By Topic

Communications, IEEE Transactions on

Issue 3 • Date March 2003

Filter Results

Displaying Results 1 - 25 of 26
  • Abstracts of forthcoming manuscripts

    Publication Year: 2003 , Page(s): 517 - 518
    Save to Project icon | Request Permissions | PDF file iconPDF (148 KB)  
    Freely Available from IEEE
  • SVD iterative detection of turbo-coded multiantenna unitary differential modulation

    Publication Year: 2003 , Page(s): 441 - 452
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (649 KB) |  | HTML iconHTML  

    A new suboptimal demodulator based on a singular value decomposition for estimation of unitary matrices is introduced. Noncoherent communication over the Rayleigh flat fading channel with multiple transmit and receive antennas, where no channel state information is available at the receiver is investigated. Codes achieving bit-error rate (BER) lower than 10-4 at bit energy over the noise spectral density ratio (Eb/N0) of 1.6-1.9 dB from code restricted capacity limit were found. At higher data rates, computation of code restricted capacity is impractical. Therefore, the mutual information upper bound of the capacity attaining isotropically random unitary transmit matrices was used. The codes achieve BER lower than 10-4 at Eb/N0 of 3.2-6 dB from this bound, with coding rates of 1.125-5.06 bits per channel use, and different modulation decoding complexities. The codes comprise a serial concatenation of turbo code and a unitary matrix differential modulation code. The receiver employs the high-performance coupled iterative decoding of the turbo code and the modulation code. Information theoretic arguments are harnessed to form guidelines for code design and to evaluate performance of the iterative decoder. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Learning automata-based polling protocols for wireless LANs

    Publication Year: 2003 , Page(s): 453 - 463
    Cited by:  Papers (42)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (549 KB) |  | HTML iconHTML  

    A learning automata-based polling (LEAP) protocol for wireless LANs, capable of operating efficiently under bursty traffic conditions, is introduced. We consider an infrastructure wireless LAN, where the access point (AP) is located at the center of a cell which comprises a number of mobile stations. According to the proposed protocol, the mobile station that is granted permission to transmit is selected by the AP by means of a learning automaton. The learning automaton takes into account the network feedback information in order to update the choice probability of each mobile station. It is proved that the learning algorithm asymptotically tends to assign to each station a portion of the bandwidth proportional to the station's needs. LEAP is compared to the randomly addressed polling and group randomly addressed polling protocols and is shown to exhibit superior performance under bursty traffic. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Linear constellation precoding for OFDM with maximum multipath diversity and coding gains

    Publication Year: 2003 , Page(s): 416 - 427
    Cited by:  Papers (158)  |  Patents (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (955 KB) |  | HTML iconHTML  

    Orthogonal frequency-division multiplexing (OFDM) converts a frequency-selective fading channel into parallel flat-fading subchannels, thereby simplifying channel equalization and symbol decoding. However, OFDM's performance suffers from the loss of multipath diversity, and the inability to guarantee symbol detectability when channel s occur. We introduce a linear constellation precoded OFDM for wireless transmissions over frequency-selective fading channels. Exploiting the correlation structure of subchannels and choosing system parameters properly, we first perform an optimal subcarrier grouping to divide the set of subchannels into subsets. Within each subset, a linear constellation-specific precoder is then designed to maximize both diversity and coding gains. While greatly reducing the decoding complexity and simplifying the precoder design, subcarrier grouping enables the maximum possible diversity and coding gains. In addition to reduced complexity, the proposed system guarantees symbol detectability regardless of channel s, and does not reduce the transmission rate. Analytic evaluation and corroborating simulations reveal its performance merits. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Coherent and differentially coherent detections of orthogonally multiplexed orthogonal phase-modulated signals

    Publication Year: 2003 , Page(s): 428 - 440
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1092 KB) |  | HTML iconHTML  

    The family of orthogonally multiplexed orthogonal phase modulations (OMOPMs) is investigated in this paper. Both coherent and differentially coherent signaling formats are considered and compared with the recently reported orthogonally multiplexed orthogonal amplitude-modulated (OMOAM) signals. When constructed from the same basis set, both OMOPM and OMOAM signals exhibit the identical power spectral density and, thus, the similar spectral performance characteristics. Based on the maximum-likelihood principle, coherent and differentially coherent detection algorithms are developed. Tight approximate upper bounds are derived and verified by simulation to evaluate the bit error probability characteristics of the maximum likelihood algorithms. It is shown that both coherent and differentially coherent OMOPM can provide a great choice of power and spectral efficiencies ranging among the efficiencies achieved by the classical modulations based on the orthogonal multiplexing technique. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Constellation mappings for two-dimensional signaling of nonuniform sources

