Low-rate Wireless Personal Area Networks Research Articles

An overview of the IEEE 802.15.4a Standard

This article presents the IEEE 802.15.4a standard, the first international standard that specifies a wireless physical layer to enable precision ranging. As an amendment to the popular IEEE 802.15.4-2006, the IEEE 802.15.4a-2007 standard introduces new options for the physical layer in order to support higher data rates, extended range, improved robustness against interference, and mobility, while enabling new applications based on distance information of the devices in a low-rate wireless personal area network.

Logical Position Exchange Algorithm for Efficient Management in ZigBee Tree Networks

Currently, there are various routing methods that consider the energy in a wireless sensor environment. The algorithm we consider is a low-rate wireless personal area network, viz., 802.15.4, and ZigBee routing network. Considering, the overall organization of the network energy efficiency, we suggest a logical position exchange (LPE) algorithm between specified nodes. Logical positioning means connecting high sub-networks and low sub-networks based on the neighbor nodes information of the address ID, and depth in the ZigBee tree topology network. When one of the nodes of the tree topology network, which is responsible for connecting multiple low sub-networks and high sub-networks, has difficulty performing its important roles in the network, because of energy exhaustion, it exchanges essential information and entrusts logical positioning to another node that is capable of it. A partial change in the logical topology enhances the energy efficiency in the network.

Meshing wireless personal area networks: Introducing IEEE 802.15.5

This article presents an overview of the IEEE project 802.15.5 that targets providing mesh capabilities to both high-rate and low-rate wireless personal area networks. Low-rate mesh is built on IEEE 802.15.4 MAC, while high-rate mesh utilizes IEEE 802.15.3 MAC. We seek to share our insights and motivations of the approach adopted in the major components of the standard instead of presenting a la carte items drawn in the specification. We hope this article helps readers of the 802.15.5 standard to better understand the rationale and intent of the protocol design.

Routing Strategy Selection for Zigbee Mesh Networks

Based on IEEE 802.15.4 Low Rate-Wireless Personal Area Network (LR-WPAN) standard, the Zigbee standard has been proposed to interconnect simple, low rate and battery powered wireless devices. The deployment of Zigbee network is expected to facilitate numerous applications such as Home-appliance networks, home healthcare, medical monitoring and environmental sensors. An effective routing scheme is more important for Zigbee mesh networks. In order to achieve effective routing in Zigbee Mesh networks, a Zigbee protocol module is realized using NS-2. The suitable routing for different data services in the Zigbee application layer and a best routing strategy for Zigbee mesh network are proposed. The simulation shows the selection of suitable routing for continuous data services and for bursting data services in the Zigbee application layer and the comparison of three routing strategies namely ERD (All packets Enable Route Discovery), SRD (All packets Suppress Route Discovery) and BOS (routing Based on Data Services) in the aspects of Efficiency and Overhead.

Reliability Analysis and Modeling of ZigBee Networks

The architecture of ZigBee networks focuses on developing low-cost, low-speed ubiquitous communication between devices. The ZigBee technique is based on IEEE 802.15.4, which specifies the physical layer and medium access control (MAC) for a low rate wireless personal area network (LR-WPAN). Currently, numerous wireless sensor networks have adapted the ZigBee open standard to develop various services to promote improved communication quality in our daily lives. The problem of system and network reliability in providing stable services has become more important because these services will be stopped if the system and network reliability is unstable. The ZigBee standard has three kinds of networks ; star, tree and mesh. The paper models the ZigBee protocol stack from the physical layer to the application layer and analyzes these layer reliability and mean time to failure (MTTF). Channel resource usage, device role, network topology and application objects are used to evaluate reliability in the physical, medium access control, network, and application layers, respectively. In the star or tree networks, a series system and the reliability block diagram (RBD) technique can be used to solve their reliability problem. However, a division technology is applied here to overcome the problem because the network complexity is higher than that of the others. A mesh network using division technology is classified into several non-reducible series systems and edge parallel systems. Hence, the reliability of mesh networks is easily solved using series-parallel systems through our proposed scheme. The numerical results demonstrate that the reliability will increase for mesh networks when the number of edges in parallel systems increases while the reliability quickly drops when the number of edges and the number of nodes increase for all three networks. More use of resources is another factor impact on reliability decreasing. However, lower network reliability will occur due to network complexity, more resource usage and complex object relationship.

