• Cognitive Radio Networking

When we take a look at spectrum allocation chart in US, we can see that almost all spectrum has already been allocated and it requires license to operate. Small portion of unlicensed spectrum is already overcrowded because of the successful deployment of innovative wireless networking including Wireless LAN (WLAN), Mesh networks, Blue tooth and so on. On one hand, there is no more spectrum left to be allocated for future wireless technologies, on the other hand recent surveys have shown that the most of the licensed spectrum is either underutilized or idle most of the time. Thus the motivation is to develop the adaptive algorithms through which the wireless devices change their transmission parameters such as transmit power, modulation schemes, frequency, networks, and so on, according to their operating wireless environment in which they operate. Wireless devices can access underutilized or idle licensed spectrum dynamically and opportunistically without creating harmful interference to the licensed users, and the technology is regarded as Cognitive Radio. One challenge in Cognitive Radio Network (CRN) is to detect the spectrum optimally and reliably so that the cognitive radio users (unlicensed users) would not create harmful interference to licensed users while they use idle spectrum opportunities dynamically. Major research challenges are: to sense and detect the idle or underutilized spectrum in wide band regime, to allocate wireless resources such as power, channel, etc., to secure/protect primary users, to design robust routing protocols. For more details on the projects, please visit the following web page(s).

• Dynamic Spectrum Access (DSA) in Interference Systems 
• Interference Management in Cognitive Radio Networks

• Vehicular Communications/Vehicular ad hoc Networks

A Vehicular Ad-hoc Network (VANET) is a special case of Mobile Ad-hoc Network (MANET) to enable exchange of information among nearby vehicles using vehicle-to-vehicle (V2V) communications and between vehicles as well as nearby roadside unit (RSU) using vehicle-to-roadside (V2R) communications. VANETs are expected to implement variety of wireless technologies to provide safety as well as comfort for passengers and to make more efficient roads in the future by providing timely information to drivers and concerned authorities. The message forwarding and propagation in VANET should be done in small amount of time. Reliability and low delay are extremely important factors for VANET applications to propagate and disseminate the message toward the region of interest. In V2V based vehicular communications, it is also important to check the legitimate of the received message since a given vehicle can work as a router, source and destination for the message. VANETs are expected to implement variety of wireless technologies to provide safety as well as comfort for passengers and to make more efficient roads in the future by providing timely information to drivers and concerned authorities. For more details on the projects, please visit the following web page(s).

• CRAVE: Cognitive Radio Enabled Vehicular Communication System
• Cross-layer based information dissemination in VANETs
• Vehicular Ad hoc Network (VANET) Security
• Vehicular Cloud
• VANET Prototype

The future generation wireless networking will incorporate a large number of autonomous wireless objects, which includes humans, machines, cars or unmanned aerial vehicles, moving with diverse speed and pattern, and generating, relaying and/or absorbing data requiring global interoperability among objects. For more details on the projects, please visit the following web pages:

• WiN-MOves

Application of Game Theory in Resource Allocation in Wireless Networks

Game theory is regarded as an optimization tool for resource allocation in wireless networks. Players, which are active users in wireless networks, change their strategies based on the wireless environment in which they operate. After few steps, each player would reach to socially optimal point called Nash equilibrium at which no players would be benefited by deviating its own strategies. Resource allocation in wireless systems using game is scalable and easy to measure the performance. 

When we take a look at spectrum allocation chart in US, we see that almost all spectrum has already been allocated and requires license to operate. Small portion of unlicensed spectrum is already overcrowded because of the successful deployment of innovative wireless networking including Wireless LAN (WLAN), Mesh networks, Blue tooth and so on. On the one hand there is no more spectrum left to be allocated for future wireless technologies, on the other hand recent surveys have shown that the most of the licensed spectrum is either underutilized or idle most of the time. Thus the motivation is to develop the real time adaptive algorithms to sense the spectrum to identify spectrum opportunities and use them opportunistically and dynamically without creating harmful interference to primary users.

Due to the recent changes in electrical consumption behavior and technological advancement, demand of power grids have increased drastically. Robust and efficient delivery and distribution of electricity, integration of renewable energy sources into the grid cannot function without an extensive data communication system.

Wireless communication is the fastest growing sector of the communication industry. Over the last decade, small portion of unlicensed spectrum has encouraged innovations in wireless networking including wireless LAN, Mesh, blue tooth, and so on. These wireless device has become popular in recent years and has received wide deployments.The known fact is that the devices operating in same band create interference to others and hurt overall system performance. Therefore we need to have some adaptive algorithms through which wireless device can adapt their transmission parameters according to their operating environment. One solution is, for a given system in which K users operate in a signal space dimension N (aka processing gain in CDMA system), assign orthogonal signatures to the users when the number of users K is less than or equal to N. And assign precoders such that they satisfy the GWBE when the number of users K > N.

IEEE 802.11e has a coordination function, which has both contention-based and contention free medium access methods, in order to support applications with Quality of Service (QoS) requirements. The contention based MAC protocol that is Enhanced Distributed Channel Access (EDCA) supports QoS however it cannot guarantee strict QoS required by real-time applications without proper tuning of QoS parameters and network control mechanisms. The performance of wireless LAN (WLAN) for real-time or delay sensitive applications can be improved by admission control and tuning QoS parameters based on the environment in which the devices operate.

Wireless networks are ubiquitous, inexpensive, and anyone can setup a wireless network. In wireless network, vulnerability of security and privacy are major concern to protect from malicious actions.

Wireless sensor network consist of distributed autonomous sensors in which each node is typically equipped with a radio transceiver, a small computing device and an energy source. Energy efficient resource allocation is of vital importance in sensor network. An ad-hoc or short-live network is the network of two or more mobile devices connected to each other without the help of intervening infrastructure. A mobile ad-hoc sensor or hybrid ad-hoc network consists of a number of sensor spreads in a geographical area. Each sensor is capable of mobile communication and has some level of intelligence to process signals and to transmit data.

Advanced signal processing technology not only dramatically increases wireless system capacity, but also improve communication quality, including the reduction of the effects of all types of interference.

Applying learned social, group behavior and communication systems of certain species (many unforeseen great concepts) to engineering domains is likely to inspire solutions to a number of problems.

License-free 60GHz radios have unique characteristics that make them significantly different from traditional 2.4GHz or 5GHz license-free radios and from licensed-band millimeter-wave radios. These characteristics give 60GHz radios operational advantages not found in other wireless systems.