Low-Complexity and Low-Feedback-Rate Channel Allocation in CA MIMO Systems with Heterogeneous Channel Feedback

Abstract

In this paper, we propose a low complexity and low-feedback-rate channel allocation for carrier aggregation (CA) MIMO systems as an application to heterogeneous networks (HetNets) with multiple component carriers (CCs) and users. The proposed channel allocation technique relies on the heterogeneous channel feedback concept due to the heterogeneous channel statistics of the different CCs. We apply the heterogeneous channel feedback, where the channel feedback granularity is provided using best- $M$ selected feedback strategy. The precoding matrix indicator (PMI) and rank indicator (RI) are designed with a low complexity so that the PMI/RI reports are calculated more efficiently per CC and user. This approach reduces the complexity significantly in a multiuser and multichannel scenario. Next, we deal with the low-feedback rate and thus devise a channel allocation problem. The problem on one hand provides the minimization of the feedback overhead and, on the other hand, it guarantees the quality-of-service request of each user for a specific target throughput. The problem is considered as a channel assignment problem; thus, the Hungarian method is first used. Next, a low complexity solution is devised using the stable matching algorithm. A complexity analysis and evaluation among the original and the proposed approach for the low-complexity and the low-feedback-rate channel allocation is carried out. This comparison reveals the benefits of the proposed solution for CA MIMO system in HetNets. The proposed approach can be considered as a proposal to the future massive CA, i.e., up to 32 CCs.