REACT is a distributed resource allocation protocol that can be used to negotiate airtime among nodes in a wireless network. In this thesis, REACT is extended to support quality of service (QoS) airtime in an updated version called REACT QoS . Nodes can request the higher airtime class to receive priority in the network. This differentiated service is provided by using the access categories (ACs) provided by 802.11, where one AC represents the best effort (BE) class of airtime and another represents the QoS class. Airtime allocations computed by REACT QoS are realized using an updated tuning algorithm and REACT QoS is updated to allow for QoS airtime along multi-hop paths. Experimentation on the w-iLab.t wireless testbed in an ad-hoc setting shows that these extensions are effective. In a single-hop setting, nodes requesting the higher class of airtime are guaranteed their allocation, with the leftover airtime being divided fairly among the remaining nodes. In the multi-hop scenario, REACT QoS is shown to perform better in each of airtime allocation and delay, jitter, and throughput, when compared to 802.11. Finally, the most influential factors and 2-way interactions are identified through the use of a locating array based screening experiment for delay, jitter, and throughput responses. The screening experiment includes a factor on how the channel is partitioned into data and control traffic, and its effect on the responses is determined.

Medium access control (MAC) is a fundamental problem in wireless networks.

In ad-hoc wireless networks especially, many of the performance and scaling issues

these networks face can be attributed to their use of the core IEEE 802.11 MAC

protocol: distributed coordination function (DCF). Smoothed Airtime Linear Tuning

(SALT) is a new contention window tuning algorithm proposed to address some of the

deficiencies of DCF in 802.11 ad-hoc networks. SALT works alongside a new user level

and optimized implementation of REACT, a distributed resource allocation protocol,

to ensure that each node secures the amount of airtime allocated to it by REACT.

The algorithm accomplishes that by tuning the contention window size parameter

that is part of the 802.11 backoff process. SALT converges more tightly on airtime

allocations than a contention window tuning algorithm from previous work and this

increases fairness in transmission opportunities and reduces jitter more than either

802.11 DCF or the other tuning algorithm. REACT and SALT were also extended

to the multi-hop flow scenario with the introduction of a new airtime reservation

algorithm. With a reservation in place multi-hop TCP throughput actually increased

when running SALT and REACT as compared to 802.11 DCF, and the combination of

protocols still managed to maintain its fairness and jitter advantages. All experiments

were performed on a wireless testbed, not in simulation.