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Broadcasting, IEEE Transactions on

Issue 2 • Date Jun 2001

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Displaying Results 1 - 9 of 9
  • Soft selection combining for terrestrial digital audio broadcasting in the FM band

    Publication Year: 2001 , Page(s): 103 - 114
    Cited by:  Papers (5)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB) |  | HTML iconHTML  

    Methods of adaptive soft combining and channel decoding are developed to combat the effects of multipath fading and nonuniform interference channels, with particular application to digital reception in hybrid in-band on-channel (HIBOC) digital audio broadcast (DAB) systems in the FM band. These systems transmit near CD quality digital audio and analog FM simultaneously within the same license band, requiring the digital audio to be protected with powerful channel codes and sophisticated decoding algorithms to provide broad coverage under a variety of fading and potentially severe interference conditions created by first adjacent FM stations. In an example HIBOC DAB system, digital transmissions are DQPSK/OFDM modulated in two sidebands of the analog FM host signal, and a complementary punctured pair convolutional (CPPC) inner coding scheme allows for higher diversity benefit than code combining when both sidebands are interference-free as well as full recovery of the audio information when one of the sidebands is severely corrupted by first adjacent interference. For the intermediate cases in which one of the sidebands is partially useful, we demonstrate via simulations that an unmodified receiver designed for a Gaussian channel and corresponding to equal-gain combining performs ineffectively for moderate to high interference levels. Motivated by a clear need for more sophisticated receivers, we examine soft combiners derived from the maximum-likelihood principle and provide simulated performance bounds for the case in which perfect channel parameter estimates are available. We then discuss more practical methods for performing adaptive soft combining and channel decoding, focusing in particular on an appealing soft selection combining technique, based on successive erasures and Viterbi decoding, that requires only coarse estimates of the channel parameters. An outer code used for error concealment may be further utilized to perform the selection function. The performance of this soft selection combining scheme under a variety of interference scenarios is also evaluated via simulation. Further improvements may be obtained with a list Viterbi decoder View full abstract»

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  • Mixed BB-IF predistortion of OFDM signals in non-linear channels

    Publication Year: 2001 , Page(s): 137 - 146
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    It is well known that power amplifier induced non-linear distortions produce a signal spectral regrowth at the IF transmitter output of digital radio communication systems. This effect is responsible for both adjacent channel interference and BER degradation. Signal predistortion is a technique that counteracts such phenomena. Technological advances in the last decade, renewing the interest in this technique, led to the realization of digital baseband (BB) predistorters that overcome the performance of the existing analog IF (intermediate frequency) ones. However, the substitution of an analog IF predistorter with a digital BB one forces one to partially redesign the system architecture. An alternative approach is proposed in this paper, based on digital and analog techniques, which combines the precision of the digital BB solution with the practicality of an IF architecture. This solution is particularly interesting to substitute an old analog IF predistorter simply plugging-in the new digital one, without further changes in the transmitter architecture. Critical aspects, predistortion algorithms and simulation performance are presented with respect to a digital video broadcasting system which is based on an OFDM modulation and is very sensitive to non-linear distortions because of the adopted multicarrier modulation View full abstract»

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  • A theoretical and experimental study of noise and distortion in the reception of FM signals

    Publication Year: 2001 , Page(s): 164 - 179
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB) |  | HTML iconHTML  

    A mathematical model is developed that can be used to analyze the effects of multipath on any modulation of an FM carrier. The predictions of this model are verified by simulation and by actual field testing. The model is used to analyze the existing FM stereo system and the proposed FMX system. The analysis, confirmed by field tests in over 15 000 locations, shows that FMX transmission significantly degrades reception on existing FM stereo receivers and that FMX receivers are inferior to FM stereo receivers for receiving FMX transmissions View full abstract»

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  • Reed-Solomon decoding algorithms for digital audio broadcasting in the AM band

    Publication Year: 2001 , Page(s): 115 - 122
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB) |  | HTML iconHTML  

    Digital audio broadcasting (DAB) systems for the AM band are being developed to provide higher-quality radio broadcasts, broader coverage, and data services. Transmission is typically done by means of multistreaming with QAM/OFDM in the high bits/sec/Hz regime in which Reed-Solomon codes, either alone or in concatenation with inner trellis coded modulation (TCM), are natural choices for error control. For the AM DAB application, Reed-Solomon codes with suboptimal decoders of the bounded-distance type offer error correction important for bringing down the error probability, but also offers error detection important for generating block detected-error flags for use in the error concealment, or error mitigation, algorithm in the audio decoder. For multistream systems, the block detected-error flags can also be used to select the component streams retained by the audio decoder. In this paper, we evaluate the performance of Reed-Solomon codes in terms of both detected (flag) and undetected error rates for DAB applications. We provide simulation results for a variety of decoding algorithms, including hard-decision decoding (HDD), successive-erasure decoding (SED), and fixed-erasure decoding (FED), and discuss the channel environments in which each of these algorithms may be appropriate. Among other results, for example, we address the issue of matching the blocklength of the Reed-Solomon code to the audio decoder with its variable frame structure. From our simulation results for HDD, we conclude that the increased error correction capability of longer Reed-Solomon codes more than compensates for the mismatch in terms of error mitigation in the audio decoder. We also observe that SED provides only small improvements for uniform interference channels, while FED offers considerable improvements for some partial-band interference channels. We describe an appealing two-mode adaptive configuration using HDD and FED for mitigating partial-band interference caused by some second-adjacent AM broadcasts View full abstract»

