Patent ID: 7729411

Claim:
A joint detector in a spread spectrum code division multiple access (CDMA) receiver that receives a code-multiplexed signal in a time-varying channel, reduces cross-interference between a plurality of Orthogonal Variable Spreading Factor (OVSF) code sharing control signals, and estimates a symbol of interest, wherein the code-multiplexed signal includes a set of user-specific signature sequences and a common channelization code, and the joint detector is a minimum mean squares estimator (MMSE) detector, said joint detector comprising: means for despreading and combining the received code-multiplexed signal to produce a plurality of combined signal components; means for generating decision statistics from the plurality of combined signal components for detecting each of the plurality of OVSF code sharing control signals; means for reducing cross-interference between the OVSF code sharing control signals based on both code information and time-varying channel information, said means for reducing cross-interference including a processing matrix that includes: an element, C, which is a function of the set of user-specific signature sequences; and an element, H, which is a function of the time-varying channel; and means for estimating the symbol of interest from the OVSF code sharing control signals, each of said signals having reduced interference; wherein the processing matrix in the MMSE detector also includes: an element, A, which is a diagonal matrix having E s ⁡ ( k ) as a kth diagonal element, wherein E s (k) represents symbol energy for a kth control signal; and an element σ, which is an estimate of noise variance.