METHOD THAT DETERMINES THE BANDWIDTH, DEVICE, STORAGE MEDIUM AND PROGRAM OUTPUT

Abstract

A bandwidth determination method, a device, a storage medium, and a program product are provided. In the bandwidth determination method, a first device receives a Physical Layer Protocol Data Unit (PPDU) from a second device. The PPDU is used to determine an encoding sequence and a service field. The first set of bits in the encoding sequence and the second set of bits in the service field indicate a bandwidth. If a check error occurs in the second set of bits, the first device determines a bandwidth for communication between the first and second devices based on the first set of bits. When the check error occurs in the second set of bits, the bandwidth determination for communication is not abandoned. This avoids unnecessary retransmission or channel contention.

Description

METHOD THAT DETERMINES THE BANDWIDTH, DEVICE, STORAGE MEDIUM AND PROGRAM OUTPUT TECHNICAL FIELD OF THE INVENTION The modalities of this disclosure relate primarily to the field of communication, and in particular, to a method of determining bandwidth, a device, a storage medium, and a program product. BACKGROUND OF THE INVENTION In a wireless local area network, a transmitting end and a receiving end are in different wireless channel environments. Before the transmitting and receiving ends can communicate, they must obtain sufficient bandwidth through negotiation based on their respective channel availability. Furthermore, during communication, a corresponding frame and a trigger frame typically require the same bandwidth. In an existing solution, to perform this negotiation, the transmitting end can send a channel bandwidth to the receiving end during data communication. For example, the transmitting end can use a group of bits in an encoding sequence and a group of bits in a service field to jointly indicate the bandwidth. BRIEF DESCRIPTION OF THE INVENTION One form of this disclosure provides a solution that determines bandwidth. A first aspect of this disclosure provides a method for determining bandwidth. The method includes: A first device receives a Physical Layer Protocol Data Unit (PPDU) from a second device, where the PPDU is used to determine an encoding sequence and a service field, and a first group of bits in the encoding sequence and a second group of bits in the service field indicate a bandwidth; and if a check error occurs in the second group of bits, it determines a bandwidth for communication between the first device and the second device based on the first group of bits. In this specification, the PPDU received by the first device can carry either a control frame or a management frame. In some instances of the former, the received PPDU is either a non-HT (non-high-throughput) PPDU or a duplicate non-HT (non-high-throughput) PPDU. Examples of the control frames carried include, but are not limited to, an RTS (Request to Send) frame, a CTS (Ready to Send) frame, a PS-Poll (Power Saving Poll) frame, a CF-end (No Contention End) frame, a BAR (Request to Block Acknowledge) frame, or an NDP (Null Data PPDU Advertisement) frame. In this specification, the first bit group and / or the second bit group can include one or more bits. For example, the first bit group can include bits B5 and B6 in the encoding sequence, and the second bit group can include bit B7 in the service field. Different values ​​for the first and second bit groups can indicate different bandwidths. A bandwidth size might include, for example, 20 MHz, 40 MHz, 80 MHz, 160 (80+80) MHz, 320 MHz, or 480 MHz. According to the solution in this disclosure, when the check error occurs in the second group of bits, the first device does not simply discard the frame, but can continue attempting to determine the bandwidth for communication based on the first group of bits. In this way, the solution in this disclosure can reduce unnecessary retransmission or channel contention, save valuable air interface resources, and improve system efficiency. In some forms of the first aspect, the determination of a bandwidth for communication between the first device and the second device based on the first group of bits includes: if the first group of bits indicates a unique candidate bandwidth, the determination of the unique candidate bandwidth as the bandwidth for communication. In some forms of the first aspect, the determination of a bandwidth for communication between the first device and the second device based on the first group of bits includes: if a value of the first group of bits is 1, it indicates that the bandwidth for communication is a first bandwidth; if a value of the first group of bits is 2, it indicates that the bandwidth for communication is a second bandwidth; or if a value of the first group of bits is 3, it indicates that the bandwidth for communication is a third bandwidth. In some versions of the first aspect, the first