Abstract—2×2 unitary precoding based on receiver feedback

is applied alongside spatial multiplexing at the base station in

HSDPA (D-TxAA) when the mobile terminal supports MIMO

transmissios [1]. This precoding will influence achievable sumrate

of the MIMO channel if it influences the Signal-to-

Interference-plus-Noise Ratio (SINR) of streams at the receiver

(RX) output. We propose a set of MIMO HSDPA receivers, all

based upon a LMMSE chip-level matrix filter (equalizer) front

end, and introduce the notion of joint bias for the MIMO chip

equalizer. Statistical properties of the spatial model thus obtained

are exploited to analyze the performance of proposed MIMO

receivers. It is shown that precoding choice depends upon the

MIMO receiver and the extent of its impact depends on the

MIMO RX.