Showing papers in "IEEE Transactions on Broadcasting in 1999"
TL;DR: The peak-to-average power ratio of an OFDM system and the optimal companding coefficient are determined and the symbol error rate of the systems after the companding is derived.
Abstract: A companding technique is proposed to reduce the peak-to-average-power ratio of the orthogonal frequency division multiplexing (OFDM) signal in this paper. The probability density function of the amplitude of the OFDM signal is determined. Because of the Gaussian distribution of the OFDM signal, the companding technique can be quite effective, since a large OFDM signal only occurs infrequently. The peak-to-average power ratio of an OFDM system and the optimal companding coefficient are determined in this paper. The symbol error rate of the systems after the companding is derived. The performances of the system with and without the companding are also compared.
515Â citations
TL;DR: The proposed novel subblock partition scheme for PTS OFDM shows almost same PAPR reduction performance as compared to the conventional pseudo-random SPS which has been known to have the best performance, and computational complexity can be reduced extensively.
Abstract: In general, there has been a trade-off between performance of peak-to-average power ratio (PAPR) reduction and computational complexity in partial transmit sequence (PTS) orthogonal frequency division multiplexing (OFDM). In this paper, a novel subblock partition scheme (SPS) for PTS OFDM is proposed and analyzed. In this scheme, signals assigned randomly in partial subbands are duplicated and concatenated repetitively to generate each subblock. The proposed scheme, therefore, has a form of concatenation of pseudo-random and interleaved SPS. As results of simulations, the proposed scheme shows almost same PAPR reduction performance as compared to the conventional pseudo-random SPS which has been known to have the best performance. However, computational complexity can be reduced extensively. Hence, the proposed scheme may be considered to be more suitable than the conventional ones for application in high speed transmission systems such as digital terrestrial broadcasting.
200Â citations
TL;DR: Two time-domain channel estimation methods are proposed, based on theoretical analysis and computer simulation, for a channel with multipath distortion and AWGN, that perform better than the conventional frequency- domain channel estimation techniques.
Abstract: Channel estimation techniques using pilot tones in OFDM systems are investigated. Two time-domain channel estimation methods are proposed. Based on theoretical analysis and computer simulation, for a channel with multipath distortion and AWGN, the proposed time-domain channel estimation schemes perform better than the conventional frequency-domain channel estimation techniques.
78Â citations
TL;DR: This work focuses on the cost efficient design of an SFN providing broadcasting services over a predefined service area with requirements both on the received signal quality and on the allowable interference level experienced by existing services in the same spectrum.
Abstract: OFDM based single frequency networks (SFNs) have been standardized for terrestrial broadcasting systems, for digital audio broadcasting (DAB) as well as for digital video broadcasting (DVB). Due to the multipath tolerance of the OFDM scheme, the receiver is able to combine signals coming from several transmitters, despite of the varying propagation delays, i.e., heavy artificial multipath propagation. In order to take full advantage of the diversity gain provided by the SFN architecture, proper network design is required. We focus on the cost efficient design of an SFN providing broadcasting services over a predefined service area with requirements both on the received signal quality and on the allowable interference level experienced by existing services in the same spectrum. We formulate the problem as a discrete optimization problem, where the network design parameters such as power, antenna heights and transmitter locations are the decision variables. The general stochastic optimisation algorithm simulated annealing has been adapted for solving the above problem. The novelty of our method is that cost factors and interference constraints are embedded in the optimisation procedure. Through numerical examples we demonstrate that significant reduction in network cost can be achieved by our approach.
73Â citations
TL;DR: For a popular video, in order to approach a near VOD service, the harmonic broadcasting scheme is an optimal broadcasting scheme that needs the least bandwidth for a given viewers' waiting time.