bandwidth is 40 MHz, the second bandwidth is 80 MHz, and the third bandwidth is 160 MHz. For example, B5, B6, and B7 described above indicate bandwidth modes, and the three bits can indicate up to eight bandwidth types. Currently, commonly used bandwidths primarily include 20 MHz, 40 MHz, 80 MHz, 160 (80+80) MHz, and 320 MHz. For example, if B5B6 is 0 and B7 is 0, it indicates 20 MHz; if B5B6 is 1 and B7 is 0, it indicates 40 MHz; if B5B6 is 2 and B7 is 0, it indicates 80 MHz; if B5B6 is 3 and B7 is 0, it indicates 160 MHz; if B5B6 is 0 and B7 is 1, it indicates 320 MHz; or if B5B6 is 1, 2, or 3, and B7 is 1, it can IVIA / indicates a reserved bandwidth, meaning the bandwidth is not temporarily specified. In a protocol, a sequence is used in which the least significant bit is sent first. For example, if B5B6 is 2, the corresponding binary number is 10. In this case, B5 = 0 and B6 = 1. In this example, when B5B6 is 1, 2, or 3, it can indicate a corresponding single bandwidth. For example, when B5B6 is 1, it indicates 40 MHz; when B5B6 is 2, it indicates 80 MHz; or when B5B6 is 3, it indicates 160 MHz. In this case, even if a check error occurs at B7, the first device can still determine the bandwidth for communication based on a single bandwidth corresponding to B5B6. In some forms of the first aspect, determining a bandwidth for communication between the first device and the second device based on the first bit group includes: if the first bit group indicates a plurality of candidate bandwidths, determining the bandwidth for communication from the plurality of candidate bandwidths based on a bandwidth negotiation process between the first device and the second device. In this specification, the bandwidth negotiation process indicates whether bandwidth negotiation is accepted between the first and second devices. The bandwidth negotiation process may include a dynamic bandwidth negotiation process. The dynamic bandwidth negotiation process is as follows: When sending an RTS frame, a station that supports dynamic bandwidth negotiation sets B4 (indicating DYN_BANDWIDTH_IN_NON_HT) in the first seven bits of the encoding sequence to 1 (indicating a dynamic mode). After a receiving station receives the RTS frame, if a NAV (Network Allocation Vector) indicates idle, and a candidate bandwidth less than or equal to the bandwidth of the RTS frame meets the following condition, the receiving station sends a CTS (Ready To Send) frame using the candidate bandwidth. Otherwise, no CTS is returned.The condition that must be met is that a COA (Channel Clear Assessment) detection result for a candidate bandwidth secondary channel is idle within a PIFS (Point Coordination Function Interframe Space) time before the RTS is sent. The bandwidth negotiation process may include a static bandwidth negotiation process. The static bandwidth negotiation process is as follows: When sending an RTS frame, a station that does not support dynamic bandwidth negotiation sets B4 (indicating DYN_BANDWIDTH_IN_NON_HT) in the first seven bits of the encoding sequence to 0 (indicating a static mode); and after a receiving station receives the RTS frame, if a NAV indicates idle, and the bandwidth of the RTS frame meets the following condition, the receiving station sends a frame CTS using the same bandwidth as the RTS frame. Otherwise, no CTS is returned. The condition that must be met is that a CCA detection result for a secondary channel of the RTS bandwidth is idle within a PIFS time before the RTS is sent. The bandwidth negotiation process can also include a bandwidth-free process. The bandwidth-free process is as follows: When a station sends a non-HT or non-HT PPDU carrying content that is not an RTS frame, a DYN_BANDWIDTH_IN_NON_HT indication is not used. In other words, B4 in the first seven bits of the encoding sequence can be randomly generated, provided that the first seven bits of the encoding sequence are not all 0. In this case, a receiving station must return a response frame using the same bandwidth as the received frame. In some variations of the first aspect, the bandwidth negotiation process is determined by whether the PPDU specifies a preset parameter (e.g., DYN_BANDWIDTH_IN_NON_HT) or is based on a preset parameter value specified by the PPDU. For example, when the parameter DYN_BANDWIDTH_IN_NON_HT is not specified in the PPDU, the bandwidth negotiation process can be determined to be the no-bandwidth-negotiation process; when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 0 in the PPDU, the bandwidth negotiation process can be determined to be the static bandwidth negotiation process; or when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 1 in the PPDU, the bandwidth negotiation process can be determined to be the dynamic bandwidth negotiation process. In some forms of the first aspect, determining the bandwidth for communication from the plurality of candidate bandwidths includes: