Bernhard Walke

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In recent years, there has been an upsurge of interest in multihop-augmented infrastructurebased networks in both industry and academia, such as the seed concept in 3GPP, mesh networks in IEEE 802.16, and coverage extension of HiperLAN/2 through relays or user-cooperative diversity mesh networks. This article, a synopsis of numerous contributions to Working(More)
and Introduction Legacy 802.11 • Distributed Coordination Function • Point Coordination Function QoS Support Mechanisms Of 802.11e • Basic Improvements of the Legacy 802.11 Mac • HCF Contention-based Medium Access • Hybrid Coordination Function, Controlled Medium Access • Improved Efficiency Evaluation Summary and Conclusions
The wireless local area network standard IEEE 802.11 is the preferred solution for lowcost data services. Key to its success are the 2.4 and 5 GHz unlicensed bands. The transmit power limitations imposed due to regulatory requirements limit the range (coverage) that can be achieved by WLANs in these bands. However, the demand for “larger” wireless(More)
The future cellular radio networks like 3G-LTE [1] are based on an OFDMA physical layer. The duplex scheme is preferably frequency division (FDD) because of its advantages in long range. Huge area coverage in a cost-efficient way is important problem for the early deployment. Time after time the demand in densely populated areas will grow, so a higher cell(More)
Multihop cellular networks offer increased coverage and capacity compared to singlehop cells of the same size. This is not as huge as using more base stations (BS) instead of wireless relay nodes (RN), but by this way there is no need for a fixed network access to each node. Therefore a cost-efficient deployment is easily achieved (less CAPEX and OPEX).(More)
Inter-cell interference (ICI) mitigation is always a big challenge issue in cellular systems. In this work we propose an Enhanced Fractional Frequency Reuse (EFFR) scheme combined with power allocation and an interference-aware reuse mechanism to achieve not only ICI limitation at cell edge but also enhancement of overall cell capacity in orthogonal(More)