Time varying channel conditions with high bit error rate causes frequent packet corruptions in wireless communication networks. Cyclic Redundancy Checks (CRCs) and Automatic Repeat reQuest (ARQ) mechanisms are heavily used for effective error detection and recovery, respectively. In previous studies, the performance of CRC generator polynomials is evaluated solely based on Undetected Error (UE) probability without taking retransmission and overhead dynamics into account. This paper presents a new performance evaluation criterion (i.e., link layer goodput) which takes both CRC coding and ARQ dynamics into account. The proposed criterion is used as an objective function to compute the best polynomial and message length pairs corresponding to varying network conditions. We, then, propose an adaptive CRC coding mechanism which dynamically updates the CRC polynomial and message length pair at run-time in accordance with the time varying conditions. Simulation experiments show that dynamic selection of CRC polynomial and message length pair yields significant performance gains.

In this paper we propose cooperative/noncooperative operation models for revenue seeking spectrum brokers who coordinate to manage access to the same spectrum bands in adjacent areas. We consider a setting where users of spectrum are involved in peer-to-peer links with QoS requirements. Each wireless transmission (link) is priced collectively by all revenue seeking brokers whose responsibility areas are affected by the transmission (via interference). We propose a two-level coordination mechanism. At the pricing-level, the brokers affected by a given link collectively determine prices. At the admission level, all brokers potentially affected by all transmissions collectively determine the set of link requests that are to be permitted. The links are modeled as price sensitive users who may or may not form connections, based on the total price asked. Experimental results show that cooperation significantly increases both the number of active links and broker revenues. Relative gains achieved by pricing level cooperation alone or admission level cooperation alone depend on price sensitivity parameters for the links as well as the total number of link formation requests.

The assumption that all nodes cooperate to relay packets for each other may not be realistic for commercial wireless ad hoc networks. An autonomous (selfish) node in a wireless network has two disincentives for forwarding for others: energy expenditure (real cost) and possible delays for its own data (opportunity cost). We introduce a mechanism that "fosters cooperation through bribery" in the context of forwarding in ad hoc networks. Using a microeconomic framework based on game theory, we design and analyze a pricing algorithm that encourages forwarding among autonomous nodes by reimbursing forwarding. Taking a joint network-centric and user-centric approach, the revenue maximizing network and utility (measured in bits-per-Joule) maximizing nodes interact through prices for channel use, reimbursements for forwarding, transmitter power control, as well as forwarding and destination preferences. In a three-node (two-sources, one-access-point) network, the network converges to an architecture that induces forwarding only when the network geometries are such that forwarding is likely to increase individual benefits (network revenue and node utilities). For other geometries, the network converges to architectures that do not favor forwarding. We then generalize to a multinode network, where it is seen that the nodes' willingness to forward decrease for large ratios of the average internodal distance to the smallest distance between the access point and any source node. Pricing with reimbursement generally improves the network aggregate utility (or aggregate bits-per-Joule), as well as utilities and revenue compared with the corresponding pricing algorithm without reimbursement.

Using a microeconomic framework based on game theory, we design and analyze a pricing algorithm that encourages forwarding among autonomous (selfish) nodes by reimbursing forwarding. Taking a joint network-centric and user-centric approach, the revenue maximizing network and utility maximizing nodes interact through prices for channel use, reimbursements for forwarding, transmitter power control as well as forwarding and destination preferences. In a three-node (two sources, one access point) network, the network converges to an architecture that induces forwarding only when the network geometries are such that forwarding is likely to bring higher network efficiency. For other geometries, the network converges to architectures that do not favor forwarding. We characterize the Nash equilibria for each geometry and design specific game implementations to achieve the most Pareto superior Nash equilibrium. In a general multi-node network, our results indicate that the nodes' willingness to forward decrease for large values of the ratio of the average internodal distance to the average distance between the access point and nodes with direct connections to it.