# US 11,452,100 B2 · Low latency wireless protocol for audio and gaming

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- Number: US 11,452,100 B2
- Document ID: US11452100B2
- Status: Granted
- Kind: B2
- Application number: 17/253,463
- Filed: 2019-07-03
- Published: 2021-04-22
- Granted: 2022-09-20
- Earliest claimed: 2018-07-06
- Assignees: Rtx A/S
- Applicants: Rtx A/S
- Inventors: Jens Toftgaard Petersen; Flemming Mortensen
- Web page: https://patentgrep.com/patent/US11452100B2

## CPC

- H04L 47/00: Traffic control in data switching networks (arrangements for detecting or preventing errors in the information received H04L1/00)
- H04W 72/0453: Resources in frequency domain, e.g. a carrier in FDMA
- A63F 13/235: using a wireless connection, e.g. infrared or piconet
- A63F 13/327: using wireless networks, e.g. Wi-Fi® or piconet
- H03M 13/09: Error detection only, e.g. using cyclic redundancy check [CRC] codes or single parity bit
- H03M 13/31: combining coding for error detection or correction and efficient use of the spectrum (without error detection or correction H03M5/14 {, H03M5/145})
- H04B 7/04: using two or more spaced independent antennas
- H04B 7/12: Frequency diversity
- H04B 17/345: Interference values ({signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]} H04B17/336)
- H04B 17/373: Predicting channel quality {or other radio frequency [RF]} parameters
- H04J 1/04: Frequency-transposition arrangements {(modulation with carrier or side-band suppression H03C1/52, H03C1/60; single-band suppression H04B1/00, H04B15/00; telegraphic communication H04L27/02, H04L25/49; transference of modulation from one carrier to another, e.g. frequency- changing H03D7/00; demodulation or transference of modulation of modulated electromagnetic waves H03D9/00)}
- H04J 1/16: Monitoring arrangements {(for transmission in general H04B17/00; for amplifiers H03F1/52, H03F1/523)}
- H04L 1/004: {by using forward error control (H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00)}
- H04L 1/08: by repeating transmission, e.g. Verdan system {(H04L1/1858 and H04L1/189 take precedence)}
- H04L 5/0005: {Time-frequency}
- H04L 5/0098: {Signalling of the activation or deactivation of component carriers, subcarriers or frequency bands}
- H04L 43/0829: Packet loss
- H04L 47/32: by discarding or delaying data units, e.g. packets or frames
- H04L 67/12: specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
- H04L 69/14: Multichannel or multilink protocols
- H04W 24/10: Scheduling measurement reports {; Arrangements for measurement reports}
- H04W 28/082: among bearers or channels
- H04W 72/541: using the level of interference
- H04W 84/16: WPBX [Wireless Private Branch Exchange]
- H04W 84/20: Leader-follower arrangements
- H04W 88/08: Access point devices
- H04W 92/10: between terminal device and access point, i.e. wireless air interface
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- A63F: CARD, BOARD, OR ROULETTE GAMES; INDOOR GAMES USING SMALL MOVING PLAYING BODIES; VIDEO GAMES; GAMES NOT OTHERWISE PROVIDED FOR
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)
- H04B: TRANSMISSION
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)

## Abstract

A wireless communication method and protocol for wireless RF transmission of data, e.g. audio data, with low latency. The method involves a fixed part (FP) serving as synchronization master, and one or more portable parts (PP) being synchronization slaves. The FP performs scanning between a set of supported channels within one limited frequency band, such as within an ISM band. Further, the FP performs collecting measures of RF interference level on at least a plurality of the supported channels in response to the scanning, preferably using own interference level measurement and by collecting RSSI data from the PP for the supported channels. In response to these measures of RF interference level, the FP executes a selection algorithm for selecting and re-selecting first and second different frequencies for respective first and second duplex RF bearers from the set of supported channels to select the channels with least RF interference. Finally, the FP transmits, in one frame of such as 1 ms to 3 ms length, the same data packet on both of said first and second duplex RF bearer frequencies to the PP. This provides a roboust and low latency wireless interface suitable for Human Interface Devices and audio devices, e.g. for gaining equipment.

