emerging wireless multimedia services and technologies phần 5 docx

Equation (5.32) can be simplified to yield B 1;W i ;q ¼ 4B i ð1 À p b Þð1 À p ab Þ W i qðq þ 1Þ : ð5:34Þ Using the above equation and Equation (5.33) we have B i;j;k ¼ ðq À kÞðW i À jÞ4ð1 À pÞð1 À 2pÞp i ð1 À p b Þð1 À p ab Þ h W 0 ð1 Àð2pÞ mþ1 Þð1 À pÞþð1 À 2pÞð1 À p mþ1 Þ i W i qðq þ 1Þ : ð5:35Þ Now making j and k equal to 0 in Equation (5.35) we get B i;0;0 ¼ 4ð1 À pÞð1 À 2pÞp i ð1 À p b Þð1 À p ab Þ h W 0 ð1 Àð2pÞ mþ1 Þð1 À pÞþð1 À 2pÞð1 À p mþ1 Þ i ðq þ 1Þ : ð5:36Þ From the above equation it is easier to determine the probability of transmission, , in an arbitrary slot:  ¼ X m i¼0 B i;0;0 ¼ 4ð1 À 2pÞð1 À p b Þð1 À p ab Þð1 À p mþ1 Þ h W 0 ð1 Àð2pÞ mþ1 Þð1 À pÞþð1 À 2pÞð1 À p mþ1 Þ i ðq þ 1Þ : ð5:37Þ The above equation considers the decrementing lab as the difference between the current node’s AIFS and the highest priority’s AIFS. But if we have a system with more than one priority, we have to include intermediate priorities and their access probabilities before the considered node can decrement its backoff value. For the sake of simplicity we assume the 1 À p ab is valid even if there are multiple priorities with different AIFS and hence the above equation is valid. Example 1 Consider that there are only two ACs in the system. Let their CW min , CW max and TXOP be equal. Let AC1 have AIFS¼DIFS and the second AC2 have AIFS¼PIFS. From Equation (5.37), we get a following simple relation on the access probabilities:  2 ¼ 1 À p ab 2  1 : ð5:38Þ This implies that the access probability is lowered by half and if the number of stations of priority 1 is very large then it further lowers the probability of priority 2’s access. Let us now introduce the four access categories as in EDCA and determine all the associated probabilities. The probability that the tagged station of priority (AC ¼ lð¼ 0; 1; 2; 3Þ) transmits at slot t is given by  l t ¼ P m i¼0 B l i;0;0 : if t > AIFS½l 0 : if t AIFS½l: & ð5:39Þ Equation (5.39) states that after the medium becomes idle following the busy period, the transmission probability of the node with priority l is 0 if AIFS½l is not completed. If the number of stations of each class is N l ðl ¼ 0; ; 3Þ, then the probability of the channel is busy at an offset slot t is given by p l b;t ¼ 1 Àð1 À  l t Þ N l À1 Y h6¼l ð1 À  h t Þ N h : ð5:40Þ 164 Multimedia Wireless Local Area Networks Equation (5.40) accounts for the fact that the tagged station of class l sees the channel is busy only when at least one of the other station transmits. After calculating the busy probability, we go on to find the probability of successful transmission of priority l in an offset slot t. This is given by p l succ;t ¼ N l 1   l t ð1 À  l t Þ N l À1 Y h 6¼ l ð1 À  h t Þ N h : ð5:41Þ Similarly we the probability that the offset slot t is idle is given by p idle;t ¼ Y 3 h¼0 ð1 À  h t Þ N h : ð5:42Þ Now we can easily evaluate the probability of collision at offset slot t as p coll;t ¼ 1 À p idle;t À X 3 h¼0 p h succ;t : ð5:43Þ Based on the above three equations, it is easy to calculate the throughput of the EDCA system. The transmission cycle under the EDCA of the IEEE 802.11e MAC consists of the following phases, which are executed repetitively: the AIFS½AC=SIFS deferral phase, the backoff/contention phase if necessary, the data/fragment transmission phase, the SIFS deferral phase, and the ACK transmission phase. The related characteristics for the IEEE 802.11a PHY are listed in Table 5.3. As indicated in [19,21], we assume that each transmission, whether successful or not, is a renewal process. Thus it is sufficient to calculate the throughput of the EDCA protocol during a single renewal interval between two successive transmissions. We extend the same philosophy for the EDCA bursting. The throughput of the protocol without bursting is given by Equation (5.44): S h ¼ E½Time for successful transmission in an interval E½Length between two consecutive transmissions ¼ P t P 3 h¼0  h t p h succ;t L h P t  h t ð P 3 