A novel distributed power allocation scheme for coordinated multicell systems

Abstract

Coordination between base stations (BSs) is a promising solution for cellular wireless systems to mitigate intercell interference, improving system fairness, and increasing capacity in the years to come. The aim of this manuscript is to propose a new distributed power allocation scheme for the downlink of distributed precoded multicell MISO-OFDM systems. By treating the multicell system as a superposition of single cell systems we define the average virtual bit error rate (BER) of one single-cell system, allowing us to compute the power allocation in a distributed manner at each BS. The precoders are designed in two phases: first the precoder vectors are computed in a distributed manner at each BS considering two criteria, distributed zero-forcing and virtual signal-to-interference noise ratio; then the system is optimized through distributed power allocation with per-BS power constraint. The proposed power allocation scheme minimizes the average virtual BER over all user terminals and the available subcarriers. Both the precoder vectors and the power allocation are computed by assuming that the BSs have only knowledge of local channel state information. The performance of the proposed scheme is compared against other power allocation schemes that have recently been proposed for precoded multicell systems based on LTE specifications. The results also show that although our power allocation scheme is based on the minimization of the virtual uncoded BER, it also has significant gains in coded systems.

An Overview on Resource Allocation Techniques for Multi-User MIMO Systems

“…In multi-cell scenarios, assuming full CSIT and shared user data across the transmitter, the precoders can be computed by techniques described in Section IV-B. However, the power should be constrained on a per-transmitter basis, instead of global power allocation as in single-transmitter scenarios [240]. The precoding design can be oriented to optimize different objective functions, e.g.…”

Receiver design for the uplink of base station cooperation systems employing SC-FDE modulations

“…In fact, BS cooperation allows not only universal frequency reuse but also substantial macro-diversity effects, significantly improving the overall performance of wireless systems, as well as the coverage and power requirements associated with each individual link. The signal separation in the downlink transmission (i.e., the link from the BSs to the MTs) of BS cooperation schemes is usually achieved by appropriate pre-processing schemes [10][11][12]. In the uplink transmission (i.e., the link from the MTs to the BSs), the overall signals received by different BSs (with contributions from all MTs) are sent to the CPU that performs the signal separation, to extract the data blocks transmitted by each MT, before sending them to the corresponding BS [3].…”

Robust leakage‐based distributed precoder for cooperative multicell systems

“…It is assumed that each BS has only the knowledge of local channel state information (CSI) and based on that a parameterisation of the beamforming vectors used to achieve the outer boundary of the achievable rate region was derived. Distributed precoding schemes based on zero‐forcing (ZF) criterion with several centralised power allocation approaches, which minimise the average bit error‐ratio (BER) and sum of inverse of signal‐to‐noise ratio was proposed in [15]. In [13–15], it was considered that the BSs share the entire data of the all jointly processed users, whereas in [16] the distributed precoding was designed so that the transmitters do not share the data which fall into the interference channel framework.…”

“…Distributed precoding schemes based on zero‐forcing (ZF) criterion with several centralised power allocation approaches, which minimise the average bit error‐ratio (BER) and sum of inverse of signal‐to‐noise ratio was proposed in [15]. In [13–15], it was considered that the BSs share the entire data of the all jointly processed users, whereas in [16] the distributed precoding was designed so that the transmitters do not share the data which fall into the interference channel framework. One of the considered criteria to design the precoders was the signal‐to‐leakage‐and‐noise (SLNR) ratio maximisation, introduced first in the context of multiuser MIMO [17].…”

“…In the previous distributed approaches, the precoders were designed by assuming perfect knowledge of local CSI. In [13–18], the authors assume that perfect channel knowledge is available. Nevertheless, this is not a realistic assumption for practical scenarios.…”