2,318 research outputs found
Fairness Comparison of Uplink NOMA and OMA
In this paper, we compare the resource allocation fairness of uplink
communications between non-orthogonal multiple access (NOMA) schemes and
orthogonal multiple access (OMA) schemes. Through characterizing the
contribution of the individual user data rate to the system sum rate, we
analyze the fundamental reasons that NOMA offers a more fair resource
allocation than that of OMA in asymmetric channels. Furthermore, a fairness
indicator metric based on Jain's index is proposed to measure the asymmetry of
multiuser channels. More importantly, the proposed metric provides a selection
criterion for choosing between NOMA and OMA for fair resource allocation. Based
on this discussion, we propose a hybrid NOMA-OMA scheme to further enhance the
users fairness. Simulation results confirm the accuracy of the proposed metric
and demonstrate the fairness enhancement of the proposed hybrid NOMA-OMA scheme
compared to the conventional OMA and NOMA schemes.Comment: 6 pages, accepted for publication, VTC 2017, Spring, Sydne
A Framework for Uplink Intercell Interference Modeling with Channel-Based Scheduling
This paper presents a novel framework for modeling the uplink intercell
interference (ICI) in a multiuser cellular network. The proposed framework
assists in quantifying the impact of various fading channel models and
state-of-the-art scheduling schemes on the uplink ICI. Firstly, we derive a
semianalytical expression for the distribution of the location of the scheduled
user in a given cell considering a wide range of scheduling schemes. Based on
this, we derive the distribution and moment generating function (MGF) of the
uplink ICI considering a single interfering cell. Consequently, we determine
the MGF of the cumulative ICI observed from all interfering cells and derive
explicit MGF expressions for three typical fading models. Finally, we utilize
the obtained expressions to evaluate important network performance metrics such
as the outage probability, ergodic capacity, and average fairness numerically.
Monte-Carlo simulation results are provided to demonstrate the efficacy of the
derived analytical expressions.Comment: IEEE Transactions on Wireless Communications, 2013. arXiv admin note:
substantial text overlap with arXiv:1206.229
Resource allocation for transmit hybrid beamforming in decoupled millimeter wave multiuser-MIMO downlink
This paper presents a study on joint radio resource allocation and hybrid precoding in multicarrier massive multiple-input multiple-output communications for 5G cellular networks. In this paper, we present the resource allocation algorithm to maximize the proportional fairness (PF) spectral efficiency under the per subchannel power and the beamforming rank constraints. Two heuristic algorithms are designed. The proportional fairness hybrid beamforming algorithm provides the transmit precoder with a proportional fair spectral efficiency among users for the desired number of radio-frequency (RF) chains. Then, we transform the number of RF chains or rank constrained optimization problem into convex semidefinite programming (SDP) problem, which can be solved by standard techniques. Inspired by the formulated convex SDP problem, a low-complexity, two-step, PF-relaxed optimization algorithm has been provided for the formulated convex optimization problem. Simulation results show that the proposed suboptimal solution to the relaxed optimization problem is near-optimal for the signal-to-noise ratio SNR <= 10 dB and has a performance gap not greater than 2.33 b/s/Hz within the SNR range 0-25 dB. It also outperforms the maximum throughput and PF-based hybrid beamforming schemes for sum spectral efficiency, individual spectral efficiency, and fairness index
Dynamic Time-domain Duplexing for Self-backhauled Millimeter Wave Cellular Networks
Millimeter wave (mmW) bands between 30 and 300 GHz have attracted
considerable attention for next-generation cellular networks due to vast
quantities of available spectrum and the possibility of very high-dimensional
antenna ar-rays. However, a key issue in these systems is range: mmW signals
are extremely vulnerable to shadowing and poor high-frequency propagation.
Multi-hop relaying is therefore a natural technology for such systems to
improve cell range and cell edge rates without the addition of wired access
points. This paper studies the problem of scheduling for a simple
infrastructure cellular relay system where communication between wired base
stations and User Equipment follow a hierarchical tree structure through fixed
relay nodes. Such a systems builds naturally on existing cellular mmW backhaul
by adding mmW in the access links. A key feature of the proposed system is that
TDD duplexing selections can be made on a link-by-link basis due to directional
isolation from other links. We devise an efficient, greedy algorithm for
centralized scheduling that maximizes network utility by jointly optimizing the
duplexing schedule and resources allocation for dense, relay-enhanced OFDMA/TDD
mmW networks. The proposed algorithm can dynamically adapt to loading, channel
conditions and traffic demands. Significant throughput gains and improved
resource utilization offered by our algorithm over the static,
globally-synchronized TDD patterns are demonstrated through simulations based
on empirically-derived channel models at 28 GHz.Comment: IEEE Workshop on Next Generation Backhaul/Fronthaul Networks -
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