A survey on short-range WBAN communication; technical overview of several standard wireless technologies

In a healthy environment, a WBAN system is the key component or aspect of the patient monitoring system. WBAN systems allow for easy networking with other devices and networks so that healthcare professionals can easily access critical and non-critical patient data. One of the main advantages of WBAN is the remote monitoring of patients using an Intranet or the Internet. There are two main components to the type of communication technology used in WBAN. This page shows an insight of a variety of short-range standardized wireless devices, as well as a taxonomy of short-range technologies. These are proposed as intra-BAN communication candidates for communication within and between body area network (BAN) entities. This paper also highlights the advantages and disadvantages of the WBAN perspective. Finally, a side-by-side comparison of the basic principles of using MICS frequency bands and preparatory technologies

Ultra Low Power Communication Protocols for UWB Impulse Radio Wireless Sensor Networks

This thesis evaluates the potential of Ultra Wideband Impulse Radio for wireless sensor network applications. Wireless sensor networks are collections of small electronic devices composed of one or more sensors to acquire information on their environment, an energy source (typically a battery), a microcontroller to control the measurements, process the information and communicate with its peers, and a radio transceiver to enable these communications. They are used to regularly collect information within their deployment area, often for very long periods of time (up to several years). The large number of devices often considered, as well as the long deployment durations, makes any manual intervention complex and costly. Therefore, these networks must self-configure, and automatically adapt to changes in their electromagnetic environment (channel variations, interferers) and network topology modifications: some nodes may run out of energy, or suffer from a hardware failure. Ultra Wideband Impulse Radio is a novel wireless technology that, thanks to its extremely large bandwidth, is more robust to frequency dependent propagation effects. Its impulsional nature makes it robust to multipath fading, as the short duration of the pulses leads most multipath components to arrive isolated. This technology should also enable high precision ranging through time of flight measurements, and operate at ultra low power levels. The main challenge is to design a system that reaches the same or higher degree of energy savings as existing narrowband systems considering all the protocol layers. As these radios are not yet widely available, the first part of this thesis presents Maximum Pulse Amplitude Estimation, a novel approach to symbol-level modeling of UWB-IR systems that enabled us to implement the first network simulator of devices compatible with the UWB physical layer of the IEEE 802.15.4A standard for wireless sensor networks. In the second part of this thesis, WideMac, a novel ultra low power MAC protocol specifically designed for UWB-IR devices is presented. It uses asynchronous duty cycling of the radio transceiver to minimize the power consumption, combined with periodic beacon emissions so that devices can learn each other's wake-up patterns and exchange packets. After an analytical study of the protocol, the network simulation tool presented in the first part of the thesis is used to evaluate the performance of WideMac in a medical body area network application. It is compared to two narrowband and an FM-UWB solutions. The protocol stack parameters are optimized for each solution, and it is observed that WideMac combined to UWB-IR is a credible technology for such applications. Similar simulations, considering this time a static multi-hop network are performed. It is found that WideMac and UWB-IR perform as well as a mature and highly optimized narrowband solution (based on the WiseMAC ULP MAC protocol), despite the lack of clear channel assessment functionality on the UWB radio. The last part of this thesis studies analytically a dual mode MAC protocol named WideMac-High Availability. It combines the Ultra Low PowerWideMac with the higher performance Aloha protocol, so that ultra low power consumption and hence long deployment times can be combined with high performance low latency communications when required by the application. The potential of this scheme is quantified, and it is proposed to adapt it to narrowband radio transceivers by combining WiseMAC and CSMA under the name WiseMAC-HA