## Claims

### Claim 1

A method for wireless RF transmission of a digital signal in data packets between a fixed part being a timing master and one or more portable parts being timing slaves, wherein the wireless RF transmission comprises frames each containing one or more time slots, the method comprising
scanning, by the fixed part between a set of at least three supported channels within one limited frequency band,
collecting, by the fixed part, measures of interference level on at least a plurality of the supported channels in response to the scanning,
selecting, by a selection algorithm in the fixed part, first and second different frequencies for respective first and second RF bearers from the set of supported channels in response to the measure of interference level on the plurality of the supported channels, and
transmitting, in one frame, the same data packet on both of said first and second RF bearers from the fixed part to the one or more portable parts.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the selection algorithm is arranged to determine the first and second frequencies which are indicated as the RF bearers having the lowest measure of interference level.

### Claim 3 (depends on 1)

The method according to claim 1, wherein said collecting of measures of interference level on the plurality of the supported channels comprises measuring, by the fixed part, a level of RF activity in the respective frequency bands for RF bearers of each of the plurality of the supported channels.

### Claim 4 (depends on 1)

The method according to claim 1, wherein said collecting of measures of interference level on the plurality of the supported channels comprises collecting reported measurement data from the one or more portable part to the fixed part a channel quality indicator value measured for a plurality of the supported channel.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the selection algorithm is further arranged to determine packet error rates for a plurality of the supported channels, and to select the first and second frequencies in response thereto, wherein the fixed part calculates statistics of packet error rates for each of the supported channels.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the selection algorithm is arranged to select the first and second frequencies in response to a combination of two or more of:
1) levels of RF activity in the respective frequency bands for RF bearers of each of a plurality of the supported channels,
2) reported measurement data from the one or more portable part to the fixed part indicative of channel quality indicator values measured for a plurality of the supported channels,
3) a frequency distance between a currently used RF bearer and another channel of the supported channels, and
4) packet error rates collected for a plurality of the supported channels.

### Claim 7 (depends on 1)

The method according to claim 1, wherein a frame comprises a first part allocated for RF transmission of the data packet at the first RF bearer, a second part allocated for RF transmission of the data packet at the second RF bearer, wherein the first and second parts are separated by a third part allocated for scanning of the supported channels, and wherein a time length of the frame is within 1 ms to 5 ms.

### Claim 8 (depends on 7)

The method according to claim 7, wherein the first part comprises at least one time slot for downlink data, and one or more time slots for uplink data.

### Claim 9 (depends on 1)

The method according to claim 1, wherein said set of supported channels have RF bearers located within a frequency range of less than 100 MHz, and wherein a frequency distance between two of the supported channel is below 5 MHz.

### Claim 10 (depends on 1)

The method according to claim 1, wherein the fixed part (FP) transmits, when a new frequency has been selected for the first or second RF bearer, information to the one or more portable parts about the new frequency and a value indicating a number of frames until the first or second RF bearer will be shifted to the new frequency.

### Claim 11 (depends on 1)

The method according to claim 1, wherein the fixed part and the portable part comprises two or more different RF antennas for the RF transmission.

### Claim 12 (depends on 1)

The method according to claim 1, wherein each time slot comprises a Cyclic Redundancy Check (CRC) error check field, and wherein seeding of the CRC is used as a hidden system identification.

### Claim 13 (depends on 1)

A wireless RF transmitter comprising at least one RF transmitter circuit connected to an antenna, and being arranged to operate as the fixed part according to the method of claim 1.

### Claim 14 (depends on 1)

A wireless RF receiver comprising at least one RF receiver circuit connected to an antenna, and being arranged to operate as the portable part according to the method of claim 1.

### Claim 15 (depends on 1)

A system comprising at least one of: (i) a wireless RF transmitter comprising at least one RF transmitter circuit connected to an antenna and being arranged to operate as the fixed part according to the method of claim 1, and (ii) one or more wireless RF receivers comprising at least one RF receiver circuit connected to an antenna and being arranged to operate as the portable part according to the method of claim 1, wherein the system is one of:
a wireless headset, a wireless mouse, a wireless gaming controller, a wireless keyboard, a wireless microphone, a wireless loudspeaker, a wireless intercom system, a video system, and a Virtual Reality system.