Interference Mitigation in Wireless Body Area Networks Using Modified and Modulated MHP

Wireless Body Area Networks (WBAN) is an emerging area in field of remote health monitoring and telemedicine. UWB is a preferred candidate for the WBAN as it provides very high data rate at minimal cost and power consumption. Since the UWB-WBAN is wireless, it will be affected by interference from existing wireless personal and local area networks. Interference immunity is a major issue in wireless Body Area Networks as patients’ vital data containing details of functioning of vital organs and blood flow are carried. The paper investigates the performance of modified and modulated hermite pulses (MHP) for narrowband interference mitigation in the 4,940–4,990 MHz band IEEE 802.11y Public Safety band interference. This 50 MHz interfering band will be a critical interferer due to the higher power levels of interfering system. Performance of the proposed technique have been shown in comparison with Gaussian pulse shapes and has been further validated by transmitting ECG and MRI data by it in presence of strong interference.     

Coexistence mechanisms for interference mitigation in the 2.4-GHz ISM band

Wireless technologies sharing the same frequency band and operating in the same environment often interfere with each other, causing severe decrease in performance. We propose two coexistence mechanisms based on traffic scheduling techniques that mitigate interference between different wireless systems operating in the 2.4-GHz industrial, medical, and scientific band. In particular, we consider IEEE 802.11 wireless local area networks (WLANs) and Bluetooth (BT) voice and data nodes, showing that the proposed algorithms can work when the two systems are able to exchange information as well as when they operate independently of one another. Results indicate that the proposed algorithms remarkably mitigate the interference between the IEEE 802.11 and BT technologies at the expense of a small additional delay in the data transfer. It is also shown that the impact of the interference generated by microwave ovens on the IEEE 802.11 WLANs performance can be significantly reduced through the mechanisms presented.     

基于无线Mesh网络技术构建无线城市

无线Mesh网络(WMN)可以和多种无线网络系统,如无线局域网(WLAN)、无线城域网(WMAN)等相结合,改善无线网络的性能,提高网络的覆盖范围.以WMN网络技术在IEEE 802系列标准中的发展为基础,提出了一种无线城市的覆盖方案,最底层网络覆盖采用WiFi+wireless Mesh技术,WiMAX网络与WiFi...     

无线体域网信道特性研究

无线体域网(WBAN)包含一系列低功耗、微型化、侵入式或非侵入式无线传感器节点,通过短距离无线通信技术实现与外界的通信,提供医疗保健、消费电子、个人娱乐等多项服务。由于WBAN应用于人体,WBAN信道的传播特性与其他传统的无线信道特性有着显著的不同。本文从频点、环境和人体状态3个方面详细研究了WBAN的信道特性。UWB频段采用了冲激响应模型,而路径损耗模型适用于所有频段;在不同环境下,多径效应是影响信号在体外空间传播的主要因素;此外,天线的位置和人体的运动状态,也是WBAN信道建模和仿真时考虑的关键因素。     

Network selection in cognitive radio enabled Wireless Body Area Networks

In recent years, the great interest in Wireless Body Area Networks (WBANs) has been aroused significantly due to the advancement in wireless communications. In wireless communication, all WBAN nodes that monitor the human body's vital functions transfer information to a central sink node, which is directly connected to a Cognitive Radio enabled Controller called CRC. To transfer this information from a CRC to an e-health server, it requires long-range wireless networks, such as UMTS, LTE, WiMAX, WiFi, and satellite internet provider. It is challenging for a CRC to select the best networks for different WBAN data traffic, such as emergency mandatory, delay sensitive, and general monitoring. This paper proposes a scheme for selecting the best network from the available networks depending on the Quality of Service(QoS) requirements for different WBAN applications. Different multiple attribute decision-making algorithms are used in the proposed scheme. Numerical results and discussion reveal that the proposed scheme is effective in making a good network selection in situations where there is a conflict among different QoS requirements for different WBAN applications.     

Impact of priority differentiation on the bridged WBAN/WLAN healthcare networks

In this work, we develop a prioritized bridging mechanism between the IEEE 802.15.6‐based wireless body area networks (WBANs) and the IEEE 802.11e enhanced distributed channel access (EDCA)‐based wireless local area network (WLAN) to convey the medical data to the medical center. We map the eight WBAN user priorities (UPs) into the four WLAN access categories (ACs) to provide the required quality of service and prioritization for the health variables generated by the WBAN nodes. By assignment of WBAN UPs with default medium access control parameters to eight different medical data streams and under the presence of ordinary nodes, we investigate the impact of WLAN AC differentiation by arbitrary inter‐frame space (AIFS) and contention window (CW) on performance of medical and regular nodes’ data streams. The results of this work indicate that the AC differentiation by AIFS outperforms the differentiation by CW in the sense that it does not deteriorate the end‐to‐end delay of relayed WBAN traffic and ordinary WLAN traffic.Copyright © 2012 John Wiley & Sons, Ltd.     