Improving Spectral and Temporal Efficiency of Collocated IEEE 802.15.4 LR-WPANs

The number of frequency channels specified for IEEE 802.15.4 low-rate wireless personal area networks (LR-WPANs) does not suffice to operate a variety of collocated WPAN applications that the standard is targeting. To overcome this limit, we introduce virtual channel, a novel concept to increase the number of available channels by efficiently managing given spectral and temporal resources. A virtual channel is created by scheduling a superframe and selecting a logical channel. This extends the notion of a channel from spectral domain to spectral and temporal domain. Specifically, we propose a superframe scheduler using throughput estimation (SUTE) of the IEEE 802.15.4 carrier sense multiple access with collision avoidance (CSMA/CA). In addition, nearest vacancy search (NEVS) is proposed, both of which are for temporal efficiency of the collocation. For both spectral and temporal efficiency, virtual channel selector (VCS) is proposed. The simulation results show that a remarkable improvement on the collocation efficiency of IEEE 802.15.4 can be achieved by our proposals. Moreover, this study also reveals the fundamental drawback of the current standard in terms of the collocation efficiency that the beacon interval and superframe duration are adjustable only by exponent parameters.

A comprehensive analysis of low-power operation for beacon-enabled IEEE 802.15.4 wireless networks

ZigBee, a unique communication standard designed for low-rate wireless personal area networks, has extremely low complexity, cost, and power consumption for wireless connectivity of inexpensive, portable, and moving devices. ZigBee uses the IEEE 802.15.4 standard as its communication protocol for medium access control (MAC) layer and physical (PHY) layer. The IEEE 802.15.4 MAC layer achieves duty-cycle operations by setting two system parameters, macBeaconOrder (BO) and macSuperFrameOrder (SO), to achieve low power consumption for ZigBee devices. This study comprehensively analyzes IEEE 802.15.4 duty-cycle operation. Specifically, a novel analytical model that accommodates a general traffic distribution is developed. An NS-2 based simulation model, which is validated by the developed analytical model is also proposed. Through the experiments conducted by the analytical and simulation models, some important performance-evaluation insights are gained that can be used as guidelines for future low-power ZigBee network deployment.

Study on a delayed backoff algorithm for IEEE 802.15.4 low-rate wireless personal area networks

IEEE 802.15.4 standard applies the slotted carrier sense multiple access with collision avoidance (CSMA/CA) for its contention mechanism in the contention access period (CAP). In CAP, channel utilisation is significantly affected by backoff time and collision. A delayed backoff algorithm (DBA) in CAP is proposed for the beacon-enabled networks. DBA improves the goodput and power consumption by decreasing the backoff time between packets and assuring that the different nodes will not finish their backoffs at the same time. Simulation results show that the proposed algorithm outperforms the slotted CSMA/CA and other schemes in terms of goodput and power consumption.

EAMTR: energy aware multi-tree routing for wireless sensor networks

IEEE 802.15.4 is the prevailing standard for low-rate wireless personal area networks. It specifies the physical layer and medium access control sub-layer. Some emerging standards such as ZigBee define the network layer on top of these lower levels to support routing and multi-hop communication. Tree routing is a favourable basis for ZigBee routing because of its simplicity and limited use of resources. However, in data collection systems that are based on spanning trees rooted at a sink node, non-optimal route selection, congestion and uneven distribution of traffic in tree routing can adversely contribute to network performance and lifetime. The imbalance in workload can result in hotspot problems and early energy depletion of specific nodes that are normally the crucial routers of the network. The authors propose a novel light-weight routing protocol, energy aware multi-tree routing (EAMTR) protocol, to balance the workload of data gathering and alleviate the hotspot and single points of failure problems for high-density sink-type networks. In this scheme, multiple trees are formed in the initialisation phase and according to network traffic, each node selects the least congested route to the root node. The results of simulation and performance evaluation of EAMTR show significant improvement in network lifetime and traffic distribution.