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  • Prototype constant-efficiency amplifiers

    Publication Year: 2001 , Page(s): 147 - 152
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB) |  | HTML iconHTML  

    This paper describes two constant efficiency amplifiers (CEA) using cathodes, novel grids and novel cavities similar to those used in our inductive output tubes together with five-electrode, multi-stage, depressed collectors in either poly alpha olefin (PAO) oil-cooled or forced-air-cooled versions. The air-cooled version is capable of 65 kW peak 8VSB or COFDM operation, and the oil-cooled tube will provide the performance of our higher power IOTs in either 8VSB, COFDM or NTSC service with much higher average efficiency. The PAO oil (similar to synthetic automobile engine oil) is a low-cost coolant that simultaneously solves insulation and corrosion problems. These tubes meet the expectations that were discussed in our previous papers. The design and performance are described together with application data useful to transmitter designers. Collectors may be connected together to minimize the number of independent voltages required or operated independently to maximize efficiency and minimize power supply size for a wide variety of signal statistics. A single thyratron crowbar circuit which will simultaneously short circuit up to five voltage sources is described. The CEA design and its application are covered by US and foreign patents issued and pending. Adoption of this technology will save television broadcasters in the order of one billion dollars of electrical power cost over the life of these patents View full abstract»

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  • PC-based receiver for Eureka-147 digital audio broadcasting

    Publication Year: 2001 , Page(s): 95 - 102
    Cited by:  Papers (13)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB) |  | HTML iconHTML  

    We present the design and implementation for a Eureka-147 digital audio broadcasting (DAB) receiver. We establish the specifications for the receiver and design the blocks required for DAB reception. Due to the fact that orthogonal frequency division multiplexing (OFDM) is the transmission technique used in the DAB system, the synchronization block plays a key role in the overall system performance among the receiving blocks in the DAB receiver, and for this reason we describe it in detail here. We also include descriptions of several implementation techniques that enable the receiver to run in real-time on a PC. Our findings show that the receiver implemented as described here satisfactorily meets our predetermined specifications View full abstract»

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  • Interactive digital terrestrial television. The wireless return channel and the EU sponsored WITNESS project

    Publication Year: 2001 , Page(s): 160 - 163
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (120 KB) |  | HTML iconHTML  

    There is a growing consensus among broadcasters that the key difference between digital and analog television will be the new level of interactivity that digital broadcasting will allow. In 1999 the digital video broadcasting (DVB) project mandated work within an Ad-hoc Group (AHG) group (DVB-RCCL) to develop a wireless terrestrial return channel technology (to be known as DVB-TRC, digital video broadcasting return channel terrestrial). In parallel with this the European Union agreed in 2000 to fund an accompanying measure project known as WITNESS (Wireless Interactive Terrestrial Network Systems and Services) in order to verify and validate technical issues relating to operation of such a system. These issues include identification and allocation of suitable spectrum, set top box (STB) development work, and technical field trials in Ireland and France to allow investigation of system performance. The objective of the work is to aid the DVB-TRC subgroup in specifying this new system, and to build a wider consensus among the many stakeholders on the important issues related to this subject. This paper aims to introduce the technologies, and some of the organizations involved in this field of study, and to describe some of the socio-economic drivers behind these activities View full abstract»

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  • Effects of HPA nonlinearity on frequency multiplexed OFDM signals

    Publication Year: 2001 , Page(s): 123 - 136
    Cited by:  Papers (38)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB) |  | HTML iconHTML  

    The paper analyzes the performance of the downlink channel of a multimedia interactive service system which transmits the desired information by the frequency multiplexing of several OFDM signals compliant with the DVB-T standard. The effects of the nonlinear distortions introduced by a high power amplifier on the system performance are evaluated both in terms of the bit error rate (BER) degradation in AWGN channels and of the spectral regrowth. The performance comparison to the case of a single DVB-T signal as well as the benefits of an ideal predistortion is also considered by comparing analytical results to computer simulations View full abstract»

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  • Understanding the effects of phase noise in orthogonal frequency division multiplexing (OFDM)

    Publication Year: 2001 , Page(s): 153 - 159
    Cited by:  Papers (135)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    Phase noise must be carefully considered when designing an OFDM-based communication system since an accurate prediction of the tolerable phase noise can allow the system and RF engineers to relax specifications. This paper analyzes the performance of OFDM systems under phase noise and its dependence on the number of sub-carriers both in the presence and absence of a phase correction mechanism. Besides some practical results are provided so as to give some insight into the phase noise spectral specifications that should be required of the local oscillator View full abstract»

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Aims & Scope

IEEE Transactions on Broadcasting covers the field of broadcast technology, including the production, distribution, transmission, and propagation aspects of broadcasting.

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Editor-in-Chief
Yiyan Wu
Communications Research Ctr Canada