devices in a cluster a primary base station to which each MTC device is assigned, updating an activation status of the one or more MTC devices to the cluster head by each of the MTC device, requesting for a network resource from a particular base station whenever a transmission is ready for a sub-cluster MTC device, requesting for a secondary base station, by the primary base station, if there is a disruption in communication due to unavailability of network resources, shifting the one or more MTC devices from a sub cluster corresponding to the primary base station to a sub cluster corresponding to the secondary base station, wherein the shifting occurs when half of a delay tolerance associated with the one or more MTC devices is over and the MTC device does not get the network resources associated with the base station and informing by the cluster head of the secondary base station on which one or more MTC devices corresponding to the sub cluster can shift.

[0027] The various embodiments herein further describe a method for providing data communication for machine type communication (MTC) devices with multiple base-stations in a wireless communication. The method comprising steps of informing, by a sub-cluster head, to one or more MTC devices in a cluster a primary base station to which each MTC device is assigned, updating an activation status of the MTC device to the sub-cluster head by each of the MTC device, requesting for a network resource from a particular base station whenever a transmission is ready for a sub-cluster MTC device, requesting for a secondary base station, by the primary base station, if there is a disruption in communication due to unavailability of network resources, providing information of the secondary base station from which the sub cluster head can initiate MTC communication, searching for the sub cluster head which is linked to the secondary base station in the grouping information, shifting the one or more MTC devices from a sub cluster corresponding to the primary base station to a sub cluster corresponding to the secondary base station, informing by the sub cluster head of the secondary base station on which one or more MTC devices corresponding to the sub cluster can shift and initiating data traffic transfer from the one or more MTC devices to the secondary base station through the connection established between the sub cluster head and the secondary base station.

[0028] According to an embodiment of the present invention, the sub cluster head request for the secondary base station when half of a delay tolerance associated with the one or more MTC devices is over and the MTC device does not get the network resources associated with the base station.

[0029] According to an embodiment of the present invention, the method further comprises of providing the information of the one or more MTC devices that require network resources to the sub-cluster corresponding to the secondary base station, storing the one or more MTC devices that require network resources as sub cluster members and requesting for network resources from the secondary base station by the sub cluster head.

[0030] According to an embodiment of the present invention, each sub cluster head serving one or more related MTC devices is connected to a serving base station through a dedication connection.

[0031] According to an embodiment of the present invention, the method further comprises of providing grouping information of secondary MTC devices to the plurality of MTC devices in the cluster. The grouping information informs the MTC device which base station is associated to which MTC device and enabling the MTC devices of one sub cluster to join another sub cluster through one or more MTC devices using a device to device communication.

[0032] According to an embodiment of the present invention, the MTC devices of one sub cluster joins another sub cluster through the device to device communication during at least one of an expiry of the delay tolerance of the MTC device and the MTC device is in a sub cluster does not get resources from the associated base station and if the sub cluster head connected to macro base station cannot serve the MTC device in the sub cluster.

[0033] Embodiments herein further describe a method for providing data communication for machine type communication (MTC) devices in a group-based wireless communication. The method comprising steps of selecting, at least one cluster head for a plurality of clusters, wherein each of the plurality of clusters comprises of one or more MTC devices which are members of a cluster associated with the cluster head, receiving, by the cluster head, a message from the one or more MTC devices for data traffic transfer when the one or more MTC devices are activated, wherein the message comprises at least one of an activation status, a buffer occupancy status and a delay tolerance of the one or more MTC devices, determining availability of a network resources for transferring the data traffic based on the buffer occupancy status of the one or more MTC devices, establishing a dedicated connection with a base station for transferring the data traffic and transferring the data traffic from the one or more MTC devices to the base station through the connection established between the cluster head and the base station.

[0034] Embodiments herein further provide a system for providing data communication for machine type communication (MTC) devices in a group-based wireless communication. The system comprising at least one network element adapted for selecting, at least one cluster head for a plurality of clusters, wherein each of the plurality of clusters comprises of one or more MTC devices which are members of a cluster associated with the cluster head, receiving a message from the one or more MTC devices for data traffic transfer when the one or more MTC devices are activated, wherein the message comprises at least one of an activation status, a buffer occupancy status and a delay tolerance of the one or more MTC devices, determining availability of a network resources for transferring the data traffic based on the buffer occupancy status of the one or more MTC devices, establishing a dedicated connection with a base station for transferring the data traffic and transferring the data traffic from the one or more MTC devices to the base station through the connection established between the cluster head and the base station. The delay tolerance is defined as a total tolerable time of communication without impacting a quality of service for the MTC member device.

[0035] According to an embodiment of the present invention, the system further comprises at least one element adapted for performing sub-clustering of the plurality of MTC devices within a cluster based on a first set of parameters. The first set of parameters comprises of a congestion level and Signal-to-noise ratio (SINR) associated with the plurality of MTC devices.

[0036] The foregoing has outlined, in general, the various aspects of the invention and is to serve as an aid to better understanding the more complete detailed description which is to follow. In reference to such, there is to be a clear understanding that the present invention is not limited to the method or application of use described and illustrated herein. It is intended that any other advantages and objects of the present invention that become apparent or obvious from the detailed description or illustrations contained herein are within the scope of the present invention.

Brief Description of Drawings



[0037] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

Figure 1 is a high-level architecture of an LTE system, illustrating a working environment according to an embodiment of the present invention.

Figure 2 is a scenario diagram illustrating the RAN overload problem due to requests from the MTC devices, according to a prior art illustration.

Figure 3 is a scenario diagram illustrating a method of communicating data to MTC devices through a dedicated connection with the cluster head, according to an embodiment of the present invention.

Figure 4 is a schematic diagram illustrating a RAN overload problem solved by a dedicated connection between the MTC device and the cluster head, according to an embodiment of the present invention.

Figure 5 is a schematic representation of a timing diagram for single base station based MTC communication, according to an embodiment of the present invention.

Figure 6 is a scenario diagram illustrating data transmission for single base station based MTC communication, according to an embodiment of the present invention.

Figure 7 is a flow diagram illustrating a messaging sequence for MTC dedicated connection based communication, according to an embodiment of the present invention.

Figure 8 is a schematic representation of a timing diagram for MTC dedicated connection based communication, according to an embodiment of the present invention.

Figure 9 is a scenario diagram illustrating data transmission for multiple base stations dedicated connection based communication for MTC devices, according to an embodiment of the present invention.

Figure 10 is a schematic diagram illustrating a load index and SINR based sub cluster information, according to an embodiment of the present invention.

Figure 11 is a scenario diagram illustrating data transmission through a cluster head dedicated connection based communication for MTC devices for multiple base stations, according to an embodiment of the present invention.

Figure 12 is a schematic representation of a timing diagram for multiple base station cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention.

Figure 13 is a flow diagram illustrating a messaging sequence for cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention.

Figure 14 is a scenario diagram illustrating data transmission through a sub cluster head dedicated connection based communication for MTC devices for multiple base stations, according to an embodiment of the present invention.

Figure 15 is a flow diagram illustrating a messaging sequence for sub cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention.

Figure 16 is a schematic representation of a timing diagram for multiple base station sub cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention.



[0038] Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

Mode for the Invention



[0039] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments. The present invention can be modified in various forms. Thus, the embodiments of the present invention are only provided to explain more clearly the present invention to the ordinarily skilled in the art of the present invention. In the accompanying drawings, like reference numerals are used to indicate like components.

