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—In this paper, we introduce the concept of " route robustness " for path selection in multi-hop cognitive radio networks. We demonstrate that the aggregate throughput and the robustness of routes determined by the proposed route selection strategy are superior to existing rate-based selection strategies. The rationale behind our approach is to guarantee a(More)
—Beamforming is used in IEEE 802.15.3c networks to avoid high propagation attenuation and path loss and improve the overall system throughput by exploiting spatial channel reuse. In this paper, we introduce design challenges of scheduling in beamforming-enabled IEEE 802.15.3c networks. These challenges include positioning, axis alignment, and interference(More)
IEEE 802.16 Broadband Wireless Access system (BWA) is a promising emerging technology. In the IEEE 802.16 standard, multiple data transmission rates are defined by employing different modulation and channel coding schemes. How to select a proper mode affects the system performance significantly. In this paper, an efficient link adaptation scheme with QoS(More)
networks in the near future. In such an environment, heterogeneous handoff is possible. How to keep guaranteeing the handoff connection its QoS demand, and in the meantime, avoid impacting on other connections is a challenge to support real-time applications in a heterogeneous network. In this paper, we develop a heterogeneous network in NS-2 simulator. In(More)
—In this paper, we study the determination of down-link (DL) and uplink (UL) channel split ratio for Time Division Duplex (TDD)-based IEEE 802.16 (WiMAX) wireless networks. In a TDD system, uplink and downlink transmissions share the same frequency at different time intervals. The TDD framing in WiMAX is adaptive in the sense that the downlink to uplink(More)
One of the most challenging issues in cognitive radio networks is efficient channel sensing and channel accessing. In this paper, an analytical queueing model is used to derive the probability of successful transmission, channel sensing time, and transmission quota, for each data channel. Each CR node records the derived statistics in a channel preference(More)