Performance of Space-Time Diversity in CDMA Over Frequency-Selective Fading Channels
Bibliographic record
Abstract
Asynchronous direct-sequence code-division multiple-access (DS - CDMA) using space-time spreading system is investigated over frequency-selective fast-fading channels. The underlaying transmit diversity scheme, previously introduced in the literature, is based on two transmit and one receive antenna. It was shown that when employed in flat fast-fading channels, the received signal quality can be improved by utilizing the spatial and temporal diversities at the receiver side. Here, the bit-error-rate (BER) performance of the underlying system is investigated for an uplink transmission where a decorrelator detector is used at the base station receiver. In particular, we derive a closed form expression for the probability of error over frequency-selective fast-fading channels. The analytical BER is derived as a function of both the number of multipath and users. The BER results show that the space-time spreading scheme exploits both the temporal and spatial diversity in a time-varying multipath channel. The results also show the accuracy of the derived expression when compared with simulation results for different number of users.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".