    Publication Year: 2003 , Page(s): 400 - 408
    Cited by:  Papers (22)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB) |  | HTML iconHTML  

    The design of two-dimensional constellation mappings for the transmission of binary nonuniform memoryless sources over additive white Gaussian noise channels using standard M-ary PSK and QAM modulation schemes is investigated. The main application of this problem is the incorporation of an adaptive mapping assignment in modem devices that employ fixed PSK/QAM modulation schemes for the transmission of heterogenous data (such as multimedia information) containing various levels of nonuniformity. In general, the optimal mapping depends on both the probability distribution of the input signals and the signal-to-noise ratio (SNR) in the channel, in addition to the geometry of the signal constellation. We show that constellation mappings which follow the objective of minimizing the average symbol energy and, given this, maximizing the decoding probability of the most likely signals, can yield symbol-error-rate and bit-error-rate performance that is substantially better than Gray encoding maps. Gains as high as 3.5 dB in SNR Eb/N0 are obtained for highly nonuniform sources. Finally, we note that the mappings techniques result in nonzero mean constellations and briefly consider their performances when they are converted to zero mean constellations by shifting. In this case, we observe that the shifted zero-mean Gray map outperforms our shifted maps for small- to medium-sized constellations (M≤32), but not for larger sizes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dependence of dfree in MPCCC systems

    Publication Year: 2003 , Page(s): 318 - 325
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (618 KB) |  | HTML iconHTML  

    This letter first investigates the distribution of the free distance, parameter dfree for multiple parallel concatenated schemes based on random interleavers. The distribution is obtained by computer search for information weight IW=2 error events, which are the most likely events to produce dfree, at least for turbo codes. The dependence upon interleaver length and code memory is also studied. The design of the S-interleaver for turbo codes is shown to depend upon a combination of IW=2 error events (which are dependent on S) and IW=2+2 "crossed" error events (which are independent of S). The limiting value of S (for which the two effects are equal) is calculated for turbo codes and a novel algorithm to increase this limit (and hence, dfree) is presented. The S-random interleaver design is extended to schemes with two interleavers, for which the use of paired S-random interleavers is proposed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Approximate equation of average bit-error rate in DS-CDMA systems over fading channels

    Publication Year: 2003 , Page(s): 409 - 415
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (503 KB) |  | HTML iconHTML  

    The transmission quality in mobile wireless communications is affected not only by additive white Gaussian noise, but also by multipath fading, which drastically changes the amplitudes and phases of wireless signals. It is one of the key themes in direct-sequence code-division multiple-access systems to evaluate average bit error rate (BER) performances as parameters of the Doppler frequency, the delay profile, the number of simultaneous access users, and so on. This paper proposes the approximate equation for easily calculating the average BER over fading channels (multiray fading models). The performance evaluations are carried out in the two-ray model, the IMT2000 model, and the COST207 model. It is confirmed from the coincidence of approximate results with computer simulation results that the proposed approach is applicable to a variety of parameters. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Efficient dc-free RLL codes for optical recording

    Publication Year: 2003 , Page(s): 326 - 331
    Cited by:  Papers (9)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (375 KB) |  | HTML iconHTML  

    We report on new dc-free runlength-limited codes (DCRLL) intended for the next generation of DVD. The efficiency of the newly developed DCRLL schemes is extremely close to the theoretical maximum, and as a result, significant density gains can be obtained with respect to prior art coding schemes. With a newly developed DCRLL (d=2) code we can achieve a 9% higher overall rate than that of DVD's EFMPlus. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Downlink adaptive array algorithms for cellular mobile communications

    Publication Year: 2003 , Page(s): 476 - 488
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (669 KB) |  | HTML iconHTML  