[0040] The specification may refer to "an", "one" or "some" embodiment(s) in several locations. This does not necessarily imply that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

[0041] As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms "includes", "comprises", "including" and/or "comprising" when used in this specification, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Furthermore, "connected" or "coupled" as used herein may include operatively connected or coupled. As used herein, the term "and/or" includes any and all combinations and arrangements of one or more of the associated listed items.

[0042] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0043] Figure 1 is a high-level architecture of an LTE system, illustrating a working environment according to an embodiment of the present invention. The MTC Gateway is a type of MTC device with 3GPP mobile communication capability. The MTC Gateway connects to the MTC Capillary network which contains local access devices using short range technologies for communication. The MTC Gateway device acts as a middle agent between the local access devices and the MTC Server. The MTC Server operates within the 3GPP network.

[0044] Figure 2 is a scenario diagram illustrating the RAN overload problem due to requests from the MTC devices, according to a prior art illustration. The plurality of MTC devices are generally deployed in massive numbers. Consequently the RACH burst from MTC devices overloads the RACH access at the eNodeB. This in turn deprives cellular users from normal service due to over loading of RACH by higher density of M2M devices.

[0045] Figure 3 is a scenario diagram illustrating a method of communicating data to MTC devices through a dedicated connection with the cluster head, according to an embodiment of the present invention. The user equipment establishes a dedicated connection from a cluster head to the eNodeB based on a pattern of the data traffic received from the MTC devices. Similarly, the UE releases the dedicated connection based on the traffic pattern of the MTC devices. The traffic pattern should provide a duration of a dedicated RRC connection since most of the traffic is expected to be intermittent in nature. In order to release the dedicated connection, the cluster head uses the RRC connection release timer.

[0046] The dedicated connection established between the cluster head and the eNodeB as shown in Figure. 3, provides continuous flow of traffic from cluster head to eNodeB, thereby minimizing the RACH access for RRC Connection, brings more adaptive power control between MTC device and eNodeB for MTC traffic and reduces the latency to access the eNodeB.

[0047] Figure 4 is a schematic diagram illustrating a RAN overload problem solved by a dedicated connection between the MTC device and the cluster head, according to an embodiment of the present invention. At a time instance T1, a dedicated connection is assumed to be established between the cluster head and the base station and the MTC devices D1 and D2 will be active for MTC transmission/reception. Here the data from D2 and D1 devices will be either carried /received through the cluster head. The embodiments herein avoid the opportunistic RACH transmission to the base station, thereby preventing the overload at RAN. The dedicated connection between the cluster head and base station to carry data from the MTC devices which are associated with the cluster head to come under the vicinity of the cluster head.

[0048] Figure 5 is a schematic representation of a timing diagram for single base station based MTC communication, according to an embodiment of the present invention. The MTC devices herein correspond to cluster members of a cluster wherein the cluster members update the cluster head of their activation status, buffer occupancy and delay tolerance once the cluster members are activated. The cluster head prepares a priority list of the active MTC devices based on their delay tolerances left. For instance, let TBS be the time required for establishing a dedicated connection between the cluster head and the base station. The delay tolerance left of the higher priority device is then with the TBS. The cluster head triggers a connection request with the base station, when the delay tolerance left for the higher priority device is equal to the TBS. The cluster head then asks for the network resources with a buffer occupancy BOTotal. Here, buffer occupancy is defined as Math Figure 1:
MathFigure 1


where i= 1 to N and N is the maximum number of active cluster members.

[0049] At instant t1, the cluster head triggers connection request to base station as the delay tolerance left for device 2 (the highest priority device at that instant) becomes equal to TBS. At instant t2, the cluster head sends a buffer occupancy report to eNb, which is summation of all buffer occupancy of the plurality of MTC devices at the eNb. For example, if buffer occupancy for device Di is BOi, then



[0050] At instant t2, the data transfer occurs through a dedicated connection formed between the channel head and the network.

[0051] Figure 6 is a scenario diagram illustrating data transmission for single base station based MTC communication, according to an embodiment of the present invention.

[0052] Acknowledgement of Packet Delivery (ACK) or Non-Acknowledgement of Packet Delivery (NACK) message from the network 601 is received through the dedicated channel established between the cluster head 701 (ref:Fig.7) and the network (eNb) 601. The cluster head 701 then relays the ACK/NACK message from the network to the respective MTC devices.

[0053] Figure 7 is a flow diagram illustrating a messaging sequence for MTC dedicated connection based communication, according to an embodiment of the present invention. When one or more MTC devices/Cluster members CM-1, CM-2 and CM-3 701a, 701b and 701c respectively send a message to the selected cluster head 701 for data transfer when the one or more MTC devices are activated. The message comprises the activation status, the buffer occupancy status and the delay tolerance left of the one or more MTC devices. The channel head 701 then creates a priority list of active MTC devices based on the delay tolerance. The delay tolerance is defined as a total tolerable time of communication without impacting a quality of service for the MTC member device, The cluster head 701 then compares the delay tolerance of the active MTC devices with a time required for establishing a connection with a base station, triggers a connection request with the base station when the delay tolerance for a high priority MTC device is equal to the pre-set time. The network 601 further determines the availability of network resources for transferring the data traffic based on the buffer occupancy status of the plurality of MTC devices. And cluster head 701 further establishes a dedicated connection with the base station for transferring the data traffic. The cluster head 701 then receives at least one of an ACK or NACK message from the base station through the dedicated connection established between the cluster head 701 and the base station and relay at least one of an ACK or NACK message from the base station to a corresponding MTC device.

[0054] Figure 8 is a schematic representation of a timing diagram for MTC dedicated connection based communication, according to an embodiment of the present invention. The timing diagram illustrates the various activities or actions performed by each of the cluster member or MTC device, cluster head and the network and their time instances.

[0055] Figure 9 is a scenario diagram illustrating data transmission for multiple base stations dedicated connection based communication for MTC devices, according to an embodiment of the present invention. According to an embodiment of the present invention, the following factors are taken into consideration according to the standards for clustering procedure in a multi-station based scenario. Consider, CHi be the cluster head of cluster i, where i=1,2,..n, N be the total number of MTC devices in the system and Ni be the number of devices in cluster i. The Ni devices are connected by short range communication using single hop. The short range technology which dictates the transmission range between devices is assumed to be TR in metres. Out of Ni devices, there are S devices serving safety applications, P devices serving periodic applications, NP devices serving non periodic applications and D devices serving non real time and real time applications. Each CHi maintains four queues one for each application S, P, NP and D. A MTC device can be in any one of state such as a cluster member (CLM) or a cluster head (CH). The MTC device can either be an active device where it has its own application running with service requests to send or receive data or a passive device where there is no current data transmission.

[0056] Consider BSj,BSj+1...BSm be the base stations in the system where j=1,2,...m. CHi be under the coverage range of multiple base stations BSk (where k ∈ {j+1, j+2...m}). The method for selecting a cluster head considers four main parameters mobility of the device, drain rate of the device, Signal to Noise Ratio and Passive Device. A weight factor is chosen for each metric dependent based on system requirements and is combined with the system parameters effectively. The method uses a combined weight metric of the above four parameters to select a cluster head. The MTC device with the highest weight is chosen as a cluster head 701. For determining the SINR parameter, any device which is closer to the BS is assumed to have good SINR values and higher data rates and will be chosen as a candidate for CH. In multi base station scenario, the BSj with which the CHi has higher SINR value is selected as a Master BS. The remaining BSs which cover CHi are considered as Secondary BSs. A ranking table is generated by the CHi with a list of BS sorted in the descending order of SINR values. The first BSj in the list is the Master BS and second BSj+1 is the first secondary and so on. This list will cover the entire BSs with which CHi has coverage. Further a group of Secondary BSs referred to as "candidate Secondary BSs" are determined from the SINR ranking table, Qos requirement of the CHi and resource availability at each secondary BS. For delay non sensitive applications, low SINR is tolerable but for delay sensitive applications SINR is taken at priority. So, in all, cooperation of BS should be based on nature of the application.