A survey on wireless body area networks

The increasing use of wireless networks and the constant miniaturization of electrical devices has empowered the development of Wireless Body Area Networks (WBANs). In these networks various sensors are attached on clothing or on the body or even implanted under the skin. The wireless nature of the network and the wide variety of sensors offer numerous new, practical and innovative applications to improve health care and the Quality of Life. The sensors of a WBAN measure for example the heartbeat, the body temperature or record a prolonged electrocardiogram. Using a WBAN, the patient experiences a greater physical mobility and is no longer compelled to stay in the hospital. This paper offers a survey of the concept of Wireless Body Area Networks. First, we focus on some applications with special interest in patient monitoring. Then the communication in a WBAN and its positioning between the different technologies is discussed. An overview of the current research on the physical layer, existing MAC and network protocols is given. Further, cross layer and quality of service is discussed. As WBANs are placed on the human body and often transport private data, security is also considered. An overview of current and past projects is given. Finally, the open research issues and challenges are pointed out.     

无线局域网和蓝牙技术的共存

目前IEEE802.11b无线局域网(WLANwireless local area network)技术和蓝牙(BTbluetooth)技术均受到了广泛的关注,但是由于两者均工作在2.4GHz ISM频段,因此研究这两种技术的共存性以减少相互干扰显得尤为重要.文中对这两种技术的共存性开展深入的研究,重在探讨解决这一问题的实现机制和方案.     

CHAMELEON: A Framework for Coexistence of Wireless Technologies in an Unlicensed Band

The recent increase in the number of technologies operating in the 2.4 GHz ISM band has drawn attention towards the impact they can have on each other. In this paper, we have conducted a case study about coexistence of IEEE 802.11 and IEEE 802.15.4 which has led us to discover previously unknown interactions. We show through extensive experiments that CCA method used by a wireless device can significantly change the coexistence scenario. We also highlight the ways in which coexistence can be improved by making runtime adjustments to some MAC/PHY layer parameters and show their effectiveness. Furthermore, we propose a framework which exploits the pervasiveness and ubiquity of Wi-Fi to improve coexistence among wireless technologies in the 2.4 GHz ISM band. Our framework has the capability to detect the presence of wireless technologies operating anywhere in the 2.4 GHz ISM band and also accounts for devices whose signatures do not exist in the database. It facilitates the Wi-Fi AP to make decisions such as changing the channel or making MAC/PHY layer adjustments which are compliant with the configured coexistence policy thus improving the performance of the wireless devices. We have implemented our framework on real hardware and evaluated its performance in the presence of ZigBee.     

Performance Evaluation of Video,Voice and Web Traffic Over Heterogeneous Access Networks

By simulation using NS-3 we evaluated the performance of voice, video and web traffic sharing a wireless access network connected to a wired core. We compared the performance in terms of end-to-end delay, end-to-end delay variation, average throughput and loss percentage. For the wireless access network, we considered cases when it consisted of a single technology type, e.g., WiFi (IEEE 802.11), WiMAX (IEEE 802.16) and LTE, and when it was heterogeneous, i.e., when the three technologies coexisted and simultaneously shared the same IP core. We attempted to ascertain the impact of this type of heterogeneity on end-to-end performance. It was found that this heterogeneity in the wireless access portion of the network can improve, degrade or have no impact on application performance depending on the network conditions and the application itself. Some key research challenges in Fifth Generation wireless communications are heterogeneous Cloud Radio Access Networks (HC-RANS), backward compatiblity with 4G/3G networks and providing low-latency and QoE. To achieve end-to-end QoS guarantees in such settings the interface with the core must also be addressed, especially when backward compatibility is to be assured. This simulation study attempts to highlight the impact of this type of heterogeneity on network performance.     

