蓝牙与IEEE802.11g系统的共存

蓝牙与IEEE802.11g无线局域网(Wireless Local Area Network,WLAN)都工作在2.4GHz频段上,因此它们之间存在一定的干扰。分析了蓝牙与IEEE802.11g通信系统之间的干扰,并提出了解决这一问题的两种方法:自适应跳频和删除标记法,并对两种方法的性能做了比较。     

Personal Area Networks: Bluetooth or IEEE 802.11?

Interconnecting all our electronic devices we carry around, such as cellular phones, PDAs, and laptops, with wireless links requires a cheap, low-power radio technology that still delivers good performance. In this context, the Bluetooth wireless technology was developed to meet the requirements introduced by these personal area networks (PANs). However, today we see a widespread deployment of wireless local area network (WLAN) radios (primarily IEEE 802.11b) also in small devices, such as PDAs. This paper will compare the PAN capabilities of a Bluetooth-based system with an IEEE 802.11b-based system. In order to focus the comparison on link and networking functionality, the IEEE 802.11b radio is assumed to be operating at the same power level as the Bluetooth radio (i.e., assuming a 0 dBm radio). Results are obtained by means of simulations in which throughput and delay are measured for multihop and overlaid PANs. Estimations on power usage are also given in the simulations. The results indicate that as the number of PANs increases, the Bluetooth-based PANs basically maintain the same bandwidth per PAN, while the corresponding IEEE 802.11-based PANs suffer significantly from the increased co-channel interference. However, for cases with a few co-channel-interfering PANs (2-3 PANs hosting about 10-15 nodes), the IEEE 802.11b-based PANs offer a higher bandwidth per user than the corresponding Bluetooth PANs, which corresponds to the difference in link bandwidth between the two systems. At high interference levels, the Bluetooth PAN offers a higher capacity than the IEEE 802.11 PAN. The latter also shows unfairness among TCP connections in the PAN at high loads. The energy efficiency, defined as successfully transmitted bits per energy unit, decreases sharply for IEEE 802.11 with increased number of PANs, while Bluetooth maintains a constant level. Packet delays are also shown to be more stable for the Bluetooth PAN than for the IEEE 802.11 PAN as the number of PANs increases.     

Coexistence of IEEE 802.11b and Bluetooth: An Integrated Performance Analysis

IEEE 802.11b wireless networks and Bluetooth networks provide complimentary services using the same unlicensed radio frequency band. As the benefits of utilizing these services become increasingly apparent, the likelihood of mutual interference also increases. The well-known frequency hopping algorithm and adaptive frequency hopping algorithm do not fully consider the interference level of the operating environment. In this paper an algorithm called interference-aware adaptive frequency hopping (IAFH) is presented and implemented on Bluetooth devices to mitigate the interference between IEEE 802.11b and Bluetooth wireless networks. An analytical model of IAFH is developed to evaluate the performance of 802.11b stations and Bluetooth devices in a mutual interference environment. The analysis comprises the collision probability, packet error rate, and throughput performance for both IEEE 802.11b and Bluetooth wireless networks. Simulation results confirm that 802.11b station and IAFH-enabled Bluetooth devices experience lower packet error rates and better throughput as compared to the frequency hopping and adaptive frequency hopping algorithms.     

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.     

Ultra-Wideband Signal Impact on the Performances of IEEE 802.11b and Bluetooth Networks

This paper presents the results of a coexistence study investigating the impact of ultra-wideband (UWB) interference on IEEE 802.11b and Bluetooth networks. The results are based on the experimental test measurements made at the University of Oulu, Finland. Simple high-power UWB transmitters are used to interfere with victim networks. Preliminary results show that only under extreme interference conditions with thousands of equivalent Federal Communications Commission– (FCC)-compliant devices in close proximity, will the IEEE 802.11b and Bluetooth networks experience significant performance degradation. The impact of the UWB interference on the IEEE 802.11b network was insignificant if the distance to UWB transmitters was greater than 40 cm. The impact on Bluetooth was even less noticeable. In our study, several high-power UWB transmitters that greatly exceed the FCC radiation regulations have been used, and the measurement settings presents the worst case scenario because of the very short distance between the interferers and the victim system. Effectively our study approximates the use of thousands of FCC-complaint UWB devices in the same space.     