[0057] The Master BS together with candidate Secondary BSs forms a virtual cell for the CHi. The CSI (CQI/PMI/RI) of the UE is exchanged between the BSs of the virtual cell to co-ordinate between the BS. Consider Ri is the data rate between CHi and BSj in bits/second. The rate Ri is decided based on the physical channel conditions between CHi and BSj, λ1, λ2... λNi is the mean arrival rate of the data in the devices being served by CHi, assuming the arrival rates are in poisson process and µi is the mean service rate for CHi offered by the BSj.

where the sum of the arrival rate of the packets at CHi queue should be less than or equal to the mean service rate offered by the BSj to CHi. Let RAi be the resources allocated to CHi, δS, δP, δNP and δD, be the delay tolerance for S, P, NP and D applications and E (DELa) be the expected delay for the application a (where a ∈ {S,P,NP,D}). It is defined as sum of the queuing delay at the cluster head, transmission delay and propagation delay.
  1. a. E (DELa) for each application type should satisfy the following constraints:
    1. a.E(DELS) ≤ δS
    2. b.E(DELP) ≤ δP
    3. c.E(DELNP) ≤ δNP
    4. d.E(DELD) ≤ δD
  2. b. Let βS, βP, βNP and βD, be the packet loss ratio tolerance for S, P, NP and D applications.
  3. c. Let EPLR(.) be the expected packet loss ratio of application (.) and is defined as the ratio of number of packets lost to the total number of packets transmitted.
  4. d. EPLR (.) for each application type should satisfy the following constraints
    1. a.EPLR(S) ≤ β S
    2. b.EPLR(P) ≤ β P
    3. c.EPLR(NP) ≤ β NP
    4. d.EPLR(D) ≤ β D


[0058] In this scenario, the mean arrival rate of packets at CHi is greater than the service rate at CHi.

this implies that queues at CHi increase without bounds causing an increase in E (DELa) and EPLR. There will be a dedicated connection to the set of base stations, either from the cluster head or a sub cluster head, which are in the vicinity of the CHi. The cluster device get resources for transmission from the serving or master base station.

[0059] The secondary cluster devices CMk (where k ∈ {1, 2...n}) are grouped into sub-clusters (grouping of sub-clusters) that are then associated to particular BSk (where k ∈ {j+1, j+2...m}) from which it obtain resources for communication, wherein BSk (where k ∈{j+1, j+2...m}) are assumed to be the in descending order of received SINR by the cluster head CHi. The grouping of sub-clusters within a cluster comprises of Congestion Level Based sub cluster formation and SINR Based sub cluster formation.

[0060] Figure 10 is a schematic diagram illustrating a load index and SINR based sub cluster information, according to an embodiment of the present invention. In a network assisted grouping, network (BSj) gives the information of the congestion level of the base stations BSk (where k ∈ {j+1, j+2...m}). Depending on the information provided by the network, the congestion level based grouping is based on the information of Load Index (LI) of BS's BSk (where k ∈ {j+1, j+2...m}). Load index, as per definition provides time average occupancy of the physical resources at each BS. The primary network (BSj) asks for the Load Index from the secondary BS's via the BACK HAUL link and forward to CH(CHi) the Load Index values LIk (where k ∈ {j+1, j+2...m}) corresponding to secondary BS's through the dedicated connection. The Load index (LI, ratio of free to allocated resources) of a particular BS is calculated on taking the time average of 'n' samples of load index samples a certain time interval as Math Figure 2. See Math Figure 2.
MathFigure 2



[0061] If the Load Index {(LI) retrieved} of any network is too less i.e. the network is too congested to provide resources for the MTC devices. If the Load index {(LI) retrieved} is very high i.e. very few devices are using that network. From the power optimization purpose, it is required to power shut down such BS. The MTC devices must not be allocated to the network if the load index is very less or very high. Instead shifting of current devices to other BS helps to shut down the serving BS. A threshold (Th) is to be defined for the Load Index values such that the MTC devices must not be associated to the network, if the Load index values LIk (where k ∈ {j+1, j+2...m}) is greater than the (Th)max Load Index or less than the (Th)min Load Index.

[0062] For allocation of MTC devices to a particular BS, the Load Index value LIk (where k ∈ {j+1, j+2...m}) should be in the range:

[0063] (Th)min Load Index < LIk < (Th)max Load Index(where k ∈{j+1, j+2...m})

[0064] The base station with the lowest congestion level is allocated first to the number of the cluster devices according to the load index of the base station (LIk) and the devices are selected on the basis of SINR values to that BS. The secondary MTC devices within a cluster are supposed to send the SINR values corresponding to all of the secondary BS's to the cluster head. SINR values to that BS of the devices may be as shown in Table 1

[0065] The grouping of secondary MTC devices is performed at the cluster head:

Table 1



[0066] 
[Table 1]
 BS-1BS-2BS-3
Device 1 (SINR)1,1 (SINR)1,2 (SINR)1,3
Device 2 (SINR)2,1 (SINR)2,2 (SINR)2,3
Device 3 (SINR)3,1 (SINR)3,2 (SINR)3,3
Device 4 (SINR)4,1 (SINR)4,2 (SINR)4,3
Device 5 (SINR)5,1 (SINR)5,2 (SINR)5,3


[0067] The grouping of secondary MTC devices is performed at the cluster head:

[0068] The grouping is done such that if there are n MTC devices that are to be grouped in BS's BSk (where k ∈ {j+1, j+2...m}) arranged in an increasing congestion level sequence with info of Load Index.

BSj+1 → (LIj+1) MTC devices

BSj+2 → (LIj+2) MTC devices

BSj+3 → (LIj+3) MTC devices

:

:

BSm → (n-((LIj+1)+(LIj+2)+...+(Lim-1)))



[0069] Where (CL)j+1<(CL)j+2<(CL)j+3<...<(CL)m, (Th)min Load Index < LIk (where k ∈ {j+1, j+2...m}) < (Th)max Load Index.

[0070] Further triggering condition is added. The devices CMk (where k ∈ {1, 2...n}) are first allocated to the BS with lowest Congestion Level (BSj+1) depending on their SINR values to that BS. The number of devices allocated is the Load Index of that BS (LIj+1). In the same way all BS's BSk are allocated to the secondary MTC devices in the way that the base station, BSk with lowest congestion level is allocated first and then moving on to highest. The MTC devices are grouped into sub-clusters SCk (where k ∈ {j+1, j+2...m}) based on the SINR values corresponding to different BSk and the load index information of the BS's. Since the Load index of the BS's keeps on changing, the grouping of devices needs to be updated corresponding to the new load index values of BS's. The time interval (Tnew LI) after which new load index is retrieved and grouping needs to be updated depends on the scheduling mechanism.

