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Author

Mike Darnell

Bio: Mike Darnell is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 679 citations.

Papers
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Book•
01 Jan 1996

691 citations


Cited by
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Journal Article•DOI•
16 Aug 1998
TL;DR: A previously unrecognized connection between Golay complementary sequences and second-order Reed-Muller codes over alphabets Z/sub 2/h is found to give an efficient decoding algorithm involving multiple fast Hadamard transforms.
Abstract: We present a range of coding schemes for OFDM transmission using binary, quaternary, octary, and higher order modulation that give high code rates for moderate numbers of carriers. These schemes have tightly bounded peak-to-mean envelope power ratio (PMEPR) and simultaneously have good error correction capability. The key theoretical result is a previously unrecognized connection between Golay complementary sequences and second-order Reed-Muller codes over alphabets Z/sub 2/h. We obtain additional flexibility in trading off code rate, PMEPR, and error correction capability by partitioning the second-order Reed-Muller code into cosets such that codewords with large values of PMEPR are isolated. For all the proposed schemes we show that encoding is straightforward and give an efficient decoding algorithm involving multiple fast Hadamard transforms. Since the coding schemes are all based on the same formal generator matrix we can deal adaptively with varying channel constraints and evolving system requirements.

1,030 citations

Journal Article•DOI•
Kenneth G. Paterson1•
16 Aug 1998
TL;DR: A powerful theory linking Golay complementary sets of polyphase sequences and Reed-Muller codes is developed and shows that any second-order coset of a q-ary generalization of the first order Reed-muller code can be partitioned into Golay additive sets whose size depends only on a single parameter that is easily computed from a graph associated with the coset.
Abstract: Controlling the peak-to-mean envelope power ratio (PMEPR) of orthogonal frequency-division multiplexed (OFDM) transmissions is a notoriously difficult problem, though one which is of vital importance for the practical application of OFDM in low-cost applications The utility of Golay complementary sequences in solving this problem has been recognized for some time In this paper, a powerful theory linking Golay complementary sets of polyphase sequences and Reed-Muller codes is developed Our main result shows that any second-order coset of a q-ary generalization of the first order Reed-Muller code can be partitioned into Golay complementary sets whose size depends only on a single parameter that is easily computed from a graph associated with the coset As a first consequence, recent results of Davis and Jedwab (see Electron Lett, vol33, p267-8, 1997) on Golay pairs, as well as earlier constructions of Golay (1949, 1951, 1961), Budisin (1990) and Sivaswamy (1978) are shown to arise as special cases of a unified theory for Golay complementary sets As a second consequence, the main result directly yields bounds on the PMEPRs of codes formed from selected cosets of the generalized first order Reed-Muller code These codes enjoy efficient encoding, good error-correcting capability, and tightly controlled PMEPR, and significantly extend the range of coding options for applications of OFDM using small numbers of carriers

467 citations

Journal Article•DOI•
TL;DR: It turns out that with this optimal allocation of signature sequences and powers, the linear MMSE receiver is just the corresponding matched filter for each user, and the effect of transmit power constraints on the user capacity is characterized.
Abstract: There has been intense effort in the past decade to develop multiuser receiver structures which mitigate interference between users in spread-spectrum systems. While much of this research is performed at the physical layer, the appropriate power control and choice of signature sequences in conjunction with multiuser receivers and the resulting network user capacity is not well understood. In this paper we will focus on a single cell and consider both the uplink and downlink scenarios and assume a synchronous CDMA (S-CDMA) system. We characterize the user capacity of a single cell with the optimal linear receiver (MMSE receiver). The user capacity of the system is the maximum number of users per unit processing gain admissible in the system such that each user has its quality-of-service (QoS) requirement (expressed in terms of its desired signal-to-interference ratio) met. This characterization allows one to describe the user capacity through a simple effective bandwidth characterization: users are allowed in the system if and only if the sum of their effective bandwidths is less than the processing gain of the system. The effective bandwidth of each user is a simple monotonic function of its QoS requirement. We identify the optimal signature sequences and power control strategies so that the users meet their QoS requirement. The optimality is in the sense of minimizing the sum of allocated powers. It turns out that with this optimal allocation of signature sequences and powers, the linear MMSE receiver is just the corresponding matched filter for each user. We also characterize the effect of transmit power constraints on the user capacity.

461 citations

Journal Article•DOI•
TL;DR: A class of binary sequences with the defined ZCZ property can be used in spread spectrum systems and CDMA systems to eliminate multipath and cochannel interference.
Abstract: Based on the idea of the zero correlation zone (ZCZ), a class of binary sequences with the defined ZCZ property is presented. The ZCZ spreading code sequences can be used in spread spectrum systems and CDMA systems to eliminate multipath and cochannel interference.

345 citations

Journal Article•DOI•
TL;DR: Several new lower bounds on the size p of the frequency slot set F, the sequence length L, the family size M, and correlation properties are established and the aperiodic FH bounds which have not yet been previously reported are presented and discussed in this correspondence.
Abstract: Frequency hopping (FH) sequences have found wide applications in various modern FH spread-spectrum communications and radar systems. In FH spread-spectrum communications, the interference occurs when two distinct transmitters use the same frequency simultaneously. In order to evaluate the goodness of FH sequence design, the Hamming correlation function is used as an important measure. In this correspondence, by considering separately the maximum Hamming autocorrelation sidelobe H/sub a/, and the maximum Hamming cross correlation H/sub c/, several new lower bounds on the size p of the frequency slot set F, the sequence length L, the family size M, and correlation properties are established. The new periodic bounds include the known Lempel-Greenberger bounds as special case when M=2, and are tighter than the Seay bounds under certain conditions when M>2. Furthermore, the new bounds disclose more information on the relationship between the maximum autocorrelation sidelobe and the maximum cross correlation compared with the Lempel-Greenberger bounds and Seay bounds. Besides, the aperiodic FH bounds which have not yet been previously reported are also presented and discussed in this correspondence.

186 citations