Abstract: In order to approach a video-on-demand (VOD) service, we can allocate more bandwidth to broadcast a popular video more frequently to reduce viewers' waiting time. Using a broadcasting scheme to support a popular video periodically, in order to guarantee a given waiting time, the harmonic broadcasting scheme needs the least bandwidth in the existing schemes. In this paper, we show that using any broadcasting scheme, the minimum bandwidth requirement for the same waiting time is the same as the harmonic broadcasting scheme. Therefore, for a popular video, in order to approach a near VOD service, the harmonic broadcasting scheme is an optimal broadcasting scheme that needs the least bandwidth for a given viewers' waiting time.
59Â citations
TL;DR: The numerical analysis shows that the unequal packet loss protection can significantly improve the communication quality, in the sense of packet loss rate on reconstructing pictures, without any additional complexity in the network infrastructure.
Abstract: A general model for the transmission of layered video is introduced. The effect of packet dropping in different layers on the reconstruction of pictures is analysed. The application of unequal packet loss protection (UPLP) for layered video is proposed and the performance is investigated. An algorithm for the design of the UPLP parameters is described. The numerical analysis shows that the unequal packet loss protection can significantly improve the communication quality, in the sense of packet loss rate on reconstructing pictures, without any additional complexity in the network infrastructure. It is also shown that application of UPLP can achieve a more efficient bandwidth utilization than the application of ARQ protocols. This technique is suitable for multimedia multicasting in heterogeneous networks, as well as for digital video broadcasting systems which support a variety of receivers with different resolutions and signal processing powers.
56Â citations
TL;DR: Computer simulation, using the Common Simulation Framework (CSF) 12 version of the CableLabs DOCSIS 1.0 computer model, has been used to predict the upstream system throughput and mean access delay and a prioritised first come first served scheduling algorithm has been considered.
Abstract: The Multimedia Cable Networks Systems (MCNS) Data Over Cable Service Interface Specifications (DOCSIS) is established as the primary cable network data communications standard. The head-end scheduling algorithm is not defined within the standard but it is the key function for providing the required performance capability. Computer simulation, using the Common Simulation Framework (CSF) 12 version of the CableLabs DOCSIS 1.0 computer model, has been used to predict the upstream system throughput and mean access delay. A prioritised first come first served scheduling algorithm has been considered to provide a baseline reference set of performance statistics against which other algorithms can be compared. The simulations, with theoretical confirmation, have shown that the maximum sustainable system throughput is 1965 kbps for a channel capacity of 2560 kbps and a packet size of 1500 octets, whereas for packet size of 100 octets the maximum sustainable throughput is only 1550 kbps. The mean access delay is found to vary between 10-900 ms depending on the offered load and assuming that the offered load does not exceed the capacity of the channel. Excess offered load causes service starvation according to the assigned priority.
45Â citations
TL;DR: The flexibility of the software approach along with the obtained performance make the proposed implementation very interesting in professional and high-end receivers for interactive, multimedia applications of DVB-T.
Abstract: This work treats the design of base-band processing subsystems for professional DVB-T receivers using 1600 MIPS, fixed point DSPs. We show the results about the implementation of OFDM demodulation, channel estimation and equalization functional blocks, for the 2k/8k modes. The adoption of general purpose DSPs provides a great flexibility in the development of different configurations of the receiver. Furthermore it enables the feasibility of adaptive equalization schemes, where the quality of the channel estimation varies according to both channel characteristics and speed of the channel variations. The 16/32 bit fixed point architecture leads to a very low implementation loss, and a careful optimization of the pipeline architecture of the processor allows the receiver to obtain short processing delays. The flexibility of the software approach along with the obtained performance make the proposed implementation very interesting in professional and high-end receivers for interactive, multimedia applications of DVB-T.
36Â citations
TL;DR: It is shown that the proposed optical fiber CDMA networks have a distinguishing feature of high bit-rate flexibility and fast access tunability, which can effectively support both VBR and CBR video communications as well as multimedia broadcasting/distributions in a given network without any violation of the minimum correlation constraint /spl lambda/=1.
