Kento Takabayashi

Error control scheme using decomposable codes for various QoS in multiple WBAN environment

Recently, studies on medical and health monitoring systems using wireless communications have been actively conducted. In the field of health monitoring systems, Wireless Body Area Network (WBAN) is one of the key technologies and its standardization activities have also been extensively carried out. As our previous work, we proposed an optimal QoS control scheme employing a multiplexing layer and a decomposable error control coding scheme [1]. However, in our past work, we did not assume a situation where several WBANs are coexistent and give interference each other. Besides, the error correction capacity of our decomposable code was not sufficient. In this paper, we improve dependability of our scheme by extending code rates of the decomposable code. We also evaluate the performances comparing with IEEE 802.15.6 in a multiple WBAN environment by computer simulations.

Energy efficiency evaluation of ECC scheme utilizing decomposable codes in IEEE std 802.15.6 based WBANs

Recently, studies on medical and health monitoring systems using wireless communications have been actively conducted. In the field of health monitoring systems, wireless body area network (WBAN) is one of the key technologies and its standardization activities have also been extensively carried out. In previous work we proposed an optimal QoS control scheme employing a decomposable error control coding scheme. Furthermore, we extended the error correction capacity of our decomposable code and evaluated its bit error ratio and throughput performance in a multiple WBAN environment. In this paper, we evaluate the energy efficiency of the proposed scheme by computer simulations and compare it with energy efficiency of error control scheme defined in the IEEE Std. 802.15.6. Based on the results it can be stated that the proposed ECC method is more energy efficient especially in poor channel conditions.

Effective error control scheme with channel state information for WBAN

This paper proposes and investigates an effective error control scheme using channel state information (CSI) for Body Area Network (BAN). In February 2012, an international standard of WBAN, IEEE802.15.6, was published and it supports error control schemes. This standard also defines seven different QoS modes. However, how to utilize them is not clearly specified. In this paper, an effective method of the QoS is proposed, especially in user priority 7. Then, the Hybrid ARQ in IEEE 802.15.6 is modified to employ decomposable codes for more associations with CSI. The proposed scheme has been able to transmitted data more effectively according to the required QoS.

An error control scheme with weldon's ARQ considering various qos in medical and non-medical uses for wireless bans

This paper proposes and investigates an novel hybrid ARQ type of error control scheme using Weldons ARQ in order to satisfy different requirement of QoS in medical and nonmedical data for wireless body area networks (WBANs). Although an international standard of WBANs has been established as IEEE802.1S.6 in February 2012, its optional hybrid ARQ scheme has not properly designed so that error detecting and correcting capabilities and permissible delay can be optimized for each requirement of 7 different QoS modes. The proposed scheme employs decomposable codes in order to adjust balance between error-correcting capability of codes and number of retransmission according to each QoS. Numerical results illustrate the proposed scheme can improve BER and throughput performances satisfying each QoS.

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.

A study for the adaptive error correction using QoS-HARQ toward dependable implant body area network

In this paper, we apply HARQ to a wireless feedback control system for realizing high dependable communication. We assume that a controller transmits packets of controlled variables through the propagation channel equivalent with the IEEE 802.15.6 CM2 using some punctured convolutional codes whose code rate is different each other. We propose QoS-HARQ which changes the code rate responding to the status of a rotary inverted pendulum before application for an implant medical actuator device. As a result, we confirm by computer simulations that our proposal can reduce the redundant bits in a packet while keeping the rotary inverted pendulum stable.

Performance analysis of cross-layer approach about error control scheme for WBANs

In this paper, we analyze performance of our error control scheme in a cross-layer design for wireless body area networks (WBANs). As in our previous work, we have proposed an optimal QoS control scheme that employs a multiplexing layer for priority scheduling and a decomposable error control coding scheme for WBANs. However, a cross-layer approach has not been considered yet. In this paper, we utilize a crosslayer approach at physical (PHY) and medium access control (MAC) layers and analyze performance of our proposed error control scheme and the standard scheme. Numerical results show that our proposed scheme has better performances than the standard scheme. For instance, we show that the proposed system obtains over 6dB gain than the standard about the probability of unsuccessful transmission. Additionally, the case utilizing a schedule access protocol has better performances than a random access protocol.

Cross-Layer Design and Performance Analysis of Quality of Service Control Scheme for Wireless Body Area Networks

We analyze and optimize the performance of a quality of service (QoS) control scheme in a cross-layer design for wireless body area networks (WBANs). Smart health monitoring systems that incorporate WBANs and multimedia services have recently been studied and developed. In a WBAN system, wearable and implantable vital sensor nodes can include various types of sensors. Thus, QoS control is a key technique to ensure that different kinds of data are communicated in such a system. In previous work, we proposed an optimal QoS control scheme that employs a multiplexing layer for priority scheduling and a decomposable error control coding scheme for WBANs. However, a cross-layer approach, which is an important technique to optimize the QoS requirements of various kinds of data, has not been considered. In this paper, we utilize a cross-layer design between physical and medium access control layers and analyze and compare the performance of our QoS control scheme and a standard scheme. Numerical results demonstrate that the proposed scheme outperforms the standard scheme. The proposed system achieves a more than 5 dB gain compared with the standard scheme relative to the probability of unsuccessful transmission. We also show that a scheduled access protocol outperforms a random access protocol, except for delay time. In addition, we optimize some factors of the proposed system and the standard scheme in a cross-layer design.

An adaptive error control scheme considering various channel conditions and QoS in medical and non-medical data for WBAN

Recently, Wireless Body Area Network (WBAN) is attracting attention as a technology utilizes both medical care and communication technology. In WBAN, both medical and non-medical applications are assumed. Furthermore, different quality of service (QoS) is required depending on each kind of handled data. IEEE 802.15.6, which is an international standard of WBAN, specifies PHY and MAC layers in order to satisfy the requirements. However, it is difficult to cope with changes in channel environment with just BCH code which is adopted in IEEE 802.15.6 as an error-correcting code. In this paper, therefore, we propose an adaptive error control scheme to change channel codes in response to channel conditions and the types of data to be transmitted. Our simulation result shows that the proposed scheme can fulfill the requirements set by each type of data with changes in channel conditions.