h¼0 T h s p h succ;t þ T c p coll;t þ aSlotTime Á p idle;t Þ : ð5:44Þ T s is the average time the channel is captured with successful transmission and T c is the average time the channel is captured by unsuccessful transmission. The values of T s and T c are given by T s ¼ AIFS½ACþ þ T m data ðLÞþaSIFSTime þ T m ack þ  ð5:45Þ T c ¼ AIFS½ACþT m data ðLÞþaSIFSTime þ T m ack : ð5:46Þ The  in the above equation represents the propagation delay. Also the T c is equal to the frame transmission time excluding the propagation delay because of Network Allocation Vector (NAV) set by the transmitting QSTA. 5.A.4 Throughput Analysis for EDCA Bursting In the case of EDCA bursting, we need to know the maximum number of frames that can be transmitted during the EDCA TXOP limit. Let T l EDCA txop represent the TXOP limit for this AC. Therefore the maximum number of frames of priority l, N l max , that can be transmitted by a specific queue when it gets to access the channel T l EDCA txop is given by Equation (5.47): N max ¼ T l EDCA txop ðAIFS½lÀaSIFSTimeÞþ2 ÁðaSIFSTime þ ÞþT m data ðLÞþT m ack ðLÞ $% : ð5:47Þ Appendix 165 In Equation (5.47) , the first term on the denominator comes from the fact that we have used aSIFSTime as the time between the transmission of the data frame as well as acknowledgment frame. In reality the first frame has deference given by AIFS½l. For the throughput analysis, as we considered for single frame transmission, we consider the period between two transmissions. This assumption is valid as each WSTA that contends for the channel normally and if it gets the channel time, it transmits multiple frames instead of one. Once the WSTA wins the contention, the number of frames it transmits is upper bounded by Equation (5.47) . So on an average, the number of successful frame transmissions during and EDCA TXOP limit is given by: N 0 max ¼ T EDCA txop ½l ½ðAIFS½lÀaSIFSTimeÞþ2 ÁðaSIFSTime þ ÞþT m data ðLÞþT m ack ðLÞN Transmissions " # : ð5:48Þ The throughput is the same as discussed in the previous subsection. References [1] ETSI, HiperLAN Functional Specification, ETSI Draft Standard, July 1995. [2] G. Anastasi, L. Lenzini and E. Mingozzi, Stability and Performance Analysis of HiperLAN, IEEE JSAC, 30(90), 1787–1798, 2000. [3] K. Pahlavan and P. Krishnamurthy, Principles of Wireless Networks, Prentice Hall, 2002. [4] B. Walke, N. Esseling, J. Habetha, A. Hettich, A. Kadelka, S. Mangold, J. Peetz, and U. Vornefeld, IP over Wireless Mobile ATM – Guaranteed Wireless QoS by HiperLAN/2, in Proceedings of the IEEE, 89, pp. 21–40, January 2001. [5] IEEE Std 802.11-1999, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications, Reference number ISO/IEC 8802-11:1999(E), IEEE Std 802.11, 1999. [6] IEEE Std 802.11a, Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Higher-speed Physical Layer Extension in the 5 GHz Band, Supplement to Part 11, IEEE Std 802.11a-1999, 1999. [7] IEEE 802.11e/D7.0, Draft Supplement to Part 11: Wireless Medium Access Control (MAC) and physical layer (PHY) specifications: Medium Access Control (MAC) Enhancements for Quality of Service (QoS), June 2003. [8] IEEE 802.1d-1998, Part 3: Media Access Control (MAC) bridges, ANSI/IEEE Std. 802.1D, 1998. [9] Sunghyun Choi, Javier del Prado, Sai Shankar N and Stefan Mangold, IEEE 802.11e Contention-Based Channel Access (EDCA) Performance Evaluation, in Proc. IEEE ICC’03, Anchorage, Alaska, USA, May 2003 [10] Javier del Prado and Sai Shankar et al. Mandatory TSPEC Parameters and Reference Design of a Simple Scheduler, IEEE 802.11-02/705r0, November 2002. [11] C.T. Chou, Sai Shankar N and K.G. Shin, Distributed control of airtime usage in multi-rate wireless LANs, submitted to IEEE Transactions on Networking. [12] Maarten Hoeben and Menzo Wentink, Enhanced D-QoS through Virtual DCF, IEEE 802.11-00/351, October 2000. [13] Stefan Mangold, Sunghyun Choi, Peter May, Ole Klein, Guido Hiertz and Lothar Stibor, IEEE 802.11e Wireless LAN for Quality of Service, in Proc. European Wireless ’02, Florence, Italy, February 