# US 12,224,894 B2 · Low-complexity resource-efficient demodulation reference for 5G and 6G > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,224,894 B2 - Document ID: US12224894B2 - Status: Granted - Kind: B2 - Application number: 18/117,519 - Filed: 2023-03-06 - Published: 2023-08-10 - Granted: 2025-02-11 - Earliest claimed: 2021-06-14 - Applicants: David E. Newman; R. Kemp Massengill - Inventors: David E. Newman; R. Kemp Massengill - Web page: https://patentgrep.com/patent/US12224894B2 ## CPC - H04L 27/3863: {Compensation for quadrature error in the received signal} - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04L 27/345: {Modifications of the signal space to allow the transmission of additional information} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A compact demodulation reference is disclosed for compatibility with reduced-capability user devices, and for enhanced throughput for high-performance user devices of 5G and 6G in high-density environments. The demodulation reference, in some embodiments, occupies only one resource element, yet provides sufficient information to enable a receiver to calculate all of the amplitude or phase modulation levels of the modulation scheme. For example, if the modulation scheme is 16QAM, the demodulation reference can include an I branch with the highest amplitude level of the modulation scheme and an orthogonal Q branch with the lowest amplitude level. Further examples apply to a multiplexed amplitude-phase modulation scheme. In each case, the receiver can calculate the remaining amplitude (or phase) modulation levels, and thereby demodulate a proximate message. Further examples show how to reveal faulted message elements by comparing demodulation with QAM and amplitude-phase demodulation, and how to optimize noise margins. ## Claims ### Claim 1 A method for a base station of a wireless network to communicate with reduced-capability user devices, the method comprising: a) allocating a low-complexity channel for contention-based messaging with reduced-capability user devices; b) receiving, on the low-complexity channel, a first message from a particular reduced-capability user device; and c) transmitting, on the low-complexity channel, a second message to the particular reduced-capability user device; d) wherein each reduced-capability user device comprises a wireless device that is incapable of performing one or more 5G protocols; and e) wherein the low-complexity channel is a frequency band comprising subcarriers on which reduced-capability user devices are permitted to transmit messages without requesting an uplink grant from the base station. ### Claim 2 (depends on 1) The method of claim 1, wherein the first and second messages are configured according to 5G protocols that the particular reduced-capability user device can perform. ### Claim 3 (depends on 1) The method of claim 1, wherein the first message is associated with a demodulation reference comprising a single resource element modulated according to a quadrature amplitude modulation (“QAM”) modulation scheme. ### Claim 4 (depends on 3) The method of claim 3, wherein the demodulation reference comprises an I branch signal multiplexed with an orthogonal Q branch signal, wherein one branch signal, of the I and Q branch signals, is amplitude modulated according to a maximum positive amplitude of the modulation scheme, and the other branch signal is modulated according to a maximum negative amplitude of the modulation scheme. ### Claim 5 (depends on 3) The method of claim 3, wherein the demodulation reference comprises an I branch signal multiplexed with an orthogonal Q branch signal, wherein one branch signal, of the I and Q branch signals, is amplitude modulated according to a maximum positive amplitude of the modulation scheme, and the other branch signal is modulated according to a minimum positive amplitude of the modulation scheme. ### Claim 6 (depends on 1) The method of claim 1, wherein the first message is associated with a demodulation reference comprising a single resource element modulated according to a quad phase-shift keying (“QPSK”) modulation scheme comprising a single amplitude level. ### Claim 7 (depends on 6) The method of claim 6, wherein the demodulation reference comprises an I branch signal multiplexed with an orthogonal Q branch signal, wherein the I and Q branch signals are both amplitude modulated according to the single amplitude level of the modulation scheme. ### Claim 8 (depends on 1) The method of claim 1, wherein the first message includes a plurality of demodulation references, wherein: a) each demodulation reference comprises a single resource element comprising an amplitude modulated I branch signal multiplexed with an orthogonal amplitude modulated Q branch signal; b) a first demodulation reference, of the plurality of demodulation references, is concatenated with a beginning of the first message; and c) a second demodulation reference, of the plurality of demodulation references, is concatenated with an ending of the first message. ### Claim 9 (depends on 8) The method of claim 8, wherein: a) at least one additional demodulation reference, of the plurality of demodulation references, is embedded in the first message.