Scalability of Wireless Networks

This paper investigates the existence of scalable protocols that can achieve the capacity limit of c/radicN per source-destination pair in a large wireless network of N nodes when the buffer space of each node does not grow with the size of the network N. It is shown that there is no end-to-end protocol capable of carrying out the limiting throughput of c/radicN with nodes that have constant buffer space. In other words, this limit is achievable only with devices whose buffers grow with the size of the network. On the other hand, the paper establishes that there exists a protocol which realizes a slightly smaller throughput of c/radicNlogN when devices have constant buffer space. Furthermore, it is shown that the required buffer space can be very small, capable of storing just a few packets. This is particularly important for wireless sensor networks where devices have limited resources. Finally, from a mathematical perspective, the paper furthers our understanding of the difficult problem of analyzing large queueing networks with finite buffers for which, in general, no explicit solutions are available