Telefonaktiebolaget Lm Ericsson (publ)

Jan E Uddenfeldt

Alex K Raith

Jan E Dahlin

Hans Hermansson

A method and apparatus for frequency planning in a multi-system cellular communications network is disclosed in which a plurality of systems operate over a frequency range comprising a plurality of frequency bands. The systems each provide communications services to a plurality of subscribers located within substantially the same geographic region. Each of the systems is assigned one or more of the network frequency bands for use as control channels. The systems then share the unassigned frequency bands to provide communications service. The systems may share the frequency bands without coordination or synchronization or, as an alternative, the sharing may be controlled by a processor.

Method and apparatus for frequency planning in a multi-system cellular

A telecommunications network including a CDMA system and FDMA/TDMA system, both operating in a common frequency range, is disclosed. In an embodiment of the invention, the transmission and reception of narrowband FDMA/TDMA signals on a plurality of radio frequency channels within FDMA/TDMA system is synchronized such that at least one time slot of each TDMA frame on each radio channel is reserved. The transmission and reception of CDMA signals in the CDMA system is then performed during the reserved time slots of each TDMA frame. In an alternative embodiment, complete TDMA frames on each radio channel are reserved for CDMA transmission and reception.

Telecommunication network having time orthogonal wideband and narrowband

In a cellular mobile telephone system of the type having TDMA channels, a plurality of mobile station operate at either a full rate or a half rate. If the mobile stations are operating on the periphery of a cell they are assigned to full rate channels. If the mobile stations are operating in the vicinity of the base station, they are assigned to half rate channels. The mobile station are reassigned from full rate to half rate channels depending upon a measured parameters relating to signal strength or quality, such as the bit error rate of communications between the mobile station and the base station. If the measured bit error rate between the mobile station and a neighboring station is less than the bit error rate between the mobile station and its presently assigned base station, the mobile station is handed off to the neighboring base station.

Handoff of a mobile station between half rate and full rate channels

The invention relates to a method in a mobile radio system having both digital and analog radio channels. An object of the invention is that a connection established on a digital radio channel often shall be possible to maintain even when the time dispersion on available digital radio channels exceeds the designed maximum time dispersion of equalizers in receiving stations. According the invention equalizers in the receivers of the system may be designed for a smaller maximum time dispersion than the total time dispersion the whole system shall be capable to handle. Instead handoff is made to an other channel when the time dispersion of a used digital channel tends to become too big. When an other digital radio channel with low time dispersion is available handoff is preferably done to this channel. Alternatively or in the absence of such a digital radio channel handoff is performed to an analog radio channel.

Method of maintaining an established connection in a mobile radio system

A method in a mobile radio station to select one of a number of dedicated control channels (DCCH1-21) which are transmitted from a number of base stations (B1-B21) in a mobile radio system. In the mobile station there is an equalizer to compensate for the multipath propagation characteristics of the radio medium between the mobile station and a certain base station. This equalizer is power consuming and should not be used if not necessary. According to the method an investigation is carried out in the mobile station whether or not the equalizer can be disconnected during the initialization of a call from the mobile to a base station. The signal quality of the dedicated channel (DCCH1) which has the greatest signal strength is measured without the equalizer. If the signal quality is not acceptable, a new detection is made with the use of the equalizer. If the signal quality then is acceptable another detection is made without equalizer on the dedicated control channel (DCCH2) which has the next strongest signal and if this detection revealed an acceptable signal quality the base station (B2) transmitting this control channel is selected by the mobile station for the further call progress.

Method for reducing equalizer usage in mobile radio communication systems

The invention relates to a cellular digital mobile radio system including base stations (B.sub.m, B.sub.n) and mobile stations (MS.sub.1, MS.sub.2) with transmitters and receivers. The invention also relates to a method of transmitting message information digitally between mobile and base stations in such a system. In accordance with the invention, at least two base station transmitters (B.sub.ma, B.sub.mb, B.sub.na, B.sub.nb) at a given transmitting distance from each other are assigned to each of certain cells (C.sub.m, C.sub.n) within a restricted geographical area. The base station transmitters which are assigned to the same cell transmit digitally modulated radio signals within the same frequency range at least partially simultaneously to the mobile stations of the cell. The radio signals from different base station transmitters associated with the same cell are digitally modulated with the same message information to the mobile stations in the cell. Different base station transmitters (9A, 9B) preferably transmit the digitally modulated radio signals with the same message information to a given mobile station with a given mutual transmission time shift. Here, the transmission time shift is selected individually for each mobile station, such that corresponding digitally modulated radio signals with the same message information to a given mobile station from different base station transmitters arrive practically simultaneously at the mobile station.

Cellular digital mobile radio system and method of transmitting

Method of transmitting data information in a mobile, cellular, radio communication system operating according to the TDMA principle. Within certain large cells (C2) in the system the number of calls in progress is less than the number of slots (CH1, CH2 . . . ) in each frame, where these slots have been allotted to the mobiles (M1) within the cell. The unoccupied slots thus occuring are utilised in accordance with the method such that the bit frequency (f) of the data information is reduced to a new value (f.sub.r) in response to the number of unoccupied time slots. The transmission range between mobile and base station is thus increased.

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Vallingby, Sweden

Jan E Uddenfeldt