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Z arg min X (mf + Probs (j l)(x- cs y)2 , (7.5) i.e., where i is a value of for which the expression in square brackets is minimum. Then reconstruct the yth codeword with It is insightful to note that the cost of assigning x to yi in (7.5) is a weighted sum of distortion and energy associated with this decision, which is a variation of the entropy-constrained vector quantization (ECVQ) 76 problem in which an equivalent entropy term in ECVQ is replaced by an energy term. At this step, we find...

Modularity of Services and Bitway Layers

To allow different transmission media to work with the same source coding, and different source coders to work with different transmission media, it is especially important that we logically separate the design of source coders (in the services layer) from the transmission (in the bitway layer) as much as possible. (As discussed in Section 6.3, this separation is even more advantageous in heterogeneous transport environments.) This separation requires a careful partitioning of functionality...

Sinr

Figure 2.17 Distributions for signal-to-interference ratio assuming random signature sequences. Results for both the linear MMSE detector and the matched filter are shown. strong (i.e., intracell) users, 50 weak (i.e., other-cell) users, and the signal-to-background noise ratio is 25 dB. The received powers (for members of each set of strong and weak users) were selected from a log-normal distribution. The SINR distribution for the matched-filter receiver is also shown. The results in Figure...

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Macro-multipath structure, 373 delay-spread function, 342-45 Marconi, Guglielmo, 381 Matched-filter (MF) receiver, 130,143 4 performance of, 216-17 See also RAKE receiver Maximal ratio combining, 45 Maximum-likelihood (ML) sequence detection, 18,130,138-42 additive white Gaussian noise channels, sufficient statistics for, 141-42 LTI channels, sufficient statistics for, 140-41 Maxwell-Hertz laws, 388 Maxwell, James Clerk, 381 MBone, 251, 263 Minimum mean-square error (MMSE) equalizer, See MMSE...

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Order estimation, 94-95 Orthogonally anchored (blind) algorithms, 95-101 Orthogonal multiuser modulation, 29-31 Outage, 8,16, 43 Outage probability, 252 Oversampling, 160,196-97 Packet-based communications networks, 236 Packet transmission, substreams, 246-48 Packet transport impairments, 236, 245 Partial-response equalization, 362 Path loss, 107 Phase-locked loop, 359 PicturePhone, 389 Platform constraints, underwater acoustic communications, 352-53 Point-to-point image video transmission with...

Linear Diversity Techniques for Fading Channels

Signal fading due to multipath propagation is a dominant source of impairment in wireless communication systems, often severely impacting performance. However, the effects of fading can be substantially mitigated through the use of diversity techniques via appropriately designed signal processing algorithms at both the transmitters and receivers. Practical, high-performance systems require that such diversity techniques be efficient in their use of resources such as power, bandwidth, and...

Arg max 2 Re J yMsln

Where the superscriptt denotes the conjugate transpose operator, Re denotes the real part of its argument, s J00 ws dt, and y n f r t iCn t dt 3.20 The vector sequence y n is a set of sufficient statistics for sequence detection via observation of the waveform r . The ML sequence detector first precomputes the vector waveform t for any n, using knowledge of h t z and cz- i , then obtains y n at time n as the response of r t to a matched filter h - at time t 0, and finally solves 3.19 . The...

David Brady James C Preisig

Much of the development of the preceding chapters is applicable to a broad range of wireless networks, although there is a strong emphasis on radio-frequency RF systems and their applications. And while underwater acoustic channels and systems share many features with their RF counterparts, there are also important differences. In this chapter, we describe the special characteristics of underwater acoustic channels and show how they impact system design. The underwater acoustic channel UAC is...

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Figure 6.6 Abstracted view of the service from the perspective of the bitway. shown in Figure 6.6. The stream of packets is logically divided into substreams, which are visible to the bitway. The integrity of substreams is maintained across multiple links see Section 6.3 . Each substream is associated with distinct QoS and rate attributes established by negotiation with the application. The QoS attributes are aggregated values from the individual links, so that each substream on each link has a...

Architectural Principles for Multimedia Networks

Messerschmitt Louis Yun Many treatments of wireless communications focus on a wireless link as an isolated entity Our concern here is with networks that support all multimedia services including data, graphics, audio, images, and video for tetherless not physically wired to the network , nomadic able to access the network from many locations , and mobile accessing the network while moving users. Such a network is termed an integrated-services multimedia network with...

Edge vs Link Architecture for Service Layer

In Section 6.2, we addressed the problem of separating the designs of the service from the bitway while leaving open most possibilities for JSCC. Our motivation was to allow the flexibility to substitute freely the service or bitway realizations. In this section, we consider a related set of issues in the provision of CM services through two or more heterogeneous subnets. Many of the issues addressed in Section 6.2 become more important. Consider two basic architectures, illustrated in Figure...

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Thus, the bit-error rate achieved depends strongly on the channel gain a. If the fading is sufficiently severe that a drops below some minimum SNR level necessary for adequate performance, then the system is said to experience an outage '8 Since with a complex-valued Gaussian amplitude the SNR 1.8 is an exponentially distributed random variable with mean then for a given threshold the outage probability can be readily calculated as the integral under the tail of the exponential density. This...

Concluding Remarks

The most important point of this chapter is that in an integrated-services multimedia network, it is advantageous to take an overall systems perspective, rather than designing wireless access networks in isolation. We have seen how, by coordinating the design of the backbone network, terminals, and servers with the wireless access network, greater traffic capacity can be achieved subject to subjective quality objectives. At the same time, it is important to adhere to good principles of...

And Effective Bandwidth

As the preceding chapters have emphasized, the mobile wireless environment provides several unique challenges to reliable communication not commonly found in wireline networks. These include scarce bandwidth, limited transmit power, interference between users, and time-varying channel conditions. A central problem in the design of wireless networks is how to use the limited resources most efficiently in such adverse environments, in order to meet the quality-of-service QoS requirements of...

Vel

Figure 6.5 Abstracted model of the bitway from the perspecti ve of the service, for a single substream. Since the bitway core function is to transport packets, the abstract view should focus on the fundamental packet transport impairments of corruption, loss, and delay. A basic model incorporating these three elements is shown schematically in Figure 6.5. Often, the service will be interested in the temporal properties of these impairments that is, a characterization of whether impairments like...