Wireless communications

Wireless Communications

Wireless cellular networks are experiencing enormous growth due to factors such as improved infrastructure and standards, as well as a tremendous increase in data, in particular, video traffic. Efficient utilization of these networks is important to end users and network operators alike.

Network capacity refers to how the amount of traffic and users that a network can support. We are developing techniques to improve network capacity by dynamically responding to changes in the traffic load and locations of users.

We are particularly interested in the opportunities offered by overlapping coverage – i.e. when a mobile phone is within the service region of multiple base stations. This occurs in traditional cellular networks when the mobile phone is at a location where it is visible to multiple base stations. It also occurs in certain types of femtocell environments. A femtocell is a very small, “personal” base station that can be placed indoors in a business or home, and that uses the internet for backhaul. We have found that significant improvements in service quality can be achieved by making base station assignment decisions based of a combination of factors including the type of traffic and the load on the network.

More Intelligent Use of Spectrum

The current and emerging generations of wireless communications technologies offer the promise of very high data rates, but will put increasing strain on wireless spectrum, which is a fundamentally limited resource. This resource can be more effectively used if radios are “cognitive” – i.e., if they can sense the presence of other users of spectrum and adapt their own behavior accordingly.

While the concept of cognitive radio has been studied for several years, there remain many open issues that must be resolved in order for these techniques to have significant commercial impact. Our research in this area is aimed at addressing challenges including how to most efficiently monitor the spectrum to determine appropriate transmission behavior. For example, as described in small pdf icon one our papers in IEEE Communications Letters, statistical methods can be used to identify important information about spectrum usage in a given area.