if the bandwidth negotiation process is the dynamic bandwidth negotiation process, selecting a smaller candidate bandwidth from the plurality of candidate bandwidths. For example, when B5B6 in the encoding sequence is 0 and B7 is 0, it indicates 20 MHz; or when B5B6 is 0 and B7 is 1, it indicates 320 MHz. That is, when B5B6 is 0, it indicates two possible bandwidths. In this case, if the bandwidth negotiation process is dynamic bandwidth negotiation, the first device can select a smaller bandwidth from the two possible bandwidths. This way, direct PPDU discarding can be avoided, and system efficiency can be improved. In some forms of the first aspect, determining the bandwidth for communication from the plurality of candidate bandwidths includes: if the bandwidth negotiation process is a non-dynamic bandwidth negotiation process, determining the bandwidth for communication from the plurality of candidate bandwidths through blind detection, where the non-dynamic bandwidth negotiation process includes the static bandwidth negotiation process or the no bandwidth negotiation process. For example, through blind detection, bandwidth can be determined autonomously with reference to information obtained from the PPDU. For instance, in a PPDU reception process, an EHT (very high throughput) receiving station records the received signal strength in each 20 MHz subchannel within 320 MHz, performs cross-correlation on the received signals in each 20 MHz subchannel, or separately performs frame header synchronization in each 20 MHz subchannel. This determines whether there is a received signal only in the primary 20 MHz or whether there is a received signal in each 20 MHz within 320 MHz. Thus, for example, when B5B6 is 0, it indicates both 20 MHz and 320 MHz. In this case, the first device can distinguish, through blind detection, whether a current bandwidth is 20 MHz or 320 MHz. A second aspect of this disclosure provides a method for determining bandwidth. The method includes: A first device receives a Physical Layer Protocol Data Unit (PPDU) from a second device, where the PPDU is used to determine a group of bits that are associated with bandwidth and are in a service field; and if a check error occurs in the bit group, it determines a bandwidth for communication between the first and second devices based on a bandwidth negotiation process between the first and second devices. In this specification, the PPDU received by the first device can carry either a control frame or a management frame. In some instances of the latter, the received PPDU is a non-HT (non-high-throughput) PPDU or a duplicate non-HT (non-high-throughput) PPDU. Examples of the control frames carried include, but are not limited to, an RTS (Request to Send) frame, a CTS (Ready to Send) frame, a PS-Poll (Power Saving Poll) frame, a CF-end (No Contention End) frame, a BAR (Request to Acknowledge Block) frame, or an NDP (Null Data PPDU Advertisement) frame. In this specification, the bit group in the service field can include one or more bits. For example, the bit group can include a seventh bit, B7, in the service field. In this specification, the bandwidth negotiation process indicates whether bandwidth negotiation between the first and second devices is accepted. The bandwidth negotiation process may include a negotiation process of IVIA / Dynamic Bandwidth. The dynamic bandwidth negotiation process is as follows: When sending an RTS frame, a station that supports dynamic bandwidth negotiation sets B4 (indicating DYN_BANDWIDTH_IN_NON_HT) in the first seven bits of an encoding sequence to 1 (indicating a dynamic mode); and after a receiving station receives the RTS frame, if a NAV (Network Allocation Vector) indicates idle, and a candidate bandwidth less than or equal to a bandwidth in the RTS frame meets the following condition, the receiving station sends a CTS (Ready To Send) frame using the candidate bandwidth. Otherwise, no CTS is returned.The condition that must be met is that a CCA (Clear Channel Assessment) detection result for a candidate bandwidth secondary channel is idle within a PIFS (Point Coordination Function Interframe Space) time before the RTS is sent. The bandwidth negotiation process may include a static bandwidth negotiation process. The static bandwidth negotiation process is as follows: When sending an RTS frame, a station that does not support dynamic bandwidth negotiation sets B4 (indicating DYN_BANDWIDTH_IN_NON_HT) in the first seven bits of an encoding sequence to 0 (indicating a static mode). After a receiving station receives the RTS frame, if a NAV indicates idle, and the bandwidth of the RTS frame meets the following condition, the receiving station sends a CTS frame using the same bandwidth as the RTS frame. Otherwise, no CTS is returned. The condition that must be met is that a CCA detection result for a subchannel of the RTS bandwidth is idle within a PIFS time before the RTS