Abstract: Flexible optical fiber code-division multiple-access (CDMA) networks are proposed to support real-time multimedia communication services of constant bit rate (CBR) and variable bit rate (VBR)/multiple bit rate (MBR). Since strict optical orthogonal codes (OOCs) are employed in incoherent optical fiber CDMA networks, their use can strictly guarantee the correlation constraint /spl lambda/ to be the minimum value (i.e., an unit "1") for multimedia applications. This is achieved without increasing any system complexity compared with the use of conventional OOCs. Moreover, optimal strict OOCs can have the same length as optimal conventional OOCs or a slightly longer length than the latter. It is shown that the proposed optical fiber CDMA networks have a distinguishing feature of high bit-rate flexibility and fast access tunability. Consequently, this can effectively support both VBR and CBR video communications as well as multimedia broadcasting/distributions in a given network without any violation of the minimum correlation constraint /spl lambda/=1. The proposed network can be also used as a backbone to interconnect various local-area networks with different data bit rates. However, conventional OOC-based optical CDMA networks do not possess such characteristics because of violation of /spl lambda/=1 for VBR or MBR communications.
34Â citations
TL;DR: It seems that the noise power was constant, while the transmitted signal's power was increased as it was companded, and it would in the opinion be more meaningful to compare the performance of the companded signal to that of an uncompanded signal of equal power.
Abstract: The authors comment on the work of Xianbin Wang, Tjhung, and and Ng (see ibid., vol.45, no.3, 1999). They add that Wang et al. present a very elegant analysis of the symbol error rate in a companded COFDM system. A comment that they make is that it seems that the noise power was constant, while the transmitted signal's power was increased as it was companded. It would in our opinion be more meaningful to compare the performance of the companded signal to that of an uncompanded signal of equal power.
33Â citations
TL;DR: The authors consider a companded OFDM system with constant transmission power and observe that indeed, it would be more meaningful to compare the performance of the companded signal to that of an uncompanded signal of equal power.
Abstract: Xianbin Wang, Tjhung and Ng (see ibid., vol.45, no.3, 1999) authors reply that they would like to thank Mattsson, Mendenhall and Dittmer (see ibid., vol.45, no.4, 1999) for their constructive comments. They observe that indeed, it would be more meaningful to compare the performance of the companded signal to that of an uncompanded signal of equal power. They consider a companded OFDM system with constant transmission power.
TL;DR: The capacity and performance characteristics of the DOCSIS 1.0 protocol for the delivery of isochronous streams given the limited quality of service (QOS) features of the protocol and a modem population of up to 500 nodes are evaluated.
Abstract: The Data Over Cable Systems Interface Specification (DOCSIS) 1.0 protocol enables the delivery of Internet Protocol (IP) traffic over cable TV networks with significantly higher data rates when compared to analogue modems and integrated services digital network (ISDN) links. The availability of greater bandwidth enables the delivery of high quality audio and video services. Such services require bounded delay characteristics. This paper evaluates the capacity and performance characteristics of the DOCSIS 1.0 protocol for the delivery of isochronous streams given the limited quality of service (QOS) features of the protocol and a modem population of up to 500 nodes. Stream rates of up to 64 Kbps with different packet size were considered, suitable for compressed audio, voice and low quality video. Packet concatenation for upstream traffic was also considered. Simulation results indicated that such streams, within the given protocol limitations, can be supported for a particular system population with tradeoffs in terms of system throughput and channel utilisation of up to 50%. The network capacity, in terms of the number of simultaneous streams supported and link utilisation, is significantly affected by packet size. Support for concatenation has limited advantages. Performance benefits from concatenation are more evident when delivering higher rate bitstreams.
TL;DR: A new scheme called single-rate multicast double-rate unicast (SRMDRU) is developed to minimize the system resources for supporting full VCR functionality in a multicast VoD system and allows multicast systems to support true VoD services so customers can be served as soon as the system receives the requests.
