Method and apparatus for downlink beam forming in TD-CDMA system

摘要

The present invention discloses a method and an apparatus for downlink beam forming in a TD-CDMA system. The method includes: acquiring the spatial covariance matrixes of all uplink slot interference user signals and the downlink slots in which the interference user signals locate; obtaining the interference spatial covariance matrixes of each downlink slot based on the downlink slots in which the interference user signals locate and the spatial covariance matrixes of the interference user signals; determining the beam forming weight coefficient of downlink expected user signals based on the interference spatial covariance matrixes of each downlink slot and the spatial covariance matrixes of the downlink expected user signals; implementing beam forming based on the beam forming weight coefficient of downlink expected user signals.

主权项

1. A downlink beam forming method in a Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) system, comprising:
acquiring spatial covariance matrixes of all uplink slot interference user signals by the following formula to obtain M spatial covariance matrixes and determining downlink slots in which the interference user signals locate, RI(m)=E{HI(m)HI(m)H}, m=1, . . . , M, where E{HI(m)HI(m)H} represents an operation to solve a mathematical expectation of a random variable, M is the number of the interference user signals, HI(m) represents multiple antenna channel estimation of the mth interference user, and HI(m)H represents a conjugate transpose operation of matrix HI(m); obtaining an interference spatial covariance matrix of each downlink slot based on the downlink slots in which the interference user signals locate and the spatial covariance matrixes of the interference user signals by the following formula to calculate the interference spatial covariance matrix of each downlink slot,RI,n=∑∀um❘td⁡(m)=n⁢⁢RI(m),where um represents the mth interference user signal, td(m) represents the downlink slot in which the mth interference user signal locates, and n represents the number of any downlink slot;
determining beam forming weight coefficients of downlink expected user signals based on the interference spatial covariance matrixes of each downlink slot and spatial covariance matrixes of downlink expected user signals by the following formula to calculate the beam forming weight coefficients of the downlink expected user signals,w(k)=argmaxw(wH⁢Rxx(k)⁢wwH⁡(RI,n+λ⁢⁢I)⁢w),where k is a positive integer, w represents any variable, wH represents a conjugate transpose operation of w, I represents a unit array of antenna dimensions, λ represents noise power or a constant factor proportional to the interference power, and w(k) represents the beam forming weight coefficient of the kth downlink expected user signal; and
implementing beam forming based on the beam forming weight coefficients of the downlink expected user signals by the following formula to calculate the transmitting sequences,ska=∑k=1K⁢⁢s(k)⁢wka(k),where Ska represents the transmitting sequence of the kath antenna, s(k) represents the transmitting sequence of the kth downlink expected user signal, ka represents the kath antenna, and Wka(k) represents the beam forming weight coefficient of the kth downlink expected user signal at the kath antenna.