Research On Adaptive Resource Allocation In Wireless OFDMA System

Orthogonal Frequency Division Multiple Access (OFDMA) is a multiple access technology combining Orthogonal Frequency Division Multiplexing (OFDM) and Frequency Division Multiple Access (FDMA) and is considered as one of the key technologies in 4G mobile communication systems. Based on the OFDM modulation, OFDMA achieves the multi-user access according to allocate the subcarriers to every user independently. In the multi-user systems, to implement the optimal resource allocation, it adaptively allocates the system resource to users according to their wireless channel states, Quality of Service (QoS) parameters and so on. The results are that the system could attend higher spectrum utilization and satisfy more users' QoS requirements than no adaptive resource allocation ones. Therefore, adaptive resource allocation is a very important research direction and one of the key and imperative technologies in OFDMA system.In this thesis, a cross-layer network architecture is newly introduced in the adaptive resource allocation for OFDMA, and more, some new schemes and algorithms are developed for adaptive resource allocation. All requirements for adaptive resource allocation in OFDMA are systemically analyzed and researched. To summary, our works include the following five aspects:(1) Channel estimation is the one of the preconditions in adaptive resource allocation. In this aspect, we develop the Fast Recursive Least Squares (FRLS) channel estimation algorithm and combine it with Minimize Mean Square Error (MMSE) algorithm. This scheme is formed after analyzing the Least Squares (LS) and MMSE algorithms and the simulations result show that this algorithm is efficient.(2) For the adaptive resource allocation scheme based on the original Open System Interconnect (OSI) network architecture, we develop the grouped adaptive resource allocation scheme, after analyzing the Water-filling and Lagrange algorithms. Numerical results show that our scheme only needs little information to deliver the adaptive resource allocation scheme and this scheme is more suitable for fast-varied channel or multi-media traffic.(3) Because the available adaptive resource allocation schemes can not satisfy...