Optimal transmissions for space-time coded OFDM UWB systems

1 Introduction Recently, the high rate short range wireless personal area network (WPAN) is considered. When the inverse of the sampling rate is significantly shorter than the total delay spread, as is the case for most UWB communication systems, OFDM systems are more attractive than a single-carrier system. The multi-band OFDM physical layer proposal has been adopt by IEEE 802.15.3a Task Group[1]。 Combing STC and OFDM have the properties to achieve high data rate and mitigate int…     

A Distributed Cooperative MAC Protocol for QoS Improvement and Mobility Support in WiMedia Networks

A Distributed Medium Access Control (D-MAC) protocol based on UWB for high-rate Wireless Personal Area Networks is specified by the WiMedia Alliance. D-MAC protocol is suitable for ubiquitous connection in home networks, military/medical applications due to its inexpensive cost, low power consumption, high data rate, and distributed approach. In contrast to IEEE 802.15.3, D-MAC makes all devices have the same functionality. And its networks are self-organized and provide devices with functions such as access to the medium, channel allocation to devices, data transmission, quality of service and synchronization in a distributed manner. D-MAC fundamentally removes the problems of the centralized MAC approach revealed at IEEE 802.15.3 MAC by adopting a distributed architecture. However, the current D-MAC can’t prevent QoS degradations, occurred by mobile nodes with low data rate due to bad channel status, which cause critical problems in QoS provisioning to isochronous streams and mobile applications. Therefore, we propose a distributed cooperative MAC protocol for multi-hop WiMedia networks using virtual MIMO links. Based on instantaneous Channel State Information among WiMedia devices, our proposed protocol can intelligently select the transmission path with higher data rate to provide advanced QoS with minimum delay for real-time multimedia streaming services.     

TCP Over the IEEE 802.15.3 MAC: Analysis and Simulation

High data rate wireless technologies are now becoming a reality, and have spurred the development of new applications that were previously hindered by the lack of capacity. In particular, it is now possible to stream high definition movies from a laptop to a sound system and flat screen television seamlessly. One of the key enablers of such applications is the IEEE 802.15.3 medium access control (MAC) protocol, which is designed to support bandwidth intensive applications in wireless personal area networks (WPANs). A key observation is that a significant number of multi-media applications rely on the transmission control protocol (TCP). Unfortunately, little works have conducted a thorough performance study of TCP over the IEEE 802.15.3 MAC. Moreover, the IEEE 802.15.3 specification does not specify any strategies for allocating time slots. This paper therefore contributes to the current state-of-the-art in the following manners. From our extensive analytical and simulation studies, we reveal the impacts of different channel time allocation methods and acknowledgment policies on the performance of TCP, with particular attention on round trip time, congestion window growth, and packet recovery. We then present the following guidance to application developers: (1) channel time allocations (CTAs) should be distributed evenly over the superframe and have durations determined by TCP’s maximum congestion window, (2) CTA positioning has no impact on TCP’s performance, and (3) the specified delayed acknowledgment policy needs to be augmented with an adaptive algorithm that adjusts its burst size dynamically to varying bit error rate (BER).     

Third-Party Handshake Protocol for Efficient Peer Discovery and Route Optimization in IEEE 802.15.3 WPANs

Designed for high data rate wireless personal area networks, the IEEE 802.15.3 medium access control (MAC) protocol fits well with emerging technologies like ultra-wideband. Peer discovery is essential in 802.15.3 piconets in which devices (DEVs) exchange MAC frames in a peer-to-peer manner. If two peer DEVs are unreachable, the standard peer discovery method will fail after unproductive backoff retransmissions, and a costly network layer routing is required. For DEVs uniformly distributed over the maximum coverage area of a piconet, such failures occur in up to 41.3% of intra-piconet peer discoveries. In this paper, we propose a novel third-party handshake protocol (3PHP) that provides more reliable and prompt peer discovery than the standard method. Especially, between directly unreachable DEVs within the same piconet, 3PHP replaces network layer routing by an efficient MAC layer forwarding that utilizes the available self-learning rate information to establish optimal routes. The mean peer discovery time for 3PHP is 100 μs lower than the standard method between directly reachable DEVs. More significantly, between directly unreachable DEVs within the same piconet, 3PHP has a much lower failure probability, and is up to 10 times faster than the standard method in establishing a peer-to-peer connection as the latter fails and network layer routing is invoked. Paper accepted for publication in ACM/Kluwers MONET. This paper is based in part on a paper presented at IEEE BroadNets 2005, Boston, MA, Oct. 2005.     