Abstract: Multicast delivery is one of the solutions to reduce the cost in a large video-on-demand (VoD) system. However, multicast transmission makes much more difficult the implementation of interactive functions for individual users and introduces start-up delays for the users, which contradicts the idea of on-demand services. In this paper, we first try to explore and evaluate the performance of different multicast VoD systems. A new scheme called single-rate multicast double-rate unicast (SRMDRU) is then developed to minimize the system resources for supporting full VCR functionality in a multicast VoD system. This scheme also allows multicast systems to support true VoD services so customers can be served as soon as the system receives the requests. Computer simulations show that the multicast systems using the SRMDRU scheme perform much better than other multicast systems in terms of system blocking probabilities.
TL;DR: The VIDITER project is presented, to study the behavior of a whole digital terrestrial television network, from source coding up to the final signal reception, and the network configuration used for these first field trials and coverage measurements in Spain.
Abstract: This article presents the results of the first digital terrestrial television field trials and coverage measurements in Spain. First of all the VIDITER project is presented. The main objective of this work is to study the behavior of a whole digital terrestrial television network, from source coding up to the final signal reception. At this point, the experimental network installed in Madrid is described. Next, the measurement campaign is explained, first, by describing the network configuration used for these first field trials, and then, paying attention to the criteria used to select the measurement points and the parameter set to be tested. Some of the results obtained are shown as a first approach to the figures needed to develop and plan a fully operational digital terrestrial television service.
TL;DR: This paper addresses the implementation of a powerful wide-band mobile channel simulator, which is based on two state-of-the-art 32-bit floating point DSP processors, and can be useful to the study of space diversity.
Abstract: This paper addresses the implementation of a powerful wide-band mobile channel simulator, which is based on two state-of-the-art 32-bit floating point DSP processors. A key feature of this simulator is the ability to be reconfigured through a common serial interface and virtually simulate a wide variety of different channel models. Additionally, this simulator can be useful to the study of space diversity for it can be arranged to provide two groups of Rayleigh fading signals whose correlation coefficient can be adjusted between zero and one.
TL;DR: This paper proposes a novel adaptive chaining scheme that extends the basic chaining Scheme with two new techniques: two-way bridging and multicast chaining, which provides nearly twice the performance gain and lower data delivery cost per video session.
Abstract: In distributed video on demand (VOD) applications, a client station buffers a shifting window of its displaying video so that the video stream can be chained from the client to another one arriving within the window, instead of consuming a server stream for each new request. This scheme is called video chaining that can reduce the load of video servers significantly. In this paper, we propose a novel adaptive chaining scheme that extends the basic chaining scheme with two new techniques: two-way bridging and multicast chaining. The two-way bridging method employs video buffers as forward and/or backward bridges to extend each video chain as long as possible. It provides nearly twice the performance gain than basic chaining in terms of server I/O load reduction. Mathematical analyses for both schemes are also given. The multicast chaining method maximizes the multicast degree of each video chain so that lower data delivery cost per video session can be achieved. Our scheme maintains the video chains optimally to shift the load to active clients so that the I/O bottleneck of video servers is released.
TL;DR: It is argued that in order to be able to create video systems able to cope with cell losses encountered in computer communications systems, a structured set of error-resilient protocol mechanisms is needed.
Abstract: MPEG-2 video communications over ATM networks is one of the most active research areas in the field of computer communications. In the transmission process of a variable bit rate video signal over an ATM network, cells are inevitably exposed to delays, errors and losses due to the statistical multiplexing used in these networks. These phenomena affect the quality of the video signal and without adequate measures to control the propagation of the impairments the quality of the service may fall below acceptable levels. In this paper, we study the impact of cell losses on the quality of a MPEG-2 video sequence encoded in a variable bit rate mode. We introduce a set of control mechanisms at different levels of the protocol architecture to be used in MPEG-2-based video communications systems using ATM networks as their underlying transmission mechanism. Our results (using different video sequences) show the effectiveness to improve the video quality by using a structured set of control mechanisms to overcome for the loss of cells carrying VBR MPEG-2 video streams. We argue that in order to be able to create video systems able to cope with cell losses encountered in computer communications systems, a structured set of error-resilient protocol mechanisms is needed.
