Coordinated multi-point for future networks: field trial results

Abstract

Wireless networks face big capacity challenges, struggling to meet ever increasing user data demands. Global mobile data traffic grew by 74% in 2015 and it is expected to grow 8-fold by 2020. Future wireless network will need to deploy massive number of small cells and improve spectral efficiency to cope with this increasing demand. Dense deployment of small cells will require advanced interference mitigation techniques to improve spectral efficiency and enhance much needed capacity. Coordinated multipoint (CoMP) is a key feature for mitigating inter-cell interference and to improve throughput and cell edge performance. In this chapter, we first provide the motivation for CoMP deployment from an operator perspective. Then, we discuss different types of CoMP schemes, their associated challenges and the third generation partnership project (3GPP) standardisation roadmap. Next, we provide insights into operational requirements for CoMP implementation and discuss potential solutions to enable cost-effective CoMP deployment. We then provide results for an intra-site uplink (UL) joint reception (JR) CoMP trial in a large Long-Term Evolution-Advanced (LTE-A) operator in the United Kingdom (UK) for three different deployment scenarios namely, dense, medium density and sparse deployment at macro layer. CoMP sets consist of co-located cells only with joint baseband processing units, and hence no backhaul is required for data exchange. On the other hand, interference between cells from different locations are not mitigated. Only two cells are allowed for coordination and interference rejection combining (IRC) is employed for joint processing. Trial performance is measured based on average network counters. Results show an average increase in signal-to-interference-plus-noise ratio (SINR) on physical uplink shared channel (PUSCH) by 5.56% which is then reflected in improved usage of higher modulation schemes and better UL user throughput. An average increase of 11.32% is observed on UL user throughput. Additionally, we discuss the limitations of the trialled CoMP scheme and suggest improvements for better CoMP gains. Furthermore, we review the evolution of CoMP into 5G and potential improvements CoMP can provide for some of the key 5G network objectives such as spectral efficiency, energy efficiency, load balancing and backhaul optimisation.