SCMA for Open-Loop Joint Transmission CoMP

TL;DR

This paper introduces MU-SCMA-CoMP, a novel scheme combining SCMA with open-loop CoMP to enhance spectral efficiency, reduce CSI overhead, and improve throughput and coverage in 5G networks.

Contribution

It proposes a new MU-SCMA-CoMP scheme that integrates SCMA with CoMP, enabling open-loop user multiplexing and joint transmission with low CSI overhead.

Findings

Significant throughput and coverage gains over OFDMA.

Robustness to mobility and channel aging.

Reduced CSI acquisition overhead.

Abstract

Sparse Code Multiple Access (SCMA), a non-orthogonal multiple access scheme, has been introduced as a key 5G technology to improve spectral efficiency. In this work, we propose SCMA to enable open-loop coordinated multipoint (CoMP) joint transmission (JT). The scheme combines CoMP techniques with multi-user SCMA (MU-SCMA) in downlink. This scheme provides open-loop user multiplexing and JT in power and code domains, with robustness to mobility and low overhead of channel state information (CSI) acquisition. The combined scheme is called MU-SCMA-CoMP, in which SCMA layers and transmit power of multiple transmit points (TPs) are shared among multiple users while a user may receive multiple SCMA layers from multiple TPs within a CoMP cluster. The benefits of the proposed scheme includes: i) drastic overhead reduction of CSI acquisition, ii) significant increase in throughput and coverage, and iii) robustness to channel aging. Various algorithms of MU-SCMA-CoMP are presented, including the detection strategy, power sharing optimization, and scheduling. System level evaluation shows that the proposed schemes provide significant throughput and coverage gains over OFDMA for both pedestrian and vehicular users.