is sent. The bandwidth negotiation process can also include a bandwidth-free process. The bandwidth-free process is as follows: When a station sends a non-HT or non-HT PPDU carrying content that is not an RTS frame, a DYN_BANDWIDTH_IN_NON_HT indication is not used. In other words, B4 in the first seven bits of an encoding sequence can be randomly generated, provided that the first seven bits of the encoding sequence are not all 0. In this case, a receiving station must return a response frame using the same bandwidth as the received frame. According to the solution in this disclosure, when a check failure occurs in the bit group within the service field, the first device does not simply discard the PPDU, but can continue attempting to determine the bandwidth for communication based on the bandwidth negotiation process. In this way, the solution in this disclosure can reduce unnecessary retransmission or contention. IVIA / channel, saving valuable air interface resources and improving system efficiency. In some forms of the second aspect, the bandwidth negotiation process is determined by whether the PPDU specifies a preset parameter (e.g., DYN_BANDWIDTH_IN_NON_HT) or is based on a preset parameter value specified by the PPDU. For example, when the parameter DYN_BANDWIDTH_IN_NON_HT is not specified in the PPDU, the bandwidth negotiation process can be determined to be the no-bandwidth-negotiation process; when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 0 in the PPDU, the bandwidth negotiation process can be determined to be the static bandwidth negotiation process; or when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 1 in the PPDU, the bandwidth negotiation process can be determined to be the dynamic bandwidth negotiation process. In some embodiments of the second aspect, determining the bandwidth for communication between the first and second devices involves, if the bandwidth negotiation process is dynamic bandwidth negotiation, establishing a preset bandwidth for communication. In some embodiments of the second aspect, the preset bandwidth is 20 MHz. Thus, according to the embodiments in this disclosure, the bandwidth can be determined more simply and efficiently. In some variations of the second aspect, the bit group is a third bit group; the PPDU is also used to determine a fourth bit group in the encoding sequence, and the third and fourth bit groups indicate a bandwidth. Determining a bandwidth for communication between the first and second devices includes determining the bandwidth for communication based on the bandwidth negotiation process and the fourth bit group. In some forms of the second aspect, the determination of the bandwidth for communication based on the bandwidth negotiation process and the fourth bit group includes: if the fourth bit group indicates a plurality of candidate bandwidths, determining the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process. In some forms of the second aspect, if the fourth group of bits indicates a unique candidate bandwidth, the first device can determine the unique candidate bandwidth as the bandwidth for communication. In some forms of the second aspect, the determination of the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process includes: whether the bandwidth negotiation process IVIA / band is the dynamic bandwidth negotiation process, selecting a smaller candidate bandwidth from a plurality of candidate bandwidths. For example, when B5B6 in the encoding sequence is 0 and B7 in the service field is 0, it indicates 20 MHz; or when B5B6 is 0 and B7 is 1, it indicates 320 MHz. That is, when B5B6 is 0, it indicates two possible bandwidths. In this case, if the bandwidth negotiation process is dynamic bandwidth negotiation, the first device can select a smaller bandwidth from the two possible bandwidths. This way, direct PPDU discarding can be avoided, and system efficiency can be improved. In some forms of the second aspect, determining the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process includes: if the bandwidth negotiation process is a non-dynamic bandwidth negotiation process, determining the bandwidth for communication from the plurality of candidate bandwidths through blind detection, where the non-dynamic bandwidth negotiation process includes the static bandwidth negotiation process or the no bandwidth negotiation process. For example, through blind detection, bandwidth can be determined autonomously with reference to information obtained from the PPDU. For instance, in a PPDU reception process, an EHT (very high throughput) receiving station records the received signal strength in each 20 MHz subchannel within 320 MHz, performs cross-correlation on the receive channels in each 20 MHz subchannel, or separately performs frame header synchronization in each 20 MHz subchannel. This determines whether there is a received signal only in the primary 20 MHz or whether