    The capacity of wireless downlink communication to mobile receivers in a dense urban environment is limited primarily by co-channel interference. Downlink adaptive arrays can be used to mitigate this limitation by maximizing the power transmitted to desired in-cell mobiles in the reference cell while minimizing power to co-channel mobiles in neighboring cells. This is accomplished by using uplink measurements to estimate downlink covariance matrices and then solving a generalized eigenvalue problem. Several algorithms are proposed to adaptively estimate the optimal solution and are evaluated using a simplified signal model that allows efficient deterministic performance calculations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance of a hybrid multilevel error control with an early-stop ARQ protocol for wireless ATM networks

    Publication Year: 2003 , Page(s): 495 - 508
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (957 KB) |  | HTML iconHTML  

    This paper proposes an effective hybrid multilevel error control (HMEC) with an early-stop automatic repeat request (ARQ) scheme for wireless asynchronous transfer mode (ATM) networks. In this scheme, the source traffic is segmented into a number of blocks, each with m cells, then encoded into k(k>m) cells. The transmission of one block may be finished as long as m out of the k cells are received correctly. The ARQ protocol is applied only when too many cells are dropped or corrupted due to uncorrectable error in the radio channel. This paper also provides a detail study of the proposed scheme. In particular, the throughput efficiency with parameters (m,k) are derived analytically for the white Gaussian and Rayleigh fading channels. Simulation results show a very close match with theoretical results. All the results show that the HMEC scheme can reduce cell-retransmission probability and improve network throughput over a wide range of channel error rates when appropriate values of parameters m and k are chosen. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Incremental scheduling algorithms for WDM/TDM networks with arbitrary tuning latencies

    Publication Year: 2003 , Page(s): 464 - 475
    Cited by:  Papers (7)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (527 KB) |  | HTML iconHTML  

    We focus on all-optical broadcast and select slotted WDM networks. Each network user is equipped with one tunable transmitter and one fixed receiver; full connectivity is achieved by tuning transmitters to all different wavelengths available in the optical spectrum. Tuning latencies are considered to be not negligible with respect to the slot time. A network controller allocates fixed size slots in a TDM/WDM frame according to requests issued by users via signalling procedures. User requests are accommodated in the frame incrementally, as soon as they are received by the network controller. Since we aim at an incremental solution, we impose a transparency constraint in the scheduling algorithm: new user requests may be accepted only without affecting existing allocations, otherwise they are refused. We propose a novel scheduling algorithm that may route some flows from source to destination through some intermediate nodes, following a multi-hop approach. A formal definition of an optimal transparent incremental scheduling algorithm is provided as an integer linear programming problem. The optimal incremental scheduling algorithm is NP-hard. Thus, a heuristic quasi-optimal scheduling algorithm is proposed, and its complexity is evaluated. Performance results show that significant benefits can be achieved with respect to traditional single-hop approaches and to other multi-hop approaches. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimization of the index assignments for multiple description vector quantizers

    Publication Year: 2003 , Page(s): 336 - 340
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    The optimization criterion and a practically feasible new algorithm is stated for the optimization of the index assignments of a multiple-description unconstrained vector quantizer with an arbitrary number of descriptions. In the simulations, the index-optimized multiple-description vector quantizer achieves significant gains in source signal-to-noise ratio over scalar multiple description schemes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Improved performance in TD-CDMA mobile radio system by optimizing energy partition in channel estimation

    Publication Year: 2003 , Page(s): 352 - 355
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (401 KB) |  | HTML iconHTML  

    This letter addresses the optimum energy partition between the midamble and data fields, given the total energy per burst, in channel estimation for joint detected time-division code-division multiple-access systems. We show that, given the lengths of the data and midamble, in general, the optimal solution requires different amplitude levels. We also derive the burst structure leading to the optimum energy partition with equal amplitude symbols, and the performance degradation by using traditional choices. The analysis is validated by simulations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Improved quasi-orthogonal codes through constellation rotation

    Publication Year: 2003 , Page(s): 332 - 335
    Cited by:  Papers (166)  |  Patents (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (293 KB) |  | HTML iconHTML  

    In this letter, we show that the performance of recently proposed quasi-orthogonal space-time codes can be improved by phase-shifting the constellations of the symbols constituting the code. The optimal rotation of the symbols increases the minimum distance of the corresponding space-time codewords, leading to substantially improved performance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Diverse routing in optical mesh networks

    Publication Year: 2003 , Page(s): 489 - 494
    Cited by:  Papers (65)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (306 KB) |  | HTML iconHTML  