Simple Design of Detector in the Presence of Frequency Offset for IEEE 802.15.4 LR-WPANs

A simple detector for orthogonal modulation that is robust to large frequency offsets is proposed. The complexity of the detector is significantly reduced by implementing the correlator using multiplexers instead of complex floating-point multiplications. The performance of this design is comparable to the optimal value obtained by double correlation in offset quadrature phase-shift keying (O-QPSK) and nearly reaches that of noncoherent maximum likelihood (NCOHML) detection with 10-ppm frequency offset in the additive white Gaussian noise (AWGN) channel. Therefore, the proposed design can be used in low-cost and low-power IEEE 802.15.4 low-rate wireless personal area network (LR-WPAN) applications.

다중 차분 필터에 의한 IEEE 802.15.4b LR-WPAN 주파수 옵셋의 개선

본 논문에서는 915MHz 대역 IEEE 802.15.4b LR-WPAN(Low-Rate Wireless Personal Area Network) 비동기 DSSS O-QPSK 기반 수신 시스템의 주파수 옵셋 영향을 분석하고, 차분 필터를 추가 함으로써 주파수 옵셋을 보상할 수 있는 방법을 제시한다. IEEE 802.15.4b 915MHz 규격에서는 DSSS PSSS-ASK 변조방식과 DSSS O-QPSK 변조방식을 채용하여 250kbps의 전송율을 갖는 새로운 방식을 제시하고 있다. 본 논문에서 사용한 DSSS O-QPSK 변조방식은 40ppm(주파수 옵셋 36.6kHz)까지는 BER에 변화가 없으나, 그 이상의 주파수 옵셋이 발생하면 BER이 높아져 안정적인 수신이 어려운 문제가 있다. 이 문제를 해결하기 위해 DSSS O-QPSK 기반 수신기의 상관기에 MDDF(Multiple Delay Differential Filter)를 적용하여 <TEX>${\pm}80ppm$</TEX>에서도 안정적인 수신이 가능함을 보인다. 제안 알고리즘의 성능을 검증하기 위해, 다양한 AWGN 및 주파수 옵셋 환경을 가정한 컴퓨터 모의실험의 결과를 제시하고, 그 유효성을 입증한다. This paper analyze the effect of frequency offset for the IEEE 802.15.4b LR-WPAN(Low-Rate Wireless Personal Area Network) with 915MHz bandwidth noncoherent DSSS O-QPSK based receiver system, and presents a compensation method with addition of differential filter to the system for compensation of frequency offset problem. DSSS PSSS-ASK and DSSS O-QPSK modulation techniques are accepted within the regularization of IEEE 802.15.4b. These new method can obtain 250kbps transmission rate. The DSSS O-QPSK modulation method that is used in this paper has no BER variation below 40ppm(frequency offset 36.6kHz), but if the offset frequency become high above 40ppm, then the system cannot have stable receiving condition due to worse BER. To solve this problem, we present a more stabilized receiver system at maximum frequency offset <TEX>${\pm}80ppm$</TEX> using MDDF unti a correlator of DSSS O-QPSK modulator. Moreover computer simulation results will be presented to evaluate the performance of the proposed algorithm unde various AWGN and frequency offset environment.

Simulation study of IEEE 802.15.4 LR‐WPAN for industrial applications

AbstractThe IEEE 802.15.4 protocol has become the primary solution for many low‐rate wireless personal area network (LR‐WPAN) applications. This is especially the case for industrial sensor network applications such as automation control. We contribute to the better understanding of the protocol behavior by presenting a set of results of simulation experiments. Our results outline the capabilities of this protocol in the selected scenarios but also the limitations. In particular, we investigated the dependency of the protocol on protocol‐inherent parameters such as the beacon order and the superframe order but also to different traffic load. Our results can be used for planning and deploying IEEE 802.15.4‐ based sensor networks with specific performance demands. We put a special focus on application scenarios in industrial sensor network applications. The primary requirements are reduced end‐to‐end latency and energy consumption. Our studies are based on our new implementation of IEEE 802.15.4 developed for the simulation framework OMNeT++. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Traffic Adaptive Contention Differentiation Scheme for LR-WPANs

