1,451 research outputs found
Performance Analysis of Heterogeneous Feedback Design in an OFDMA Downlink with Partial and Imperfect Feedback
Current OFDMA systems group resource blocks into subband to form the basic
feedback unit. Homogeneous feedback design with a common subband size is not
aware of the heterogeneous channel statistics among users. Under a general
correlated channel model, we demonstrate the gain of matching the subband size
to the underlying channel statistics motivating heterogeneous feedback design
with different subband sizes and feedback resources across clusters of users.
Employing the best-M partial feedback strategy, users with smaller subband size
would convey more partial feedback to match the frequency selectivity. In order
to develop an analytical framework to investigate the impact of partial
feedback and potential imperfections, we leverage the multi-cluster subband
fading model. The perfect feedback scenario is thoroughly analyzed, and the
closed form expression for the average sum rate is derived for the
heterogeneous partial feedback system. We proceed to examine the effect of
imperfections due to channel estimation error and feedback delay, which leads
to additional consideration of system outage. Two transmission strategies: the
fix rate and the variable rate, are considered for the outage analysis. We also
investigate how to adapt to the imperfections in order to maximize the average
goodput under heterogeneous partial feedback.Comment: To appear in IEEE Trans. on Signal Processin
Opportunistic Scheduling for Full-Duplex Uplink-Downlink Networks
We study opportunistic scheduling and the sum capacity of cellular networks
with a full-duplex multi-antenna base station and a large number of
single-antenna half-duplex users. Simultaneous uplink and downlink over the
same band results in uplink-to-downlink interference, degrading performance. We
present a simple opportunistic joint uplink-downlink scheduling algorithm that
exploits multiuser diversity and treats interference as noise. We show that in
homogeneous networks, our algorithm achieves the same sum capacity as what
would have been achieved if there was no uplink-to-downlink interference,
asymptotically in the number of users. The algorithm does not require
interference CSI at the base station or uplink users. It is also shown that for
a simple class of heterogeneous networks without sufficient channel diversity,
it is not possible to achieve the corresponding interference-free system
capacity. We discuss the potential for using device-to-device side-channels to
overcome this limitation in heterogeneous networks.Comment: 10 pages, 2 figures, to appear at IEEE International Symposium on
Information Theory (ISIT) '1
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