The present invention refers to the field of mobile radio communications and is relative to a method that allows terminal mobile radio apparatuses able of using the FM (Frequency Modulation) analog radio technology and/or the digital radio technology, in particular the type 4FSK (4-level Frequency Shift Keying) digital radio technology, to perform voice and/or data communications using a single radio infrastructure. The technology introduced here can, for instance, be used in the PMR (Professional Mobile Radio) systems, which are systems typically used by public bodies or big private enterprises to solve the problem of the migration of a radio communication system or, in other words, to manage the transition phase of a communication system from FM analog radio technology to the 4FSK digital radio technology.
A mobile radio communication system is composed of two separate elements:
A terminal apparatus is an electronic device which is able of communicating with other terminal apparatuses by exploiting the use of radio waves. By means of the terminal apparatuses, the human users of the mobile radio communication system can carry out voice and/or data communication by suitably acting on the terminal apparatuses themselves. The set of the terminal apparatuses belonging to the same communication system constitutes the system fleet.
The terminal apparatuses can communicate between themselves either directly or through a radio infrastructure.
The radio infrastructure is a set of electronic devices which has the task of allowing communication between two or more terminal apparatuses which are far from each other and cannot communicate directly with each other.
The radio infrastructure operates in the following way: it receives the radio signal transmitted by a terminal apparatus and rebroadcasts it so that the signal can reach the terminal or the terminals involved in the communication in progress.
The radio infrastructure can be concentrated in a single location (in case of the single relay) or it can be distributed in various locations interconnected with each other (in case of multiple interconnected relays). The use of one solution or the other depends fundamentally on the extension of the territorial area which is to be served by the communication system.
An example of the utilization of said technology is offered by the system and devices described in the
To achieve the above object, a mobile phone set comprises a base unit and at least one handset capable of radio transmission/reception with said base unit, said base unit being capable of digital transmission/reception between a fixed transmitting station and the base unit and the handset being capable of analog transmission/reception between the base unit and the handset.
According to the purpose of that solution, all the handsets have the same structure and the same circuitry and operate in the same manner.
From the 70's, the terminal apparatuses of the communication systems of the PMR type used the FM analog modulation for radio communication. Consequently, the radio infrastructure of the system was specifically designed for the reception, elaboration and transmission of a FM analog modulated radio signal.
Starting from the 90's [H.P. A. Ketterling, "Introduction to Digital Professional Mobile Radio", Artech House Publishers - 2004, page 1], the PMR world has greatly developed toward digital communication systems or toward systems which use a digital radio modulation to perform radio communication between the terminal apparatuses. In particular, next to proprietary communication systems, for instance iDEN (Integrated Digital Enhanced Network) of Motorola and TETRAPOL of EADS Telecom, other standardization activities for communication systems have been started such as, for instance, APCO P.25 (Association of Public Safety Communication Officials, Project 25) by TIA/EIA (Telecommunication Industry Association / Electronic Industry Association) in the United States and TETRA (TErrestrial TRunked RAdio) by ETSI (European Telecommunication Standard Institute) in Europe. Therefore, at present, there are radio communication systems in the market composed of terminal apparatuses which use the digital radio modulation and radio infrastructures which specifically handle such digitally modulated signals.
The concurrent existence of these two radio technologies (FM analog and digital) brought, as a consequence, the introduction in the market of a certain type of terminal apparatuses able of using both technologies to communicate. Such terminal apparatuses are therefore able of communicating either by using an FM analog radio modulation or by using a digital radio modulation.
The situation which occurs more and more frequently in a PMR type communication system is that in which there is a fleet composed of terminal apparatuses of mixed type or , in other words, of terminal apparatuses that use different radio technologies. In particular, the terminal apparatuses can be of three types:
The various types of terminal apparatuses present in the same fleet might be used, for instance, to perform different communication; in such case the T1 and T3(used in analogic mode) type terminal apparatuses could be used to perform voice communication, while the T2 and T3 (used in digital mode) type could be used for data transmission. Alternatively, the various types of terminal apparatuses can be assigned to different types of users, inside the same fleet. The T1 type apparatuses, for instance, can be assigned to generic customers, while the T2 or T3 type terminal apparatuses can be assigned to users with more sophisticated communication requirements.
