Demodulation structure for fast fading cellular channels
US6151487A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 31, 1999 |
| Grant date | Nov 21, 2000 |
| Priority date | — |
| Expiry date | Aug 31, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2025/03566
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A demodulator and demodulating technique is provided which automatically switches modes according to the flat-fading or multipath channel status of an incoming signal. If an incoming signal has delay spread in addition to fading a standard Maximum Likelihood Sequence Estimator (MLSE) equalization is selected as an optimum demodulation mode. If the incoming signal is only flat-fading a symbol-based demodulation mode is selected. The Maximum Likelihood Sequence Estimator (MLSE) equalizer mode is thus integrated with the symbol based mode. Channel status is first identified in order to do mode selection in the demodulator. A dual-mode receiver for demodulating both flat-fading and multipath signals in a communications system (FIG. 1) comprises a Baseband Digital Signal (DSP) Processor further comprising a Channel Identification Processor, the Channel Identification Processor computing a Maximum Likelihood Sequence Estimate x=(x.sub.0 x.sub.1).sup.t of a first ray channel response and a second ray channel response x.sub.0 and x.sub.1, t denoting a transpose, and determining a demodulation mode based upon a squared magnitude ratio .GAMMA. of x.sub.1 and x.sub.0 relative to a predetermin…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.