Toward Secure Low Rate Wireless Personal Area Networks

Low rate wireless personal area networks (LR-WPANs) offer device level wireless connectivity. They bring to light a host of new applications as well as enhance existing applications. Due to their low cost, low power consumption and self-organization features, LR-WPANs are ideal for applications such as public security, battle field monitoring, inventory tracking, as well as home and office automation. Nevertheless, one critical issue, security, needs to be solved before LR-WPANs are commonly accepted. Pursuing security in LR-WPANs is a challenging task. On one hand, wireless communications are inherently susceptible to interception and interference. On the other hand, most devices in LR-WPANs are resource-constrained and lack physical safeguards. This paper presents a systematic analysis of the threats faced by LR-WPANs with respect to the protocol stack defined by IEEE 802.15.4 and the ZigBee Alliance. Attacks are modeled and their impacts are evaluated. Some security problems within the current LR-WPAN security architecture are identified and remedies are suggested. Countermeasures of various attacks are also given.     

Frame‐Size Adaptive MAC Protocol in High‐Rate Wireless Personal Area Networks

In this letter, we propose a frame‐size adaptive MAC protocol for high rate wireless personal area networks (WPANs). In the proposed scheme, during communication, frame error rate is periodically reported to a transmitting device and the frame size is changed according to the measured results. Thus, the channel can be more effectively utilized by adapting to variable radio conditions. Analytical results show that this scheme achieves a much higher throughput than a non‐frame‐size adaptive media access control protocol in high‐rate WPANs.     

高速率无线个人域网(WPAN)

未来的无线通信系统大到覆盖全球的卫星网,小到个人域网。高速无线个人域网（WPAN）工作在不需许可证2.4GHz频段,最高速率可达55Mbit/s。本文阐述了WPAN的基本概念、目标应用以及媒体接入控制（MAC）层与物理层（PHY）的标准情况,还与无线局域网（WLAN）进行了比较。     

Adaptive Distributed Channel Assignment in Wireless Mesh Networks

From the channel assignment schemes in time division multiple access (TDMA) slot assignment protocols developed in previous studies, we have found that these protocols do not have a convenient frame length reduction scheme after the expansion of the frame length. As the network size grows, the frame length expands rapidly, particularly when we set it as a power of two. A very long frame may result in poor channel utilization when it contains many unused slots. In this paper, we consider a wireless mesh network with a TDMA structure. We divide each code into time slots to form the channels. We propose a dynamic frame length expansion and recovery method termed adaptive distributed channel assignment (ADCA). This strategy is designed to enhance the utilization of the available channels by taking advantage of the spatial reuse concept. In ADCA, an increase in spatial reuse is achieved by adding a certain amount of control overhead. We show that the bandwidth saved due to the channel spatial reuse is larger than the additional bandwidth spent on the control overhead.

Adaptive Rate System for Wireless Packet Networks

The severe channel and interference condition can limit the throughput of the wireless packet networks. We thus propose an adaptive rate system to increase the throughput of the wireless packet networks. In this system, the data rate is adapted to the channel and interference condition. By optimizing the data rate for a given channel and interference condition, we establish the optimal adaptive rate system. It can be shown that the optimal adaptive rate system provides higher throughput than the fixed rate system.     

A Generic Framework for Cross-Layer Optimisation in Wireless Personal Area Networks

Wireless Personal Area Networking (WPAN) is introduced as a new concept for next generation wireless systems. WPANs are short-range wireless systems operating in the direct surrounding of the user. A reference architecture for short-range wireless communications has been designed covering the end-to-end system design. Traditional protocol stack implementations based on layering do not function efficiently in wireless environments due to inefficiency, inflexibility and suboptimality of the functionalities in the different layers. Specifically in WPAN and other short-range wireless systems the performance benefits from a cross-layer design strategy, supporting adaptability and optimizing the use of resources over multiple layers of the protocol stack. In this paper we advocate cross-layer optimisation for WPAN systems and introduce a centralised control structure for interaction between different layers in master or leader devices. The control structure adapts the link characteristics to the channel state and user requirements. Allowing for the support of heterogeneous services, each with their own quality-of-service demands, in wireless environments.     

