Category Archives: Publications

The Future of WiMAX: Multihop Relaying with IEEE 802.16j

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Abstract: Relaying and cooperation have re-emerged as important research topics in wireless communication over the past half-decade. Although multihop relaying for coverage extension in wireless networks is an old concept, it became practical only recently. Nowhere is this better illustrated than in the IEEE 802.16 working group, which has devoted a task group to incorporating relay capabilities in the foundation of mobile WiMAX-IEEE 802.16e-2005. Currently, this task group is in the process of finishing IEEE 802.16j, the Multihop Relay Specification for 802.16. This amendment will be fully compatible with 802.16e-2005 mobile and subscriber stations, but a BS specific to 802.16j will be required for relays to operate. This article presents an introduction to the upcoming IEEE 802.16j amendment and provides insight about the obstacles that practical system designers face when incorporating relaying into a wireless broadband network.

by Kuma CEO Steven Peters and CINO Robert Heath, Jr.
Copyright 2009 IEEE. Reprinted from IEEE Communications Mag., v. 47, no. 1, pp. 104-111, Jan. 2009.

A Current Perspective on Distributed Antenna Systems for the Downlink of Cellular Systems

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Abstract: Providing uniformly high capacity in cellular systems is challenging due to fading, path loss, and interference. A partial solution to this problem is the deployment of distributed antenna systems, where transmission points are distributed throughout the cell using coax cable or fiber, instead of being centrally located on a single tower. This article reviews how distributed antenna systems are evolving to provide higher performance on the downlink in cellular systems. Research trends in distributed antennas for the downlink of cellular systems are described along with current progress on their integration into commercial wireless cellular standards. A key observation is that distributed antenna systems are tightly integrated into the cellular architecture, and incorporate physical layer technologies like MIMO communication and multiuser MIMO to provide higher data rates.

by Kuma CINO Robert Heath, Jr., CEO Steven W. Peters, et al.
Copyright 2013 IEEE. Reprinted from IEEE Wireless Mag., Apr. 2013.