MIMO techniques supported by IEEE 802.16 networks improve either throughput or reliability in the network. But these MIMO techniques do not always perform optimally, especially in the presence of high mobility. In this paper, we propose a cross layered mapping technique that exploits multiple antenna available at each MS. An optional error correction mechanism is proposed at the receiver to correct erroneously received signal. Finally, using extensive simulations we show that the proposed technique achieves higher throughput compared to the existing techniques while providing the same reliability. We also show that the proposed technique can be a stand alone technique and adaptive switching of MIMO techniques is not required.

Stanford University Interim (SUI) channel model has been proposed for simulations, design, development and testing of technologies suitable for IEEE 802.16 networks. SUI channel model proposes a set of six empirical time-dispersive channels for three typical terrain types. Most of the simulation studies for IEEE 802.16 networks involving Multi-Input Multi-Output (MIMO), either use a flat fading channel model or adopt an existing analytical/standard model, such as Kronecker model, 3GPP, IEEE 802.11 Broadband wireless models, and Pedestrian model A-B. Although this reduces the complexity of the channel models, it results in lower accuracy. This paper presents the evaluation of Bit Error Rate (BER) performance of various MIMO techniques for 2×2 and 4×4 antenna configurations, over SUI channel models. The encoding and decoding equations for Space-Time Block Code (STBC) \(\mathcal{G}4\) and Spatial Multiplexing (SM) for frequency selective channels are also presented.

Although the IEEE 802.16 standard defines various QoS classes and their associated parameters, it does not define the scheduling, routing, and Call Admission Control (CAC) algorithms to be used in the network. It is left unstandardized for vendor differentiation. Currently, scalable distributed scheduling and routing algorithms are available for IEEE 802.16 mesh networks. But, the existing CAC algorithms are not entirely distributed and hence are not scalable. The algorithms not only create a bottleneck at the first hop nodes, but may also introduce an unbounded delay during the connection setup phase. In this paper, we propose an Instantaneous CAC algorithm which uses per-hop multi path routing for IEEE 802.16 mesh networks. Also, the proposed CAC algorithm eliminates the unbounded connection initiation delay and generates information for distributed routing tables. Finally, using extensive simulations, we compare the proposed protocol with Shortest Widest Efficient Bandwidth (SWEB) and Greedy Choice with Bandwidth Availability aware Defragmentation (GCAD). Simulations show that the proposed protocol eliminates the CAC delay and also improves the system throughput. The proposed protocol, reduces the number of packets (VBR and CBR) exceeding the delay requirements by about 15% and the connection delay by about 40%.

A novel method to solve the pairing problem for Collaborative Spatial Multiplexing (CSM) in IEEE 802.16 networks is proposed in this letter. This method profiles the traffic generated by mobile stations according to their QoS requirements. User pairs with similar traffic profiles and physical layer compatibility are chosen. We show how the pairing problem can be reduced to a minimum weight perfect matching problem which can be polynomially solved using Edmond's algorithm. Simulation results show that the proposed method improves the capacity of the system by at least 20% while reducing the delay for real-time traffic by about 15%.