2002. [14] Sunghyun Choi, Javier del Prado, Atul Garg, Maarten Hoeben, Stefan Mangold, Sai Shankar and Menzo Wentink, Multiple Frame Exchanges during EDCA TXOP, IEEE 802.11-01/566r3, January 2002. [15] J. G. Proakis, Digital Communications, 3rd ed, McGraw Hill, New York, NY, 1995. [16] M. B. Pursley and D. J. Taipale, Error probabilities for spread spectrum packet radio with convolutional codes and viterbi decoding, IEEE Trans. Commun., 35(1), pp. 1–12, Jan. 1987. [17] D. Haccoun and G. Begin, High-rate punctured convolutional codes for Viterbi and sequential decoding, IEEE Trans. Commun., 37(11), pp. 1113–1125, November 1989. [18] F. Cali, M. Conti and E. Gregori, Dynamic Tuning of the IEEE 802.11 Protocol to achieve a theoretical throughput limit, IEEE/ACM Trans. Netw., 8(6), December 2000. [19] G. Bianchi, Performance Analysis of the IEEE 802.11 Distributed Coordination Function, IEEE Journal on Selected Areas in Communications, 18(3), March 2000. 166 Multimedia Wireless Local Area Networks [20] H. S. Chhaya and S. Gupta, Performance modeling of asynchronous data transfer methods of IEEE 802.11 MAC protocol, Wireless Networks, 3, pp. 217–234, 1997. [21] H. Wu et al., Performance of reliable transport protocol over IEEE 802.11 Wireless LAN: Analysis and enhancement, Proc. IEEE INFOCOM’02, New York, June 2002. [22] Daji Qiao and Sunghyun Choi, Goodput enhancement of IEEE 802.11a wireless LAN via link adaptation, in Proc. IEEE ICC’01, Helsenki, Finland, June 2001. [23] Daji Qiao, Sunghyun Choi, Amjad Soomro and Kang G. Shin, Energy-efficient PCF operation of IEEE 802.11a wireless LAN, in Proc. IEEE INFOCOM’02, New York, June 2002. [24] M. Zorzi, Ramesh R. Rao and L. B. Milstein, On the accuracy of a first-order Markov model for data transmission on fading channels, in Proc. IEEE ICUPC’95, pp. 211–215, November 1995. [25] J. I. Marcum, A Statistical theory of target detection by pulsed radar: mathematical appendix, IEEE Trans. Info. Theory, pp. 59-267, Apr. 1960. [26] M. Heusse, Franck Rousseau, Gilles Berger-Sabbatel and Andrzej Duda, Performance anomaly of IEEE 802.11b, in IEEE INFOCOM 2003, San Francisco, USA. [27] Delprado, J. and Sai Shankar N., Impact of frame size, number of stations and mobility on the throughput performance of IEEE 802.11e WLAN, in IEEE WCNC 2004, Atlanta, USA. [28] Sunghyun Choi, Chiu Ngo, and Atul Garg, Comparative Overview on QoS Support via IEEE 802.11e and HIPERLAN/2 WLANs, Philips Research USA Internal Document, June 2000. [29] Sai Shankar N., Javier Delprado, and Patrick Wienert, Optimal packing of VoIP calls in an IEEE 802.11a/e WLAN in the presence of QoS Constraints and Channel Errors, to appear in IEEE Globecom 2004, Dallas, USA. [30] Chou, C. T., Sai Shankar N, and Shin K. G. Per-stream QoS in the IEEE 802.11e Wireless LAN: An integrated airtime-based admission control and distributed airtime allocation, submitted to IEEE INFOCOM 2005, Miami, USA. References 167 6 Wireless Multimedia Personal Area Networks: An Overview Minal Mishra, Aniruddha Rangnekar and Krishna M. Sivalingam 6.1 Introduction The era of computing has now shifted from traditional desktop and laptop computers to small, handheld personal devices that have substantial computing, storage and communications capabilities. Such devices include handheld computers, cellular phones, personal digital assistants and digital cameras. It is necessary to interconnect these devices and also connect them to desktop and laptop systems in order to fully utilize the capabilities of the devices. For instance, most of these devices have personal information management (PIM) databases that need to be synchronized periodically. Such a network of devices is defined as a Wireless Personal Area Network (WPAN). A WPAN is defined as a network of wireless devices that are located within a short distance of each other, typically 3–10 meters. The IEEE 802.15 standards suite aims at providing wireless connectivity solutions for such networks without having any significant impact on their form factor, weight, power