A receiver for detecting and recovering payload data from a received signal comprises a radio frequency demodulation circuit, a detector circuit and a demodulator circuit. The radio frequency demodulation circuit detects the received signal. The received signal carries the payload data as OFDM symbols in one or more of a plurality of time divided frames, each frame including a bootstrap signal, a preamble signal and a plurality of sub-frames. The demodulator circuit detects bootstrap OFDM symbols to identify communications parameters for detecting the fixed length signalling data, detects the fixed length signalling data to identify the communications parameters for detecting the variable length signalling data, detects the variable length signalling data, and uses the fixed and variable length signalling data to detect the payload data.

A wireless communication method includes sending, by a first device in a wireless network, a poll packet (32, 38, 44) for polling a second device in the wireless network. The poll packet includes an address of the second device. The second device receives and at least partially decodes the poll packet. The second device sends a response packet (36, 40, 46) in response to the poll packet. The sending of at least part of the response packet is substantially simultaneous with the receiving of at least part of the poll packet by the second device. Wireless communication systems, transmitters and receivers using the method are also described.

An apparatus and method for broadcast signal frame using layered division multiplexing are disclosed. An apparatus for generating broadcast signal frame according to an embodiment of the present invention includes a combiner configured to generate a multiplexed signal by combining a core layer signal and an enhanced layer signal at different power levels; a power normalizer configured to reduce the power of the multiplexed signal to a power level corresponding to the core layer signal; a time interleaver configured to generate a time-interleaved signal by performing interleaving that is applied to both the core layer signal and the enhanced layer signal; and a frame builder configured to generate a broadcast signal frame including a preamble for signaling, start position information of Physical Layer Pipes (PLPs) and time interleaver information shared by the core layer signal and the enhanced layer signal.

An apparatus and method for generating a broadcast signal frame including preamble for signaling injection level information. An apparatus for generating broadcast signal frame according to an embodiment of the present invention includes an injection level controller configured to generate a power reduced enhanced layer signal by reducing a power of an enhanced layer signal; a combiner configured to generate a multiplexed signal by combining a core layer signal and the power reduced enhanced layer signal; a power normalizer configured to reduce the power of the multiplexed signal to a power level corresponding to the core layer signal; a time interleaver configured to generate a time-interleaved signal by performing interleaving that is applied to both the core layer signal and the enhanced layer signal; and a frame builder configured to generate a broadcast signal frame including a preamble for signaling injection level information corresponding to the injection level controller.

For synchronizing user devices to the base station of a 5G or 6G network, the base station can transmit brief prepared signals at a pre-scheduled time and frequency. All of the user devices in the network can then synchronize simultaneously, using amplitude measurements with standard signal processing. The user devices can thereby avoid the complex and time-consuming measurements of prior art. This simplified synchronization procedure may be especially relevant for reduced-capability IoT devices. Examples are provided in which each user device can measure a ratio of amplitudes or energy values in sequential symbol-times as determined by the local user device clock, and compare to the expected ratio as determined by the base station clock. Any deviation in the ratio indicates a timing offset, which the user devices can then use to precisely synchronize the local clock.

Current methods for synchronizing user devices with the base station of a 5G/6G network require multiple exchanges with each user device, consuming limited resources. Disclosed herein are systems and methods for generating and then detecting precision-timing timestamp points. Importantly, the timestamp points can be used by all of the user devices simultaneously, instead of just one at a time. In a first embodiment, the timestamp includes three resource elements with a first modulation (amplitude or phase) in the first and third resource elements, and a different modulation in the middle one. In a second embodiment, the base station transmits a first signal in the first half of a single resource element, and a different signal modulation in the second half. In either case, the user devices can receive the signal, determine the time of interface between the modulation states, and thereby determine the symbol boundaries according to the base station.

A base station can cause a multitude of user devices in a network to be synchronized with the base station's clock using an ultra-lean low-complexity procedure in 5G or 6G. On a predetermined interval, the base station can transmit a timing signal in the guard-space of a predetermined resource element. The timing signal is a 180-degree phase reversal of the cyclic prefix centered in the guard-space. Each user device can receive the timing signal, determine how far the received timestamp point is from the middle of the guard-space (as viewed by the user device), and thereby determine a timing error between the user device clock and the base station clock, and correct the user device clock accordingly. In addition, the user device can average the timing adjustments over a number of instances, thereby determining a frequency offset if the average differs significantly from zero, and thereby adjust the clock frequency.

A unified frame structure for filter bank multi-carrier (FBMC) and orthogonal frequency division multiplexed (OFDM) waveforms may allow FBMC and OFDM frames to be communicated over a common channel without significant inter-frame gaps. The unified frame structure may set an FBMC frame duration to an integer multiple of an OFDM frame element duration to enable alignment of FBMC frames and OFDM frames in the time domain. The unified frame structure may also map control channels in the FBMC and OFDM frames to common resource locations so that the respective control channels are aligned in the time and/or frequency domains. The unified frame structure may also share synchronization channels between FBMC and OFDM frames. Additionally, overhead in an FBMC time division duplexed (TDD) communications channel can be reduced by overlapping time windows appended to FBMC blocks.

A signal multiplexing apparatus and method using layered division multiplexing are disclosed. A signal multiplexing apparatus according to an embodiment of the present invention includes a combiner configured to generate a multiplexed signal by combining a core layer signal and an enhanced layer signal at different power levels; a power normalizer configured to reduce the power of the multiplexed signal to a power level corresponding to the core layer signal; a time interleaver configured to generate a time-interleaved signal by performing interleaving that is applied to both the core layer signal and the enhanced layer signal; and a frame builder configured to generate a broadcast signal frame using the time-interleaved signal and L1 signaling information.

In busy 5G and 6G networks, precise timing and synchronization are key to maintaining throughput with low fault rates. Disclosed are systems and methods for adjusting each user device's clock for proper reception, including downlink propagation delays, uplink propagation delays, round-trip propagation delays, and Doppler shifts, individually for each user device, and including any uplink/downlink asymmetries. The clock adjustment and timing advance of each user device is based on a predetermined transmission schedule for timing signals, broadcast by the base station. The Doppler shift is measured by the base station, according to uplink timing signals, and communicated to the user device in a single final timing signal. The single final timing signal is either frequency-shifted by the measured Doppler shift, or delayed proportional to the Doppler shift, either of which indicates, to the user device, how to apply the correct timing to future uplink messages.