107 research outputs found
Cooperative Non-Orthogonal Multiple Access in 5G Systems
Non-orthogonal multiple access (NOMA) has recently received considerable
attention as a promising candidate for 5G systems. A key feature of NOMA is
that users with better channel conditions have prior information about the
messages of the other users. This prior knowledge is fully exploited in this
paper, where a cooperative NOMA scheme is proposed. Outage probability and
diversity order achieved by this cooperative NOMA scheme are analyzed, and an
approach based on user pairing is also proposed to reduce system complexity in
practice
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
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