Dividable transmit antenna array for a cellular base station and associated method

A time division multiple access (TDMA) base station for communicating with a plurality of mobile stations in a cellular communications system using a plurality of time division multiple access (TDMA) time slots in a time division multiple access (TDMA) time frame, said base station comprising:

• an antenna comprising an array of transmit antenna elements;
• high power transmit means for transmitting a high power cellular radio signal from a first plurality of said transmit antenna elements during a first time division multiple access (TDMA) time slot of the time division multiple access (TDMA) time frame;
• and
• low power transmit means for transmitting a low power cellular radio signal from a second plurality of said transmit antenna elements during a second time division multiple access (TDMA) time slot of the time division multiple access (TDMA) time frame wherein said first and second pluralities of said transmit antenna elements comprise different numbers of said transmit antenna elements.

A method for transmitting a plurality of cellular radio signals from a cellular base station to a plurality of mobile stations using a plurality of time division multiple access (TDMA) time slots in a TDMA frame, said method comprising the steps of:

• transmitting a first cellular radio signal during a first time division multiple access (TDMA) time slot of the TDMA frame wherein said first cellular radio signal is transmitted at a first power level;
• transmitting a second cellular radio signal during a second time division multiple access (TDMA) time slot of the TDMA frame wherein said second cellular radio signal is transmitted at a second power level less than said first power level;
• and
• transmitting a third cellular radio signal during said second time division multiple access (TDMA) time slot of the TDMA frame wherein said third cellular radio signal is transmitted at said second power level.

A time division multiple access (TDMA) cellular system for communicating with a plurality of mobile stations, said cellular system comprising:

• a first base station having a first antenna for transmitting a first cellular radio signal at a first power level during a first time division multiple access (TDMA) time slot of a time division multiple access (TDMA) time frame, and for transmitting a second cellular radio signal at a second power level during a second time division multiple access (TDMA) time slot of the time division multiple access (TDMA) time frame, wherein said first power level is high relative to said second power level;
• and
• a second base station adjacent said first base station, said second base station having a second antenna for transmitting a third cellular radio signal at a third power level during said second time division multiple access (TDMA) time slot of the time division multiple access (TDMA) time frame and for transmitting a fourth cellular radio signal at a fourth power level during said first time division multiple access (TDMA) time slot of the time division multiple access (TDMA) time frame, wherein said third power level is high relative to said fourth power level, thereby reducing interference between said first and second base stations wherein each of said first, second, third, and fourth cellular radio signals is transmitted over a common frequency.

A cellular base station for transmitting different signals using TDMA to each of a plurality of mobile stations at different distances from the base station comprising:

• timeslot and frequency allocation means for allocating a timeslot within a TDMA time frame and a frequency for transmitting to each mobile station in dependence on its distance from the base station;
• radio frequency switching means having a number of radio frequency signal inputs and a number of radio frequency signal outputs and a control input for controlling separately for each output which input signal shall appear at that output during each TDMA time slot of the TDMA time frame;
• multiple element antenna means for radiating signals each connected to respective outputs of said radio frequency switching means;
• multiple transmit signal generation means for generating TDMA signal outputs each using a different frequency and each comprising the same number of timeslots of the TDMA time frame, information for a particular mobile being modulated on to its respectively allocated frequency during its allocated timeslot of the TDMA time frame, and each TDMA signal output being connected to a respective input of said radio frequency switching means during respective TDMA time slots of the TDMA time frame;
• control means connected to said control input of said radio frequency switching means for controlling on a TDMA timeslot by timeslot basis of the TDMA time frame the selection of said switch input signals to appear on said switch outputs such that in at least one of said TDMA timeslots of the TDMA time frame at least one of said input signals appear on at least two of said outputs and in at least one other timeslot of the TDMA time frame at least two of said switch input signals each appear on different outputs.

A radio frequency switch for use in a phased array antenna transmitting Tiime Division Multiplex (TDM) signals in a number of time division multiplex (TDM) timeslots of a time division multiplex (TDM) time frame comprising:

• a plurality of inputs for modulated time-division multiplexed radio frequency (TDM RF) signals;
• a plurality of outputs for outputing selected ones of said TDM RF input signals;
• selection means for selecting which of said input signals are output from each of said outputs;
• memory means for storing for each of said TDM timeslots of the TDM timeframe a set of input to output signal selections that shall be used;
• cycling means for retrieving said selections from said memory in synchronism with said TDM timeslots of the TDM time frame so that a first one of the TDM RF input signals is coupled to a first plurality of the outputs during a first TDM time slot of the TDM time frame, and second and third ones of the TDM RF input signals are coupled to mutually exclusive subsets of the first plurality of the outputs during a second TDM time slot of the TDM time frame.