Security analysis of the IEEE 802.15.6 standard

A wireless body area network (WBAN) consists of low‐power devices that are capable of sensing, processing, and wireless communication. WBANs can be used in many applications such as military, ubiquitous health care, entertainment, and sport. The IEEE Std 802.15.6‐2012 is the latest international standard for WBAN. In this paper, we scrutinize the security structure of the IEEE 802.15.6‐2012 standard and perform a security analysis on the cryptographic protocols in the standard. We show that some protocols have subtle security problems and are vulnerable to different attacks. Such vulnerabilities neutralize the security provisions in the standard specifically for medical applications that deal with sensitive information and security problems can be life‐threatening. Copyright © 2016 John Wiley & Sons, Ltd.     

A game theory-based approach for the study of inter-interference in coexisting wireless body area networks

A wireless body area network (WBAN) enables the continuous monitoring of health conditions including heart rate, temperature, and glucose levels. It is composed of several sensors that are placed on the body. The network's performance is significantly affected by the unpredictable movements of the human body. Due to the varying proximities between them, the existence of several WBANs creates a challenge when mobility is involved. In this fictitious scenario, we consider a park area with both mobile and static WBANs or WBAN-equipped individuals passing through the park who have varying degrees of mobility. When a mobile WBAN passes a static WBAN and is within a minimum distance of the static WBAN, they pair up and immediately interfere. Inter-interference caused by WBANs operating in a limited area causes packet loss and performance deterioration. In this work, static WBAN locations are optimised to minimise interference and system inter-interference problems are addressed by a game theoretic method. This paper formulates a flexible game theoretic framework to study WBAN coexistence using the expected pay-off function considering a two-player game. It is observed from the results obtained that the probability of interference caused by fast mobile WBANs is reduced to a maximum of 50% compared with that caused by slow mobile WBANs thereby reducing the need for relocation of static WBANs.     

IEEE 802.15.6中能量有效的无线体域网拓扑结构优化研究

提出一种无线体域网(WBAN, wireless body area network)的网络拓扑结构设计方案。该方案针对IEEE 802.15.6标准的2跳扩展星型拓扑结构,建立基于混合整数非线性规划的能耗成本优化模型,通过调整中继节点的位置和数量,以及数据到汇聚节点的路由,获得优化的网络拓扑结构。实验结果分析表明,与Elias提出的EAWD(energy aware WBAN design) 模型相比,所提出的方案能使网络能耗减少40.5%,网络时延平均降低52.4%,网络寿命提高了一倍。     

IEEE 802.11n MAC Enhancement and Performance Evaluation

The IEEE 802.11-based WiFi wireless technology is one of the most promising technologies to provide ubiquitous networking access. The IEEE 802.11 working group has always strived to improve this wireless technology through creating new amendments to the base 802.11 standard. Recently, IEEE 802.11n amendment was created to enhance 802.11 for higher throughput operation. Not only new Physical Layer enhancements are standardized, but new Medium Access Control Layer mechanism are also defined. In this paper, we examine the network performance enhancement by the proposed 802.11n MAC layer features: aggregation, block acknowledgement, and reverse direction mechanism. We implemented a new 802.11n module in the NS-2 simulation platform. The simulation results demonstrated the effectiveness of 802.11n MAC layer enhancement. VoIP performance is effectively improved with 802.11n MAC enhancement.     

A decision theoretic approach for channel ranking in crowded unlicensed bands

Interference is disruptive to the operation of wireless sensor networks (WSNs) in unlicensed bands as wireless systems proliferate on the spectrum. The design of a spectrum sharing scheme for WSNs to enable coexistence with geographically collocated heterogeneous wireless systems having multiple parallel interfering channels is a persistent challenge. In this context, interference identification and channel ranking in terms of spectrum access opportunities are addressed in this paper. The goal is to develop a low complexity channel ranking algorithm from channel energy measurements at sensors when a packet-reception-ratio to signal-to-interference-and-noise-ratio (PRR-SINR) interference model is unavailable at network initialization phase. The interference characterizing estimators, temporal occupancy and strength level of a channel, are proposed for interference identification. The effectiveness of the estimators is tested on a sensor platform at 2.4 GHz ISM band under interference from WLAN. Subsequently, the impact of the interference estimators on a channel quality from a receiver perspective is determined with a decision theoretic approach. The estimators are weighted according to their influence on the fitness of a channel and channel ranking is established. The proposed channel ranking achieves a significant gain over heuristic channel ranking (HCR) and gives an accurate interference profile of the channels.     