there is a received signal in each 20 MHz within 320 MHz. Thus, for example, when B5B6 is 0, it indicates either 20 MHz or 320 MHz. In this case, the first device can distinguish, through blind detection, whether a current bandwidth is 20 MHz or 320 MHz. In some forms of the second aspect, the bandwidth negotiation process is determined depending on whether the PPDU indicates a preset parameter or based on a value of a preset parameter indicated by the PPDU. In some forms of the second aspect, the PPDU is a PPDU in a non-high-performance (non-HT) format or a duplicated non-high-performance (non-HT) PPDU. A third aspect of this disclosure provides a first device. The first device includes: a receiving unit, configured to receive a Physical Layer Protocol Data Unit (PPDU) from a second device, where the PPDU is used to IVIA / determine an encoding sequence and a service field, and a first group of bits in the encoding sequence and a second group of bits in the service field indicate a bandwidth; and a processing unit, configured to: if a check error occurs in the second group of bits, determine a bandwidth for communication between the first device and the second device based on the first group of bits. In some modalities of the third aspect, the processing unit is configured to: if the first group of bits indicates a unique candidate bandwidth, determine the unique candidate bandwidth as the bandwidth for communication. In some forms of the third aspect, if a value in the first group of bits is 1, it indicates that the bandwidth for communication is a first bandwidth; if a value in the first group of bits is 2, it indicates that the bandwidth for communication is a second bandwidth; or if a value in the first group of bits is 3, it indicates that the bandwidth for communication is a third bandwidth. In some modalities of the third aspect, the first bandwidth is 40 MHz, the second bandwidth is 80 MHz, and the third bandwidth is 160 MHz. In some modalities of the third aspect, the processing unit is configured to: if the first group of bits indicates a plurality of candidate bandwidths, determine the bandwidth for communication from the plurality of candidate bandwidths based on a bandwidth negotiation process between the first device and the second device. In some forms of the third aspect, the bandwidth negotiation process is determined by whether the PPDU specifies a preset parameter (e.g., DYN_BANDWIDTH_IN_NON_HT) or is based on a preset parameter value specified by the PPDU. For example, when the parameter DYN_BANDWIDTH_IN_NON_HT is not specified in the PPDU, the bandwidth negotiation process can be determined to be a non-negotiation process; when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 0 in the PPDU, the bandwidth negotiation process can be determined to be a static bandwidth negotiation process; or when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 1 in the PPDU, the bandwidth negotiation process can be determined to be a dynamic bandwidth negotiation process. In some forms of the third aspect, the processing unit is further configured to: if the bandwidth negotiation process is the dynamic bandwidth negotiation process, select a smaller candidate bandwidth from the plurality of candidate bandwidths. In some forms of the third aspect, the processing unit is further configured to: if the bandwidth negotiation process is a non-dynamic bandwidth negotiation process, determine the bandwidth for communication from the plurality of candidate bandwidths through blind detection, where the non-dynamic bandwidth negotiation process includes the static bandwidth negotiation process or the no bandwidth negotiation process. In some forms of the third aspect, the PPDU is a PPDU in a non-high-performance (non-HT) format or a duplicated non-high-performance (non-HT) PPDU in a duplicated format. A fourth aspect of this disclosure provides a first device. The first device includes: a receiving unit, configured to receive a Physical Layer Protocol Data Unit (PPDU) from a second device, where the PPDU is used to determine a group of bits that are associated with a bandwidth and are in a service field; and a processing unit, configured to: if a check error occurs in the bit group, determine a bandwidth for communication between the device and the second device based on a bandwidth negotiation process between the first and second devices. In some forms of the fourth aspect, the processing unit is also configured to: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, determine a preset bandwidth as the bandwidth for communication. In some modalities of the fourth aspect, the preset bandwidth is 20 MHz. In some fourth-aspect modes, the bit group is a third bit group; the PPDU is also used to determine a fourth bit group in an encoding sequence, and the third and fourth bit groups indicate bandwidth. The processing unit is further configured to determine the bandwidth