CASE 1 - LI new > LI previous



[0071] When the new load index (LInew) of a particular BS (BSj+1) is greater than the number of devices allocated to it (the previous load index) i.e. it can allocate resources to more devices.

(LInew) < (Th)max Load Index



[0072] In this case, (BSj+1) can be allocated to more of the MTC devices, so the MTC devices those are allocated to the BS with high congestion level(BSm,BSm-1) for those Lim, Li m-1 < (Th)min Load Index is allocated to this Base Station (BSj+1).

[0073] The grouping will be such that if there are 'n' MTC devices that are to be grouped in BS's BSk (where k ∈ {j+1, j+2...m}), arranged in an increasing congestion level sequence according to the load index LIk (where k ∈ {j+1, j+2...m}), the BSj+1 can be allocated further to 'x' devices.

(BSj+1) → ((LIj+1) + x) MTC devices

(BSj+2) → (LIj+2) MTC devices

:

:

(BSm-1) → ((Lim-1) - (Lim-1)) MTC devices

(BSm) → ((LIm) - (LIm)) MTC device



[0074] Where (CL)j+1<(CL)j+2<(CL)j+3<...<(CL)m, the 'x' devices may be devices that are allocated to BSm-1 and BSm.

[0075] The BSm-1 and BSm is removed from the cloud cell with respect to this cluster, as devices allocated to these BS's earlier are now allocated to BSj+1.

CASE 2 - LI new < LI previous and LI new < (Th) min Load Index



[0076] When the load index retrieved (LInew) from a particular BS (BSj+1) is less than the previous Load Index (LI previous) i.e. it cannot allocate resources efficiently to all the MTC devices allocated to this BS (BSj+1) earlier. In this case, as the number of MTC devices allocated to BS (BSj+1) is much higher than the resources it can allocate to MTC devices, so the extra MTC devices that can create congestion on this BS is shifted to next BS, provided that the next BS should have Load index higher than the resources allocated to it.

[0077] If the BS next to the BSj+1 also have a load index lower than the required, then devices from BSj+1 and BSj+2 will be shifted to BSj+3.

[0078] The grouping is such that if there are 'n' MTC devices that are to be grouped in BS's BSk (where k ∈ {j+1, j+2...m}) arranged in an increasing congestion level sequence according to the load index, the BSj+1 cannot allocate 'x' devices among the devices allocated to it earlier.

(BSj+1) → ((LIj+1) -x) MTC devices

(BSj+2) → ((LIj+2) +x) MTC devices

:

:

(BSm) → (LIm) MTC devices



[0079] Where (CL)j+1<(CL)j+2<(CL)j+3<...<(CL)m, (LI)New →(LIj+1) - x and the BSj+1 may allocate the 'x' devices to the BSj+2.

CASE 3- LI new > (TH)max load Index



[0080] When the load index retrieved (LInew) from a particular BS (BSj+1) is higher than the maximum bound of Load Index i.e. it contains very few number of devices. In this case, where the (BSj+1) has a Load Index higher than the upper bound of Load Index, the MTC devices associated with this BS will be shifted to next BS for power optimization (as proposed by 3GPP), provided that the next BS should have Load index higher than the previous value. In such case (BSj+1) can be power shut down in order to optimize the BS power. If the BS next to the BSj+1 also has a load index higher than the threshold, then devices from BSj+1 and BSj+2 will be shifted to BSj+3. The grouping will be such that if there are 'n' MTC devices that are to be grouped in BS's BSk (where k ∈ {j+1, j+2...m}) arranged in an increasing congestion level sequence according to the load index, the MTC devices associated to BSj+1 will be shifted to BSj+2 for power optimization.

(BSj+1) → ((LIj+1) - (LIj+1)) MTC devices

(BSj+2) → ((LIj+2) + (LIj+1)) MTC devices

:

:

(BSm) → (LIm) MTC devices

Where (CL)j+1<(CL)j+2<(CL)j+3<...<(CL)m

(LI)New > (TH)max load Index

SINR Based sub cluster formation



[0081] When there is no information of the Load Index values of BS's from the network, then the sub clusters SCk (where k ∈ {j+1, j+2...m}) are formed on the basis of the SINR values corresponding to BS's BSk (where k ∈ {j+1, j+2...m}). The CHi will retrieve the SINR values from each of the secondary MTC devices CMk (where k ∈ {1, 2...n}) corresponding to the BS's BSk (where k ∈ {j+1, j+2...m}) and then divides the MTC devices into sub clusters accordingly. The MTC devices of sub-clusters formed (sub-cluster allocated to them and sub-Cluster Head sCHk (where k ∈ {j+1, j+2...m}) is also assigned for each sub-cluster SCk (where k ∈ {j+1, j+2...m}) which will do the contention resolution in its sub-cluster. The conditions for a cluster device to become a sub cluster head will be same as the one described earlier in cluster formation model in case of single BS.

[0082] The s-CH sCHk (where k ∈ {j+1, j+2...m}) asks for resources from the BS {BSk where k ∈ (j+1, j+2...m)} for the active devices in its sub-cluster via dedicated connection to associated BS.

Table 2



[0083] 
[Table 2]
 BS-1BS-2BS-3
Device 1 (SINR)1,1 (SINR)1,2 (SINR)1,3
Device 2 (SINR)2,1 (SINR)2,2 (SINR)2,3
Device 3 (SINR)3,1 (SINR)3,2 (SINR)3,3
Device 4 (SINR)4,1 (SINR)4,2 (SINR)4,3
Device 5 (SINR)5,1 (SINR)5,2 (SINR)5,3
Device 6 (SINR)6,1 (SINR)6,2 (SINR)6,3


[0084] The grouping on the basis of SINR values to secondary BS's can be shown by the following example. Assume there are '6' secondary MTC devices in a cluster and '3' secondary BS's and the SINR values as shown earlier- SINR values to that BS of the devices may be as shown in Table 2.

(BS1) → t(SINR)1,1; (SINR)2,1; (SINR)3,1; (SINR)6,1; (SINR)4,1; (SINR)5,1}

(BS2) → {(SINR)2,2; (SINR)5,2; (SINR)6,2; (SINR)1,2; (SINR)3,2; (SINR)4,2}

(BS3) → {(SINR)4,3; (SINR)3,3; (SINR)2,3; (SINR)1,3; (SINR)5,3; (SINR)6,3}



[0085] The examples are SNR values in the decreasing order corresponding to each BS.

Device 1 → t(SINR)1,1; (SINR)1,2; (SINR)1,3}

Device 2 → {(SINR)2,2; (SINR)2,1; (SINR)2,3}

Device 3 → {(SINR)3,3; (SINR)3,1; (SINR)3,2}

Device 4 → {(SINR)4,3; (SINR)4,1; (SINR)4,2}

Device 5 → {(SINR)5,2; (SINR)5,3; (SINR)5,1}

Device 6 → {(SINR)6,2; (SINR)6,1; (SINR)6,3}



[0086] The examples are SNR values of devices to BS's in the decreasing order. According to one embodiment, the grouping with the 'AND' of these two set of sequences may be performed.

[0087] The groups are formed on the basis of the sequences of SINR values corresponding to the BS's and devices:

(BS)1 → {device1}

(BS)2 → {device2, device 5 , device 6 }

(BS)3 → {device 4, device 3}



[0088] The devices 1, 2 and 4 are the sCH' s of the sub clusters formed corresponding to the base station 1,2 and 3 respectively as they have highest SINR value corresponding to that BS. After grouping by any of the method, the grouping info message is to be sent to all MTC devices from Cluster head (CHi).