An Adaptive Energy-Aware Relay Mechanism for IEEE 802.15.6 Wireless Body Area Networks

Wireless Personal Communications - A Mobile Ad hoc Network (MANET) is a network composed of numerous autonomous mobile nodes. In recent times, the opportunistic network, a type of MANET is gaining...     

A Hybrid Adaptive Wireless Channel Access Protocol for Multimedia Personal Communication Systems

This paper proposes a new medium access protocol (MAC) protocol for futurewireless multimedia personal communication systems, denoted hybrid andadaptive multiple access control (HAMAC) protocol. The HAMAC protocolintegrates fixed assignment TDMA protocol, reservation-based protocols, andcontention-based protocols into a single wireless network so as tosimultaneously and efficiently support various classes of traffic such asconstant-bit-rate (CBR), variable-bit-rate (VBR), and available-bit-rate (ABR)traffic. In particular, the HAMAC protocol uses a novel preservationslot technique to overcome the packet contention overhead in packetreservation multiple access (PRMA) like protocols, while keeping mostisochronous service features of TDMA protocols to serve voice and CBR trafficstreams. A preservation slot is a very short slot which is used torepresent a CBR connection when the traffic in the CBR connection is in asilent period in which there is no meaningful data to transmit. Due to thevery short length of the preservation slot, it only takes minimalportion of the bandwidth pre-allocated to the CBR connection, so that theremaining bandwidth can be freed for other connections to use. When the CBRsource becomes active again, the preservation slot is replaced bynormal data slots without any reservation operation, extra delay, orsignificant bandwidth loss. Consequently, the guaranteed service andsimplified signaling features of TDMA protocols, together with the adaptivebandwidth allocation features of PRMA-like protocols, are both realized in theHAMAC protocol. We have analyzed the performance of the HAMAC protocol usingextensive simulations. The results show that the HAMAC protocol can achievevery low loss rates for various multimedia traffic with stringent quality ofservice (QoS) requirements and outperforms state-of-the-art PRMA-likeprotocols. As a result, the HAMAC protocol appears to be a good candidate forfuture generation multimedia personal communication systems.     

Dynamic Channel Allocation in Wireless Networks Using Adaptive Learning Automata

Single-channel based wireless networks have limited bandwidth and throughput and the bandwidth utilization decreases with increased number of users. To mitigate this problem, simultaneous transmission on multiple channels is considered as an option. In this paper, we propose a distributed dynamic channel allocation scheme using adaptive learning automata for wireless networks whose nodes are equipped with single-radio interfaces. The proposed scheme, Adaptive Pursuit learning automata runs periodically on the nodes, and adaptively finds the suitable channel allocation in order to attain a desired performance. A novel performance index, which takes into account the throughput and the energy consumption, is considered. The proposed learning scheme adapts the probabilities of selecting each channel as a function of the error in the performance index at each step. The extensive simulation results in static and mobile environments provide that the proposed channel allocation schemes in the multiple channel wireless networks significantly improves the throughput, drop rate, energy consumption per packet and fairness index—compared to the 802.11 single-channel, and 802.11 with randomly allocated multiple channels. Also, it was demonstrated that the Adaptive Pursuit Reward-Only (PRO) scheme guarantees updating the probability of the channel selection for all the links—even the links whose current channel allocations do not provide a satisfactory performance—thereby reducing the frequent channel switching of the links that cannot achieve the desired performance.     

