CDMA Implementation for Many-to-Many Cooperation in Mobile Ad Hoc Networks Renato M. de Moraes 1 , Hamid R. Sadjadpour 2 , J.J. Garcia-Luna-Aceves 3 1 Department of Computing Systems – University of Pernambuco (UPE) Recife, PE 50720-001, Brazil 2 Department of Electrical Engineering – University of California (UCSC) Santa Cruz, CA 95064, USA 3 Dept. of Computer Engineering at UCSC and Palo Alto Research Center 3333 Coyote Hill Road, Palo Alto, CA 94304, USA renato@dsc.upe.br, {hamid,jj}@soe.ucsc.edu Abstract. We describe a collaboration-driven approach to the sharing of the avail- able bandwidth in wireless ad hoc networks, which we call many-to-many cooper- ation, that allows concurrent many-to-many communication. This scheme is based on the integration of multi-user detection and position-location information with frequency and code division in mobile ad hoc networks (MANETs). Transmissions are divided in frequency and codes according to nodal locations, and successive interference cancellation (SIC) is used at receivers to allow them to decode and use all transmissions from strong interfering sources. Many-to-many cooperation allows multi-copy relaying of the same packet, which reduces the packet delivery delay compared to single-copy relaying without any penalty in capacity. 1. Introduction Today, communication protocols used in ad hoc networks are meant to support reliable communication among senders and receivers that are competing with one another for the use of the common channel. This “competition-driven” view of bandwidth sharing has had profound implications on network architectures and methods used to access the channel and disseminate information. Gupta and Kumar showed that, in a wireless connected network with static nodes, the throughput for each node degrades as the number of nodes increases under the competition-driven view of networking [Gupta and Kumar 2000]. That is, it scales as Θ(1/  n log(n)), 1 where n is the number of nodes in the network. Grossglauser and Tse analyzed a two-hop, single-relay forwarding scheme for MANETs in which a source passes a packet to a relay that in turn delivers it to the destination when the two nodes are close to each other [Grossglauser and Tse 2001]. This and many subsequent studies on how to make MANETs scale by using mobility [Grossglauser and Tse 2001], [Bansal and Liu 2003], [de Moraes et al. 2004], [Gamal et al. 2004], consider each transmission as competing with all the other concurrent transmissions in the network. However, because a relay cooperates with a source by storing the source’s packet until it is close enough to the intended destination, the throughput of MANETs can be increased. 2 1 Ω, Θ and O are the standard order bounds. log(·) is the natural logarithm. 2 In [Grossglauser and Tse 2001], the per source-destination throughput scales as Θ(1). SBRC 2007 - Cooperação e Auto-Organização. 249