An Uplink Control Channel Design with Complementary Sequences for Unlicensed Bands
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In this study, we propose two schemes based on non-contiguous complementary sequences (CSs) for the uplink control channels in unlicensed bands. The first scheme is designed for non-coherent detectors and allows the users to transmit 1-2 bit information via CSs. This scheme addresses two complicated problems, i.e., minimization of peak-to-average-power ratio (PAPR) and multi-access interference, without introducing tradeoff between them. The second scheme exploits the generic CS encoder and enables at least 21 information bits for a single user or 11 bits/user for three users on the same frequency resources, respectively, while limiting the PAPR to a maximum of 3 dB for an orthogonal frequency division multiplexing (OFDM) symbol. To derive the proposed schemes, we use an extension of Golay's concatenation and interleaving methods. We obtain a new theorem which leads to a CS encoder compatible with a wide variety of non-contiguous resource allocations. The numerical results show that the proposed schemes maintain the PAPR benefits without increasing the error rate for non-contiguous resource allocations in the frequency domain.
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