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—The fairness concept has been widely studied in the area of data networks. The most well-known fairness criterion (max–min fairness) gives priority to the minimum-rate session. Kelly questioned its appropriateness in his works on the band-width sharing among the end-to-end flows and proposed another fairness criterion preferring short-distance flows to(More)
—Orthogonal frequency-division multiple access (OFDMA) systems are considered promising candidates for implementing next-generation wireless communication systems. They provide multiple channels that can be accessed via random access schemes. However, traditional random access schemes could result in an excessive amount of access delay. To address this(More)
Mobile stations in the cell boundary experience poor spectral efficiency due to the path loss and interference from adjacent cells. Therefore, satisfying QoS requirements of each MS at the cell boundary has been an important issue. To resolve this spectral efficiency problem at the cell boundary, deploying fixed relay stations has been actively considered.(More)
— It was recently shown that 802.11b MAC has an " anomaly " that the throughput of high bit-rate terminals in good channel condition is down-equalized to that of the lowest bit-rate peer in the network. In this letter, we analytically prove that the phenomenon can be cleanly resolved through configuring the initial contention window size inversely(More)
— The OFDMA systems are emerging for future cellular networks. Creating multiple data channels, they can support the flexible frequency reuse factor (FRF). Although FRF 1 is the best choice in terms of cell throughput, it causes intercell interference at the cell boundary, thereby being unable to serve the whole cell area. Therefore it was proposed to use(More)
—Due to the limited battery in wireless sensor networks (WSNs), energy efficiency is an important factor when designing a MAC Protocol. To minimize energy consumption, most of MAC Protocols in WSNs exploit low duty cycling. Among those, RMAC [5] allows a node to transmit a data packet for multiple hops in a single duty cycle, which is made possible by(More)
By adopting multiple-input-multiple-output (MIMO) antenna technologies, IEEE 802.11 wireless LANs are evolving into high speed systems. While only one user can transmit at a time in the conventional IEEE 802.11 systems, we investigate the possibility of multiuser transmission by using MIMO antennas, which is now known as multiuser MIMO. The multiuser MIMO(More)
— Opportunistic scheduling provides a good chance to improve wireless system performance by exploiting the underlying channel condition. There has been a lot of work on opportunistic scheduling, but the problem of finding the right feedback mechanism to convey channel information has largely been untouched. In emerging multichannel systems, the per-channel(More)
— It is well known that opportunistic scheduling by using feedback information significantly improves wireless network performance. Most opportunistic scheduling works have focused on the case where a single channel is shared by multiple users. However, emerging wireless technologies (e.g., MIMO, OFDMA, etc.) are characterized by multiple shared channels,(More)