In a fleet with all three types of terminal apparatuses, or even with a subset of those, there is the problem of how to guarantee communication between these terminal apparatuses.
In effect, if the radio infrastructure is specific for an FM analog modulated signal, the only apparatuses that can comunicate are those of the T1 and T3 type. In this case, however, the T3 type terminal apparatuses cannot exploit the digital communication mode and the whole set of services that such mode can offer to the user. The T2 type terminal apparatuses, instead, are completely excluded from the communication.
If the radio infrastructure is specific for a digitally modulated radio signal, the only terminal apparatuses which can communicate are those of the T2 and T3 type, while the T1 type terminal apparatuses are completely excluded from the communication.
Therefore, the problem which emerges is the difficulty of guaranteeing to all types of terminal apparatuses the possibility of performing communication using the existing radio infrastructures.
The present invention applies to the field of narrow band professional mobile radio communication (PMR) and refers to radio mobile systems which use, for communication between terminals, FM analog radio modulation or 4FSK digital radio modulation.
The subject of the present invention is a type of radio infrastructure which allows the terminal apparatuses to radio communicate both through the FM analog radio modulation and through the 4FSK digital radio modulation.
Considering the fact that the system fleet is composed of the following types of terminal apparatuses:
It is the purpose of the present invention to guarantee the possibility of performing, automatically and transparently for the user, all the following radio communication:
The invention refers to a set of electronic devices, forming the mobile radio infrastructure, which are able of receiving, transmitting and elaborating both radio technologies used for communication: the FM analog and the digital one, in particular the one of the 4FSK type, and refers to a method to make said electronic devices operational.
In detail, the functionalities of the devices forming the radio infrastructure are the following:
The set of blocks 2, 3, and 7 constitutes the functional part of the radio infrastructure which allows the management of the radio communication automatically and transparently for the user. In particular, blocks 2 and 3 operate in parallel, analyzing the real signal in base band received from block 1.
If at the input of the radio infrastructure there is a signal with FM analog modulation with an access key, block 2 performs the identification of the access key, informs block 7 of the presence of an analog type signal and forwards the analog signal to block 4 for its elaboration. At the same time, block 3 does not acknowledge any signal of the 4FSK digital type, in the real signal in base band coming from block 1, and therefore blocks 5 and 6 do not start to operate.
Vice versa, if at the input of the radio infrastructure there is a signal with 4FSK digital modulation block 3 performs its identification, informs block 7 of the presence of a digital type signal, estimates the bit sequence and forwards the bit sequence to block 5 for its elaboration. In its turn, block 5 forwards the bit sequence elaborated by block 6 for building the modulating waveform. At the same time block 2 does not acknowledge any access key inside the real signal in base band coming from block 1, and therefore block 4 does not start to operate.
The set of blocks 3, 10 and 11 constitutes the functional part of the radio infrastructure which allows the management of radio communication automatically and transparently for the user. In particular, blocks 3 and 10 operate in parallel, analyzing the real signal in base band received from block 1.
If at the input of the radio infrastructure there is an analog modulation signal, without an access key, block 10 acknowledges the presence of a generic signal, informs block 11 and forwards said signal to block 4 for its elaboration. At the same time, block 3 does not acknowledge any 4FSK digital type signal, inside the real signal in base band coming from block 1, and, therefore, blocks 5 and 6 do not start to operate. Block 11, receiving in input from block 10 the information of the presence of a generic signal and without receiving any information from block 3, presumes that the signal at the input of the radio infrastructure is of the analog type and activates block 8 so that the signal produced by block 4 reaches block 9.
Vice versa, if at the input of the radio infrastructure there is a signal with a 4FSK digital modulation, block 3 performs its identification, informs block 11 of the presence of a digital type signal, assesses the bit sequence and forwards the bit sequence to block 5 for its elaboration. In its turn, block 5 forwards the sequence of elaborated bits to block 6 for building the modulating waveform. At the same time, block 10 acknowledges the presence of a generic signal coming from block 1, informs block 11 and forwards the signal to block 4 for its elaboration. Block 11, receiving in input from block 10 the information of the presence of a generic signal and from block 3 the information of the presence of a digital type signal, presumes that the signal at the input of the radio infrastructure is of the digital type and activates block 8 so that block 9 receives the signal produced by block 6.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.