Pham Thanh Hiep

Optimizing distance, transmit power, and allocation time for reliable multi-hop relay system

In multi-hop relay systems, the end-to-end channel capacity is restricted by bottleneck node. In order to prevent some relay nodes from being the bottleneck of system and to guarantee the end-to-end channel capacity, the method of optimizing transmit power, distance and allocation time is proposed in this article. We show that the optimizing distance has more end-to-end channel capacity than the optimizing transmit power in case that both the distance and the transmit power are changeable. However, the optimizing transmit power can let the system reach high end-to-end channel capacity when the relay nodes have to shift from the desired location. We also propose the Markov Chain Monte Carlo method to optimize all transmit power, distance and allocation time simultaneously. The optimizing all transmit power, distance and allocation time is the most effective and achieves the highest channel capacity. Based on the average signal-to-noise-ratio, the average channel capacity is evaluated in this article.

Control superframe for high throughput of cluster-based WBAN with CSMA/CA

Due to rapidly increasing of elderly population all over the world and quickly developing of entertainment devices, wireless body area network (WBAN) attracts attention. For both medical and non-medical applications, a reliability, high energy-efficiency and high throughput of WBAN communication are requested. The well-known cluster-based is proposed to obtain the high energy-efficiency, however the transmission in every cluster is controlled on MAC layer by superframe in order to obtain the high throughput. The performance of original cluster-based, complete control and spatial reuse superframe scenarios is analyzed and compared. The calculation result indicates that the spatial reuse superframe outperforms the original cluster-based when the access probability and/or the total number of sensors are high. Furthermore, there are the optimal number of clusters, the access probabilities and the total number of sensors that achieve the highest throughput. The optimization method of number of spatial reuse superframe (k) is proposed to obtain the highest throughput when another factors change. k increases when another factors of system model increase, excepted the payload. The optimization method of another factors is similar and the proposed method can be applied to not only IEEE802.15.6 WBAN but also another cluster-based wireless sensor networks.

End-to-end channel capacity of MAC-PHY cross-layer multiple-hop MIMO relay system with outdated CSI

For high end-to-end channel capacity, the amplify-and-forward scheme multiple-hop multiple-input multiple-output relay system is considered. The distance between each transceiver and the transmit power of each relay are optimized to prevent some relays from being the bottleneck and guarantee high end-to-end channel capacity. According to the proposed transmission environment coefficient, the path loss can be described in a new way, and then the distance of multiple-hop relay system can be optimized more simply than the original one. However, when the system has no control on media access control (MAC) layer, performance of the system deteriorates because of the presence of interference signal. Thus, the specific transmission protocol on the MAC layer for multiple-hop system is proposed to reduce the power of interference signal and to obtain high end-to-end channel capacity. According to the proposed transmission protocol on the MAC layer, the system indicates the trade-off between the end-to-end channel capacity and the delay time. The end-to-end channel capacity of the outdated channel state information system is also analyzed.

Capacity bound for full-duplex multiple-hop MIMO relays system in rayleigh fading

In multiple-hop relay systems, the system channel capacity is restricted by the bottleneck relay. In order to prevent some relays from being the bottleneck and guarantee the system channel capacity, the method for optimizing distance between each relays and transmit power of each relay is proposed in this paper. The optimizing both the distance and the transmit power is effective and can achieves high channel capacity. The bound of the downlink, the uplink channel capacity for each number of relays and the limitation of channel capacity when the number of relays tends to infinity, are found. The channel model is indicated the flat Rayleigh fading.

Statistical method for performance analysis of WBAN in time-saturation

Performance analysis of carrier sense multiple access with collision avoidance (CSMA/CA) scheme based on IEEE 802.15.6 standard has been discussed in many literatures. In previous works on IEEE 802.15.6 and another standards, the performance was analyzed by using access probability in one slot duration and the Markov chain model was proposed to calculate the access probability in both saturation and non-saturation models. However, for both saturation and non-saturation models, the access probability or the packet arrival rate was assumed to be fixed and the effect of remained packets that was transmitted unsuccessfully due to busy channel or collision was not considered. In this paper, in order to evaluate the system performance more accurately, the effect of the remained packet is taken into account and a statistical method is proposed to calculate the successful probability of wireless body area networks (WBANs). Moreover, a time-saturation model is defined as a system model in which the system performance is changed following the operating time, and then, the change between three models, i.e., saturation, non-saturation, and time-saturation models, is analyzed. The calculation result indicates that the proposal method can achieve the same performance as the Markov chain method in both saturation and non-saturation models. However, in the time-saturation model, the proposal statistical method is more accurate.

