In multicarrier modulation schemes like Orthogonal Frequency Division Multiplex (OFDM) or Discrete Multi Tone (DMT) a guard interval represented by a cyclic prefix (CP) is inserted between successive multicarrier symbols in order to reduce intersymbol interference (ISI). The length of the guard interval is determined by the length of the channel impulse response (CIR). For a fixed guard interva...

High rate underwater communications have traditionally relied on equalization methods to overcome the intersymbol interference (ISI) caused by multipath propagation. An alternative technique has emerged in the form of time-reversal, which comes at virtually no cost in computational complexity, but sacrifices the data rate and relies on large arrays to reduce ISI. In this paperer, optimal multip...

Intersymbol interference (ISI) can be a major speed-limiting factor in high-speed communications links, and must be mitigated to achieve an acceptable bit-error rate (BER). One efficient method of ISI mitigation is channel equalization using a decision-feedback equalizer (DFE) [1]. One system in which DFEs have been implemented extensively to combat severe ISI is the magnetic storage read chann...

Chaos-based communications systems have shown to be of potential interest in some kinds of dispersive channels. In this paper we analyze the behavior of a class of chaos-based coded modulations (CCM’s) in channels with time-invariant intersymbol interference (ISI). We use the ISI distance spectrum of the CCM’s to calculte bounds for the bit error rate (BER), and we provide the analytical condit...

We study the efficacy of a generalised form of differential encoding of binary phase shift keyed (BPSK) signals transmitted through a shallow underwater acoustic communication channel. Using simulations involving a fixed source and a receiver moving about with the surface waves, we show that no advantage arises from using the generalised differential encoding methods. On the contrary, the best ...

Broadband multiple-input multipleoutput (MIMO) communication systems using spatial multiplexing are facing multi-stream interference (MSI) from the transmit antennas and intersymbol interference (ISI) due to the time-dispersive nature of the channel. Appropriate detection requires the minimization of both sources of interference, usually at the receiver. Orthogonal frequency division multiplexi...

This paper investigates the performance of digital pulse interval modulation (DPIM) in the presence of multipath propagation and additive white Gaussian noise. To combat intersymbol interference (ISI) guard slots and a non-linear equaliser have been introduced. The average optical power requirements (AOPR) due to ISI for cases with/without guard slots and with equaliser are analysed using a cei...

1 COMBINED BLIND EQUALIZATION AND TURBO DECODING Javier Garcia-Frias and John D. Villasenor Electrical Engineering Department University of California, Los Angeles Abstract| We describe parallel concatenated codes for communication in the presence of intersymbol interference (ISI). Two iterative decoder structures which combine channel equalization and turbo decoding are presented. The rst one ...

In this paper, we examine the use of differential pulse-position modulation (DPPM) for optical communication systems using intensity modulation with direct detection in the presence of additive white Gaussian noise. We present expressions for the error probability and power spectral density of DPPM. We show that for a given bandwidth, DPPM requires significantly less average power than pulse-po...

apitalizing on the tremendous per formance gains of turbo codes and the turbo decoding algorithm, turbo equalization is an iterative equalization and decoding technique that can achieve equally impressive performance gains for communication systems that send digital data over channels that require equalization, i.e., those that suffer from intersymbol interference (ISI). In this article, we dis...