Method for transmitting a signal in a WiFi (wireless fidelity) system and WiFi system configured accordingly

Abstract

A vehicle has a Wi-Fi system for transmitting a signal. The Wi-Fi system includes a channel with a primary subchannel and one or more secondary subchannels. A sensor measures the energy of the signals in the primary subchannel and in each of the one or more secondary subchannels. A processor determines that the primary subchannel is clear if the energy in the primary subchannel is less than an energy threshold of the primary subchannel, assigns a score to each of the one or more secondary subchannels based on the secondary subchannel energy, calculates the sum of the scores, and transmits the signal over the channel if the sum of the scores is less than a score threshold.

Description

[0001] The present invention relates to communication networks in vehicles and, in particular, to a method according to the preamble of claim 1 for transmitting a signal in a WiFi (Wireless Fidelity) system, as well as to a correspondingly configured WiFi system according to the preamble of claim 5, as essentially known from US 2016 / 0 135 224 A1. Further prior art can be found in the documents US 11 895 679 B2 and DE 10 2021 126 867 A1.

[0002] A vehicle may have a wireless communication (WiFi) system for various communication needs, such as providing passengers with internet access, telephone functions, wireless cameras, etc. A Wi-Fi channel has many subchannels that can be selected by a communication device. Each subchannel may have varying levels of usage or congestion, limiting its availability for transmitting a particular signal. Accordingly, it is desirable to provide a method for managing Wi-Fi communications based on channel congestion. SUMMARY

[0003] According to the invention, a method for transmitting a signal in a wireless fidelity (WiFi) system is presented, which is characterized by the features of claim 1.

[0004] A primary subchannel of a channel of the WiFi system is determined to be idle if the energy in the primary subchannel is less than a primary subchannel energy threshold, the channel comprising the primary subchannel and one or more secondary subchannels. The subchannel energy through each of the one or more secondary subchannels is measured. Each of the secondary subchannels is assigned a score based on the subchannel energy. A sum of the scores is calculated. The signal is transmitted over the channel if the sum of the scores is below a score threshold. A history of transmission over the subchannel indicates a periodic stream, and the score for the subchannel is determined based at least in part on a duty cycle of the periodic stream.

[0005] In addition to one or more of the features described herein, the method further comprises assigning the score for a selected secondary subchannel based on an energy interval in which the energy of the secondary subchannel is located.

[0006] In addition to one or more of the features described herein, the method further comprises determining the channel as idle if the energy of each of the secondary subchannels is less than a threshold for the secondary subchannel.

[0007] In addition to one or more of the features described herein, the method further comprises transmitting the signal with a selected probability, wherein the selected probability is a function of at least one of the following: the access category, the age of a packet, and the urgency of the packet.

[0008] In addition to one or more of the features described herein, the method further comprises lowering the score threshold if at least one of the following applies: a physical layer protocol data unit (PPDU) is part of a high data rate frame, and the PPDUs are part of a low latency flow.

[0009] In addition to one or more of the features described herein, the method further comprises assigning a maximum rating number to the secondary subchannel when the energy in the secondary subchannel originates from a Wi-Fi packet associated with a PPDU transmission having overlapping sets of basic services.

[0010] Furthermore, the invention provides a wireless fidelity (WiFi) system, which is characterized by the features of claim 5. The WiFi system comprises a channel with a primary subchannel and one or more secondary subchannels, a sensor for measuring the energy of signals in the primary subchannel and in each of the one or more secondary subchannels, and a processor. The processor is configured to: determine that the primary subchannel is clear when the energy in the primary subchannel is less than an energy threshold of the primary subchannel, assign a score to each of the one or more secondary subchannels based on the subchannel energy, calculate the sum of the scores, and transmit a signal over the channel if the sum of the scores is less than a score threshold.A history of transmission over the subchannel indicates a periodic stream, and the score for the subchannel is determined based at least in part on a duty cycle of the periodic stream.

[0011] In addition to one or more of the features described herein, the processor is further configured to assign the score for a selected secondary subchannel based on an energy interval in which the energy of the secondary subchannel is located.

[0012] In addition to one or more of the features described herein, the processor is further configured to determine that the channel is clear when the energy of each of the secondary subchannels is less than a secondary subchannel threshold.

[0013] In addition to one or more of the features described herein, the processor is further configured to transmit the signal with a selected probability, wherein the selected probability is a function of at least one of the following: the access category, the age of a packet, and the urgency of the packet.

[0014] In addition to one or more of the features described herein, the processor is further configured to lower the score threshold when at least one of: a physical layer protocol data unit (PPDU) is part of a high data rate frame, and the PPDUs are part of a low latency flow.