TL;DR: The Canadian digital terrestrial television system technical parameters for implementation and frequency planning: interference protection ratios, reference system parameters, and radio frequency emission masks, as well as their design methodology are discussed.
Abstract: On November 8, 1997, Canada formally adopted the ATSC Digital Television Standard for terrestrial transmission as defined in document A/53 of the Advanced Television Systems Committee of the USA and as modified by the FCC document MM Docket No. 87-268. This paper discusses the Canadian digital terrestrial television system technical parameters for implementation and frequency planning: interference protection ratios, reference system parameters, and radio frequency emission masks, as well as their design methodology. First, the Canadian terrestrial DTV design guidelines are presented, followed by the introduction of DTV reference receiving system set up and the parameter selection of the interference protection ratios. Last, the design methodology of the emission masks is discussed.
TL;DR: The analyses and simulations show that in the complex gain predistorter only a DC offset will affect the adjacent channel interference (ACI), and according to these guidelines the design process can be simplified and the ACI can be improved.
Abstract: Any errors in a linearization system for power amplifiers will affect linearization results. In this paper the effect of the demodulator errors on a few adaptive predistortion techniques is studied. The investigations are focused on the complex gain predistorter and the mapping predistorter. The analyses and simulations show that in the complex gain predistorter only a DC offset will affect the adjacent channel interference (ACI). Gain imbalance and phase imbalance of the demodulator have no effect on the ACI in the complex gain predistorter system. In the mapping predistorter system, although the predistorter was also misadjusted because of errors, the ACI will not be deteriorated. But due to these errors, linear distortions will emerge in both systems and bit error rate (BER) of both systems will be degraded. The conclusions obtained in this paper can be used to guide the predistorter design. According to these guidelines the design process can be simplified and the ACI can be improved.
TL;DR: New approaches to hybrid in band on channel (HIBOC) FM systems for digital audio broadcasting based on multistream transmission methodology and multidescriptive audio coding techniques are introduced, resulting in robust transmission and graceful degradation in variable interference channels.
Abstract: New approaches to hybrid in band on channel (HIBOC) FM systems for digital audio broadcasting based on multistream transmission methodology and multidescriptive audio coding techniques are introduced. These ideas combined with a lower per sideband audio coding rate and more powerful channel codes result in robust transmission and graceful degradation in variable interference channels. By also using orthogonal frequency division multiplexing techniques with a nonuniform power profile combined with unequal error protection and sideband time diversity, we arrive at new HIBOC FM schemes with extended coverage and better peak audio quality than previously proposed. The paper provides approximate performance analysis for potential systems including audio coding quality.
TL;DR: The Advanced Television Systems Committee (ATSC) has provided guidelines for broadcasters in the form of suggested compliance specifications, which are covered in this paper.
Abstract: Terrestrial digital (DTV) broadcasting is now underway in the major markets in the United States after the Federal Communications Commission (FCC) in several Reports and Orders set the standard on December 24, 1996, and subsequently released rules of operation and broadcaster channel allocations. Broadcasters are concerned with many in-band and out-of-band transmission parameters, including data signal quality, clock tolerance, radiated power tolerance, carrier phase noise, adjacent channel emissions, and precision frequency offset requirements. The FCC permits DTV power-level changes and/or transmitting antenna location and height and beam tilt in the context of the minimum interference levels. The Advanced Television Systems Committee (ATSC) has provided guidelines for broadcasters in the form of suggested compliance specifications, which are covered in this paper.