IEEE 802.15.4 is a new standard, uniquely designed for low rate wireless personal area networks (LR-WPANs). It targets ultra-low complexity, cost, and power, for low-data-rate wireless connectivity. However, one of the main problems of this new standard is its insufficient, and inefficient, media access control (MAC) for priority data. This paper introduces an extended contention access period (XCAP) concept for priority packets, also an traffic adaptive contention differentiation utilizing the XCAP (TACDX). The TACDX determines appropriate transmission policy alternatively according to the traffic conditions and type of packet. TACDX achieves not only enhanced transmission for priority packets but it also has a high energy efficiency for the overall network. The proposed TACDX is verified with simulations to measure the performances.

An Adaptive Beacon Scheduling Mechanism Using Power Control in Cluster-Tree WPANs

This paper presents an adaptive beacon scheduling mechanism using power control in cluster-tree network. We consider the emerging low-rate wireless personal area networks (LR-WPANs) technology as specified in the IEEE 802.15.4 standard that can support environmental monitoring applications. Node clustering is a useful topology management approach to reduce channel contention and improve the network lifetime in wireless sensor networks. A cluster-tree network conforming to the IEEE 802.15.4 standard is formed by several coordinators that periodically send beacon frames to the nodes of their cluster. However, if these periodic beacon frames are sent without any particular scheduling, they will collide with each other and those nodes that wait for them will lose synchronization with their coordinators. The purpose of this paper is to overcome this problem by proposing an adaptive beacon scheduling mechanism using power control, cluster grouping, and the group identifier (GID) in cluster-tree WPANs. This mechanism is designed such that all of the sensing devices send the measured received power level back to their cluster heads (CHs), thus enabling them to adjust their transmission power level after the construction of the topology. Following this, the PAN coordinator divides all of the CHs into several cluster groups (CGs) in order to transmit their beacon frames simultaneously without encountering any direct or indirect beacon frame collision problems. The PAN coordinator selects the group heads (GHs) and assigns the GID for each cluster group. In addition, the PAN coordinator controls the beacon transmission time of all of the CHs and GHs in the CGs using the GID information located in the beacon frame of the PAN coordinator in order to avoid beacon frame collisions. Accordingly, the overall lifetime of the network in cluster-tree WPANs is prolonged by solving the problem of beacon frame collisions. We evaluated the performance of our scheme through a mathematical analysis and a series of simulations using the Network Simulator 2 (NS-2).

A Low-Complexity Frequency Offset Insensitive Detection for 2.45 GHz LR-WPAN

In this paper, we propose a low-complexity frequency offset insensitive detection method for the 2.45GHz LR-WPAN demodulator. In IEEE 802.15.4 LR-WPAN (Low-Rate Wireless Personal Area Network) specification, the frequency offset as highest±80ppm in the 2.45GHz band is recommended for low-complexity, low-cost, and low-power implementation. The proposed detection method is verified such that the performance is within 2dB of the optimal coherent detection with low complexity, which is less than half in comparison with conventional detection methods.

Optimal beacon scheduling mechanisms using cluster identifier for healthcare application

This paper presents optimal beacon scheduling mechanisms using the cluster identifier (CID) for medical and healthcare applications. We consider the emerging low-rate wireless personal area networks (WPAN) technology as specified in the IEEE 802.15.4 standard that can support medical and healthcare applications. In addition, we have adopted the concept of cluster-tree human body networks (HBNs) for use in healthcare applications. A cluster-tree network conforming to the IEEE 802.15.4 standard is formed by several coordinators that periodically send beacon frames to the nodes of their cluster. If these periodic beacon frames are sent without any particular scheduling, they will collide with each other and the nodes that wait for the periodic beacon frames will loose synchronization with their coordinators. The purpose of this paper is to overcome this problem by proposing optimal beacon scheduling mechanisms using the CID for cluster-tree HBNs. These mechanisms are designed such that the PAN coordinator controls the beacon transmission time of all of the cluster heads (CHs) using the CID field located in the beacon frame of the PAN coordinator, in order to avoid beacon frame collisions. In particular, only those sensor nodes located in the cluster that needs the medical attention of the hospital staff according to the patients’ condition transmit their sensing data to the PAN coordinator via the CH, while those sensor nodes located in other clusters return to sleep mode. Accordingly, the lifetime of the sensor nodes is prolonged by using the cluster-tree HBNs model. We evaluated the performance of our scheme through a mathematical analysis and a series of simulations using the Network Simulator 2 (NS-2).