Water-filling for full-duplex multiple-hop MIMO relay system

A water-filling (WF) method is one of the techniques to improve a performance of multiple-input multiple-output (MIMO) systems. However, the application of the WF method to multiple-hop MIMO relay systems (MMRSs) has not been discussed, especially in amplify-and-forward (AF) schemes. In this paper, the WF method for MMRSs with AF scheme is proposed and evaluated in both perfect and imperfect channel state information (CSI). The effect of imperfect CSI on optimization of transmit power at all transmitters and on co-channel interference is taken into account. Compared to the average transmit power, the end-to-end channel capacity of the WF method is higher in the perfect CSI; however, it is subject to the effect of imperfect CSI. Additionally, half-duplex and full-duplex transmission methods are also discussed in this paper. The end-to-end channel capacity of full duplex is higher and more robust than that of the half duplex due to a double of allocation time and a half of delay time.

End-to-end channel capacity of multiple-hop MIMO relay system with MAC-PHY cross-layer

For high end-to-end channel capacity, the amplify-and-forward scheme multiple-hop MIMO relays system is considered. The distance between each transceiver and the transmit power of each relay node are optimized to prevent some relays from being the bottleneck and guarantee the high end-to-end channel capacity. By proposing the transmission environment coefficient, the path loss is described in a new way and then the distance of multiple-hop relay system can be optimized more simply than the original one. However, when the system has no control on Mac layer, the performance of system is deteriorated because of the presenting of interference signal. Thus the specific control protocol on MAC layer for multiple-hop system is proposed to reduce the power of interference signal and obtain the high end-to-end channel capacity. According to proposed control protocol on MAC layer, the system indicates the trade-off between the end-to-end channel capacity and the delay time.

Frame-patch matching based robust video watermarking using KAZE feature

A frame-patch matching based robust video watermarking using KAZE feature is proposed in this paper. We employed the KAZE feature for matching the feature points of frame-patch with those of all frames in video. In our method, the watermark information is embedded in Discrete Cosine Transform (DCT) domain of randomly generated blocks in the matched region. In the extraction process, we synchronized the embedded region from the distorted video by using KAZE feature matching. RST (rotation, scaling, translation) parameters are estimated and the watermark information can be extracted. Experimental results showed that our proposed method is very robust against geometrical attacks, video processing attacks, temporal attacks, and so on.

Optimizing data rate for multiple hop wireless body area network

Since the elderly population is increasing all over the world, health care market keeps growing and there is a need for monitoring of health issues. Body Area Network consists of wireless sensors attached on or inside human body for monitoring vital Health related problems, i.e, Electro Cardiogram (ECG), ElectroEncephalogram (EEG), Electronystagmogram(ENG) etc. Data is recorded by each sensor and sent toward coordinator through other sensors meaning multiple hop sensors WBAN system. The multiple hop system is being researched in many fields of wireless system, i.e, ad hod, mobile, ITS and so on. However, in these systems, the relay node just services as forwarding the data even in the multiple sources to multiple receivers system. Whereas, in wireless body area network (WBAN) system, almost the sensors forward the vital data of the other sensors while recording and sending the data of itself to the neighbor one. Therefore, due to the number of packets that is generated at all sensors, the probability of successful transmission and the packet loss are changed. It means that the vital data is lost and the transmit power is wasted. Main aim of this paper is to analyze the successful transmission probability and to optimize the packet rate of all sensors to obtain the highest efficiency in utilization.

Proposal methods for performance analysis of WBANs based on CSMA/CA

There have been burning issues on Wireless Body Area Networks (WBANs) in which performance analysis for media access layer (MAC) protocol is essential and has been discussed in many literatures. By using Markov chain model, saturation and non-saturation conditions, many works can calculate access probability and throughput of system. However, previous works usually assumed that channel is ideal and with both saturation and non-saturation conditions effect of remained packets, which were transmitted unsuccessfully due to collision or busy channel, was not considered adequately. The target of this paper is to evaluate system performance more accurately and flexibly, considering channel is non-ideal, taking into account the remained packets and using statistical mathematics instead of saturation and non-saturation condition and then to optimize parameters to achieve higher performance.