    We study the diverse routing problem in optical mesh networks. We use a general framework based on shared risk link groups to model the problem. We prove that the diverse routing problem is indeed NP-complete, a result that has been conjectured by several researchers previously. In fact, we show that even the fiber-span-disjoint paths problem, a special case of the diverse routing problem, is also NP-complete. We then develop an integer linear programming formulation and show through numerical results that it is a very viable method to solve the diverse routing problem for most optical networks found in many applications which typically have no more than a few hundred nodes and fiber spans. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Sequence error probability lower bounds for joint detection and estimation

    Publication Year: 2003 , Page(s): 347 - 351
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (314 KB) |  | HTML iconHTML  

    A commonly used lower bound on the probability of error of joint detection and estimation (JDE) algorithms is derived under the assumption that estimation is performed using the transmitted sequence, in a genie-aided fashion. Although it seems reasonable that this genie-aided receiver performs better than the original receiver, a proof of this fact is not available in the literature. In this letter, the validity of this bound is established for a general class of JDE algorithms, as well as for an important special case when the maximum-likelihood sequence detection criterion is used. The results are then extended to a well-known suboptimal JDE algorithm, namely, the T-algorithm. It is shown, however, that the technique used to prove this bound is not sufficient for establishing the validity of the bound for the M-algorithm and the per-survivor processing algorithm. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Achieving near-capacity on a multiple-antenna channel

    Publication Year: 2003 , Page(s): 389 - 399
    Cited by:  Papers (961)  |  Patents (96)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (618 KB) |  | HTML iconHTML  

    Recent advancements in iterative processing of channel codes and the development of turbo codes have allowed the communications industry to achieve near-capacity on a single-antenna Gaussian or fading channel with low complexity. We show how these iterative techniques can also be used to achieve near-capacity on a multiple-antenna system where the receiver knows the channel. Combining iterative processing with multiple-antenna channels is particularly challenging because the channel capacities can be a factor of ten or more higher than their single-antenna counterparts. Using a "list" version of the sphere decoder, we provide a simple method to iteratively detect and decode any linear space-time mapping combined with any channel code that can be decoded using so-called "soft" inputs and outputs. We exemplify our technique by directly transmitting symbols that are coded with a channel code; we show that iterative processing with even this simple scheme can achieve near-capacity. We consider both simple convolutional and powerful turbo channel codes and show that excellent performance at very high data rates can be attained with either. We compare our simulation results with Shannon capacity limits for ergodic multiple-antenna channel. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the computation of weight enumerators for convolutional codes

    Publication Year: 2003 , Page(s): 313 - 317
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (419 KB) |  | HTML iconHTML  

    Performance bounds for maximum-likelihood decoding of convolutional codes over memoryless channels are commonly measured using the distance weight enumerator T(x,y), also referred to as the transfer function, of the code. This paper presents an efficient iterative method to obtain T(x,y) called the state reduction algorithm. The algorithm is a systematic technique to simplify signal flow graphs that algebraically manipulate the symbolic adjacency matrix associated with the convolutional code. Next, the algorithm is modified to compute the first few terms of the series expansion of T(1,y) and {∂T(x,y)/∂x}x=1 (the distance spectra) without first computing the complete T(x,y). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new decoding algorithm for correcting both erasures and errors of Reed-Solomon codes

    Publication Year: 2003 , Page(s): 381 - 388
    Cited by:  Papers (10)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (610 KB) |  | HTML iconHTML  

    In this paper, a high efficient decoding algorithm is developed here in order to correct both erasures and errors for Reed-Solomon (RS) codes based on the Euclidean algorithm together with the Berlekamp-Massey (BM) algorithm. The new decoding algorithm computes the errata locator polynomial and the errata evaluator polynomial simultaneously without performing polynomial divisions, and there is no need for the computation of the discrepancies and the field element inversions. Also, the separate computation of the Forney syndrome needed in the decoder is completely avoided. As a consequence, the complexity of this new decoding algorithm is dramatically reduced. Finally, the new algorithm has been verified through a software simulation using C++ language. An illustrative example of (255,239) RS code using this program shows that the speed of the decoding process is approximately three times faster than that of the inverse-free Berlekamp-Massey algorithm. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimal grouping algorithm for a group decision feedback detector in synchronous CDMA communications