[0089] The grouping info message: (secondary BS's {BSk where k ∈ (j+1, j+2...m)})

[0090] Device association to BS; Sub cluster head

{CM2,CM3,...,CMm} → BSj+1; sCHj+1 → CM2

{CM1,CM5,...,CMp} → BSj+2; sCHj+2 → CM1

:

:

{CMi,CM21,...,CMz} → BSm; sCHm → CMi


Hybrid Grouping:



[0091] Hybrid grouping based on the joint optimization of SINR and load balancing is not in the scope of this document and left for the future work. Once grouping is done, there are two ways in which a dedicated channel can be formed from the sub-cluster to the respective BS such as CH based dedicated connection and Sub cluster head (sCH) based dedicated connection.

[0092] Figure 11 is a scenario diagram illustrating data transmission through a cluster head dedicated connection based communication for MTC devices for multiple base stations, according to an embodiment of the present invention. In a CH based connection, there will be a dedicated connection from the CHi to the plurality of base stations {BSk where k ∈ (j+1, j+2...m)} and all the communication from the sub-clusters to their respective BS is performed through the cluster head. Each of the MTC devices in a cluster will update the CHi with its information i.e. its activation. The contention resolution of each sub cluster will be handled at the CHi i.e. the CH will accordingly request for resources from a particular base station whenever a transmission is ready for any sub-cluster device. There will be the chances of congestion at a respective base station and sub-cluster devices don't get resources for communication and thus disruption in the MTC occurs. Each BS will have a secondary base station ('n' secondary BS's) to whom it can handover the devices whenever there is a chance of disruption in M2M communication. The shifting of devices (CM1) from the sub cluster corresponding to the serving BS (BS-2) to the sub cluster corresponding to the secondary BS (BS-3). The shifting takes place when half of the delay tolerance interval is passed and the device (CM1) does not get the resources associated base station BS (BS-2). The secondary BS's (BS-2) then informs the cluster head of the secondary BS (BS-3) on which devices (CM-1) corresponding to its sub-cluster can shift.

[0093] Figure 12 is a schematic representation of a timing diagram for multiple base station cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention. Each of the MTC devices in a cluster will update the cluster head with its activation status. The cluster head will accordingly request for resources from a particular base station whenever a transmission is ready for any sub-cluster device. There will be the chances of congestion at a respective base station and sub-cluster devices don't get resources for communication and thus disruption in the MTC occurs. The cluster head will then handover the MTC devices from a first base station to a second base station when it does not get network resources in the first half of the delay tolerance. Further, the second base station requests for resources from its network keeping the MTC devices in high priority.

[0094] Figure 13 is a flow diagram illustrating a messaging sequence for cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention. The cluster head 701 informs the plurality of MTC devices in a cluster of a primary base station 1301a to which each MTC device is assigned. When the MTC device becomes active, the MTC device updates the activation status to the respective cluster head 701. The cluster head 701 then requests for network resources from a particular base station whenever a transmission is ready for a sub-cluster MTC device. The cluster head 701 then requests the primary base station (BS-2) 1301a to provide a secondary base station (BS-3) 1301b if there is a disruption in the communication due to unavailability of network resources. The primary base station 1301a informs the cluster head 701 of the secondary base station 1301b from which it can perform MTC communication. The cluster head 701 then shifts the one or more MTC devices from a sub cluster corresponding to the primary base station (BS-2) 1301a to a sub cluster corresponding to the secondary base station (BS-3) 1301b as suggested by the network. The shifting occurs when half of a delay tolerance associated with the one or more MTC devices is over and the MTC device does not get the network resources associated with the base station. The cluster head 701nthen enquires the secondary base station (BS-3) 1301b for network resources and initiate the data communication for the MTC devices.

[0095] Figure 14 is a scenario diagram illustrating data transmission through a sub cluster head dedicated connection based communication for MTC devices for multiple base stations, according to an embodiment of the present invention. In a sub cluster head (sCH) based dedicated connection, there is a dedicated connection from the sub-cluster head sCHk {where k ∈ (j+1, j+2...m)} of a particular sub-cluster SCk {where k ∈ (j+1, j+2...m)} to the associated base station. The contention in each sub-cluster is handled at the sCH of that sub-cluster as the dedicated connection is from the sCH to the BS. The sCH starts the connection request to the associated BS for resources, as soon as any UE within its sub-cluster becomes active.

[0096] The CHi after grouping of sub-clusters forwards the information message (grouping information of secondary MTC devices) to all of the MTC devices so that each MTC device knows which BS is associated to which device. Each of the sCH knows information about the sCH's corresponding to different BS's. The handover message from a particular sCH (sCH1) to other sCH (sCH2) includes the information of the MTC devices that is to be handover. The grouping information that is sent to each of the MTC devices from the CHi contains the information as provided below.

[0097] Device association to BS; Sub cluster head

{CM2,CM3,...,CMm} → BSj+1; sCHj+1 → CM2

{CM1,CM5,...,CMp} → BSj+2; sCHj+2 →CM1



[0098] In the sCH based connection, the delay tolerance is updated to half of its original value for communication from a primary BS allocated to it. If the delay tolerance is passed and still the MTEC device does not get any resources from the associated BS (in case of congestion at the associated BS), then it will be hand over to the secondary BS for resources. The secondary BS corresponding to each BS will be then selected for handover of devices. The sCH (sCH1) will send the information to the sCH (sCH2) corresponding to the secondary base station (BS3), about the devices (sCM1) that require resources for communication. The sCH (sCH2) handover the MTC devices (sCM1) as its sub cluster members and start the request for resources from its base station.

[0099] Figure 15 is a flow diagram illustrating a messaging sequence for sub cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention. The cluster head 701 informs the plurality of TC devices in a cluster of the grouping information that which base station is allocated to which MTC device. The MTC device on activation informs the activation status to the sub-cluster head. The sub cluster head requests for a network resource from a particular base station whenever a transmission is ready for a sub-cluster MTC device 1303. The sub cluster head requests for a secondary base station (BS-3) 1301b if half of the delay tolerance is passed and no resource is found for MTC. The primary base station 1301a then provides information of the secondary base station 1301b from which the sub cluster head sCH2 1501can initiate MTC. The sub cluster head sCH2 1501then searches in the grouping information for the sub cluster head which is linked to the secondary base station 1301b. The sub cluster then performs handover of the MTC devices from a sub cluster corresponding to the primary base station 1301a to a sub cluster 1501b corresponding to the secondary base station 1301b as suggested by the network 601. The sub cluster head 1501 of the secondary base station 1301b informs on which sub cluster the one or more MTC devices can shift. The sub cluster head 1501b then initiates data traffic transfer from the one or more MTC devices to the secondary base station 1301b through the connection established between the sub cluster head 1501b and the secondary base station 1301b.

[0100] According to an embodiment of the present invention, the sub cluster head 1501b request for the secondary base station 1301b when half of a delay tolerance associated with the one or more MTC devices is over and the MTC device does not get the network resources associated with the base station. Each sub cluster head serving one or more related MTC devices is connected to a serving base station through a dedication connection.

[0101] According to an embodiment herein, the MTC devices of one sub cluster joins another sub cluster through the device to device communication during at least one of expiry of the delay tolerance of the MTC device and the MTC device is in a sub cluster does not get resources from the associated base station and if the sub cluster head connected to macro base station cannot serve the MTC device in the sub cluster.