requirements, cost, ease of use or other traits [1]. In this chapter, we will explore the various network protocol standards that are part of the IEEE 802.15 group. In particular, we describe IEEE 802.15.1 (Bluetooth 1 ) offering 1–2 Mbps at 2.4 GHz, IEEE 802.15.3 (WiMedia) offering up to 55 Mbps at 2.4 GHz, IEEE 802.15.3a offering several hundred Mbps using Ultra-wide-band transmissions, and IEEE 802.15.4, which is defined for low-bit rate wireless sensor networks. The IEEE 802.15 group adopted the existing Bluetooth 1 standard [2] as part of its initial efforts in creating the 802.15.1 specifications. This standard uses 2.4 GHz RF transmissions to provide data rates of up to 1 Mbps for distances of up to 10 m. However, this data rate is not adequate for several multimedia and bulk data-transfer applications. The term ‘multimedia’ is used to indicate that the information/data being transferred over the network may be composed of one or more of the following media types: text, images, audio (stored and live) and video (stored and streaming). For instance, transferring all the contents of a digital camera with a 128 MB flash card will require a significant amount of time. Other high-bandwidth demanding applications include digital video transfer from a camcorder, music transfer from a personal music device such as the Apple iPod TM . Therefore, the 802.15 group is examining newer technologies and protocols to support such applications. Emerging Wireless Multimedia: Services and Technologies Edited by A. Salkintzis and N. Passas # 2005 John Wiley & Sons, Ltd There are two new types of Wireless Personal Area Networks (WPAN) that are being considered: the first is for supporting low speed, long life-time and low cost sensor network at speeds of a few tens of kbps and the other is for supporting the multimedia applications with higher data rates of the order of several Mbps with better support for Quality of Service (QoS). Our focus, in this chapter, is on the second type of WPAN dealing with multimedia communication. In an effort to take personal networking to the next level, a consortium of technology firms has been established, called the WiMedia Alliance[3]. The WiMedia Alliance develops and adopts standards-based specifications for connecting wireless multimedia devices, including: application, transport, and control profiles; test suites; and a certification program to accelerate wide-spread consumer adoption of ‘wire-free’ imaging and multi- media solutions. Even though the operations of the WPAN may resemble that of WLAN (Wireless Local Area Networks), the interconnection of personal devices is different from that of computing devices. A WLAN connectivity solution for a notebook computer associates the user of the device with the data services available on, for instance, a corporate Ethernet-based intranet. A WPAN can be viewed as a personal communications bubble around a person, which moves as the person moves around. Also, to extend the WLAN as much as possible, a WLAN installation is often optimized for coverage. In contrast to a WLAN, a WPAN trades coverage for power consumption. The rest of this chapter is organized as follows. The following section gives a brief overview of the multimedia data formats and application requirements. In Section 6.3, we present the Bluetooth protocols as described in the IEEE 802.15.1 standard. In Section 6.4, we discuss issues related to coexistence of Bluetooth networks with other unlicensed networks operating in the same frequency region. The IEEE 802.15.3 protocol suite for multimedia networks is considered in Section 6.5. In addition, we also describe ultra-wide-band (UWB) based networks that offer data rates of several hundred Mbps. In order to complete the discussions of the entire IEEE 802.15 group of standards, we also present the IEEE 802.15.4 standard for low-rate Wireless Personal Area Networks. 