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— Due to the broadcast nature of wireless signals, a wireless transmission intended for a particular destination station can be overheard by other neighboring stations. A focus of recent research activities in cooperative communications is to achieve spatial diversity gains by requiring these neighboring stations to retransmit the overheard information to(More)
— In this paper, a novel idea of user cooperation in wireless networks has been exploited to improve the performance of the IEEE 802.11 medium access control (MAC) protocol. The new MAC protocol leverages the multi-rate capability of IEEE 802.11b and allows the mobile stations (STA) far away from the access point (AP) to transmit at a higher rate by using(More)
— Cooperative communications fully leverages the broadcast nature of the wireless channel and spatial diversity, thereby achieving tremendous improvements in system capacity and delay. By enabling additional collaboration from stations that otherwise will not directly participate in the transmission, cooperative communications ushers in a new design(More)
— IEEE 802.15.4-2003 [1] was introduced to address the market need for connecting low-rate devices in a wireless personal area network (WPAN). A slotted CSMA/CA medium access control (MAC) protocol is defined in the standard to coordinate the channel access of a large number of wireless devices. In this paper, we propose a novel Markov chain for IEEE(More)
Thanks to the immense potential cooperative communications displays , extensive investigations have been directed to examine its performance by means of both analysis and simulation. In this paper 3 , an implementation approach has for the first time been pursued to demonstrate the viability of realizing cooperation at the MAC layer in a real environment.(More)
Frame structure is critical to an IEEE 802.16e OFDMA network, as it governs the fundamental channel access in both time and frequency domain. The framework structure design is tremendously complicated in the new mobile multi-hop relay-based (MMR) network architecture , as numerous dimensions of design constraints and challenges have been introduced therein.(More)
— Advances in cooperative communications and directional antenna design so far have taken place in parallel , if not in isolation from each other. To explore the role they may play in the next generation of wireless networks, it is important to design and evaluate protocols that can provide co-opdirectionality, the capability of tapping into the combined(More)
—In this letter, we propose a three-dimensional Markov chain model for the 802.11e enhanced distributed channel access (EDCA) mode. This model can be used to compute the maximum sustainable throughput and service delay distribution for each priority class when under saturation load. The new framework models the performance impact of major quality-of-service(More)