Interference management in impulse-radio ultra-wide band networks

We consider networks of impulse-radio ultra-wide band (IR-UWB) devices. We are interested in the architecture, design, and performance evaluation of these networks in a low data-rate, self-organized, and multi-hop setting. IR-UWB is a potential physical layer for sensor networks and emerging pervasive wireless networks. These networks are likely to have no particular infrastructure, might have nodes embedded in everyday life objects and have a size ranging from a few dozen nodes to large-scale networks composed of hundreds of nodes. Their average data-rate is low, on the order of a few megabits per second. IR-UWB physical layers are attractive for these networks because they potentially combine low-power consumption, robustness to multipath fading and to interference, and location/ranging capability. The features of an IR-UWB physical layer greatly differ from the features of the narrow-band physical layers used in existing wireless networks. First, the bandwidth of an IR-UWB physical layer is at least 500 MHz, which is easily two orders of magnitude larger than the bandwidth used by a typical narrow-band physical layer. Second, this large bandwidth implies stringent radio spectrum regulations because UWB systems might occupy a portion of the spectrum that is already in use. Consequently, UWB systems exhibit extremely low power spectral densities. Finally IR-UWB physical layers offer multi-channel capabilities for multiple and concurrent access to the physical layer. Hence, the architecture and design of IR-UWB networks are likely to differ significantly from narrow-band wireless networks. For the network to operate efficiently, it must be designed and implemented to take into account the features of IR-UWB and to take advantage of them. In this thesis, we focus on both the medium access control (MAC) layer and the physical layer. Our main objectives are to understand and determine (1) the architecture and design principles of IR-UWB networks, and (2) how to implement them in practical schemes. In the first part of this thesis, we explore the design space of IR-UWB networks and analyze the fundamental design choices. We show that interference from concurrent transmissions should not be prevented as in protocols that use mutual exclusion (for instance, IEEE 802.11). Instead, interference must be managed with rate adaptation, and an interference mitigation scheme should be used at the physical layer. Power control is useless. Based on these findings, we develop a practical PHY-aware MAC protocol that takes into account the specific nature of IR-UWB and that is able to adapt its rate to interference. We evaluate the performance obtained with this design: It clearly outperforms traditional designs that, instead, use mutual exclusion or power control. One crucial aspect of IR-UWB networks is packet detection and timing acquisition. In this context, a network design choice is whether to use a common or private acquisition preamble for timing acquisition. Therefore, we evaluate how this network design issue affects the network throughput. Our analysis shows that a private acquisition preamble yields a tremendous increase in throughput, compared with a common acquisition preamble. In addition, simulations on multi-hop topologies with TCP flows demonstrate that a network using private acquisition preambles has a stable throughput. On the contrary, using a common acquisition preamble exhibits an effect similar to exposed terminal issues in 802.11 networks: the throughput is severely degraded and flow starvation might occur. In the second part of this thesis, we are interested in IEEE 802.15.4a, a standard for low data-rate, low complexity networks that employs an IR-UWB physical layer. Due to its low complexity, energy detection is appealing for the implementation of practical receivers. But it is less robust to multi-user interference (MUI) than a coherent receiver. Hence, we evaluate the performance of an IEEE 802.15.4a physical layer with an energy detection receiver to find out whether a satisfactory performance is still obtained. Our results show that MUI severely degrades the performance in this case. The energy detection receiver significantly diminishes one of the most appealing benefits of UWB, specifically its robustness to MUI and thus the possibility of allowing for parallel transmissions. This performance analysis leads to the development of an IR-UWB receiver architecture, based on energy detection, that is robust to MUI and adapted to the peculiarities of IEEE 802.15.4a. This architecture greatly improves the performance and entails only a moderate increase in complexity. Finally, we present the architecture of an IR-UWB physical layer implementation in ns-2, a well-known network simulator. This architecture is generic and allows for the simulation of several multiple-access physical layers. In addition, it comprises a model of packet detection and timing acquisition. Network simulators also need to have efficient algorithms to accurately compute bit or packet error rates. Hence, we present a fast algorithm to compute the bit error rate of an IR-UWB physical layer in a network setting with MUI. It is based on a novel combination of large deviation theory and importance sampling

Performance analysis of a threshold-based dynamic TXOP scheme for intra-AC QoS in wireless LANs

PublishedJournal ArticleThis is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.The IEEE 802.11e Enhanced Distributed Channel Access (EDCA) protocol has been proposed for provisioning of differentiated Quality-of-Service (QoS) between various Access Categories (ACs), i.e., inter-AC QoS, in Wireless Local Area Networks (WLANs). However, the EDCA lacks the support of the intra-AC QoS provisioning, which is indispensable in practical WLANs since the network loads are always asymmetric between traffic flows of ACs with the same priority. To address the intra-AC QoS issue, this paper proposes a Threshold-Based Dynamic Transmission Opportunity (TBD-TXOP) scheme which sets the TXOP limits adaptive to the current status of the transmission queue based on the pre-setting threshold. An analytical model is further developed to evaluate the QoS performance of this scheme in terms of throughput, end-to-end delay, and frame loss probability. NS-2 simulation experiments validate the accuracy of the proposed analytical model. The performance results demonstrate the efficacy of TBD-TXOP for the intra-AC QoS differentiation. © 2013 Elsevier B.V. All rights reserved