6.2 Multimedia Information Representation In general, the term ‘multimedia traffic’ denotes a set of various traffic types with differing service requirements. The classical set of multimedia traffic include audio, video (stored or streaming), data and images [4,5]. The different types of media have been summarized in the Figure 6.1. Some applications generate only one type of media, while others generate multiple media types. The representation and compression of multimedia data has been a vast area of research. In this section, we present an overview of multimedia information representation. We will consider an example scenario that consists of a desktop computer, a laptop computer, and several digital peripheral devices such as digital camera, digital camcorder, MP3 player, Personal Music Storage device (e.g. iPod TM ), laser printer, photo printer, fax machine, etc. The applications involving multimedia information comprise blocks of digital data. For example, in the case of textual information consisting of strings of characters entered at a keyboard, each character is represented by a unique combination of fixed number of bits known as a codeword. There are three types of text that are used to produce pages of documents: unformatted or plain text, formatted text and hypertext. Formatted text refers to text rich documents that are produced by typical word processing packages. Hypertext is a form of formatted text that uses hyperlinks to interconnect a related set of documents, with HTML, SGML and XML serving as popular examples. A display screen of any computing device can be considered to be made of a two dimensional matrix of individual picture elements (pixels), where each pixel can have a range of colors associated with it. The simplest way to represent a digitized image is using a set of pixels, where each pixel uses 8 bits of data allowing 256 different colors per pixel. Thus, a 600  300 picture will require approximately 175 kb of storage. Compression techniques can be used to further reduce the image size. An alternate representation is to describe each object in an image in terms of the object attributes. These include 170 Wireless Multimedia Personal Area Networks: An Overview its shape, size (in terms of pixel positions of its border coordinates), color of the border, and shadow. Hence the computer graphic can be represented in two different ways: a high level version (specifying the attributes of the objects) and an actual pixel image of the graphic, also referred to as the bitmap format. It is evident that the high level version is more compact and requires less memory. When the graphic is transmitted to another host, the receiver should be aware of high-level commands to render the image. Hence, bitmaps or compressed images are used more often. The commonly used image formats are GIF (graphic interchange format), TIFF (tagged image file format), JPEG (Joint Photographers Experts Group) and PNG (Portable Network Graphics). Com- pressed data formats also exist for transferring fax images (from the main computer to the fax machine). In order to understand the data requirements, let us consider a 2 Mega-Pixel (2 MP) digital camera, where the size of each image typically varies from 1 Mb to 2 Mb, depending on the resolution set by the user. A 256 Mb memory card can store approximately 200 photos. There is always a need to periodically transfer these digital files to a central repository such as a PC or a laptop. This is often done using the USB interface, which can provide data rates of up to 12 Mbps for USB 1.1 and up to 480 Mbps for USB 2.0. However, our intention is to use wireless networking for interconnecting such multimedia devices and the computer. The Bluetooth 1 standard provides data rates of 1 Mbps which is inadequate compared with the USB speeds. For instance, 128 Mb worth of multimedia files would take at least 18 minutes to transfer from a camera to PC. This is the reason for the development of the higher bit-rate IEEE 802.15.3 wireless PAN standard. For audio traffic, we are concerned with two types of data: (i) speech data used in inter-personal applications including telephony