Radio Resource Management in OFDMA-based Cellular Relay Networks.

摘要

The main objective of next-generation wireless networks is to accommodate the increasing user demand and to achieve a ubiquitous high-data-rate coverage so that mobile broadband services comparable to those of the wirelines are realized in a cost-efficient manner. This ambitious objective however faces several technical challenges in the conventional cellular architecture, e.g., the large pathloss. Wireless multihop relaying is therefore among the envisioned solutions; for that relays- with much less functionality and cost than base stations- can extend coverage, overcome shadowing through routing, and/or improve detection in a cooperative manner. Hence, a future network comprising various forms of dedicated wireless relays is envisaged in many wireless standardization bodies and forums which have adopted orthogonal frequency division multiple access (OFDMA) as the prospective air interface.;On these grounds, our objective is to devise intelligent RRM schemes that dynamically optimize the resource allocation in future networks in multiple dimensions; frequency, time, space, power, and relay route, so that bandwidth is efficiently utilized while a reliable and ubiquitous service is achieved regardless of users' locations and channel conditions. Towards that end, mathematical optimization and dynamic programming tools are employed along with novel opportunistic medium access techniques, in a centralized as well as a distributed manner. Various forms of relays of different characteristics and functionalities, such as the fixed and nomadic relays, are incorporated. In addition, algorithms with low computational complexity and signaling overhead are devised for practical implementation.;The synergy of multihop relaying and OFDMA techniques offers a very rich set of opportunities but renders an unsuitable environment for static resource planning This is due to the increased system dynamics, the portion of resources invested in operating the wireless relays, and the co-channel interference associated with the inevitable aggressive reuse of the scarce licensed spectrum. Therefore, intelligent radio resource management (RRM) schemes are required to combat the interference and to operate the relays in a dynamic and opportunistic manner. It is not immediately clear though how to perform RRM in such a complex environment. As such, RRM could be the main obstacle confronting the deployment and operation of future networks.