Wireless Cellular Networks

When aiming for achieving high spectral efficiency in wireless cellular networks, cochannel interference (CCI) becomes the dominant performancelimiting factor. This article provides a survey of CCI mitigation techniques, where both active and passive approaches are discussed in the context of both open- and closed-loop designs.More explicitly, we considered both the family of flexible frequency-reuse (FFR)-aided and dynamic channel allocation (DCA)-aided interference avoidance techniques as well as smart antenna-aided interference mitigation techniques, which may be classified as active approach

Space-Time Encoded MISO Broadcast Channel with Outdated CSIT: An Error Rate and Diversity Performance Analysis

Studies of the MISO Broadcast Channel (BC) with delayed Channel State Information at the Transmitter (CSIT) have so far focused on the sum-rate and Degrees-of-Freedom (DoF) region analysis. In this paper, we investigate for the first time the error rate performance at finite SNR and the diversity-multiplexing tradeoff (DMT) at infinite SNR of a space-time encoded transmission over a two-user MISO BC with delayed CSIT. We consider the so-called MAT protocol obtained by Maddah-Ali and Tse, which was shown to provide 33% DoF enhancement over TDMA. While the asymptotic DMT analysis shows that MAT is always preferable to TDMA, the Pairwise Error Probability analysis at finite SNR shows that MAT is in fact not always a better alternative to TDMA. Benefits can be obtained over TDMA only at very high rate or once concatenated with a full-rate full-diversity space-time code. The analysis is also extended to spatially correlated channels and the influence of transmit correlation matrices and user pairing strategies on the performance are discussed. Relying on statistical CSIT, signal constellations are further optimized to improve the error rate performance of MAT and make it insensitive to user orthogonality. Finally, other transmission strategies relying on delayed CSIT are discussed

A Closed-loop Cross-Layer Scheme for Wireless Multiuser Transmissions

AbstractTo improve transmission efficiency of wireless communication systems, cross-layer design is investigated, which can adapt to the dynamically variable wireless channel characters. In this paper, a novel cross-layer design for multi-user system is proposed to improve system performance. The Beamforming-MIMO cross-layer system is scheduled through combining multilevel adaptive modulation (AM) at physical layer with truncated automatic repeat request (ARQ) protocol at data link layer, and feed backing modulation mode, ARQ request and transmit weight vector from receiver, in order to improve multi-antennas system performance. This paper derives close-form expressions of the system spectral efficiency and the outage probability for wireless multiuser MIMO transmissions. It shows by simulation that, compared to Alamouti's cross-layer system and SISO cross-layer system, this cross-layer system can achieve better performance. And we analyze the impact of the transmit antenna number and mobile user number on the performance