[0102] Figure 16 is a schematic representation of a timing diagram for multiple base station sub cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention. As shown in Figure 16, at t1, the sub cluster head sends grouping information to each of the cluster head sends grouping information to each of the sub-cluster head. At t2, the MTC devices of subcluster-2 are active for communication. At t5, half of the delay tolerance is passed and no resources are allocated from the network. At t6, the primary base station asks for secondary base station. At t8, the network informs the sub cluster head-2 of its secondary network so that the sub cluster head-2 can shift its sub-cluster devices to sub-cluster-3. Further at t8, the sub cluster head-2 searches for grouping information for sub cluster head corresponding to that base station. At t9, sub cluster head -2 handover its sub cluster devices to sub cluster head -3 as suggested by the network. At t11, the handover devices get network resources from secondary base station.

[0103] According to an embodiment herein, the clustering based mechanism provides for the cluster head to establish a dedicated connection with eNB and other MTC device only communicate to cluster head and not to the base station. Further a semi-persistence scheduling grant is allocated to a cluster head and the cluster head receives downlink data on behalf of all the MTC devices. MTC cluster head then shares the MTC downlink data to each MTC device.

[0104] The present embodiments have been described with reference to specific example embodiments; it will be evident that various modifications and changes may be made to these embodiments without departing from the scope of the claims.


Claims

1. A method for providing data communication for machine type communication, MTC, devices in a group-based wireless communication, the method comprising steps of:

receiving, by a cluster head (701), a message for data traffic transfer from one or more MTC devices when the one or more MTC devices are activated, wherein the message comprises at least one of an activation status, a buffer occupancy status or a delay tolerance of the one or more MTC devices;

determining, by the cluster head (701), availability of one or more network resources for transferring the data traffic based on the at least one of the activation status, the buffer occupancy status or the delay tolerance of the one or more MTC devices;

establishing, by the cluster head (701), a dedicated connection with a base station for transferring the data traffic from the one or more MTC devices to the base station based on the availability of the one or more network resources; and

transferring, by the cluster head (701), the data traffic from the one or more MTC devices to the base station through the dedicated connection established between the cluster head and the base station,

wherein the cluster head (701) is selected from among the one or more MTC devices which are members of a cluster associated with the cluster head.


 
2. The method of claim 1, wherein the determining availability of network resources for transferring data traffic comprises:

creating a priority list of active MTC devices based on the delay tolerance;

comparing the delay tolerance of the active MTC devices with a time required for establishing a connection with a base station; and

triggering a connection request with the base station when the delay tolerance for a high priority MTC device is equal to a pre-set time;

wherein the delay tolerance is a total tolerable time of communication without impacting a quality of service for the MTC device.


 
3. The method of claim 1, further comprising:

sending, by the cluster head (701), at least one of an ACK or a NACK message from the base station through the dedicated connection established between the cluster head and the base station; and

relaying at least one of an ACK or NACK message from the base station to a corresponding MTC device.


 
4. The method as claimed in claim 1, wherein the cluster head (701) establishes and releases the dedicated connection with the base station based on an incoming traffic from the one or more MTC devices.
 
5. The method as claimed in claim 2, wherein the preset time is the time interval required for the establishment of dedicated connection between the cluster head (701) and the base station.
 
6. The method as claimed in claim 1, further comprising performing sub-clustering of the plurality of MTC devices within a cluster based on a first set of parameters, wherein the first set of parameters comprises a congestion level and Signal-to-noise ratio, SINR, associated with the plurality of MTC devices.
 
7. The method as claimed in claim 6, wherein the congestion level based sub cluster formation is performed based on a load index, wherein the load index is an average of a resource utilization at the base station.
 
8. The method as claimed in claim 7, further comprising:

calculating the load index of a selected base station ; and

redirecting one or more MTC devices from a first base station to a second base station if the load index of the second base station is greater than a previous load index and less than a maximum load index, wherein the maximum load index is associated with a maximum availability of network resources.


 
9. The method as claimed in claim 7, further comprising redirecting one or more MTC devices from the first base station to the second base station having a load index between the maximum load index and a minimum load index, if the load index of the first base station is less than the previous load index and is equal to or less than the minimum load index, wherein the minimum load index is associated with the minimum availability of network resources.
 
10. The method as claimed in claim 7, further comprising:

redirecting one or more MTC devices from the first base station to the second base station if the load index of the first base station is greater than the maximum load index; and

shutting down the first base station.


 
11. The method as claimed in claim 6, wherein the SINR based sub-cluster formation comprises of:

measuring the SINR by each MTC device with respect to each base station;

reporting the SINR value to a serving base station;

sharing the SINR report with a plurality of neighboring base stations by the serving base station;

sorting, by each base station, the reported SINR for the one or more MTC devices with respect to each base station; and

creating a sub cluster based on the common SINR sequence for the one or more MTC devices with respect to each base station.


 
12. The method as claimed in claim 6, wherein the cluster head have the highest SINR with serving cell and have decreasing order of SINR for the neighboring base stations or cooperative base stations which are jointly serving cluster head .
 
13. A cluster head for providing data communication for machine type communication, MTC, devices in a group-based wireless communication, the cluster head comprising at least one element adapted for :

receiving a message from one or more MTC devices for data traffic transfer when the one or more MTC devices are activated, wherein the message comprises at least one of an activation status, a buffer occupancy status or a delay tolerance of the one or more MTC devices;

determining availability of one or more network resources for transferring the data traffic based on the at least one of the activation status, the buffer occupancy status or the delay tolerance of the one or more MTC devices;

establishing a dedicated connection with a base station for transferring the data traffic from the one or more MTC devices to the base station based on the availability of the one or more network resources; and

transferring the data traffic from the one or more MTC devices to the base station through the dedicated connection established between the cluster head and the base station,

wherein the cluster head is selected from among the one or more MTC devices which are members of a cluster associated with the cluster head.


 
14. The cluster head as claimed in claim 13, wherein the at least one element adapted for:

sending at least one of an ACK or a NACK message from the base station through the dedicated connection established between the cluster head and the base station and

relaying at least one of an ACK or NACK message from the base station to a corresponding MTC device.


 


Ansprüche

1. Verfahren zum Bereitstellen von Datenkommunikation für Maschinenkommunikations(MTC)-Vorrichtungen in gruppenbasierter drahtloser Kommunikation, wobei das Verfahren folgende Phasen umfasst:

Empfang, durch einen Clusterhead (701), einer Nachricht zur Datenverkehrsübertragung von einer oder mehreren MTC-Vorrichtungen, wenn die eine oder die mehreren MTC-Vorrichtungen aktiviert werden, wobei die Nachricht mindestens einen der Folgenden umfasst: einen Aktivierungsstatus, einen Pufferfüllstandstatus oder eine Verzögerungstoleranz der einen oder mehreren MTC-Vorrichtungen;

Bestimmen, durch den Clusterhead (701), der Verfügbarkeit eines oder mehrerer Netzbetriebsmittel zum Transport des Datenverkehrs, basierend auf mindestens einem der Folgenden: dem Aktivierungsstatus, dem Pufferfüllstandsstatus oder der Verzögerungstoleranz der einen oder mehreren MTC-Vorrichtungen;

Erstellung, durch den Clusterhead (701), einer speziellen Verbindung mit einer Basisstation zum Transport des Datenverkehrs von der einen oder den mehreren MTC-Vorrichtungen an die Basisstation, basierend auf der Verfügbarkeit des einen oder der mehreren Netzbetriebsmittel; und

Übertragung, durch den Clusterhead (701), des Datenverkehrs von der einen oder den mehreren MTC-Vorrichtungen an die Basisstation durch die spezielle Verbindung, die zwischen dem Clusterhead und der Basisstation aufgebaut wird, wobei der Clusterhead (701) aus der einen oder den mehreren MTC-Vorrichtungen ausgewählt wird, die Mitglieder eines Clusters sind, das mit dem Clusterhead verbunden ist.