Clock synchronisation for UWB and DECT communication networks

Synchronisation deals with the distribution of time and/or frequency across a network of nodes dispersed in an area, in order to align their clocks with respect to time and/or frequency. It remains an important requirement in telecommunication networks, especially in Time Division Duplexing (TDD) systems such as Ultra Wideband (UWB) and Digital Enhanced Cordless Telecommunications (DECT) systems. This thesis explores three di erent research areas related to clock synchronisation in communication networks; namely algorithm development and implementation, managing Packet Delay Variation (PDV), and coping with the failure of a master node. The first area proposes a higher-layer synchronisation algorithm in order to meet the specific requirements of a UWB network that is based on the European Computer Manufacturers Association (ECMA) standard. At up to 480 Mbps data rate, UWB is an attractive technology for multimedia streaming. Higher-layer synchronisation is needed in order to facilitate synchronised playback at the receivers and prevent distortion, but no algorithm is de ned in the ECMA-368 standard. In this research area, a higher-layer synchronisation algorithm is developed for an ECMA-368 UWB network. Network simulations and FPGA implementation are used to show that the new algorithm satis es the requirements of the network. The next research area looks at how PDV can be managed when Precision Time Protocol (PTP) is implemented in an existing Ethernet network. Existing literature indicates that the performance of a PDV ltering algorithm usually depends on the delay pro le of the network in which it is applied. In this research area, a new sample-mode PDV filter is proposed which is independent of the shape of the delay profile. Numerical simulations show that the sample-mode filtering algorithm is able to match or out-perform the existing sample minimum, mean, and maximum filters, at differentlevels of network load. Finally, the thesis considers the problem of dealing with master failures in a PTP network for a DECT audio application. It describes the existing master redundancy techniques and shows why they are unsuitable for the specific application. Then a new alternate master cluster technique is proposed along with an alternative BMCA to suit the application under consideration. Network simulations are used to show how this technique leads to a reduction in the total time to recover from a master failure

Analysis of the IEEE 802.15.4a ultra wideband physical layer through wireless sensor network simulations in OMNET++

Wireless Sensor Networks are the main representative of pervasive computing in large-scale physical environments. These networks consist of a large number of small, wireless devices embedded in the physical world to be used for surveillance, environmental monitoring or other data capture, processing and transfer applications. Ultra wideband has emerged as one of the newest and most promising concepts for wireless technology. Considering all its advantages it seems a likely communication technology candidate for future wireless sensor networks. This paper considers the viability of ultra wideband technology in wireless sensor networks by employing an IEEE 802.15.4a low-rate ultra wideband physical layer model in the OMNET++ simulation environment. An elaborate investigation into the inner workings of the IEEE 802.15.4a UWB physical layer is performed. Simulation experiments are used to provide a detailed analysis of the performance of the IEEE 802.15.4a UWB physical layer over several communication distances. A proposal for a cognitive, adaptive communication approach to optimize for speed and distance is also presented. AFRIKAANS : Draadlose Sensor Netwerke is die hoof verteenwoordiger vir deurdringende rekenarisering in groot skaal fisiese omgewings. Hierdie tipe netwerke bestaan uit ’n groot aantal klein, draadlose apparate wat in die fisiese wêreld ingesluit word vir die doel van bewaking, omgewings monitering en vele ander data opvang, verwerk en oordrag applikasies. Ultra wyeband het opgestaan as een van die nuutste en mees belowend konsepte vir draadlose kommunikasie tegnologie. As al die voordele van dié kommunikasie tegnologie in ag geneem word, blyk dit om ’n baie goeie kandidaat te wees vir gebruik in toekomstige draadlose sensor netwerke. Hierdie verhandeling oorweeg die vatbaarheid van die gebruik van die ultra wyeband tegnologie in draadlose sensor netwerke deur ’n IEEE 802.15.4a lae-tempo ultra wyeband fisiese laag model in die OMNET++ simulasie omgewing toe te pas. ’n Breedvoerige ondersoek word geloots om die fyn binneste werking van die IEEE 802.15.4a UWB fisiese laag te verstaan. Simulasie eksperimente word gebruik om ’n meer gedetaileerde analiese omtrent die werkverrigting van die IEEE 802.15.4a UWB fisiese laag te verkry oor verskillende kommunikasie afstande. ’n Voorstel vir ’n omgewings bewuste, aanpasbare kommunikasie tegniek word bespreek met die doel om die spoed en afstand van kommunikasie te optimiseer.Dissertation (MEng)--University of Pretoria, 2011.Electrical, Electronic and Computer Engineeringunrestricte