[0015] In addition to one or more of the features described herein, the processor is further configured to assign a maximum rating number to the secondary subchannel when the energy in the secondary subchannel originates from a Wi-Fi packet associated with a PPDU transmission having overlapping sets of basic services.

[0016] Further, a vehicle is described. The vehicle includes a wireless fidelity (WiFi) system configured for communication over a channel having a primary subchannel and one or more secondary subchannels, a sensor of the WiFi system configured to measure the energy of signals in the primary subchannel and in each of the secondary subchannels, and a processor of the WiFi system. The processor is configured to: determine that the primary subchannel is clear when the energy in the primary subchannel is less than an energy threshold of the primary subchannel, assign a score to each of the secondary subchannels based on the subchannel energy, calculate the sum of the scores, and transmit a signal over the channel if the sum of the scores is less than a score threshold.

[0017] In addition to one or more of the features described herein, the processor is further configured to assign the score for a selected secondary subchannel based on an energy interval in which the energy of the secondary subchannel is located.

[0018] In addition to one or more of the features described herein, the processor is further configured to determine that the channel is clear when the energy of each of the secondary subchannels is less than a secondary subchannel threshold.

[0019] In addition to one or more of the features described herein, the processor is further configured to transmit the signal with a selected probability, wherein the selected probability is a function of at least one of the following: the access category, the age of a packet, and the urgency of the packet.

[0020] In addition to one or more of the features described herein, the processor is further configured to lower the score threshold when at least one of: a physical layer protocol data unit (PPDU) is part of a high data rate frame, and the PPDUs are part of a low latency flow.

[0021] In addition to one or more of the features described herein, the processor is further configured to assign a maximum rating number to the secondary subchannel when the energy in the secondary subchannel originates from a Wi-Fi packet associated with a PPDU transmission having overlapping sets of basic services.

[0022] The above features and advantages as well as other features and advantages of the invention will be readily apparent from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Further features, advantages and details are listed only as examples in the following detailed description, which refers to the drawings in which: Fig. 1 shows a vehicle according to an exemplary embodiment; Fig. 2 is a diagram illustrating various subchannels of a Wi-Fi channel in an exemplary embodiment; Fig. 3 is a diagram illustrating a method for determining a score for a secondary subchannel of the Wi-Fi channel; and Fig. 4 is a flowchart of a method for identifying occupancy of a channel of the communication system. DETAILED DESCRIPTION

[0024] The following description is merely exemplary in nature. It should be understood that corresponding reference numerals throughout the drawings indicate like or corresponding parts and features.

[0025] According to an exemplary embodiment, Fig. 1 shows a vehicle 100. The vehicle 100 has a WiFi communication device 102 that sends and receives signals to and from communication devices 104a, 104b inside the interior of the vehicle 100 or outside, but near, the vehicle. For illustrative purposes, two communication devices 104a, 104b are shown. The communication devices 104a, 104b can be, for example, a portable telephone, a portable laptop, a camera communicating via a WiFi band, etc. An external communication system 106 communicates with the WiFi communication device 102 and controls the transmission between the WiFi communication device and a remote location 108 via an antenna 110.

[0026] The WiFi communication device 102 includes a controller 112 that controls the operation of the WiFi communication device 102. The controller 112 may include processing circuitry, which may include an application-specific integrated circuit (ASIC), an electronic circuit, a processor (collectively, dedicated, or as a group), and memory executing one or more software or firmware programs, combinational logic circuitry, and / or other suitable components that provide the described functionality. The controller 112 may include a non-transitory computer-readable medium storing instructions that, when processed by one or more processors of the controller 112, implement a method for determining whether a WiFi channel is busy, idle, or semi-idle and transmitting a signal based on that status, in accordance with one or more embodiments described herein.

[0027] Fig. 2 shows a diagram 200 illustrating various subchannels of a Wi-Fi channel in an exemplary embodiment. Current Wi-Fi generations operate in a frequency band that may be centered on a carrier frequency such as 2.4 gigahertz (GHz), 5 GHz, and / or 6 GHz. A channel within a frequency band comprises a plurality of subchannels centered around the carrier frequency. The number of subchannels in a channel depends on the width of the frequency band. For illustration purposes, an 80 MHz channel with four 20 MHz subchannels is shown. The subchannels include a primary subchannel 202 and three secondary subchannels 204a-204c. The primary subchannel 202 is generally used for 802.11 clients. The WiFi communication device 102 may include a means for measuring the amount of radio frequency (RF) energy in both the primary subchannel 202 and the plurality of secondary subchannels 204a-204n.Such a tool can be a signal analyzer or a signal analysis program.

