Ergodic Capacity Analysis of Remote Radio Head Associations in Cloud Radio Access Networks

Characterizing user to Remote Radio Head (RRH) association strategies in cloud radio access networks (C-RANs) is critical for performance optimization. In this letter, the single nearest and N--nearest RRH association strategies are presented, and the corresponding impact on the ergodic capacity of C-RANs is analyzed, where RRHs are distributed according to a stationary point process. Closed-form expressions for the ergodic capacity of the proposed RRH association strategies are derived. Simulation results demonstrate that the derived uplink closed-form capacity expressions are accurate. Furthermore, the analysis and simulation results show that the ergodic capacity gain is not linear with either the RRH density or the number of antenna per RRH. The ergodic capacity gain from the RRH density is larger than that from the number of antennas per RRH,which indicates that the association number of the RRH should not be bigger than 4 to balance the performance gain and the implementation cost.Comment: 4 pages, 2 figures, accepted by IEEE Wireless Communication Letter

Fronthaul-Constrained Cloud Radio Access Networks: Insights and Challenges

As a promising paradigm for fifth generation (5G) wireless communication systems, cloud radio access networks (C-RANs) have been shown to reduce both capital and operating expenditures, as well as to provide high spectral efficiency (SE) and energy efficiency (EE). The fronthaul in such networks, defined as the transmission link between a baseband unit (BBU) and a remote radio head (RRH), requires high capacity, but is often constrained. This article comprehensively surveys recent advances in fronthaul-constrained C-RANs, including system architectures and key techniques. In particular, key techniques for alleviating the impact of constrained fronthaul on SE/EE and quality of service for users, including compression and quantization, large-scale coordinated processing and clustering, and resource allocation optimization, are discussed. Open issues in terms of software-defined networking, network function virtualization, and partial centralization are also identified.Comment: 5 Figures, accepted by IEEE Wireless Communications. arXiv admin note: text overlap with arXiv:1407.3855 by other author

Up to 4 × 192 LTE-A radio waveforms transmission in a point to multipoint architecture for massive fronthauling solutions

In this work, a novel point-to-multipoint fronthauling architecture based on the use of a Multi-Output Erbium Doped Fibre Amplifier (MO-EDFA), to deliver several digital signal processing (DSP) aggregated analogue radio waveforms, is proposed and experimentally analysed. The transmission of 4x192 20 MHz radio waveforms, according to the DSP-aggregated fronthauling (DSP-AF) Frequency Division Multiplexed (FDM) architecture originally proposed in [1]. Using the MO-EDFA, we are able to feed up to 24 remote radio head (RRH) units, experimentally demonstrating successful transmission over a link with up to 25 dB of optical path losses, including 37 km of single mode fibre