TL;DR: These bursts can deteriorate essential error correction by the interleaver-deinterleaver and Reed-Solomon forward error correction (FEC) code of the transmission systems also with a relative low bit error rate (BER) of about 10/sup -5/ before FEC.
Abstract: This article describes the measurements of composite second order (CSO), composite triple beats (CTB) frequency spectrum and time-varying distortion in the basic bandwidth (BB) (0-4 MHz) of the 64-QAM digital channels by multichannel AM/64-QAM optical and coaxial transmission systems. For any regular standard frequency plans (Europe, USA, NCTA, etc.) there is, for the I and Q components in the BB of the QAM channels, the harmonic series of the CSO/CTB with the first harmonic f/sub 1/. It has been shown that for all the same laser-optics or coaxial transmission systems the CSO/CTB distortions spectrum form in the QAM BB 60-80 /spl mu/s duration bursts of a series pulse with a pulse period T=1/f/sub 1/ and a pulse duration /spl tau//spl ap/0.4/f/sub m/, where f/sub m/ is the CSO/CTB harmonic with maximum amplitude in the QAM BB. The bursts result in the essential unevenness of error bits in time domain distribution. These bursts can deteriorate essential error correction by the interleaver-deinterleaver and Reed-Solomon (RS) forward error correction (FEC) code of the transmission systems also with a relative low bit error rate (BER) of about 10/sup -5/ before FEC. There is, white Gaussian noise like, intermodulation distortion from interaction of digital-, digital-analog channels too, that have added white Gaussian noise.
TL;DR: This paper presents the results of a field measurement campaign at the experimental COFDM 8K digital terrestrial television network developed by the partners of the VIDITER project in Madrid (Spain).
Abstract: This paper presents the results of a field measurement campaign at the experimental COFDM 8K digital terrestrial television network developed by the partners of the VIDITER project in Madrid (Spain). This article focuses on the field strength spatial variation distribution inside small coverage areas. Due to the fact that the distribution parameters strongly depend on the survey area type, during this first stage the only environments taken into account have been those traditionally considered as suburban.
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TL;DR: An overview of three types of UHF antennas on the market today are presented, their advantages and disadvantages are discussed, and a decision tree is developed to help choose the best antenna.
Abstract: The implementation of DTV is forcing every television broadcaster to purchase a new antenna. Choosing the best antenna to meet all of the station's needs is not a simple task. With tower space at a premium, tower leasing rates soaring, and FCC deadlines approaching quickly, the broadcaster faces new and non-traditional issues-for example: Do I co-locate with others? Do I go on the air with a temporary low power system now and worry about my final higher power system later? Can I or should I broadcast my current NTSC signal and my new DTV signal on the same antenna? These questions have no historic precedent. To answer them, the broadcaster needs to know about the types of antennas available and the advantages and concerns associated with each one. Three types of UHF antennas are on the market today. They are the slot, the panel, and the superturnstile. This paper presents an overview of each of these. Their advantages and disadvantages are discussed, and a decision tree is developed to help choose the best antenna.
TL;DR: An attempt is made to study the adaptability of these techniques and it was found that the ITU-R, Epstein-Peterson (1953), Deygout (1966, and Edward-Durkins (1969) methods are in closer agreement with the observed path loss where as Blomquist-Ladell (1974) over estimates the observed course loss.
Abstract: Field strength measurements are made to study the single knife edge diffraction propagation in the hilly terrain of Tirupati, southern India. TV signals originating from Narayana Giri Hill in the VHF band are monitored at 4 different locations of Tirupati for this purpose. The observed values are converted into path loss values and are compared with prediction techniques. An attempt is made to study the adaptability of these techniques and it was found that the ITU-R, Epstein-Peterson (1953), Deygout (1966) and Edward-Durkins (1969) methods are in closer agreement with the observed path loss where as Blomquist-Ladell (1974) over estimates the observed path loss.
