• Wireless multimedia home networks
• New spectrum policies and technologies in white space
• Broadband wireless communication networks
• Cognitive/software-defined radio networks
• Wireless mesh networks (WiFi/WiMax)
• Spectrum and power efficient wireless systems
• Dynamic spectrum management in wireless heterogeneous systems

Research Topic

• Adaptive Wireless Networks with Cognitive Radio Technology

    The concept of adaptive wireless network is to form a self-organizing heterogeneous network with multi-hop capability which may require MAC/PHY level cooperation and/or higher level etiquette. The mobile wireless network characteristics inherently vary in time and space. Therefore it is imperative that wireless protocols and algorithms adapt themselves to these changes in order to maximize performance and improve data rate, reliability, conserve battery power, support real-time applications, etc. Moreover, opportunities for adaptive wireless networking exist in several layers of the protocol stack. Adapting the protocols in individual layers and across layers to suit user traffic, channel and route state, congestion, security requirement, real-time constraint etc. is a big challenge to be addressed. (More ...)

• Reactive and Proactive Spectrum Coordination for Cognitive Radio

    Cognitive radio technologies with different levels of complexity are studied. Simple reactive interference avoidance algorithms as well as proactive spectrum coordination policies based on etiquette protocols are used to investigate the spectrum co-existence between IEEE 802.11b and 802.16a networks in the same shared frequency band. In reactive interference avoidance methods, radio nodes coordinate spectrum usage without exchange of explicit control information – this is done by adaptively adjusting transmit PHY parameters such as frequency, power and time occupancy based on local observations of the radio band. Because local observations provide information only about transmitters, they may not be sufficient for resolving spectrum contention in scenarios with “hidden receivers”. Proactive coordination techniques solve the hidden-receiver problem by utilizing a common spectrum coordination channel (CSCC) for exchange of transmitter and receiver parameters. Radio nodes can cooperatively select key PHY-layer variables such as frequency and power by broadcasting messages in the CSCC channel and then following specified spectrum etiquette policies. (More ...)

• Spectrum Etiquette Protocols in Unlicensed Bands

    Spectrum etiquette protocol is desiged for efficient coordination of radio communication devices in unlicensed (e.g. 2.4 GHz ISM and 5 GHz U-NII) frequency bands. The etiquette method enables effective spectrum coordination between a number of wireless devices using different radio technologies such as IEEE 802.11.x, 802.15.x, Bluetooth, Hiperlan, etc. The basic idea is to standardize a simple common protocol for announcement of radio and service parameters, called the "common spectrum coordination channel (CSCC)". The CSCC mechanism is based on a simplified low bit-rate mode of the 802.11b physical layer, along with a low-complexity periodic announcement protocol at the MAC/data-link layer. The proposed protocol is "policy neutral" in the sense that it can accommodate various different spectrum etiquette policies which allocate radio resources (frequency, power, time) in a fair and spectrally efficient manner. The CSCC protocol is described in terms of specific packet formats and channel access rules. (More ...)

Projects

• CR Network Bootstrapping and Discovery implementation using ORBIT testbed
• Install Debian Linux Tips    
• Spectrum Sensor Demo System
• Spectrum Etiquette Protocol Implementation in 802.11/Bluetooth Scenarios    
• Spectrum Etiquette Demo System
• Spectrum Coordination Lab Design
• Integration of Bluetooth card in forwarding node
• IEEE 802.11 Sniffer for Access Point