An optimal GTS scheduling algorithm for time-sensitive transactions in IEEE 802.15.4 networks

IEEE 802.15.4 is a new enabling standard for low-rate wireless personal area networks and has been widely accepted as a de facto standard for wireless sensor networking. While primary motivations behind 802.15.4 are low power and low cost wireless communications, the standard also supports time and rate sensitive applications because of its ability to operate in TDMA access modes. The TDMA mode of operation is supported via the Guaranteed Time Slot (GTS) feature of the standard. In a beacon-enabled network topology, the Personal Area Network (PAN) coordinator reserves and assigns the GTS to applications on a first-come-first-served (FCFS) basis in response to requests from wireless sensor nodes. This fixed FCFS scheduling service offered by the standard may not satisfy the time constraints of time-sensitive transactions with delay deadlines. Such operating scenarios often arise in wireless video surveillance and target detection applications running on sensor networks. In this paper, we design an optimal work-conserving scheduling algorithm for meeting the delay constraints of time-sensitive transactions and show that the proposed algorithm outperforms the existing scheduling model specified in IEEE 802.15.4.

Power saving algorithms for wireless sensor networks on IEEE 802.15.4

IEEE 802.15.4 is the global standard protocol designed for low-power and low-rate wireless personal area networks. When applied to sensor networks, extra care should be taken due to their requirements for multihop communication with minimum energy consumption. In this article we first discuss potential problems with the energy consumption in sensor networks using IEEE 802.15.4. Then six representative categories of algorithms are presented. The algorithms reside in between the MAC and a network layer. All operations of the MAC are performed through the standard interfaces of IEEE 802.15.4 without altering the standard protocol. The energy consumption and latency of the algorithms are evaluated by analysis and experiments, and the feasibility of real implementations is also discussed.

UWB Direct Chaotic Communication Technology for Low-Rate WPAN Applications

The goal of this paper is to describe the design of an ultrawideband (UWB) system that is optimized for low-complexity, low-power, low-cost, and low-rate wireless personal area network applications. To this aim, we propose a system based on novel direct chaotic communication (DCC) technology, in which a 2-GHz-wide chaotic signal is directly generated into the lower band of the UWB spectrum. Based on this system, two simple modulation schemes, namely, chaotic on-off keying and differential chaos-shift keying, are studied, and the performance of both noncoherent and differential-coherent transceiver architectures is evaluated. Various system design parameters and tradeoffs are discussed throughout the paper, including frequency band plans, data throughput, and system scalability. In particular, the frequency-division multiplexing technique is proposed as a low-cost alternative to achieving simultaneous operating piconets for short-distance applications. The average power consumption for various operating data rates and the technical feasibility of implementing the DCC system as a low-cost integrated circuit are also addressed. Finally, Monte Carlo simulations are performed based on the IEEE 802.15.4a standard channel models to evaluate the performance of the two modulation schemes. In general, both schemes experience little degradation under multipath environments due to the self-inherent wideband characteristic of the chaotic signal.

An Adaptive GTS Allocation Scheme for IEEE 802.15.4

IEEE 802.15.4 is a new standard uniquely designed for low-rate wireless personal area networks. It targets ultralow complexity, cost, and power for low-rate wireless connectivity among inexpensive, portable, and moving devices. IEEE 802.15.4 provides a guaranteed time slot (GTS) mechanism to allocate a specific duration within a superframe for time-critical transmissions. This paper proposes an adaptive GTS allocation (AGA) scheme for IEEE 802.15.4, which considers low latency and fairness. The scheme is designed based on the existing IEEE 802.15.4 medium access control protocol, and IEEE 802.15.4 devices can receive this AGA service without any modification. A simulation model and an analytical model are developed to investigate the performance of our AGA scheme. The numerical results show that the proposed scheme significantly outperforms the existing IEEE 802.15.4 implementation.