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In this paper we combine a new adaptive spatial TDMA and optimum routing for cross layer design in wireless mesh networks. For wireless media access we investigate uniform STDMA as well as a new adaptive version thereof. An overall optimization routine finds simultaneously the best route and the best capacity allocation (termed as uniform and adaptive STDMA allocation) to various nodes. This optimization routine minimizes the average end to end packet delay over all calls subject to various constraints. We also investigate the level of connectivities on the various performance criteria taking two cases of possible topologies. Given a certain wireless channel and hence average packet transmission success probability (typically relayed from PHY layer to routing network layer in cross layer design) we compute the end to end average delay and delay jitter over all calls yielded by the cross layered optimization algorithm.

The medium access control (MAC) technique of standard WLANs, called the distributed coordination function (DCF), is carrier sense multiple access based on collision avoidance (CSMA/CA) scheme with binary slotted exponential backoff. It has a two way handshaking technique for packet transmission and also defines an additional four way handshaking technique called RTS/CTS mechanism, which is used to reduce the hidden terminal problem. The RTS/CTS frames carry the information of the packet length to be transmitted which can be read by any listening stations, to update a network allocation vector (NAV) about the information of the period of time in which the channel is busy. In this paper a method is proposed called the table driven technique (which has two parts called table driven DCF and table driven RTS/CTS) which is similar to the standard DCF (IEEE802.11) and RTS/CTS (IEEE802.11) system without having the exponential backoff. In this technique users use the optimum transmission probability by estimating the number of stations from the traffic conditions in a sliding window fashion one period at a time, thereby increasing the throughput compared to the standard DCF (IEEE802.11) and RTS/CTS (IEEE802.11) mechanism while maintaining the same fairness and the delay performance.

The random access control (MAC) technique of standard WLANs is called the distributed coordination function (DCF) [3]. DCF is a carrier sense multiple access based on collision avoidance (CSMA/CA) scheme with binary slotted exponential backoff. This exponential backoff makes the system more complex, and fairness [3−13] among the stations is a major concern. This chapter shows one possible evolution of WLANs where exponential backoff is not employed. In the new techniques herein users transmit randomly but adapt themselves to traffic conditions, thus improving throughput and delay while guarantying fairness. Users in the first technique are controlled by a table which is derived from traffic measurements (table driven). In the second, users’ transmission activities are function of their buffer contents.

Wide band mesh or star oriented networks have recently become a subject of greater interest. Providing wideband access for a variety of applications has led to the inception of WIMAX. Classic access techniques such as FDMA and TDMA have been norm for such networks. Their maximum transmitter power is much less than their TDMA and FDMA counter parts, which are very important assets for mobile operation. In this paper we introduce a code division multiple access/Time division duplex technique CDMA/TDD for such networks. The CDMA approach is an almost play and plug technology for wireless access, making it amenable for implementation by WIMAX service station. In addition we adopt a virtual circuit (label) to improve packet overhead efficiency. We outline briefly the new transmitter and receiver structures then evaluate efficiency, delay and delay jitter. By analysis we show the advantages over classic counter parts with respect to total network efficiency achievable especially for larger number of hops.