Jee Hwan Ahn

An efficient subcarrier and power allocation algorithm for dual-service provisioning in OFDMA based wibro systems

This paper investigates the problem of resource allocation for quality of service (QoS) support in Orthogonal Frequency Division Multiple Access (OFDMA) based WiBro systems. We identify the key QoS parameters as data rate and bit error rate (BER), which are used to determine the individual traffic demands. We propose a resource allocation algorithm to provide dual-service, Guaranteed Performance (GP) and Best Effort (BE) differentiated on the basis of required QoS. Subcarrier assignment and power allocation are carried out sequentially to reduce the complexity, and GP users are given priority over BE users in assigning subcarrier and allocating power. We present the simulation results of the proposed algorithms applied to frequency selective Rayleigh fading channel with additive white Gaussian noise (AWGN) and OFDMA.

Experimental Analysis for TDMA MAC Design/Implementation of the IEEE 802.16 SS

This paper presents the analysis of TDMA MAC applied to the IEEE 802.16 subscriber station and the uplink timing constraints. And this paper also shows results of the experiments with a few design approaches to check whether each design approach meets uplink timing constraints or not and which additional considerations are required. With a few experiments, although the total sum of the processing latencies of each functional component in MAC design meets the requested uplink timing, additional considerations for a burst of processing latencies with large difference from the average processing time which mainly depends on the characteristics of real-time operating system, traffic load, and the uplink burst length are needed. Considering this additional latency, this paper shows which hardware/software codesign model is analytically more suitable for TDMA MAC than that written in the software and how general partitioning criteria expression also needs to be revised to describe these characteristics.