Abstract
The uplink uses a shorter OFDM numerology than the downlink: in the embodiment a 128-point FFT with 25 µs symbols on the uplink against a 256-point FFT with 45 µs symbols on the downlink, at one sample rate and on one RF channel. Each numerology is used in one direction only. The cyclic prefix (CP) has the same length in both directions (5 µs, 32 samples; 10 µs in the Range mode). The numerology is fixed by the operating mode and is never signalled. A microphone pack transmits one burst every Nth frame (N = 1, 2 or 4 in the modes below), so its fixed per-burst overhead is spread over N frames of audio. Packs that use the same slot position in the frame share it by frame phase: with U slots per frame and a cycle of N frames there are U x N positions per carrier. Each uplink burst has K >= 2 OFDM symbols. Symbol 0 carries a comb of pilots on every 3rd used sub-carrier and data on the rest. Symbols 1 to K-1 carry data only, with no pilots of any kind. The pilot values are points of the burst’s data constellation, complex-valued, and no symbol of the burst is the complex conjugate of another.
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Recommended Citation
Anonymous, "Uplink of a two-way OFDM time-division-duplex wireless audio system: a shorter uplink numerology than the downlink, microphone bursts every Nth frame, pilots only in the first symbol of each uplink burst, open-loop uplink power, and the operating modes that follow", Technical Disclosure Commons, ()
https://www.tdcommons.org/dpubs_series/12149