 
2. Verfahren nach Anspruch 1, wobei das Bestimmen der Verfügbarkeit von Netzbetriebsmitteln zum Transport des Datenverkehrs Folgendes umfasst:

Erstellen einer Prioritätenliste von aktiven MTC-Vorrichtungen, basierend auf der Verzögerungstoleranz;

Vergleich der Verzögerungstoleranz der aktiven MTC-Vorrichtungen mit einer Zeit zum Aufbau einer Verbindung mit einer Basisstation; und

Auslösen einer Verbindungsanfrage mit der Basisstation, wenn die Verzögerungstoleranz für eine MTC-Vorrichtung hoher Priorität gleich einer voreingestellten Zeit ist;

wobei die Verzögerungstoleranz eine gesamte tolerierbare Kommunikationszeit ist, ohne eine Servicequalität für die MTC-Vorrichtung zu beeinträchtigen.


 
3. Verfahren nach Anspruch 1, ferner umfassend:

Senden, durch den Clusterhead (701), einer ACK- und/oder einer NACK-Nachricht von der Basisstation durch die spezielle Verbindung, die zwischen dem Clusterhead und der Basisstation aufgebaut wurde, und

Weiterleitung einer ACK- und/oder einer NACK-Nachricht von der Basisstation zu einer entsprechenden MTC-Vorrichtung.


 
4. Verfahren nach Anspruch 1, wobei der Clusterhead (701) die spezielle Verbindung mit der Basisstation aufbaut und freigibt, basierend auf eingehendem Verkehr von der einen oder den mehreren MTC-Vorrichtungen her.
 
5. Verfahren nach Anspruch 2, wobei die voreingestellte Zeit das Zeitintervall ist, das für den Aufbau der speziellen Verbindung zwischen dem Clusterhead (701) und der Basisstation erforderlich ist.
 
6. Verfahren nach Anspruch 1, ferner umfassend die Ausführung von Subclustern der Vielzahl von MTC-Vorrichtungen innerhalb eines Clusters, basierend auf einem ersten Satz von Parametern, wobei der erste Satz von Parametern Verkehrsaufkommen und Signal-Rausch-Verhältnis, SINR, umfasst, verbunden mit der Vielzahl von MTC-Vorrichtungen.
 
7. Verfahren nach Anspruch 6, wobei die auf dem Verkehrsaufkommen basierende Subclusterbildung auf Basis eines Lastindex durchgeführt wird, wobei der Lastindex ein Durchschnitt einer Ressourcennutzung an der Basisstation ist.
 
8. Verfahren nach Anspruch 7, ferner umfassend:

Berechnen des Lastindexes einer ausgewählten Basisstation; und

Umleiten einer oder mehrerer MTC-Vorrichtungen von einer ersten Basisstation zu einer zweiten Basisstation, wenn der Lastindex der zweiten Basisstation größer als ein vorheriger Lastindex und geringer als ein maximaler Lastindex ist, wobei der maximale Lastindex mit einer maximalen Verfügbarkeit von Netzbetriebsmitteln verbunden ist.


 
9. Verfahren nach Anspruch 7, ferner umfassend die Umleitung einer oder mehrerer MTC-Vorrichtungen von der ersten Basisstation zu der zweiten Basisstation mit einem Lastindex zwischen dem maximalen Lastindex und einem Mindestlastindex, wenn der Lastindex der ersten Basisstation geringer als der vorherige Lastindex und gleich oder geringer als der Mindestlastindex ist, wobei der Mindestlastindex mit der minimalen Verfügbarkeit von Netz-Betriebsmitteln verbunden ist.
 
10. Verfahren nach Anspruch 7, ferner umfassend:

Umleiten einer oder mehrerer MTC-Vorrichtungen von der ersten Basisstation zu der zweiten Basisstation, wenn der Lastindex der ersten Basisstation größer als der maximale Lastindex ist; und

Schließen der ersten Basisstation.


 
11. Verfahren nach Anspruch 6, wobei die SINR-basierte Subclusterbildung aus Folgendem besteht:

Messen des SINR jeder MTC-Vorrichtung in Bezug auf jede Basisstation;

Mitteilen des SINR-Wertes an eine bedienende Basisstation;

Teilen der SINR-Mitteilung mit einer Anzahl von benachbarten Basisstationen durch die bedienende Basisstation;

Sortieren des angegebenen SINR für die eine oder die mehreren MTC-Vorrichtungen in Bezug auf jede Basisstation durch jede Basisstation; und

Erstellen eines Subclusters basierend auf der gemeinsamen SINR-Sequenz für die eine oder die mehreren MTC-Vorrichtungen in Bezug auf jede Basisstation.


 
12. Verfahren nach Anspruch 6, wobei der Clusterhead das höchste SINR mit Bedienzelle hat und eine abnehmende Reihenfolge von SINR für die benachbarten Basisstationen oder kooperativen Basisstationen, die den Clusterhead gemeinsam bedienen.
 
13. Clusterhead zur Bereitstellung von Datenkommunikation für Maschinenkommunikations(MTC)-Vorrichtungen in clusterbasierter drahtloser Kommunikation, wobei der Clusterhead mindestens ein Element aufweist, das angepasst ist zum:

Empfang einer Meldung von einer oder mehreren MTC-Vorrichtungen zur Datenverkehrsübertragung, wenn die eine oder die mehreren MTC-Vorrichtungen aktiviert werden, wobei die Nachricht mindestens eine der Folgenden umfasst: einen Aktivierungsstatus, einen Pufferfüllstandsstatus oder eine Verzögerungstoleranz der einen oder mehreren MTC-Vorrichtungen;

Bestimmen der Verfügbarkeit eines oder mehrerer Netzbetriebsmittel zum Transport des Datenverkehrs, basierend auf mindestens einem der Folgenden:

dem Aktivierungsstatus, dem Pufferfüllstandstatus oder der Verzögerungstoleranz der einen oder mehreren MTC-Vorrichtungen;

Aufbau einer speziellen Verbindung mit einer Basisstation zum Transport des Datenverkehrs von der einen oder den mehreren MTC-Vorrichtungen an die Basisstation, basierend auf der Verfügbarkeit des einen oder der mehreren Netzbetriebsmittel; und

Übertragen des Datenverkehrs von der einen oder den mehreren MTC-Vorrichtungen an die Basisstation durch die spezielle Verbindung, die zwischen dem Clusterhead und der Basisstation aufgebaut wird,

wobei der Clusterhead aus der einen oder den mehreren MTC-Vorrichtungen ausgewählt ist, die Mitglieder eines Clusters sind, das mit dem Clusterhead verbunden ist.


 
14. Clusterhead nach Anspruch 13, wobei das mindestens eine Element angepasst ist zum:

Senden einer ACK- und/oder einer NACK-Nachricht von der Basisstation durch die spezielle Verbindung, die zwischen dem Clusterhead und der Basisstation aufgebaut wird, und

Weiterleiten einer ACK- und/oder einer NACK-Nachricht von der Basisstation zu einer entsprechenden MTC-Vorrichtung.


