Cooperative signal reception and down-link beam forming in cellular mobile communications

A cooperative signal reception and down-link beam-forming algorithm is proposed for mobile communication systems employing phase-shift-keying (PSK) modulation. Down-link beam optimality is defined as maximizing the desired reference user's average received power while keeping the noise power plus total amount of average powers received by other users less than or equal to a certain constant level. The proposed algorithm requires neither the detection of other user's signals nor knowledge about the direction-of-arrivals (DOA)'s of the incident path components. Results of a series of exhaustive simulations are presented to demonstrate the overall performance of the proposed algorithm. For a hexagonal cell layout, the distribution of signal-to-interference power ratio (SIR) in a reference (central) cell with the optimal down-link beam is evaluated and compared with that with a unit gain omnidirectional antenna through computer simulations for an eight-element circular array. The beam-forming performances are also evaluated under several sets of practical parameter values with regard to the fading correlation.