一种高效太赫兹无线个域网MAC协议

太赫兹无线通信技术越来越多地受到人们关注,MAC协议作为无线通信的关键,如何适应太赫兹超高速率的无线网络是一个急需解决的问题。文章提出了两种新的机制用于改进现有太赫兹MAC协议存在的不足,最大可能地利用了信道资源,除去了冗余的控制开销,从而提高了无线网络通信的吞吐量。最后通过实际验证结果,对太赫兹无线网络MAC协议的进一步研究提供了支持。     

Multi-user Synchronisation in ad hoc OFDM-based Wireless Personal Area Networks

In this paper, a procedure for dealing with the multi-user synchronisation problem in Orthogonal Frequency Division Multiple Access (OFDMA)-based systems for ad hoc environments is proposed and analysed. We show with this novel approach that it is possible to re-use much of the already extent literature for single-user synchronisation in OFDM and apply it to multi-user ad hoc scenarios. Also a distributed version of the procedure is proposed in order to fairly share out the power consumption among all the devices. The proposed procedure makes use of higher layer capabilities in a cross-layer design and it does not incur too much complexity or power. This issue is specially critical in wireless heterogeneous ad hoc networks where devices can be very limited in terms of transmission and/or computational power.     

Technology Challenges in the Development of Wireless Personal Area Networks

Wireless personal area networks (WPANs) will be major components of the heterogeneous communication environment of the future. The devices in a WPAN must be low cost and operate for a long time from a battery. As a consequence, they pose demanding requirements on the utilized integration technology. In this paper we confront these requirements with the newly released international technology roadmap for semiconductors (ITRS-2001). Power consumption is identified as the key problem, motivating a large research effort in low power design techniques. In addition, it is pointed out that WPAN devices will consist of different technologies, requiring a better design support for mixed-technology integration.     

Wireless Channel State-Aware and Adaptive Epidemic Dissemination in Ad Hoc Networks

Ad hoc networks are characterized by limited resources (e.g. energy, bandwidth). Efficient information dissemination while avoiding excessive energy cost can be achieved through the suitable design of a network. To this end we propose an information dissemination scheme which couples epidemic dissemination with adaptive modulation and coding (AMC). The proposed scheme tunes the message forwarding probability and the coding and modulation mode in order to achieve a balance between maximum coverage over the network and minimum energy expenditure. We achieve this based on the evaluation of suitably defined indicators related to the lower network layers and exploiting information on the current status of the wireless medium. Building on established previous AMC-related work, our simulation results indicate that our scheme brings significant improvement over non-adaptive approaches, comparable with other adaptive epidemic dissemination schemes. Our findings are quite promising for adaptive epidemic-based information dissemination schemes with a strong cross-layer component.     

A Utility-Based Joint Power and Rate Adaptive Algorithm in Wireless Ad Hoc Networks

In this paper, a utility-based joint power and rate adaptive algorithm (UPRA) is proposed to alleviate the influence of channel variation by using softened signal-to-interference-and-noise ratio (SINR) requirements. The transmission power and rate of each user will be adjusted to maximize its own net-utility according to the states of channel, which results in a balance between the effective transmission rate and power consumption. Although the UPRA works based on a non-cooperative game, cooperation among users can be achieved so that the throughput of the whole network will be improved. The convergence of the algorithm has also been studied in both feasible and infeasible cases.     

Channel and Error Modeling for Wireless Body Area Networks

Wireless Body Area Networks (WBANs) have been developed as the human-body monitoring systems to predict, diagnose, and treat diseases. Since the signal transmission in WBANs takes place in or around the human body the channel fading significantly affects packet error rate and overal network performance. In this work, we discuss the channel models and error performance formalization for WBANs. In the first phase of this work, we study channel fading models for WBANs. In the second phase, we survey the models which calculate the error performance metrics in WBANs. We select most appropriate error models to design and develop the error performance evaluation models for IEEE 802.15.6-based WBANs and show how to integrate them with the error model in Medium Access Control (MAC). We then discuss integrated PHY and MAC error performance in WBANs.     