TL;DR: A new network architecture which using an intelligent node (IN) to stand for a group of subscribers to request the demand resources is proposed, which has the ability to reduce the collision probability as well as the collision resolving period.
Abstract: In the hybrid fiber/coax (HFC) architecture, a number of 500-2000 subscribers in the CATV (community antenna TV) network may cause serious collisions during the request phase. In this paper, we propose a new network architecture which using an intelligent node (IN) to stand for a group of subscribers to request the demand resources. The intelligent node has the ability to reduce the collision probability as well as the collision resolving period. The simulation results shown that the throughput and average buffer delay obtained by the proposed architecture is better than that of the standard architecture.
TL;DR: The purpose of this survey has been to determine the degradation suffered by analogue PAL-G signals in the presence of co-channel and adjacent channel digital emissions, resulting in a curve that estimates the protection ratios between analogue and digital received power levels.
Abstract: This paper presents some results of a measurement campaign in the service area of the digital terrestrial television (COFDM-8K system) experimental network of Madrid (Spain). The purpose of this survey has been to determine the degradation suffered by analogue PAL-G signals in the presence of co-channel and adjacent channel digital emissions. The result is a curve that estimates the protection ratios between analogue and digital received power levels.
TL;DR: It is concluded that the DTV performance degradation caused by close-in reflections from adjacent tower members may be predicted by calculation and that the degradation is small.
Abstract: Azimuth pattern analysis of a side-mounted antenna is made keeping reflections separate from the main radiated signal. Each reflection is characterized by a reflection coefficient and path difference in wavelengths at a distant receiving summing point. At each azimuth, the reflections are expressed as echoes accompanying a modulated VSB data pulse. The corresponding receiver equalizer tap weights are determined from which the DTV receiver threshold impact is calculated. Measurements of a side-mounted antenna using an azimuth fly-around technique are compared to the calculated results for specific azimuth directions. It is concluded that the DTV performance degradation caused by close-in reflections from adjacent tower members may be predicted by calculation and that the degradation is small.
TL;DR: This paper presents the design of a new type of integrated services digital broadcasting systems which use a multirate optical fiber code-division multiplexing (OF-CDM) technique, which can efficiently multiplex various kinds of digital signals with multiple bit rates.
Abstract: This paper presents the design of a new type of integrated services digital broadcasting (ISDB) systems which use a multirate optical fiber code-division multiplexing (OF-CDM) technique. The proposed system can efficiently multiplex various kinds of digital signals with multiple bit rates. This is feasibly achieved by using strict optical orthogonal codes of both auto- and cross-correlation constraints being "1" in multirate OF-CDM systems. Moreover, the low-cost design of OF-CDM transmitters is presented, and experimental demonstrations are also carried out. The measured results show that a transmission distance up to 13 km can be feasibly accomplished by using the proposed transmitter design and the external optical injection-locking scheme. It is expected that the proposed ISDB systems can be employed to cost-effectively transmit fast ethernet (125 Mbit/s), FDDI (125 Mbit/s), ATM (155 Mbit/s), and ESCON (200 Mbit/s) protocol data. Their potential applications include Internet services and multimedia broadcasting, such as videoconferencing, video on demand, HDTV, distance learning, and World Wide Web.
TL;DR: This paper describes a novel solution to the problem of bandwidth-efficient digital signal transmission in the presence of dynamic multipath distortion by consisting of two consecutive data blocks with identical data that have been processed differently.
Abstract: This paper describes a novel solution to the problem of bandwidth-efficient digital signal transmission in the presence of dynamic multipath distortion. A burst transmission is comprised of two consecutive data blocks with identical data that have been processed differently. The two data blocks are transmitted adjacent to each other in time so that the time-variable transmission channel will apply approximately the same linear distortion to each block. At the receive site, the two blocks are captured and processed together to cancel the effects of the linear distortion, while adding the signal energy from each block.