    Publication Year: 2003 , Page(s): 341 - 346
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (446 KB) |  | HTML iconHTML  

    The group decision feedback (GDF) detector is studied in this letter. Given the maximum group size, a grouping algorithm is proposed. It is shown that the proposed grouping algorithm maximizes the symmetric energy of the multiuser detection system. Furthermore, based on a set of lower bounds on asymptotic group effective energy (AGEE) of the GDF detector, it is shown that the proposed grouping algorithm, in fact, maximizes the AGEE lower bound for every group of users. The theoretical analysis of the grouping algorithm enables the offline estimation of the computational cost and the performance of a GDF detector. The computational complexity of a GDF detector is exponential in the largest size of the groups. Simulation results are presented to verify the theoretical conclusions. The results from this letter can be applied to the decision feedback detector by setting the maximum group size to one. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Markov chain model in maximum-likelihood sequence detection for free-space optical communication through atmospheric turbulence channels

    Publication Year: 2003 , Page(s): 509 - 516
    Cited by:  Papers (37)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (541 KB) |  | HTML iconHTML  

    In free-space optical communication links using intensity modulation and direct detection (IM/DD), atmospheric turbulence-induced intensity fluctuations can significantly impair link performance. Communication techniques can be applied to mitigate turbulence-induced intensity fluctuations (i.e., signal fading) in the regime in which the receiver aperture D0 is smaller than the fading correlation length d0 and the observation interval T0 is smaller than the fading correlation time τ0. If the receiver has knowledge of the joint temporal statistics of the fading, maximum-likelihood sequence detection (MLSD) can be employed, but at the cost of high computational complexity. We introduce a single-step Markov chain (SMC) model for the fading correlation and use it to derive two low-complexity, suboptimal MLSD algorithms based on per-survivor processing (PSP). Simulations are presented to verify the SMC model and the performance improvement achieved using these suboptimal per-survivor processing (PSP) algorithms. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Vector symbol decoding with list inner symbol decisions

    Publication Year: 2003 , Page(s): 371 - 380
    Cited by:  Papers (7)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB) |  | HTML iconHTML  

    Prior work showed the ability of a randomly chosen outer code of a concatenated code to correct large numbers of nonbinary symbol errors in a simple manner, provided that the error symbols as vectors are linearly independent. This paper extends the technique in two ways: 1) it is shown how to correct a large class of dependent errors with little additional complexity; and 2) if the inner code supplies a list of two (or more) candidates in some or all decisions, a slightly modified vector symbol decoder can directly reveal most correct alternatives, allowing more powerful and often simpler correction. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Antenna-diversity-assisted genetic-algorithm-based multiuser detection schemes for synchronous CDMA systems

    Publication Year: 2003 , Page(s): 366 - 370
    Cited by:  Papers (29)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (339 KB) |  | HTML iconHTML  

    A spatial diversity reception assisted multiuser code-division multiple-access detector based on genetic algorithms (GAs) is proposed. Two different GA-based individual-selection strategies are considered. In our first approach, the so-called individuals of the GA are selected for further exploitation, based purely on the sum of their corresponding figures of merit evaluated for the individual antennas. According to our second strategy, the GA's individuals are selected based on the concept of the so-called Pareto optimality, which uses the information from the individual antennas independently. Computer simulations showed that the GAs employing the latter strategy achieve a lower bit-error rate as compared to the former strategy. For a 15-user GA-assisted system employing a spreading factor of 31, a complexity reduction factor of 81 was achieved at a performance identical to that of the optimum multiuser detector using a full search. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Frequency synchronization in global satellite communications systems

    Publication Year: 2003 , Page(s): 359 - 365
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (498 KB) |  | HTML iconHTML  

    A frequency synchronization method is proposed and analyzed for global satellite communications systems employing low Earth orbit satellites or medium Earth orbit satellites. In these systems, the Doppler shift varies randomly and can be more than ten times larger than the symbol rate. The proposed method uses the satellite as the reference point and corrects frequency errors accordingly. It is shown the proposed method can achieve negligibly small frequency errors. By employing this method, the system bandwidth can be fully utilized and guard bands are no longer needed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

IEEE Transactions on Communications focuses on all telecommunications including telephone, telegraphy, facsimile, and point-to-point television by electromagnetic propagation.

 

 

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Robert Schober
University of British Columbia