Technology Implications of UWB on Wireless Sensor Network-A detailed Survey

In today’s high tech “SMART” world sensor based networks are widely used. The main challenge with wireless-based sensor networks is the underneath physical layer. In this survey, we have identified core obstacles of wireless sensor network when UWB is used at PHY layer. This research was done using a systematic approach to assess UWB’s effectiveness (for WSN) based on information taken from various research papers, books, technical surveys and articles. Our aim is to measure the UWB’s effectiveness for WSN and analyze the different obstacles allied with its implementation. Starting from existing solutions to proposed theories. Here we have focused only on the core concerns, e.g. spectrum, interference, synchronization etc.Our research concludes that despite all the bottlenecks and challenges, UWB’s efficient capabilities makes it an attractive PHY layer scheme for the WSN, provided we can control interference and energy problems. This survey gives a fresh start to the researchers and prototype designers to understand the technological concerns associated with UWB’s implementatio

The Wireless Body Area Sensor Networks and Routing Strategies: Nomenclature and Review of Literature

WBASN is an effective solution that has been proposed in terms of improving the solutions and there are varied benefits that have been achieved from the usage of WBASN solutions in communication, healthcare domain. From the review of stats on rising number of wireless devices and solutions that are coming up which is embraced by the people as wearable devices, implants for medical diagnostic solutions, etc. reflect upon the growing demand for effective models. However, the challenge is about effective performance of such solutions with optimal efficiency. Due to certain intrinsic factors like numerous standards that are available, and also due to the necessity for identifying the best solutions that are based on application requirements. Some of the key issues that have to be considered in the process of WBASN are about the impacts that are taking place from the wireless medium, the lifetime of batteries in the WBASN devices and the other significant condition like the coexistence of the systems among varied other wireless networks that are constituted in the proximity. In this study, scores of models that has been proposed pertaining to MAC protocols for WBASN solutions has been reviewed to understand the efficacy of the existing systems, and a scope for process improvement has been explored for conducting in detail research and developing a solution

Design, Modeling, and Analysis for MAC Protocols in Ultra-wideband Networks

Ultra-wideband (UWB) is an appealing transmission technology for short-range, bandwidth demanded wireless communications. With the data rate of several hundred megabits per second, UWB demonstrates great potential in supporting multimedia streams such as high-definition television (HDTV), voice over Internet Protocol (VoIP), and console gaming in office or home networks, known as the wireless personal area network (WPAN). While vast research effort has been made on the physical layer issues of UWB, the corresponding medium access control (MAC) protocols that exploit UWB technology have not been well developed. Given an extremely wide bandwidth of UWB, a fundamental problem on how to manage multiple users to efficiently utilize the bandwidth is a MAC design issue. Without explicitly considering the physical properties of UWB, existing MAC protocols are not optimized for UWB-based networks. In addition, the limited processing capability of UWB devices poses challenges to the design of low-complexity MAC protocols. In this thesis, we comprehensively investigate the MAC protocols for UWB networks. The objective is to link the physical characteristics of UWB with the MAC protocols to fully exploit its advantage. We consider two themes: centralized and distributed UWB networks. For centralized networks, the most critical issue surrounding the MAC protocol is the resource allocation with fairness and quality of service (QoS) provisioning. We address this issue by breaking down into two scenarios: homogeneous and heterogeneous network configurations. In the homogeneous case, users have the same bandwidth requirement, and the objective of resource allocation is to maximize the network throughput. In the heterogeneous case, users have different bandwidth requirements, and the objective of resource allocation is to provide differentiated services. For both design objectives, the optimal scheduling problem is NP-hard. Our contributions lie in the development of low-complexity scheduling algorithms that fully exploit the characteristics of UWB. For distributed networks, the MAC becomes node-based problems, rather than link-based problems as in centralized networks. Each node either contends for channel access or reserves transmission opportunity through negotiation. We investigate two representative protocols that have been adopted in the WiMedia specification for future UWB-based WPANs. One is a contention-based protocol called prioritized channel access (PCA), which employs the same mechanisms as the enhanced distributed channel access (EDCA) in IEEE 802.11e for providing differentiated services. The other is a reservation-based protocol called distributed reservation protocol (DRP), which allows time slots to be reserved in a distributed manner. Our goal is to identify the capabilities of these two protocols in supporting multimedia applications for UWB networks. To achieve this, we develop analytical models and conduct detailed analysis for respective protocols. The proposed analytical models have several merits. They are accurate and provide close-form expressions with low computational effort. Through a cross-layer approach, our analytical models can capture the near-realistic protocol behaviors, thus useful insights into the protocol can be obtained to improve or fine-tune the protocol operations. The proposed models can also be readily extended to incorporate more sophisticated considerations, which should benefit future UWB network design