Abstract
The base station transmits no beacon, preamble or dedicated synchronisation symbol. Packs acquire and track timing and frequency from continual and scattered pilots that are embedded in every downlink data symbol, together with cyclic-prefix (CP) correlation. The downlink in each TDD frame is one broadcast burst. Every pack decodes the whole burst. All mixes sit at fixed byte offsets of one multiplex, and control bytes are fixed fields inside the same codewords. No message assigns any resource to any device. The whole downlink burst uses one constellation; the pilots are points of that same constellation. One bit interleaver spans the whole burst, so every mix is spread over every symbol and every data sub-carrier. The operating mode (frame layout and modulation-and-coding scheme, MCS) is not transmitted; packs find it by blind detection. The uplink consists of TDMA bursts, one per pack, each made of a complex-valued training symbol followed by one or more data symbols. Each pack’s slot number is set on the pack (by the user, by a wired dock, or by optical pairing) or chosen by the pack itself by sensing which slot is free. The slot number is never sent over the air. The pack transmits a fixed delay after the end of the downlink burst it received. There is no timing advance; the cyclic prefix and the guard period absorb the round-trip spread. The pack’s radio sampling clock comes from a free-running temperature-compensated crystal oscillator (TCXO).
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Anonymous, "Two-way OFDM time-division-duplex link for wireless in-ear monitor and microphone bodypacks with in-symbol pilot synchronisation, a single broadcast downlink burst and pack-selected uplink slots", Technical Disclosure Commons, ()
https://www.tdcommons.org/dpubs_series/12160