A great deal of research has been carried out regarding increasing the capacity of wireless networks. The general findings are that increasing the number of nodes in a wireless network decreases individual throughput, simultaneous transmissions cause interference and therefore hinder capacity, and that topology control can increase network power efficiency and reduce the interference within the network. This paper demonstrates that appropriately spaced simultaneous transmissions are beneficial to the capacity of shared spectrum wireless networks and that adding nodes to a wireless network can, in fact, increase its capacity if the nodes are intelligently placed and node transmission powers are appropriately set. In this paper we firstly discuss the inefficiency of high power transmission for networks which allow simultaneous transmissions. It is then demonstrated that if multiple transmitters are utilised simultaneously with uniform transmission power, the network capacity is a local maximum if the required spacing conditions between the receivers are met. In the presence of background noise one can determine that this configuration represents the maximum network capacity achievable. The required separation is defined for the general case and shown to decrease as the number of simultaneous transmissions increases. This result is verified through simulations which demonstrate the construction of high capacity networks. Simulations are also presented which show how existing networks can be augmented with additional nodes and a reduction of transmission power, to exhibit higher uniform average network capacities.
Increasing Wireless Adhoc Network Capacity through Simultaneous Transmissions