[0028] Fig. 3 is a diagram 300 illustrating a method for determining a rating number for a secondary subchannel. The rating number relates to the energy content of the secondary subchannel and can be used as an indicator of channel utilization. For illustration, an nth secondary subchannel 204n is shown. A subchannel energy E nis measured over the nth subchannel. This subchannel energy is primarily due to the current communication over the subchannel. In addition, the subchannel energy may be the result of leakage from one or more adjacent subchannels (referred to as out-of-band emissions) or from another communication device (e.g., Bluetooth, ultra-wideband device) operating in the same or an adjacent frequency band as the subchannel. The subchannel energy E n is compared with a threshold value ED0 of a secondary channel. If the subchannel energy E n below the threshold ED0 of the secondary channel, the secondary subchannel is considered free. A free subchannel can be assigned a weighting of 0. The energy E n is compared with a variety of energy intervals, and the subchannel is assigned a rating number (S n) based on the energy interval into which the subchannel energy E n falls.

[0029] In Fig. 3, four energy intervals R1, R2, R3, and R4 are shown for illustrative purposes. The first energy interval R1 lies between ED0 and ED0+Δ1. The second energy interval R2 lies between ED0+Δ1 and ED0+Δ2. The third energy interval R3 lies between ED0+Δ2 and ED0+Δ3. The fourth energy interval R4 lies between ED0+Δ3 and ED0+Δ4. In various embodiments, the values Δ1, Δ2, Δ3, Δ4, and Δ1 are positive values whose value increases with the index. In one embodiment, the energy intervals are equal to one another. Thus, Δ n+1 - Δ n+1 a constant value. In an exemplary embodiment, an energy interval is 5 dBm.

[0030] For illustration: The rating number assigned to the energy interval R1 is 1, the rating number assigned to the energy interval R2 is 2, the rating number assigned to the energy interval R3 is 3, and the rating number assigned to the energy interval R4 is 4. In general, the rating number for the energy interval R n = n. The degree of occupancy of the subchannel is indicated by the rating number, where a higher rating number indicates a predominantly occupied subchannel and a lower rating number indicates a predominantly free or unoccupied subchannel.

[0031] Fig. 4 is a flowchart 400 of a method for identifying the occupancy of a channel of the communication system. In box 402, a preamble detection is performed on the primary channel. In box 404, the energy of the detection on the primary channel is compared to a primary channel energy threshold. If the energy is greater than or equal to the primary subchannel energy threshold EP0, the method continues with box 418. In box 418, the channel is reported as occupied. If, in box 404, the energy is below the primary subchannel energy threshold EP0, the method continues with boxes 406a-406n.

[0032] Each of the fields 406a-406n includes performing a test of a corresponding secondary subchannel 204a-204n. The test includes applying a score to the secondary subchannel 204a based on the energy of the second subchannel, as in Fig.3. Once the tests are completed, the procedure moves to field 408.

[0033] In field 408, the rating numbers of the individual secondary subchannels are checked. If the energy in each secondary subchannel is below the threshold value for the secondary subchannel (i.e., if En < ED0 for all n), the program continues with field 410. In field 410, it is determined that the channel is clear.

[0034] If in box 408 the energy in at least one of the secondary subchannels is greater than or equal to the threshold for the secondary subchannel (ie, if at least one En ≥ ED0), the method continues with box 412.

[0035] In field 412, the rating scores for each secondary subchannel are added to calculate a total rating score. In field 414, the total rating score is compared to a rating score threshold. If the total rating score is equal to or greater than the rating score threshold, the method continues with field 418. In field 418, it is determined that the channel is busy. If, in field 414, the total rating score is below the rating score threshold, the method continues with field 416.

[0036] In field 416, it is determined that the channel is half empty. A signal can be transmitted over the channel when the channel is half empty or half clear. The signal is transmitted with a probability P0. The probability P0 and / or the score threshold may be a function of the access category of the signal, the age of a packet of the signal, the urgency of the packet, or a combination thereof. An access category is one of voice, video, best effort, and background.

[0037] If a packet has a high priority or is to be sent on a half-empty channel, the coding level of the packet can be increased according to the priority.

[0038] The format of Wi-Fi data frames for transmitting data in an 802.11 network at the physical layer (PHY) is the Physical Layer Convergence Procedure Protocol Data Unit (PPDU). A PPDU contains a preamble and a data field. The preamble field contains the information about the transmission vector format. If the QoS characteristics of the signal are known, various adjustments can be made to the transmission parameters. For PPDUs that are part of a high-data-rate signal, a lower summed weighting number can be used if the channel is determined to be half-empty. In other words, the highest energy interval (e.g., ED0+Δn) in the evaluation of a subchannel can be lowered if it is known that the PPDU is part of a high-data-rate signal.