 


Revendications

1. Procédé de fourniture de communication de données pour des dispositifs de communication de type machine, MTC, dans une communication sans fil basée sur un groupe, le procédé comprenant les étapes consistant à :

recevoir, par une tête de grappe (701), un message pour un transfert de trafic de données à partir d'un ou plusieurs dispositifs de MTC lorsque les un ou plusieurs dispositifs de MTC sont activés, où le message comprend au moins l'un parmi un état d'activation, un état d'occupation de mémoire tampon ou une tolérance au retard des un ou plusieurs dispositifs de MTC ;

déterminer, par la tête de grappe (701), la disponibilité d'une ou plusieurs ressources de réseau pour transférer le trafic de données sur la base d'au moins l'un parmi l'état d'activation, l'état d'occupation de mémoire tampon ou la tolérance au retard des un ou plusieurs dispositifs de MTC ;

établir, par la tête de grappe (701), une connexion dédiée avec une station de base pour transférer le trafic de données depuis les un ou plusieurs dispositifs de MTC à la station de base en fonction de la disponibilité des une ou plusieurs ressources de réseau ; et

transférer, par la tête de grappe (701), le trafic de données depuis les un ou plusieurs dispositifs de MTC à la station de base à travers la connexion dédiée établie entre la tête de grappe et la station de base,

où la tête de grappe (701) est sélectionnée parmi les un ou plusieurs dispositifs de MTC qui sont des membres d'une grappe associée à la tête de grappe.


 
2. Procédé selon la revendication 1, où la détermination de la disponibilité de ressources de réseau pour transférer le trafic de données comprend :

créer une liste de priorités de dispositifs de MTC actifs sur la base de la tolérance au retard ;

comparer la tolérance au retard des dispositifs de MTC actifs avec un temps requis pour établir une connexion avec une station de base ; et

déclencher une demande de connexion avec la station de base lorsque la tolérance au retard pour un dispositif de MTC de haute priorité est égale à un temps prédéfini ;

où la tolérance au retard est un temps de communication tolérable total sans impact sur une qualité de service pour le dispositif de MTC.


 
3. Procédé selon la revendication 1, comprenant en outre :

envoyer, par la tête de grappe (701), au moins l'un parmi un message d'ACK ou de NACK à partir de la station de base à travers la connexion dédiée établie entre la tête de grappe et la station de base ; et

relayer au moins l'un parmi un message d'ACK ou de NACK depuis la station de base à un dispositif de MTC correspondant.


 
4. Procédé selon la revendication 1, où la tête de grappe (701) établit et libère la connexion dédiée avec la station de base en fonction d'un trafic entrant en provenance des un ou plusieurs dispositifs de MTC.
 
5. Procédé selon la revendication 2, où le temps prédéfini est l'intervalle de temps requis pour établir une connexion dédiée entre la tête de grappe (701) et la station de base.
 
6. Procédé selon la revendication 1, comprenant en outre l'exécution d'une sous-grappe de la pluralité de dispositifs de MTC à l'intérieur d'une grappe sur la base d'un premier ensemble de paramètres, où le premier ensemble de paramètres comprend un niveau d'encombrement et un rapport signal sur bruit, SINR, associés à la pluralité de dispositifs de MTC.
 
7. Procédé selon la revendication 6, où la formation de sous-grappes basée sur le niveau d'encombrement est effectuée sur la base d'un indice de charge, où l'indice de charge est une moyenne d'une utilisation de ressources au niveau de la station de base.
 
8. Procédé selon la revendication 7, comprenant en outre :

calculer l'indice de charge d'une station de base sélectionnée ; et

rediriger un ou plusieurs dispositifs de MTC d'une première station de base à une deuxième station de base si l'indice de charge d'une deuxième station de base est supérieur à un indice de charge précédent et inférieur à un indice de charge maximal, où l'indice de charge maximal est associé à une disponibilité maximale de ressources de réseau.


 
9. Procédé selon la revendication 7, comprenant en outre le redirectionnement d'un ou plusieurs dispositifs de MTC de la première station de base à la deuxième station de base ayant un indice de charge entre l'indice de charge maximal et un indice de charge minimal, si l'indice de charge de la première station de base est inférieur à l'indice de charge précédent et est égal ou inférieur à l'indice de charge minimal, où l'indice de charge minimal est associé à la disponibilité minimale de ressources de réseau.
 
10. Procédé selon la revendication 7, comprenant en outre :

rediriger un ou plusieurs dispositifs de MTC de la première station de base à la deuxième station de base si l'indice de charge de la première station de base est supérieur à l'indice de charge maximal ; et

couper la première station de base.


 
11. Procédé selon la revendication 6, où la formation de sous-grappes basée sur le SINR comprend :

mesurer le SINR par chaque dispositif de MTC par rapport à chaque station de base ;

rapporter la valeur de SINR à une station de base de desserte ;

partager le rapport de SINR avec une pluralité de stations de base voisines par la station de base de desserte ;

trier, par chaque station de base, le SINR rapporté pour les un ou plusieurs dispositifs de MTC par rapport à chaque station de base ; et

créer une sous-grappe sur la base de la séquence de SINR commune pour les un ou plusieurs dispositifs de MTC par rapport à chaque station de base.


 
12. Procédé selon la revendication 6, où la tête de grappe a le SINR le plus élevé avec la cellule de desserte et a un ordre décroissant de SINR pour les stations de base voisines ou les stations de base coopératives qui desservent conjointement la tête de grappe.
 
13. Tête de grappe pour fournir une communication de données pour des dispositifs de communication de type machine, MTC, dans une communication sans fil basée sur un groupe, la tête de grappe comprenant au moins un élément adapté pour :

recevoir un message d'un ou plusieurs dispositifs de MTC pour le transfert de trafic de données lorsque les un ou plusieurs dispositifs de MTC sont activés, où le message comprend au moins l'un parmi un état d'activation, un état d'occupation de mémoire tampon ou une tolérance au retard des un ou plusieurs dispositifs de MTC ;

déterminer la disponibilité d'une ou plusieurs ressources de réseau pour transférer le trafic de données sur la base de l'au moins un parmi l'état d'activation, l'état d'occupation de mémoire tampon ou la tolérance au retard des un ou plusieurs dispositifs de MTC ;

établir une connexion dédiée avec une station de base pour transférer le trafic de données depuis les un ou plusieurs dispositifs de MTC à la station de base en fonction de la disponibilité des une ou plusieurs ressources de réseau ; et

transférer le trafic de données depuis les un ou plusieurs dispositifs de MTC à la station de base à travers la connexion dédiée établie entre la tête de grappe et la station de base,

où la tête de grappe est sélectionnée parmi les un ou plusieurs dispositifs de MTC qui sont des membres d'une grappe associée à la tête de grappe.


 
14. Tête de grappe selon la revendication 13, où l'au moins un élément est adapté pour :

envoyer au moins l'un parmi un message d'ACK ou de NACK à partir de la station de base à travers la connexion dédiée établie entre la tête de grappe et la station de base et

relayer au moins l'un parmi un message d'ACK ou de NACK de la station de base à un dispositif de MTC correspondant.


 




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Cited references

REFERENCES CITED IN THE DESCRIPTION



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Patent documents cited in the description




Non-patent literature cited in the description