and video-conferencing and (ii) high-quality music data. Audio signals can be produced either naturally using a microphone or electronically using some form of synthesizer [5]. The analog signals are then converted to digital signals for storage and transmission purposes. Let us consider the data requirements for audio traffic. Audio is typically sampled at 44100 samples per second (for each component of the stereo output) with 1 byte per second to result in a total of approximately 705 kbps. This can be compressed using various algorithms, with MP3 (from the Motion Picture Experts Audio VideoImages Formatted Text Computer Generated Digitized documents Unformatted Text Text Speech General Audio Video Clips Movies, Films Media Types Digital form of representation Text and Image Compression Analog form of representation Analog-to-Digital Conversion Audio and video compression Integrated multimedia information streams Figure 6.1 Different types of media used in multimedia applications. Multimedia Information Representation 171 Group) [6] being one of the most popular standards that can compress music to as around 112–118 kbps for CD-quality audio. Thus, streaming audio between a single source-destination pair is possible even with Bluetooth 1 . However, if there are several users in a WPAN, each having different audio streams in parallel, then higher bandwidths are necessary. However, to store a CD-quality 4–5 minute song requires approximately 32 Mb of disk space. Hence, bulk transfer of audio files between a computer and a personal music device (such as the Apple iPod TM ) requires a large bandwidth for transmission. There are several different ways to compress this data before transmission and decompress it at the receiver’s end. The available bandwidth for transmission decides the type of audio/video compression technique to be used. Real-time video streaming with regular monitor-sized picture frames is still one of the holy grails of multimedia networking. Video has the highest bandwidth requirement. For instance, a movie with 30 frames per second (fps), with 800  600 pixels per frame and 8 bits per pixel requires an uncompressed bandwidth of 115 Mbps. There have been several compression standards for video storage. The MPEG-1 standard used on Video-CDs requires bandwidth of approximately 1.5 Mbps for a 352  288 pixel frame. The MPEG-2 standard used on DVDs today supports up to 720  576 pixel- frame with 25 fps for the PAL standard and 720  480 pixel-frame with 30 fps for the NTSC standard. The effective bandwidth required ranges from 4 Mbps to 15 Mbps. The MPEG-4 standard, approved in 1998, provides scalable quality, not only for high resolution, but also for lower resolution and lower bandwidth applications. The bandwidth requirements of MPEG-4 are very flexible due to the versatility of the coding algorithms and range from a few kbps to several Mbps. It is clear that higher bandwidth WPANs such as IEEE 802.15.3 are necessary to handle video traffic. Other video standards such as High-Definition Television (HDTV) can require bandwidths of around 80–100 Mbps, depending upon the picture quality, compression standards, aspect ratios, etc. In the following sections, we describe the various WPAN networking protocols and architectures. 6.3 Bluetooth 1 (IEEE 802.15.1) Bluetooth 1 is a short-range radio technology that enabled wireless connectivity between mobile devices. Its key features are robustness, low complexity, low power and low cost. The IEEE 802.15.1 standard is aimed at achieving global acceptance such that any Bluetooth 1 device, anywhere in the world, can connect to other Bluetooth 1 devices in their proximity. A Bluetooth 1 WPAN supports both synchronous communication channels for telephony-grade voice communication and asynchronous communications channels for data communications. A Bluetooth 1 WPAN is created in an ad hoc manner when devices desire to exchange data. The WPAN may cease to exist when the applications involved have completed their tasks and no longer