Bit error rate analysis of Wi-Fi and bluetooth under the interference of 2.45 GHz RFID

IEEE 802.11b WLAN (Wi-Fi) and IEEE 802.15.1 WPAN (bluetooth) are prevalent nowadays, and radio frequency identification (RFID) is an emerging technology which has wider applications. 802.11b occupies unlicensed industrial, scientific and medical (ISM) band (2.4-2.483 5 GHz) and uses direct sequence spread spectrum (DSSS) to alleviate the narrow band interference and fading. Bluetooth is also one user of ISM band and adopts frequency hopping spread spectrum (FHSS) to avoid the mutual interference. RFID can operate on multiple frequency bands, such as 135 KHz, 13.56 MHz and 2.45 GHz. When 2.45 GHz RFID device, which uses FHSS, collocates with 802.11b or bluetooth, the mutual interference is inevitable. Although DSSS and FHSS are applied to mitigate the interference, their performance degradation may be very significant. Therefore, in this article, the impact of 2.45 GHz RFID on 802.11b and bluetooth is investigated. Bit error rate (BER) of 802.11b and bluetooth are analyzed by establishing a mathematical model, and the simula-tion results are compared with the theoretical analysis to justify this mathematical model.     

无线局域网在蓝牙干扰下的性能分析

IEEE802.11b是目前最主要的无线局域网组网方式,与蓝牙技术分享同一频段。通过建立两者的数据帧相互干扰的概率模型,从物理层与网络层两方面定量地分析了蓝牙设备对无线局域网整体性能的影响,为实际中无线局域网的建立提供了参考。     

Interference Evaluation of Bluetooth and IEEE 802.11b Systems

The emergence of several radio technologies, such as Bluetooth and IEEE 802.11, operating in the 2.4 GHz unlicensed ISM frequency band, may lead to signal interference and result in significant performance degradation when devices are colocated in the same environment. The main goal of this paper is to evaluate the effect of mutual interference on the performance of Bluetooth and IEEE 802.11b systems. We develop a simulation framework for modeling interference based on detailed MAC and PHY models. First, we use a simple simulation scenario to highlight the effects of parameters, such as transmission power, offered load, and traffic type. We then turn to more complex scenarios involving multiple Bluetooth piconets and WLAN devices.     

Transceiver Architecture Selection: Review, State-of-the-Art Survey and Case Study

Realizing multi-standard transceivers with maximum hardware reuse amongst the given standards is of great importance to minimize the manufacturing cost of emerging multi-defined service wireless terminals. A well architecture in conjunction with a reconfigurable building-block synthesis is essential to building formulate such a kind of tunable transceiver under a wide range of specifications. In this paper, we present both fundamental and state-of-the-art techniques that help selecting transceiver architecture for single-/multistandard design. We begin by reviewing the basic schemes and examining their suitability for use in modern wireless communication systems (GSM, WCDMA, IEEE 802.11, Bluetooth, ZigBee and Ultra Wideband). The justifications are confirmed with the state of-the-art choices through a survey (with 100+ references) of the most frequently used receiver and transmitter architectures reported in 1997 to 2005 IEEE solid-state circuit forums: ISSCC, CICC, VLSI and ESS-CIRC. State-of-the-art techniques for multistandability are analyzed through careful case studies of a cellular receiver for GSM/DCS/PCS/WCDMA, and several WPAN/WLAN transceivers for Bluetooth and IEEE 802.11a/b/g. They disclose, on the architecture and circuit levels, many ideas that have successfully inspired the recent development of wireless circuits and systems     

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。     

Coexistence Performance of IEEE 802.15.4 Wireless Sensor Networks Under IEEE 802.11b/g Interference

IEEE 802.15.4 Wireless Sensor Networks (WSNs) and IEEE 802.11b/g Wireless Local Area Networks (WLANs) are often collocated, causing a coexistence issue since these networks share the same 2.4GHz Industrial, Scientific, and Medical band. In our previous work, we built a coexistence model of IEEE 802.15.4 WSNs and IEEE 802.11b/g WLANs. By identifying three distinct coexistence regions, the model explained the coexistence behavior of IEEE 802.15.4 WSNs and IEEE 802.11b/g WLANs, and the model was experimentally validated. In this paper, we improve the model by introducing two important implementation factors: the transceiver’s Rx-to-Tx turnaround time and the Clear Channel Assessment partial detection effect. The enhanced model significantly improves the accuracy on explaining and predicting the coexistence performance of IEEE 802.15.4 WSNs in the real-life environment. Furthermore, under the guidance of the model, the coexistence performance of IEEE 802.15.4 WSNs is extensively investigated in various coexistence scenarios by analysis, simulation and experiments, respectively. The simulation and experimental results agree with our analysis. The coexistence model is believed to be helpful in resolving the coexistence issue.     

