In this thesis, two new structures for improving the performance of a digital versatile disk (DVD) receiver are proposed.
First, we consider half of symbol-rate sampling to relax the requirements of A/D conversion rate in high speed partial response maximum likelihood (PRML) receivers, and develop a receiver structure suitable for half of symbol-rate sampling. This reduction in sampling rate is possible because the signal bandwidth of high density DVD RF-signal is about 1/4T, where 1/T is the recovered symbol rate. In this receiver, DVD RF-signal is filtered with analog lowpass filter whose bandwidth is 1/4T and sampled at a half of symbol rate. The original signal having rate 1/2T is recovered via interpolation. However, use of interpolated signal may degrade the detection performance, and the latency of the interpolation filter may affect the symbol synchronization; thus, we considered the influence of analog lowpass filter and the interpolator on detection performance and symbol synchronization. It is shown that the proposed receiver, which is based on 1/2T sampling, can perform like conventional receivers with sampling rate 1/T at the expense of minor increase in computation.
As the recording density increases, the channel memory is also increased and longer target response in PRML receiver is required. In this thesis, we propose partial response-delayed decision feedback sequence estimator (PR-DDFSE) that is derived by replacing the maximum likelihood sequence estimation (MLSE) of the PRML receiver with the delayed decision feedback sequence estimation (DDFSE) that is a kind of reduced complexity MLSE. Since the DDFSE trades performance for complexity reduction, the PR-DDFSE performs worse than the PRML when both of the receivers employ an identical target response. Use of the DDFSE, however, allows the freedom to employ a more complex target, i.e. a longer target. For a given PRML, we consider a class of PR-DDFSE whose complexity is comparable to that of PRML - such a PR-DDFSE can be obtained by employing a longer target. Then, as shown below through simulation results, it is possible to design a PR-DDFSE that outperforms the PRML at a comparable complexity.
These receiver structures can be easily combined into a single receiver, and employed in higher density DVD systems.