for communication based on the bandwidth negotiation process and the fourth bit group. In some forms of the fourth aspect, the processing unit is further configured to: if the fourth group of bits indicates a plurality of candidate bandwidths, determine the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process. In some fourth aspect modes, if the fourth group of bits indicates a unique candidate bandwidth, the first device can determine the unique candidate bandwidth as the bandwidth for communication. In some forms of the fourth aspect, the processing unit is further configured to: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, select a smaller candidate bandwidth from the plurality of candidate bandwidths. In some forms of the fourth aspect, the processing unit is further configured to: if the bandwidth negotiation process is a non-dynamic bandwidth negotiation process, determine the bandwidth for communication from the plurality of candidate bandwidths through blind detection, where the non-dynamic bandwidth negotiation process includes a static bandwidth negotiation process or a non-bandwidth negotiation process. In some modalities of the fourth aspect, the bandwidth negotiation process is determined depending on whether the PPDU indicates a preset parameter or based on a value of a preset parameter indicated by the PPDU. In some forms of the fourth aspect, the PPDU is a PPDU in a non-high-performance (non-HT) format or a duplicated non-high-performance (non-HT) PPDU. A fifth aspect of this disclosure provides a first device. The device includes a transceiver and a processor. The transceiver is configured to receive a PPDU from a second device, where the PPDU is used to determine an encoding sequence and a service field, and a first group of bits in the encoding sequence and a second group of bits in the service field indicate a bandwidth. The processor is configured to, if a check error occurs in the second group of bits, determine a bandwidth for communication between the first and second devices based on the first group of bits. Optionally, the first device may also include memory. The memory is configured to store instructions executed by the processor.When the instructions are executed by the processor, if the checking error occurs in the second group of bits, the processor can determine the bandwidth for communication between the first device and the second device based on the first group of bits. In some modalities of the fifth aspect, the processor is further configured to: if the first group of bits indicates a unique candidate bandwidth, determine the unique candidate bandwidth as the bandwidth for communication. In some forms of the fifth aspect, if a value in the first group of bits is 1, it indicates that the bandwidth for communication is a first bandwidth; if a value in the first group of bits is 2, it indicates that the bandwidth for communication is a second bandwidth; or if a value in the first group of bits is 3, it indicates that the bandwidth for communication is a third bandwidth. In some modalities of the fifth aspect, the first bandwidth is 40 MHz, the second bandwidth is 80 MHz, and the third bandwidth is 160 MHz. In some forms of the fifth aspect, the processor is further configured to: if the first group of bits indicates a plurality of candidate bandwidths, determine the bandwidth for communication from the plurality of candidate bandwidths based on a bandwidth negotiation process between the first device and the second device. In some modalities of the fifth aspect, the bandwidth negotiation process is determined by whether the PPDU specifies a preset parameter (e.g., DYN_BANDWIDTH_IN_NON_HT) or is based on a preset parameter value specified by the PPDU. For example, when the parameter DYN_BANDWIDTH_IN_NON_HT is not specified in the PPDU, the bandwidth negotiation process can be determined to be a non-negotiation process; when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 0 in the PPDU, the bandwidth negotiation process can be determined to be a static bandwidth negotiation process; or when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 1 in the PPDU, the bandwidth negotiation process can be determined to be a dynamic bandwidth negotiation process. In some forms of the fifth aspect, the processor is further configured to: if the bandwidth negotiation process is the dynamic bandwidth negotiation process, select a smaller candidate bandwidth from the plurality of candidate bandwidths. In some forms of the fifth aspect, the processor is further configured to: if the bandwidth negotiation process is a non-dynamic bandwidth negotiation process, determine the bandwidth for communication from the plurality of candidate bandwidths through blind detection, where the non-dynamic bandwidth negotiation process includes the static bandwidth negotiation process or the no bandwidth negotiation process. In some forms of the fifth