Wireless networks are generally characterized by a medium shared among a group of users. This makes an appropriate media access control (MAC) protocol essential for efficient channel utilization. Wireless MAC protocols show significant performance degradation in some challenging networks (e.g., military HF radio) that are characterized by long link-layer turnaround times, and most of the recent research does not address this problem. This paper develops queueing models for two functional categories of wireless MAC protocols; DCHF, a contention-based MAC protocol and token-passing, a contention-free MAC protocol, and explores their statistical performance for varying link-layer turnaround times under varying Poisson loads. Simulation models for these protocols have been developed to substantiate the statistical analysis.

Routing and related resource allocation issues present special challenges in ad hoc networks. Typically, every node in an ad hoc network serves as a router for other nodes, and paths from source to destination often require multiple hops. Compared to wired networks, wireless ad hoc networks have less bandwidth, longer paths, and less stable connectivity, all of which render routing protocols from wired networks less suitable for the wireless world. This paper presents a novel routing scheme for ad hoc networks that applies fuzzy logic to differentiated resource allocation, considering traffic importance and network state. Messages are routed over zero or more maximally disjoint paths to the destination: important packets may be forwarded redundantly over multiple disjoint paths for increased reliability, while less important traffic may be suppressed at the source. The performance of fuzzy routing is evaluated using simulation, and is compared to dynamic source routing (DSR) and split multipath routing (SMR) wireless routing protocols.

As processor microarchitectures continue to increase in complexity, so does the time required to explore the design space. Performing cycle-accurate, detailed timing simulation of a realistic workload on a proposed processor microarchitecture often incurs a prohibitively large time cost. We propose a method to reduce the time cost of simulation by dynamically varying the complexity of the processor model throughout the simulation. In this paper, we give first evidence of the feasibility of this approach. We demonstrate that there are significant amounts of time during a simulation where a reduced processor model accurately tracks important behavior of a full model, and that by simulating the reduced model during these times the total simulation time can be reduced. Finally, we discuss metrics for detecting areas where the two processor models track each other, which is crucial for dynamically deciding when to use a reduced rather than a full model.

The tremendous storage space required for a useful data base of program traces has prompted a search for trace reduction techniques. In this paper, we discuss a range of information-lossless address and instruction trace compression schemes that can reduce both storage space and access time by an order of magnitude or more, without discarding either references or interreference timing information from the original trace. The PDATS family of trace compression techniques achieves trace coding densities of about six references per byte. This family of techniques is now in use as the standard in the NMSU TraceBase, an extensive trace archive that has been established for use by the international research and teaching community.

The tremendous storage space required for a useful data base of memory reference traces has prompted a search for trace compaction techniques. PDATS is the standard trace format used in the NMSU TraceBase, a widely used archive of memory and instruction traces. The PDATS family of trace compression techniques achieves trace coding densities of about six references per byte with no loss of reference type or address information by using differential run-length encoding. This paper proposes an improvement on the PDATS scheme that doubles the typical compression ratio without losing information.