Throughput-storage tradeoff in ad hoc networks

Gupta and Kumar (2000) showed that the throughput capacity of static ad hoc networks with n randomly positioned nodes is /spl Theta/(/spl radic/(n/log n)). Grossglauser and Tse showed that node mobility increases the capacity to /spl Theta/(n), a substantial improvement. Achieving maximum capacity requires nodes to relay transmissions through other nodes. Each node must have a relay buffer for temporarily storing packets before forwarding them to their destination. We establish that if relay buffer sizes are bounded above by a constant, then mobility does not substantially increase the throughput capacity of mobile ad hoc networks. In particular, we show that the capacity of mobile networks with finite buffers is at most /spl Theta/(/spl radic/n). Finally we establish a scaling law relationship that characterizes the fundamental tradeoff between throughput capacity and relay buffer size. In particular, we show that the throughput capacity is at most /spl Theta/(/spl radic/(nb/sub n/)), where b/sub n/ is the size of the relay buffers.