[0039] For PPDUs that are part of a low-latency signal, the PPDU can be transmitted even if the sum of the scores is high. Thus, the score threshold can be raised for signals that are part of a low-latency signal.

[0040] If the energy detected on the subchannel is determined to be due to a Wi-Fi packet (PPDU) within a threshold corresponding to an Overlapping Basic Service Set (OBSS) PPDU transmission, the subchannel can be assigned a rating number to indicate that the subchannel is clear. If not, the subchannel can either be assigned a maximum rating number or the entire channel can be considered busy.

[0041] In one embodiment, the score assigned to a subchannel may be based on a history of transmission on the subchannel. For example, if the transmission is determined to be part of a periodic data stream, the duty cycle of the data stream may be measured, and the score assigned to the subchannel may be a function of the duty cycle. The score may be directly proportional to the duty cycle. The duty cycle refers to the proportion of time within a unit of time occupied by the signal. If the duty cycle indicates that the transmission will end before the subchannel is accessed, the subchannel may be used.

[0042] If the transmission is part of a periodic data stream that is not a Wi-Fi transmission, and the transmission duty cycle is low (i.e., the transmission completes before the Wi-Fi packet is transmitted), the subchannel may be assigned a low idle score. The transmission periodicity may be based on a history of transmissions over the subchannel and / or determined by machine learning. Figure description of Fig. 4 Y Yes N No

Claims

A method for transmitting a signal in a WiFi (Wireless Fidelity) system, comprising: determining that a primary subchannel (202) of a channel of the WiFi system is idle when the energy in the primary subchannel (202) is less than an energy threshold (EP0) of the primary subchannel (202), the channel comprising the primary subchannel (202) and one or more secondary subchannels (204a-204c); measuring the subchannel energy (En) by each of the one or more secondary subchannels (204a-204c); assigning a score to each of the one or more secondary subchannels (204a-204c) based on the subchannel energy (En); calculating the sum of the scores; and transmitting the signal over the channel if the sum of the scores is below a score threshold;characterized in thata history of transmission over the subchannel (202) indicates a periodic stream and the score for the subchannel (202) is determined at least in part based on a duty cycle of the periodic stream; The method of claim 1, further comprising transmitting the signal with a selected probability, wherein the selected probability is a function of at least one of the following: (i) the access category; (ii) the age of a packet; and (iii) the urgency of the packet. The method of claim 1, further comprising lowering the score threshold if at least one of the following conditions is met: (i) a physical layer protocol data unit (PPDU) is part of a high data rate frame; and (ii) the PPDUs are part of a low latency flow. The method of claim 1, further comprising: assigning a maximum rating number to the secondary subchannel (204a - 204c) if the energy in the secondary subchannel (204a - 204c) originates from a Wi-Fi packet belonging to a PPDU transmission with overlapping sets of basic services. A WiFi (Wireless Fidelity) system comprising: a channel having a primary subchannel (202) and one or more secondary subchannels (204a-204c); a sensor for measuring the energy of signals in the primary subchannel (202) and in each of the one or more secondary subchannels (204a-204c); a processor configured to: determine that the primary subchannel (202) is clear when the energy in the primary subchannel (202) is less than an energy threshold (EP0) of the primary subchannel (202); assign a score to each of the one or more secondary subchannels (204a-204c) based on the subchannel energy (En); calculate the sum of the scores; and transmit a signal over the channel if the sum of the scores is less than a score threshold;characterized in thata history of transmission over the subchannel (202) indicates a periodic stream and the score for the subchannel (202) is determined at least in part based on a duty cycle of the periodic stream; The WiFi system of claim 5, wherein the processor is further configured to transmit the signal with a selected probability, the selected probability being a function of at least one of the following: (i) the access category; (ii) the age of a packet; and (iii) the urgency of the packet. The WiFi system of claim 5, wherein the processor is further configured to lower the score threshold when at least one of the following conditions is met: (i) a physical layer protocol data unit (PPDU) is part of a high data rate frame; and (ii) the PPDUs are part of a low latency flow. The WiFi system of claim 5, wherein the processor is further configured to assign a maximum rating number to the secondary subchannel (204a-204c) when the energy in the secondary subchannel (204a-204c) originates from a Wi-Fi packet associated with a PPDU transmission having overlapping sets of basic services.

Images