Precoding Design for MIMO Relay Multicasting

Abstract

In this paper, we consider a two-hop multicasting multiple-input multiple-output (MIMO) relay system where one transmitter multicasts common message to multiple receivers with the aid of a relay node, and all nodes are equipped with multiple antennas. Joint transmit and relay precoding design problems are investigated for multicasting multiple data streams based on two design criteria. In the first scheme, we aim at minimizing the maximal mean-squared error (MSE) of the signal waveform estimation among all receivers subjecting to power constraints at the transmitter and the relay node. This problem is highly nonconvex with matrix variables and the exactly optimal solution is very hard to obtain. We develop an iterative algorithm to jointly optimize the transmitter, relay, and receiver matrices through solving convex subproblems. By exploiting the optimal structure of the relay precoding matrix, we then propose a low complexity solution which decouples the optimization of the transmitter and relay matrices under the (moderately) high first-hop signal-to-noise ratio (SNR) assumption. In the second scheme, we propose a total transmission power minimization strategy subjecting to quality-of-service (QoS) constraints. By using the optimal structure of the relay precoding matrix and the (moderately) high first-hop SNR assumption, we show that this problem can be solved using the semidefinite programming (SDP) technique. Numerical simulations demonstrate the effectiveness of the proposed algorithms. Interestingly, we show that for the special case of single data stream multicasting, the relay precoding matrix optimization problem can be equivalently converted to the transmit beamforming problem for single-hop multicasting systems.

Joint source and relay optimization for interference MIMO relay networks

“…Remark Note that the interference term in ( 3) does not appear in the received signal of the single-user MIMO relay system considered in [19] or in the multicasting MIMO relay system considered in [20,21]. Hence the subsequent analyses remain considerably simpler in [19][20][21], whereas we need to deal with this troublesome interference term in this paper.…”

“…Hence the subsequent analyses remain considerably simpler in [19][20][21], whereas we need to deal with this troublesome interference term in this paper.…”

“…where τ s is a slack variable and p (20) can be solved at a maximal complexity order [24]. The proposed iterative optimization technique for solving the original problem (9) is summarized in Table 1.…”

“…More specifically, under practically reasonable high first-hop signal-to-noise ratio (SNR) assumption, we demonstrate that the problem can be decomposed into two standard semidefinite programming (SDP) problems to optimize source and relay matrices separately. Note that high SNR assumption has also been made in [19] to simplify the joint codebook design problem in single-user MIMO relay systems and in [20,21] for multicasting MIMO relay design. Hence our work is a generalization to multi-pair communication scheme taking co-channel interference into account.…”

Multicast Linear Precoding for MIMO-OFDM Systems

“…With full channel state information (CSI), a transmitter (e.g., a base station or an access point) can precode transmit signals to increase minimum user data rate and improve the multicast communications quality in the networks. Various multicast precoding methods have been studied i) to maximize the minimum user rate [1]- [4] configuration, ii) to maximize minimum signal-to-noise ratio (SNR) [5], or iii) to minimize the maximal mean-squared error [6], typically for single-carrier systems.…”