A hardware accelerated implementation of the IEEE 802.15.3 MAC protocol

We present a hardware/software implementation of the IEEE 802.15.3 MAC protocol. Processing-intensive and time-critical protocol tasks are handled by a protocol accelerator that is integrated on-chip with a 32-bit general-purpose processor in order to achieve a moderate (20–40 MHz) system clock frequency. This enables low-power wireless devices compliant with this standard, providing high data rate, multimedia communication. One of the main tasks of the protocol accelerator is to analyze received or transmitted beacons. Based on the channel time allocations broadcast in the beacon and frame information stored in a hardware transmission queue, frames are transmitted without immediate control of the processor. Other features of the protocol accelerator include CRC generation, handling of immediate acknowledgment frames, and direct memory access.     

超宽带技术两大提案及其技术发展

短距离无线系统是今后较长时间内通信领域研究的热点，其中个人局域网概念的提出更推动了个人信息网络的发展。现着重介绍了作为无线个人局域网技术之一的超宽带技术的定义、标准化制定过程以及两种主要的物理层技术提案，并对其当前的应用和未来的发展做了相关论述。     

Location‐aided medium access control for low data rate UWB wireless sensor networks

This paper presents a distributed medium access control (MAC) protocol for low data rate ultra‐wideband (UWB) wireless sensor networks (WSNs), named LA‐MAC. Current MAC proposal is closely coupled to the IEEE 802.15.4a physical layer and it is based on its Impulse‐Radio (IR) paradigm. LA‐MAC protocol amplifies its admission control mechanism with location‐awareness, by exploiting the ranging capability of the UWB signals. The above property leads to accurate interference predictions and blocking assessments that each node in the network can perform locally, limiting at the same time the actions needed to be performed towards the admission phase. LA‐MAC is evaluated through extensive simulations, showing a significant improvement in many critical parameters, such as throughput, admission ratio, energy consumption, and delay, under different traffic load conditions. Copyright © 2010 John Wiley & Sons, Ltd.     

超宽带无线通信的技术特点与进展

随着网络和通信技术的飞速发展,基于超宽带(UWB)技术的无线个人网(WPAN)及其技术已引起国内外研究机构和厂商们的重视,IEEE802.15.3a专题组已选用UWB技术实现高速WPAN。UWB是一种利用纳秒短脉冲发送数据的无线通信新技术,文章系统介绍了UWB的历史背景、技术特点和体系结构,比较了现有几种短距离无线通信技术的异同,并对今后发展趋势进行了展望。     

Performance Analysis of Directional CSMA/CA for IEEE 802.15.3c under Saturation Environments

In this paper, the directional carrier sense multiple access/collision avoidance (CSMA/CA) protocol in the immediate acknowledgement mode for IEEE 802.15.3c is analyzed under saturation environments. For the analysis, a sensing region and an exclusive region with a directional antenna are computed probabilistically and a Markov chain model in which the features of IEEE 802.15.3c and the effects of using directional antennas are incorporated is analyzed. An algorithm to find the maximal number of concurrently transmittable frames is proposed. The system throughput and the average transmission delay are obtained in closed forms. The numerical results show the impact of directional antennas on the CSMA/CA media access control (MAC) protocol. For instance, the throughput with a small beamwidth of antenna is more than ten times larger than that for an omnidirectional antenna. The overall analysis is verified by a simulation. The obtained results will be helpful in developing an MAC protocol for enhancing the performance of mmWave wireless personal area networks.     

Novel MAC protocol for terahertz ultra-high data-rate wireless networks

Due to having a large bandwidth to support Gbps-level data rate, terahertz communication attracts more and more attention in recent years. However, there are few medium access control （MAC） protocols for terahertz ultra-high data-rate wireless networks, which affects the research and application of terahertz communications. To address this problem and to achieve ultra-high data-rate wireless access with terahertz communication, a novel MAC protocol, called medium access control for terahertz communication （MAC-TC）, is proposed. Through designing a new channel access scheme, a new superframe structure, and related key parameters, MAC-TC can support a maximum data rate up to 10 Gbit/s even higher. Theoretical analysis and simulation results show that our proposed MAC protocol realizes the function of medium access control and attains a maximum data rate of 18.3 Gbit/s, which is 2 times higher than 5.78 Gbit/s, the theoretical maximum data rate of IEEE 802.15.3c standard.     