BlueStar: Enabling Efficient Integration Between Bluetooth WPANs and IEEE 802.11 WLANs

Bluetooth is a radio technology for Wireless Personal Area Networking (WPAN) operating in the 2.4 GHz ISM frequency band. So far, there has been little research on how Bluetooth-enabled devices can effectively and efficiently have uninterrupted access to wide area networks (WAN) such as the Internet. We introduce a novel architecture (BlueStar) whereby selected Bluetooth devices, called Bluetooth Wireless Gateways (BWGs), are also IEEE 802.11 enabled so that these BWGs could serve as egress/ingress points to/from the IEEE 802.11 wireless network. We propose mitigating interference between Bluetooth and IEEE 802.11, by employing a hybrid approach of adaptive frequency hopping (AFH) and Bluetooth carrier sense (BCS) of the channels. AFH labels channels as bad or good, and Bluetooth devices only access those channels in the good state, whereas BCS is used to avoid collision by sensing the channel prior to any transmission. By combining AFH and BCS, we drastically minimize the effect of the worst-case interference scenario wherein both a Bluetooth and an IEEE 802.11 interface are co-located in a single device. BlueStar enables Bluetooth devices, belonging to either a piconet or a scatternet, to access the WAN through the BWG without the need for any fixed Bluetooth access points, while utilizing widely deployed base of IEEE 802.11 networks. Moreover, we define the protocol stack employed by BlueStar as well as indicate how BWGs efficiently manage their capacity allocation through the different systems. We also mathematically derive an upper bound on the number BWGs needed in a Bluetooth scatternet so that uninterrupted access to all Bluetooth devices could be provided.     

Packet Error Rate Analysis of ZigBee Under WLAN and Bluetooth Interferences

In this paper, the performance of IEEE 802.15.4 ZigBee under the interference of IEEE 802.11b wireless local area network (WLAN) and/or Bluetooth is evaluated using an analytic model for the coexistence among ZigBee, WLAN, and Bluetooth. The packet error rate (PER) is evaluated, where the PER is obtained from the bit error rate (BER) and the collision time. The BER is obtained from the signal-to-interference-plus-noise ratio (SINR). Finally, the analytic results are validated by simulations.     

Interference aware Bluetooth scatternet (re)configuration algorithm IBLUEREA

The paper presents a new algorithm IBLUEREA, which enables reconfiguration of Bluetooth (BT) scatternet to reduce mutual interferences between BT and Wi-Fi (IEEE 802.11b) networks operating on the same area. IBLUEREA makes use of proposed procedure for modeling ISM environment around a given BT scatternet. The mechanism is based on estimation of the probabilities of successful (unsuccessful) frame transmissions. This determination is useful to take a decision concerning co-existence of technologies which operate in the same ISM band (here Bluetooth and IEEE 802.11b).     

Enhancing IEEE 802.11n WLANs using group-orthogonal code-division multiplex

The definition of the next generation of wireless networks is well under way within the IEEE 802.11 High Throughput Task Group committee. The resulting standard, to be called IEEE 802.11n, is expected to be a backward-compatible evolution of the successful IEEE 802.11a/g systems also based on multicarrier techniques. It can be anticipated that 802.11n systems will outperform its predecessors in terms of transmission rate and/or performance, mainly, due to the use of multiple antennae technology for transmission and reception. In this paper we propose to incorporate group-orthogonal (GO) code division multiplex (CDM) into the IEEE 802.11n specifications to further enhance its performance. It is shown how GO-CDM can take full advantage of the diversity offered by the multiple antennae and multicarrier transmission by using an iterative maximum likelihood (ML) joint detector. Furthermore, the use of GO-CDM does not compromise the backward compatibility with legacy systems.     