Competitive Pricing in Heterogeneous Wireless Access Networks: Issues and Approaches

To provide seamless mobility with high-speed wireless connectivity, future generation wireless networks must support heterogeneous wireless access. Pricing schemes adopted by different service providers is crucial and will impact the decisions of users in selecting a network. In this article, we provide a comprehensive survey of the issues related to pricing in heterogeneous wireless networks and possible approaches to the solution of the pricing problem. First, we review the related work on pricing for homogeneous wireless networks in which a single wireless technology is available to the users. Then, we outline the major issues in designing resource allocation and pricing in heterogeneous wireless access networks. To this end, we propose two oligopolistic models for price competition among service providers in a heterogeneous wireless environment consisting of WiMAX and WiFi access networks. A non-cooperative game is formulated to obtain the price for the service providers. Two different equilibria, namely, the Nash and the Stackelberg equilibria are considered as the solutions of the simultaneous-play and leader-follower price competitions, respectively.     

干扰受限环境下蓝芽系统的性能及自适应跳频共存机制

随着无线局域网(WLAN)的日益普及和无线个人局域网(WPAN)的飞速发展，由于共享同一频段而产生的系统间干扰不可避免。本文着重讨论基于IEEE802．1lb标准的WLAN对基于蓝芽(Bluetooth)的短距离无线通信系统的影响。在利用MATLAB和C 搭建的系统干扰模型的仿真平台上，实现了基于蓝芽物理层的自适应跳频(Adaptive Frequency Hopping-AFH)共存机制(Co—existence Mechanism)。仿真结果显示，通过简单的AFH信道选择模块，可以有效减轻WLAN对蓝芽的干扰影响。     

On the implant communication and MAC protocols for WBAN

Recent advances in micro‐electro‐mechanical systems, wireless communication, low‐power intelligent sensors, and semiconductor technologies have allowed the realization of a wireless body area network (WBAN). A WBAN provides unobtrusive health monitoring for a long period of time with real‐time updates to the physician. It is widely used for ubiquitous health care, entertainment, and military applications. The implantable and wearable medical devices have several critical requirements such as power consumption, data rate, size, and low‐power medium access control (MAC) protocols. This article consists of two parts: body implant communication, which is concerned with the communication to and from a human body using radio frequency (RF) technology, and WBAN MAC protocols, which presents several low‐power MAC protocols for a WBAN with useful guidelines including a case study of IEEE 802.15.4, PB‐TDMA, and SMAC protocols. In body implant communication, the in‐body RF performance is affected considerably by the implant's depth and different polarization combinations inside the human body as well as by the muscle and fat. We observe best performance at a depth of 3 to 5 cm and not close to the human skin. Furthermore, the study of low‐power MAC protocols highlights the most important aspects of developing a novel low‐power and reliable MAC protocol for a WBAN. Copyright © 2010 John Wiley & Sons, Ltd.     

A Practical Traffic Scheduling Scheme for Differentiated Services of Healthcare Systems on Wireless Sensor Networks

Wireless sensor networks have recently been extensively researched due to the flexibility and cost savings they provide. One of the most promising applications of sensor networks is human health monitoring: wireless sensors are placed on the human body to form a wireless body network where the sensor node can continuously monitor real-time physiological parameters or human activities (motion detection). However, along with the flexibility, many problems arise due to a number of factors, including the bad quality of transmission media and the scarcity of resources. Moreover, sensor networks have different characteristics such as a variety of devices, different generated data, etc. From a quality of service (QoS) point of view, the healthcare domain can be seen as a real-time application demand to consider application requirements. Healthcare domains principally have stringent delay and loss requirements. Thus, considering different capabilities and ensuring time data delivery become necessary. Because wireless body area networks (WBAN) deal with human life, any delayed or lost data can endanger the user’s life. This paper proposes a differentiated traffic and scheduling scheme for WBAN. It is based on patients’ data classification and prioritization according to their current status and diseases. Through queue scheduling and path choice issues, the urgent data are delivered on time to provide a QoS guarantee for WBAN. Finally, it is shown that the proposed scheme is efficient for timely data transfer in WBAN.     

数字家庭无线网络技术的干扰性研究

随着3C融合的不断深入,将会越来越容易地将家庭中的电子产品连接成网络。数字家庭的无线技术对家庭音响、游戏机、电视机、DVD等家用电器设备在处理声音、图像和视频等不同的领域各具优势。论文以数字家庭为背景,分析了无线网络技术之间的干扰问题,进行了系统化的定性分析,并对UWB对IEEE802.11a之间的干扰进行了定量的仿真,引出研究数字家庭无线网络技术之间干扰的重要性。