Keith Conner

MUD Enabled Media Access Control for High Capacity, Low-Latency Spread Spectrum Communications

Unlike conventional wireless communication systems that operate under an interference avoidance paradigm, the DARPA Interference Division Multiple Access (IDMA) program exploits multi-access interference to enable high-capacity, low-latency spread spectrum communication that requires no infrastructure or coordination. The enabling technology behind IDMA is Multi-User Detection (MUD) at the Physical Layer, which enables a receiver to simultaneously demodulate multiple interfering users. To fully exploit this new Physical Layer capability, novel Media Access Control (MAC) protocols are required that control and encourage users to collide rather than avoid interference all together. This paper discusses the motivating factors behind the IDMA MAC design and highlights the technical challenges in developing a MAC that both facilitates and exploits MUD at the Physical Layer. Particular attention is given to key decentralized MAC mechanisms, including distributed synchronization and scheduling. Analysis is presented highlighting the performance gains of IDMA over conventional adhoc communication systems, such as 802.11. Looking to the future, insight is provided into military applications and concepts of operations where IDMA technology is expected to dramatically improve performance and provide novel capabilities to the warfighter.

A PMP-Friendly MANET Networking Approach for WiMAX/IEEE 802.16/sup TM/

WiMAX Forum certifiedtrade broadband wireless equipment is now available to military users and consumers alike. This equipment is based on the IEEE 802.16/sup TM/-2004 and IEEE 802.16e/sup TM/-2005 standards. This commercial off-the-shelf (COTS) equipment promises to greatly reduce the cost of broadband wireless access and lead to cost-effective solutions for the military. However, existing COTS equipment has performance deficiencies when considered for military and national security operational scenarios. One deficiency is the lack of mobile ad-hoc and mesh networking capabilities compatible with the currently fielded point-to-multipoint (PMP) mode. While the IEEE 802.16-2004 standard includes a mesh capability, it does not interoperate with the PMP mode, and is not being considered for implementation. The IEEE 802.16e-2005 amendment addresses subscriber mobility but does nothing to address the ad-hoc and mesh shortcomings in WiMAX and IEEE 802.16-2004. This paper reviews some current and planned capabilities of WiMAX, and recommends extensions to the IEEE 802.16 standard to facilitate mobile ad-hoc and mesh networking protocols that can interoperate with planned WiMAX deployments