need to continue exchanging data. The Bluetooth 1 radio works in the 2.4 GHz unlicensed ISM band. A fast frequency hop (1600 hops per second) transceiver is used to combat interference and fading in this band. Bluetooth 1 belongs to the contention-free, token-based multi-access networks. Bluetooth 1 connections are typically ad hoc, which means that the network will be established for a current task and then dismantled after the data transfer has been completed. The basic unit of a Bluetooth 1 system is a piconet, which consists of a master node and up to seven active slave nodes within a radius of 10 meters. A piconet has a gross capacity of 1 Mbps without considering the overhead introduced by the adopted protocols and polling scheme. Several such basic units having overlapping areas may form a larger network called a scatternet. A slave can be a part of a different piconet only in a time-multiplexing mode. This indicates that, for any time instant, the node can only transmit or receive on the single piconet to which its clock is synchronized and to be able to transmit in another piconet it should change its synchronization parameters. Figure 6.2 illustrates this with an example. A device can be a master in only one piconet, but it can be a slave in multiple piconets simultaneously. A device can assume the role of a master in one piconet and a slave in other piconets. Each piconet is assigned a frequency-hopping channel based on the address of the master of that piconet. 172 Wireless Multimedia Personal Area Networks: An Overview 6.3.1 The Bluetooth 1 Protocol Stack The complete protocol stack contains a Bluetooth 1 core of certain Bluetooth 1 specific protocols: Bluetooth 1 radio, baseband, link manager protocol (LMP), logical link control and adaptation protocol (L2CAP) and service discovery protocol (SDP) as shown in Figure 6.3. In addition, non-Bluetooth specific protocols can also be implemented on top of the Bluetooth 1 technology. The bottom layer is the physical radio layer that deals with radio transmission and modulation. It corresponds fairly well to the physical layer in the OSI and 802 models. The baseband layer is somewhat analogous to the MAC (media access control) sublayer but also includes elements of the physical layer. It deals with how the master controls the time slots and how these slots are grouped into frames. The physical and the baseband layer together provides a transport service of packets on the physical links. Next comes a layer of somewhat related protocols. The link manager handles the setup of physical links between devices, including power management, authentication and quality of service. The logical link control and adaptation protocol (often termed L2CAP) shields the higher layers from the details of transmission. The main features supported by L2CAP are: protocol multiplexing and segmentation and Master Slave c ab Figure 6.2 (a) Point-to-point connection between two devices; (b) point-to-multi-point connection between master and three slaves and (c) scatternet that consists of three piconets. Physical Radio Baseband Link Manager Logical Link Control and Adaptation Protocol LLC Other RFCOMM Telephony Service Discovery ControlAudio Application/Profiles Figure 6.3 Bluetooth 1 protocol stack. Bluetooth 1 (IEEE 802.15.1) 173 [...]... ahead, mostly Group A Group B Group C Group D Band Band Band Band #1 #2 #3 #4 Band Band Band Band Band Band Band Band Band # 5 # 6 # 7 # 8 # 9 # 10 # 11 # 12 # 13 3432 3960 4488 50 16 MHz MHz MHz MHz 58 08 6336 6864 7392 7920 8448 8976 950 4 10032 MHz MHz MHz MHz MHz MHz MHz MHz MHz Figure 6.18 Frequency spectrum allocation for multiband OFDM frequency Wireless Multimedia Personal Area Networks: An Overview... frequency 184 Wireless Multimedia Personal Area Networks: An Overview 6 .5 High-Rate WPANs (IEEE 802. 15. 3) This section presents the details of the IEEE 802. 15. 3 standard being considered for high datarate wireless personal area networks 6 .5. 1 Physical Layer The 802. 15. 