Distributed Space-Time Block Coded Transmission with Imperfect Channel Estimation: Achievable Rate and Power Allocation

Abstract

This paper investigates the effects of channel estimation error at the receiver on the achievable rate of distributed space-time block coded transmission. We consider that multiple transmitters cooperate to send the signal to the receiver and derive lower and upper bounds on the mutual information of distributed space-time block codes (D-STBCs) when the channel gains and channel estimation error variances pertaining to different transmitter-receiver links are unequal. Then, assessing the gap between these two bounds, we provide a limiting value that upper bounds the latter at any input transmit powers, and also show that the gap is minimum if the receiver can estimate the channels of different transmitters with the same accuracy. We further investigate positioning the receiving node such that the mutual information bounds of D-STBCs and their robustness to the variations of the subchannel gains are maximum, as long as the summation of these gains is constant. Furthermore, we derive the optimum power transmission strategy to achieve the outage capacity lower bound of D-STBCs under arbitrary numbers of transmit and receive antennas, and provide closed-form expressions for this capacity metric. Numerical simulations are conducted to corroborate our analysis and quantify the effects of imperfect channel estimation.

Two‐pilot channel estimation scheme for amplify‐and‐forward relay networks

“…where subscript p is also defined as (5). S p 1 and S p 2 are the pilots transmitted by the source node and relays respectively.…”

“…[5]. Moreover, the advantages of DSTC are always evaluated with the prior known channel coefficients, such as maximum likelihood (ML) decoding.…”

“…For DF relay networks, the channel estimator can employ estimation schemes designed for colocated multi-antenna system like Ref. [5]. More studies focus on the AF-based relay networks with two reasons: (1) the equivalent channel coefficient is the product of source-relay (S-R) channel and relay-destination (R-D) channel; (2) the receiver noise of relay is propagated to the destination receiver and the equivalent noise of destination is not a Gaussian variable.…”

Distributed space-time decoding with Two-Pilot channel estimation for wireless relay networks

“…Unfortunately, the channel estimation is not perfect because of the noise and finite number of pilot symbols. For DF relaying scheme, the channel estimation can use co-located multi-antenna system as a reference [5]. Most studies focus on the AF system for the reason that the equivalent channel coefficient has an specific term which is the product of S-R channel and R-D channel.…”