无线个人通信网

本文简要介绍了无线个人通信网，主要讨论了无线个人通信网的频谱分配、移动管理、呼叫和流量控制、智能网结构、网络规划和设计等技术问题。     

Mobile IP-Based Protocol for Wireless Personal Area Networks in Critical Environments

Low-power Wireless Personal Area Networks (LoWPANs) are still in their early stage of development, but the range of conceivable usage scenarios and applications is tremendous. That range is extended by its inclusion in Internet with IPv6 Low-Power Personal Area Networks (6LoWPANs). This makes it obvious that multi-technology topologies, security and mobility support will be prevalent in 6LoWPAN. Mobility based communication increases the connectivity, and allows extending and adapting LoWPANs to changes in their location and environment infrastructure. However, the required mobility is heavily dependent on the individual service scenario and the LoWPAN architecture. In this context, an optimized solution is proposed for critical applications, such as military, fire rescue or healthcare, where people need to frequently change their position. Our scenario is health monitoring in an oil refinery where many obstacles have been found to the effective use of LoWPANs in these scenarios, mainly due to transmission medium features i.e. high losses, high latency and low reliability. Therefore, it is very difficult to provide continuous health monitoring with such stringent requirements on mobility. In this paper, a paradigm is proposed for mobility over 6LoWPAN for critical environments. On the one hand the intra-mobility is supported by GinMAC, which is an extension of IEEE 802.15.4 to support a topology control algorithm, which offers intra-mobility transparently, and Movement Direction Determination (MDD) of the Mobile Node (MN). On the other hand, the inter-mobility is based on pre-set-up of the network parameters in the visited networks, such as Care of Address and channel, to reach a fast and smooth handoff. Pre-set-up is reached since MDD allows discovering the next 6LoWPAN network towards which MN is moving. The proposed approach has been simulated, prototyped, evaluated, and is being studied in a scenario of wearable physiological monitoring in hazardous industrial areas, specifically oil refineries, in the scope of the GinSeng European project.     

Performance Analysis of UWB Channels for Wireless Personal Area Networks

Ultra-wide band (UWB) communication is one of the most promising technology for high data rate networks over short-range communication. The ultra-wide bandwidth offers pulses with very short duration that provides frequency diversity and multipath resolution. Ultra-wide band (UWB) channels raise new effects in the receiver, the amplitude fading statistics being different compared to the conventional narrow band wireless channels. This review paper focuses on modeling of ultra-wide band channels, especially for simulation of personal area networks and also discusses the benefits, application potential and technical challenges in wideband communication. The concept of Orthogonal Frequency Division Multiplexing (OFDM) has recently been applied in wireless communication systems due to its high data rate transmission capability with high bandwidth efficiency and its robustness to multi-path delay. UWB OFDM communication was proposed for physical layer in the IEEE 802.15.3a standard which covers wideband communication in wireless personal area networks. Since the channel model for multicarrier UWB communication is different from that of plain ultra-wide band channel, a novel modification method in UWB channel model is proposed with specific center frequency and multipath resolution. Moreover, dynamic channel estimation is necessary before demodulation of UWB OFDM signals since the radio channel is time varying and frequency selective for wideband systems. The performance of the proposed method is statistically analyzed using LS and MMSE based channel estimation methods.     

无线Ad hoc网络速率自适应MAC协议研究

无线Ad hoc网络多采用IEEE802.11系列标准,在物理层为数据传输提供了多速率能力。为了充分利用多速率能力提高系统的吞吐量,速率自适应MAC协议根据对当前信道质量的估计,选择最佳的数据传输速率。在分析了速率自适应MAC协议的基本工作过程之后,重点综述了目前存在的速率自适应MAC协议,并讨论了进一步研究的方向。     

无线个人区域网安全机制的分析

为保护无线个人区域网的安全性,IEEE802.15.3MAC层采用了结合AES算法和CCM模式的加密和认证方式。就CCM模式如何保证消息的完整性和机密性进行了分析。提出时安全防范的补充见解。