3 PHY layer operates in the unlicensed frequency band between 2.4 GHz and 2.48 35 GHz, and is designed to achieve data rates of 11 55 Mbps,... related to multimedia wireless personal area networks We first discussed the Bluetooth1 standard that supports 1–2 Mbps This was followed by a discussion of the coexistence of Bluetooth1 and Wireless LANs that operate using the same frequency band We also discussed the multi-megabit 802. 15. 3 and 802. 15. 3a (UWB) based standard for WPANs and finally concluded with the low bit-rate IEEE 802. 15. 4 standard that... been designed for higher bandwidth and larger range and are, thus, much more expensive 6.4 Coexistence with Wireless LANs (IEEE 802. 15. 2) The global availability of the 2.4 GHz industrial, scientific, medical (ISM) unlicensed band, is the reason for its strong growth Fuelling this growth are the two emerging wireless technologies: wireless personal area networks (WPAN) and wireless local area networks... rates of 28M, 55 M, 110M, 220M, 50 0M, 660M and 1320M bits/sec The other proposal, developed by the Multiband OFDM Alliance (MBOA [26]), is based on the concept of Multi-band Orthogonal Frequency Division Multiplexing (Multi-band OFDM) and supports data rates of 55 M, 110M, 200M, 400M, 480M bits/sec Multi-band OFDM is a transmission technique where the available spectrum is divided into multiple bands Information... Franscisco, CA, 2001 [13] IEEE 802. 15 Working Group for WPAN, Part 15. 2: Coexistence of Wireless Personal Area Networks with Other Wireless Devices Operating in Unlicensed Frequency Bands, IEEE Std 802. 15. 2, 2003 [14] IEEE, Wireless LAN medium access control (MAC) and physical layer (PHY) Spec, IEEE 802.11 standard, 1998 [ 15] N Golmie, Interference in the 2.4 Ghz ism band: Challenges and Solutions, in http://w3.antd.nist.gov/pubs/... Nahrstedt, Multimedia Systems, Springer-Verlag, 2004 [5] Fred Halsall, Multimedia Communications – Applications, Networks, Protocols and Standards, AddisonWesley, 2000 [6] Motion Picture Experts Group, http://www.chiarogonline.org/mpeg/, 2004 [7] Raffaele Bruno, Marco Conti and Enrico Gregori, Traffic integration in personal, local and geographical wireless networks, in Handbook of Wireless Networks and Mobile... multi-band OFDM devices Currently two modes of operation have been specified Mode 1 is mandatory and operates in frequency bands 1–3, i.e Group A Mode 2 is optional and uses seven frequency bands, three bands from group A and four bands from group C Groups B and D are reserved for future use Channelization in multiband OFDM is achieved by using different time-frequency codes, each of which is a repetition... for the beacons and the commands exchanged between the PNC and the devices 6 .5. 7 802. 15. 3a–Ultra-Wideband An alternative PHY layer, based on Ultra-wideband radio transmission, has been proposed for the 2.4 GHz PHY layer described in IEEE 802. 15. 3 The IEEE TG802. 15. 3a is in the process of developing an alternative high-speed (greater 110 Mbps) link layer design conformal with the 802. 15. 3 multiple access... Working Group 15, was formed to begin the development of a LR-WPAN (Low Rate -Wireless Personal Area Network) standard IEEE 802. 15. 4 The goal of Task Group 4 is to provide a standard that has the characteristics of ultra-low complexity, low-cost and extremely low-power for wireless connectivity among inexpensive, fixed, portable and moving devices[19] Yet another standards group, ZigBee [ 25] (a HomeRF . examining newer technologies and protocols to support such applications. Emerging Wireless Multimedia: Services and Technologies Edited by A. Salkintzis and N. Passas # 20 05 John Wiley & Sons,. IEEE 802. 15 group of standards, we also present the IEEE 802. 15. 4 standard for low-rate Wireless Personal Area Networks. 6.2 Multimedia Information Representation In general, the term multimedia. uncompressed bandwidth of 1 15 Mbps. There have been several compression standards for video storage. The MPEG-1 standard used on Video-CDs requires bandwidth of approximately 1 .5 Mbps for a 352  288