Raungrong Suleesathira

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To achieve seamless mobility in integrated wireless and mobile networks, an intelligent vertical handoff mechanism is required to guarantee Always Best Connected. In this paper, a vertical handoff decision algorithm for nonreal time and real time services and network selection for WLAN/WiMAX/UMTS are presented. The conditions of handoff decision procedure(More)
Despite the advantages of direct sequence spread spectrum (DSSS) communications, intentional jamming or interference from other users reduces the robustness of the system to interference. Spreading the message by means of a pseudo-noise sequence, DSSS increases the bandwidth of the transmitted message making it thus di2cult to track the message. Given the(More)
Next generation wireless networks must be able to coordinate services between heterogeneous networks through multi-mode mobile terminals. Such heterogeneity poses a challenge to seamless handover since each access network has different operations. In this paper, the policies of multiple metrics for handoff to permit connectivity across UMTS and WLAN/WiMAX(More)
In this paper, we propose a method –based on the discrete evolutionary transform (DET)– to estimate the instantaneous frequency of a signal embedded in noise or noise-like signals. The DET provides a representation for non-stationary signals and a time-frequency kernel that permit us to obtain the time-dependent spectrum of the signal. We will show the(More)
In this paper, a simple method for the DOA estimation in the case of close angles is presented. By means of the spatial MUSIC, the problem of localizing multiple narrowband stationary signals impinging a uniform linear antenna array can be solved. Close direction finding based on such a noise subspace MUSIC estimator can however fail. The presented method(More)
Currently, adverse wireless and mobile networks including Worldwide Interoperability for Microwave Access (WiMAX), Wireless Local Area Network (WLAN), Third Generation (3G) mobile communications such as Universal Mobile Telecommunications Systems (UMTS), Wideband Code Division Multiple Access (WCDMA) and Bluetooth as shown in Fig. 1, have emerged and(More)
Problems encountered in IEEE 802.11 medium access control (MAC) design are interferences from neighboring or hidden nodes and collision from simultaneous transmissions within the same contention floors. This paper presents the selective de- coding schemes in MAC protocol for multiple input multiple out- put ad-hoc networks. It is able to mitigate(More)
Coherence is often encountered in sonar, radar or mobile communications. Performance of the beamspace MUSIC (MUltiple Signal Classification) deteriorates as coherent arrivals become closely space. An improvement for the beamspace MUSIC resolution is presented. Decorrelation as a preprocessing is performed by the techniques called forward-backward spatial(More)