A Multi-Hop Resource Reservation Scheme for Seamless Real-Time QoS Guarantee in WiMedia Distributed MAC Protocol

In this paper, a multi-hop range conflict-free resource reservation scheme for UWB (Ultra Wide Band) WPAN (Wireless Personal Area Network) with D-MAC (Distributed Medium Access Control) is proposed. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia Alliance supports DRP (Distributed Reservation Protocol) mechanism which makes all devices be self-organized and removes the SOP (Simultaneous Operating Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However, since each device’s mobility perspective in multi-hop environment has not been taken into account in the current WiMedia D-MAC, it may cause a “mobile” hidden node problem. In addition, once a DRP conflict occurs due to the mobile hidden node problem, only one of the DRP reservations involved in that DRP conflict maintains the reserved MASs, while the other DRP reservations must be terminated and DRP negotiations for them have to be re-started although only a few MASs are overlapped. Such DRP termination and renegotiation time delays due to the DRP conflicts can be a critical problem to the mobile devices transceiving real-time QoS traffic streams. Therefore, we propose a mechanism to prevent and resolve multi-hop range DRP conflicts due to each device’s mobility in D-MAC environment and demonstrate its guaranteed Seamless QoS and prioritized real-time QoS performances via numerical analyses.     

无线局域网与无线个域网QoS机制的对比分析

无线局域网(WLAN)和无线个域网(WPAN)技术的发展带来的多媒体业务流量的剧增,使无线网络的资源管理、服务质量(QoS)保障等问题日益突出。传统的媒体访问控制(MAC)协议需要重新设计才能对无线网络的QoS问题进行有效地解决。文中研究了IEEEWLAN和WPAN工作组分别于2002年5月和2003年2月提出的IEEE802.11eD3.0和IEEE802.15.3D16两种协议标准的工作机制并对两者的性能作出了比较分析。     

一种高效低时延的宽带电力线通信网多跳MAC协议

针对IEEE1901.1宽带电力线通信媒体接入控制(Medium Access Control,MAC)协议涉及到信标时隙利用不充分和控制开销过大等问题,提出了一种高效低时延的宽带电力线通信网多跳MAC协议(Efficient and Low Delay Multi-hop MAC,ELDM-MAC).采用基于节点层级...     

超宽带无线通信技术

超宽带(UWB)具有传输速率高、通信距离短、平均发射功率低等特点,非常适合于短距离高速无线通信.文章对UWB的发送接收技术和信道建模方式进行了讨论,指出UWB将定位于各种消费类电子设备和终端间的高速无线连接.对于IEEE的UWB标准,文章认为由于目前形成了脉冲无线电和多频带正交频分复用(OFDM)两大方案,因此最终采用哪种方案还需等待.     

Performance analysis of dual pulse transmission in UWB channels

A dual pulse transmission scheme with autocorrelation detector has recently been proposed for robust and low complexity UWB communications. This letter present bit error rate expressions of the binary pulse amplitude modulated dual pulse scheme in realistic UWB channels. The semi-analytical solutions are verified by simulation results for IEEE 802.15.3a channels.     

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.     

Medium access control in ultra-wideband wireless networks

Ultra-wideband (UWB) transmission is an emerging wireless communication technology with unique potential merits such as high-rate, low-transmission power, immunity to multipath propagation, and capability in precise positioning. It has received significant interests for future wireless communications from both academia and industry. In UWB wireless networks, medium access control (MAC) is essential to coordinate the channel access among competing devices. The unique UWB characteristics not only pose significant challenges but also offer great opportunities in efficient UWB MAC design. This paper presents a comprehensive overview of UWB MAC development on four important aspects: multiple access, overhead reduction, resource allocation, and quality of service (QoS) provisioning, and identifies some future research issues.     

UWB的Scholtz信道和其它信道的比较

研究了UWB通信系统的Scholtz室内信道传播模型,进行了信道仿真,仿真结果具有明显成簇现象,与已公布的UWB信道实测结果具有很好的相似性。同时,研究了UWB通信系统的另3种信道传播模型,S—V信道模型、IEEE802．15．3a信道模型和AT＆T信道模型,进行了信道仿真,得到了特征参数。并将Scholtz信道在3种不同房间中的传播特性以及各信道模型在同样的环境中进行了比较。为UWB系统在不同的信道模型上得到的分析值之间的转化提供参考。     

MGF based performance analysis of dual-hop regenerative relaying IR-UWB systems

In this paper, a dual-hop regenerative cooperative relaying UWB communication system with detect-and-forward (DTF) and decode-and-forward (DF) in multipath channels is studied. The average system bit error rate (BER) and the system performance with DTF and DF relaying schemes are provided. The DF relaying with convolutional coding is employed in this cooperative relaying UWB system. Gaussian quadrature numerical method is used to obtain the moment-generating function (MGF) of the received energy. Our simulation results show the advantages of the DF based cooperative IR-UWB system over IEEE 802.15.3a channels.     

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.