Code Type | $N$ | $Q$ | ${C}_{aver}$ (dBc) | ${C}_{worst}$ (dBc) |
OG | 128 | 128 | 23.28 | 18.99 |
512 | 512 | 29.80 | 27.21 | |
1024 | 1024 | 32.68 | 31.18 | |
OC | 128 | 128 | 33.79 | 24.69 |
256 | 256 | 37.11 | 26.35 | |
512 | 512 | 39.77 | 26.95 | |
1024 | 1024 | 42.65 | 25.29 |
This paper proposes a novel approach for full duplex using chaotic sequences which is known as the asynchronous code-division duplex (Async-CDD) system. The Async-CDD system can transmit and receive signals at the same time and in the same frequency channel without time slot synchronization. The data rate of the Async-CDD system is 8 times higher than the conventional CDD system and is the same as a non-spreading system. The property of low block cross-correlation of the chaotic sequence allows the Async-CDD system achieve duplex interference suppression at any duplex delay. And the huge number of available code words/blocks of the chaotic sequence allows the Async-CDD system increase the data rate by increasing the number of multiplexed sub-channels. When both of the code length of the orthogonal chaotic code and the number of multiplexed sub-channels are 128, the orthogonal chaotic code provides 30.40 dBc self-interference suppression in average, which is 6.99 dB better than the orthogonal Gold code.
Citation: |
Table 1.
The Average Duplex Self-interference Suppression Performance with Different
Code Type | $N$ | $Q$ | ${C}_{aver}$ (dBc) | ${C}_{worst}$ (dBc) |
OG | 128 | 128 | 23.28 | 18.99 |
512 | 512 | 29.80 | 27.21 | |
1024 | 1024 | 32.68 | 31.18 | |
OC | 128 | 128 | 33.79 | 24.69 |
256 | 256 | 37.11 | 26.35 | |
512 | 512 | 39.77 | 26.95 | |
1024 | 1024 | 42.65 | 25.29 |
Table 2. System parameter of the compared system
$N$ | $W$ | Max. $Q$ | $Q$ | |
CDD | 128+8 | 8 | 16 | 16 |
Async-CDD with OG code | 128 | - | 128 | 16 |
Async-CDD with OC code | 128 | - | 128 | 16 |
Table 3. The self-interference suppression performance with different delay
$Q$ | $N$ | The number of $C(p, q)$ $\leq$ 24 dBc | The number of $C(p, q)$ $\leq$ 28 dBc | The number of $C(p, q)$ $\leq$ 30 dBc | |
CDD with | 16 | 128 | 0 | 168 | 256 |
ZCZ code | |||||
Async-CDD | 16 | 128 | 225 | 256 | 256 |
with OG code | |||||
Async-CDD | 16 | 128 | 0 | 10 | 33 |
with OC code |
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Application Scenario of the CDD System
The block-correlation performance of the OG code
The block-correlation performance of the OC code