Channel fragmentation in dynamic spectrum access systems: a theoretical study

Dynamic Spectrum Access systems exploit temporarily available spectrum (‘white spaces’) and can spread transmissions over a number of non-contiguous sub-channels. Such methods are highly beneficial in terms of spectrum utilization. However, excessive fragmentation degrades performance and hence off-sets the benefits. Thus, there is a need to study these processes so as to determine how to ensure acceptable levels of fragmentation. Hence, we present experimental and analytical results derived from a mathematical model. We model a system operating at capacity serving requests for bandwidth by assigning a collection of gaps (sub-channels) with no limitations on the fragment size. Our main theoretical result shows that even if fragments can be arbitrarily small, the system does not degrade with time. Namely, the average total number of fragments remains bounded. Within the very difficult class of dynamic fragmentation models (including models of storage fragmentation), this result ...

• Type: Conference
• Year: 2010
• Where: SIGMETRICS
• Authors: Edward G. Coffman Jr., Philippe Robert, Florian Simatos, Shuzo Tarumi, Gil Zussman
• Keywords: Dynamic Fragmentation Models, Excessive Fragmentation Degrades, Hardware, Practical Fragmentation Algorithms, SIGMETRICS 2010