Sung-Jeen Jang

An Effective Frequency Sharing Method using Spectrum Etiquette and Genetic Algorithm for the Coexistence of WRAN and WLAN in TV White Space

PURPOSE: An efficient frequency sharing system of WRAN and WLAN using spectrum etiquette and genetic algorithm in TV white space and a method thereof are provided to reduce mutual interference according to co-existence of various heterogeneous communication devices like the WRAN and the WLAN. CONSTITUTION: An information acquisition unit (110) acquires information of WRAN and WLAN. An optimum resource allocation unit (120) allocates optimum frequency sub-band on the basis of the information collected from the information acquisition unit. A broadcasting unit (130) broadcasts the optimum frequency sub-band to each corresponding system. TV white space (TVWS) is idle frequency resource of TV broadcasting frequency band, and is frequency channel space which can be used without additional authorization. The information acquired by the information acquisition unit corresponds to setting state of a peripheral device, channel allocation state, installation position, access mode method and the number of access points (AP). [Reference numerals] (110) Information acquisition unit; (120) Optimum resource allocation unit; (121) First channel selection unit; (122) Second channel selection unit; (130) Broadcasting unit

Power allocation and user satisfaction-based switching method in cognitive radio MIMO system

Secondary users (SUs) should have power constraints because primary users (PUs) should not be interfered by SUs in cognitive radio (CR) network. Therefore it is important for SUs to maximize throughput and ensure quality of service (QoS) on the premise of generating no interference to PUs. In this paper, SUs are equipped with multiple antennas. Multiple-input multiple-output (MIMO) wireless communication systems can offer high data rate or reliability through spatial multiplexing or diversity. Therefore we present a method which user satisfaction-based on switching between spatial multiplexing and transmit diversity to maximize total user satisfaction. When we use spatial multiplexing, user satisfaction is formulated as a function with data rate and power consumed. In case we use transmit diversity, user satisfaction is formulated as a function with reliability and power consumed. For estimating reliability, we provide a novel bit error rate (BER) equation. And we use different power allocation method in each case. We apply capped water-filling method for spatial multiplexing and Lagrangian method for transmit diversity. Simulation results show that proposed switching scheme increase user satisfaction. And we study the effect of interference of PU on the performance

Projection of Spatial Correlation-Based Antenna Selection for Cognitive Radio Systems in Correlated Channels

Recent work has been shown that cognitive radio systems with multiple antenna at both transmitter and receiver are able to improve performance of secondary users. In such system, the main drawback is the increased complexity and raised cost as the number of antennas increase. It is desirable to apply antenna selection which select a subset of the available antennas so as to solve these problems. In this paper, we consider antenna selection method for cognitive radio systems in correlated channel from the IEEE 802.11n. For a multiple-input multiple-output(MIMO) system with more antennas at transmitter than the receiver, we select the same number of transmit antennas as that of receive antennas. The exhaustive search for optimal antenna becomes impractical. We present criterion for selecting subset in terms of projection of channel correlation vector to increase performance of secondary user with decreasing interference at primary user.