Coexistence of 2.4 GHz sensor networks in home environment

The IEEE 802.15.4 is one of the low-layer communication standards for personal area networks(PANs) and wireless sensor networks(WSNs),which may be interfered by other wireless devices in the industrial,scientific and medical(ISM) frequency bands,especially in home environment,such as devices of IEEE 802.11b,Bluetooth,cordless telephone,and microwave oven radiation.This article examines the mutual interference effects of 2.4 GHz devices widely deployed at home,via both theoretical analysis and real-life expe...     

The 802.11n MIMO-OFDM Standard for Wireless LAN and Beyond

An overview is given of the new IEEE 802.11n standard. This is the first wireless LAN standard based on MIMO-OFDM, a technique pioneered by Airgo Networks to give a significant performance increase in both range and rate relative to conventional wireless LAN. Performance results show that net user throughputs over 100 Mbps are achievable, which is about four times larger than the maximum achievable throughput using IEEE 802.11a/g. For the same throughput, MIMO-OFDM achieves a range that is about 3 times larger than non-MIMO systems. This significant improvement in range-rate performance makes MIMO-OFDM the ideal solution not only for wireless LAN, but also for home entertainment networks and 4G networks. Richard van Nee received the M.Sc. degree in Electrical Engineering from Twente University in Enschede, the Netherlands, in 1990. In May 1995, he received the PhD degree from Delft University of Technology. From 1995 to 2000, he worked for Lucent Technologies Bell Labs on wireless LAN transmission techniques. He was one of the original proposers of the CCK and OFDM modulation techniques which were adopted by the IEEE 802.11b and IEEE802.11a wireless LAN standards. In 2001, he cofounded Airgo Networks that developed the first MIMO-OFDM modem for wireless LAN and which techniques form the basis of the IEEE 802.11n standard. Together with Ramjee Prasad, he wrote a book on OFDM, entitled ‘OFDM for Mobile Multimedia Communications.’ In 2002 he received the Dutch Veder award for his contributions to standardization of wireless communications.     

Analytical Analysis of Applying Packet Fragmentation Mechanism on Both Basic and RTS/CTS Access Methods of the IEEE 802.11b DCF Network Under Imperfect Channel and Finite Load Conditions

The mathematical modeling and performance evaluation of the IEEE 802.11 network in all its various extensions (802.11b, 802.11a, 802.11g, 802.11e, 802.11n, etc.) have already been widely explored over the past years. However, the Packet Fragmentation Mechanism (PFM), which is proposed by the IEEE work group to enhance the MAC sub-layer of the IEEE 802.11 standard in an error-prone channel, has been missed in the available literature. Yet, the PFM is the only existing solution to reduce the influence of bit error rate and the length of data packets on the packet error rate, and consequently on the performances of IEEE 802.11 networks. In this paper, we propose a new three-dimensional Markov chain in order to model, for the first time in the literature, the PFM in both Basic and RTS/CTS access methods of the IEEE 802.11b DCF network under imperfect channel and finite load conditions. Then, we develop mathematical models to derive a variety of performance metrics, such as: the overall throughput, the average packet delay successfully transmitted, the average packet drop time, the delay jitter and the packet delay distribution. Performance analysis of applying PFM on both Basic and RTS/CTS access methods of the IEEE 802.11b DCF network under imperfect channel and finite load conditions shows original results and leads to new conclusions that could not be intuitively expected.     

无线局域网系统对蓝牙piconet干扰的理论分析

从理论的角度阐明了无线局域网系统(802.11b)对蓝牙piconet产生干扰的原因及后果。     

A 10-bit 44-MS/s 20-mW configurable time-interleaved pipeline ADC for a dual-mode 802.11b/Bluetooth receiver

This work presents a configurable time-interleaved pipeline architecture as an efficient solution for the ADC design in high data rate multi-standard radios. The ADC is implemented in a 0.25-/spl mu/m BiCMOS process as part of an integrated dual mode 802.11b/Bluetooth direct conversion receiver. Its structure can be configured to accommodate the different sampling rate and dynamic range requirements of both standards. The different techniques employed at the system and circuit levels to optimize the power consumption are described. An on-line digital calibration scheme is also incorporated to assure the conversion linearity and reduce mismatch among the parallel branches. The proposed ADC is a switched-capacitor implementation occupying an area of 2.1 mm/sup 2/. It achieves 60 dB/64 dB dynamic range at 44 MHz/11 MHz sampling frequency with a power consumption of 20.2 mW/14.8 mW for the 802.11b/Bluetooth baseband signals.