Abstract: A cellular mobile radio system selects the best cell to be accessed for a given position of a mobile station by determining the distance of the mobile station relative to the base transceiver station of a cell with which it is communicating by measuring the propagation time between the mobile station and the base transceiver station, resolving the indeterminacy associated with the direction in which said mobile station is located relative to said base transceiver station, and then determining which cell the mobile station is situated in the coverage area of, this cell constituting the best cell. The resolving of the indeterminacy is rendered independent of the synchronized or non-synchronized state of the system.

Abstract: A transmission frame comprises a locking row, synchronization bits and data bits, the synchronization bit being placed immediately after the locking row. The frame terminates with a synchronization bit. A transmitter and a receiver are linked by a transmission channel carrying these frames.

Abstract: A cellular mobile radio system comprises cells divided into P sectors each having its own timebase. The system uses time division multiple access and accordingly transmission is effected in bursts each transmitted during a time slot, or channel time slot, of predetermined rank relative to a reference of the timebase of the sector concerned. N time slots form a frame which repeats periodically. A control channel is reserved for each sector for transmitting signalling and control data, a different control channel being associated with each sector. The timebase of each sector is shifted a predetermined number of time slots relative to the timebases of the other sectors of the same cell. The offsets are such that the control channels relating to each sector are conveyed at different times.

Abstract: A method of handover between two cells of a TDMA cellular mobile radio network, wherein, after a mobile receives a handover command (HANDOVER CMD) from its base station, the mobile transmits a message (SABM) containing connection set-up information or wanted data to a new base station according to a timing advance. The handover command tells the mobile not to transmit access bursts to the new base station, thus avoiding speech interruption. The timing advance is determined by the mobile or communicated to the mobile in the handover command.

Abstract: In a cellular mobile radio system including a plurality of cells grouped into identical patterns, each of at least two cells, repeated periodically in space and such that: each cell is associated with one or more base transceiver stations to send radio signals to or to receive radio signals from mobile stations. Each transceiver station sends and receives radio signals using a set of frequencies associated with its cell and including at least two different frequencies, all the frequencies of sets of frequencies associated with cells of the same pattern being different. The frequency of the signals exchanged between a mobile station and a base transceiver station of a cell changes in time with the result that several frequencies of the set of frequencies associated with the cell are used successively during the transmission. In this system, the plan of the mobile radio system is obtained by superposing the plans of a plurality of mobile radio systems each having a different number of cells per pattern.

Abstract: A transmission frame comprises a synchronization flag, synchronization bits and data bits. A control bit is substituted for one of the synchronization bits if any sequence of bits the same length as the synchronization flag including the synchronization bits differs from the synchronization flag by at least one bit in addition to the synchronization bit.

Abstract: A mobile radio network comprises a base transceiver station for transmitting and receiving radio signals to and from mobiles on different basic frequencies and a radio booster for receiving, amplifying and retransmitting radio signals to and from at least one shadow area. To cover the shadow areas a radio signal received by a radio booster from the base transceiver station on a basic frequency is retransmitted to a mobile station on a translated frequency different from the basic frequency and associated with the latter by a translation law. This law is such that, firstly, each of the basic frequencies is either associated with at least one translated frequency or is not associated with any translated frequency and, secondly, the difference between the value of a translated frequency and the value of the associated basic frequency is not the same for all the translated frequencies.

Abstract: A transmitter transmits blocks to a receiver by means of frames formed of a locking row and data rows. It receives an acknowledgement from the receiver sent by the latter on recognizing a locking row. A block comprises control bits, data bits and adaptation bits. During a first phase preceding reception of the acknowledgement the transmitter transmits blocks in which the adaptation bits have been eliminated by means of short frames comprising an initial number of data rows. During a second phase following on from reception of the acknowledgement it transmits blocks incorporating the adaptation bits by means of complete frames comprising a final number of data rows which is greater than said initial number. The receiver includes an analyzer for determining if the blocks are conveyed by a short frame or by a complete frame in order to identify the nature of the blocks.

Abstract: In a method for handover between old and new cells of a time-division multiple access (TDMA) cellular mobile radio system a call between a mobile station and the system, initially effected via the old cell on a first channel defined by a first on air timeslot and a first set of frequencies comprising at least one frequency, is effected via the new cell on a new channel defined by a second on air timeslot and a second set of frequencies comprising at least one frequency. The first and second on air timeslots are identical, the first and second sets of frequencies are separate, and the method consists in transmitting, after verifying that the second on air timeslot identical to the first on air timeslot is available in the new cell, a frequency indication message indicating to the mobile station the second set of frequencies so that the mobile station continues the call using the same on air timeslot and the second set of frequencies.

Abstract: The invention relates to a method of managing transmission errors between a base station and a transcoder, in a digital radiocommunications system for mobile stations, in which method the transcoder, in the presence of a transmission error, systematically inserts (29, 221, 228) an error message in a frame addressed to the base station without interrupting useful data transmission to the base station, and in which method the base station decides to interrupt data transmission to the transcoder (down direction) and generates an up-direction transmission interruption request when the transmission errors detected in the down direction and/or reported by an error message in the up direction satisfy predetermined conditions. In this way, all call-interruption decisions are centralized in the base station.

Abstract: In a reliable step by step method of controlling frequency redefinition in a cellular mobile radio system with no severe constraints on the network or on the mobile and using only existing procedures between mobiles and the network, frequency redefinition is effected time slot by time slot by freeing each time slot step by step by first eliminating any calls in said time slot, then effecting frequency redefinition of said freed time slot by assigning it the new list of frequencies, and finally making said time slot available for traffic again.

Abstract: A base transceiver station of a GSM type cellular network exchanges data by radio with mobiles in a specific geographical area or main cell divided into a plurality of sectors each corresponding to a specific portion of the main cell and each associated with a receiver having a directional antenna. The base transceiver station includes a single transmitter having an omni-directional antenna and providing the transmit radio coverage of all the sectors so that the data transmitted by the base transceiver station in the form of radio signals to a mobile in any sector is transmitted by the transmitter.

Abstract: In a method for allocating a timeslot within a frame to a communication mobile entering a mobile radio system cell from a set of concentric cells around a basic cell managed by a base transceiver station the uplink temporal structure is offset relative to the downlink temporal structure by a time-delay equal to the sum of a basic offset between the basic downlink temporal structure and the basic uplink temporal structure of the basic cell and an offset time dependent on the rank of the cell within said set of cells.

Abstract: A method of transmitting data from a base transceiver station or base station to a transcoder. Prior to transmission to the base station, the data is organized in streams of frames (T1, T2, T3). The streams are assembled into groups (G1, G2, G3), and the transmission of the data to the base station starts at the start of a stream of frames (T1, T2, T3). The method includes the following operations: after activation of a channel of the base station for reception of the data frames, the first stream of frames (T1, T2, T3) received on the channel by the base station is associated with a reference number within the corresponding group of frames (G1, G2, G3); and transmission of data by the base station to the transcoder is then delayed by an amount (R.sub.1/3, R.sub.2/3) depending on the reference number and the group of frames of the first stream of frames, whereby a continuous stream of data (A1, A2, A3) is transmitted by the base station to the transcoder.