aspect, the PPDU is a PPDU in a non-HT format or a duplicate non-HT format. A sixth aspect of this disclosure provides a first device. The device includes a transceiver and a processor. The receiver is configured to receive a PPDU from a second device, where the PPDU is used to determine a group of bits that are associated with a bandwidth and are in a service field. The processor is configured to: if a check error occurs in the bit group, determine a IVIA / bandwidth for communication between the first and second devices is determined through a bandwidth negotiation process between them. Optionally, the first device may also include memory. This memory is configured to store instructions executed by the processor. When instructions are executed by the processor, if a check error occurs in a group of bits, the processor can determine the bandwidth for communication between the first and second devices based on the bandwidth negotiation process between them. In some modalities of the sixth aspect, the processor is further configured to: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, determine a preset bandwidth as the bandwidth for communication. In some modalities of the sixth aspect, the preset bandwidth is 20 MHz. In some sixth aspect modes, the bit group is a third bit group; the PPDU is also used to determine a fourth bit group in an encoding sequence, and the third and fourth bit groups indicate bandwidth. The processing unit is further configured to determine the bandwidth for communication based on the bandwidth negotiation process and the fourth bit group. In some forms of the sixth aspect, the processor is further configured to: if the fourth group of bits indicates a plurality of candidate bandwidths, determine the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process. In some sixth aspect modes, if the fourth group of bits indicates a unique candidate bandwidth, the first device can determine the unique candidate bandwidth as the bandwidth for communication. In some forms of the sixth aspect, the processor is further configured to: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, select a smaller candidate bandwidth from the plurality of candidate bandwidths. In some modalities of the sixth aspect, the processor is further configured to: if the bandwidth negotiation process is a non-dynamic bandwidth negotiation process, determine the bandwidth for communication from the plurality of candidate bandwidths through blind detection, where the non-dynamic bandwidth negotiation process includes a static bandwidth negotiation process or a non-bandwidth negotiation process. In some modalities of the sixth aspect, the bandwidth negotiation process is determined depending on whether the PPDU indicates a preset parameter or based on a value of a preset parameter indicated by the PPDU. In some forms of the sixth aspect, the PPDU is a PPDU in a non-HT format or a duplicate non-HT format. A seventh aspect of this disclosure provides a first device, including an input interface and a processing circuit. The input interface is configured to receive a PPDU from a second device, where the PPDU is used to determine an encoding sequence and a service field, and a first group of bits in the encoding sequence and a second group of bits in the service field indicate a bandwidth. The processing circuit is configured to: if a check error occurs in the second group of bits, determine a bandwidth for communication between the first and second devices based on the first group of bits. In some forms of the seventh aspect, the processing circuit is further configured to: if the first group of bits indicates a unique candidate bandwidth, determine the unique candidate bandwidth as the bandwidth for communication. In some forms of the seventh aspect, if a value in the first group of bits is 1, it indicates that the bandwidth for communication is a first bandwidth; if a value in the first group of bits is 2, it indicates that the bandwidth for communication is a second bandwidth; or if a value in the first group of bits is 3, it indicates that the bandwidth for communication is a third bandwidth. In some forms of the seventh aspect, the first bandwidth is 40 MHz, the second bandwidth is 80 MHz, and the third bandwidth is 160 MHz. In some forms of the seventh aspect, the processing circuit is further configured to: if the first group of bits indicates a plurality of candidate bandwidths, determine the bandwidth for communication from the plurality of candidate bandwidths based on a bandwidth negotiation process between the first device and the second device. In some forms of the seventh aspect, the bandwidth negotiation process is determined by whether the PPDU specifies a preset parameter (e.g., DYN_BANDWIDTH_IN_NON_HT) or is based on a preset parameter value specified by the PPDU. For example, when the parameter DYN_BANDWIDTH_IN_NON_HT is not specified in the PPDU, the bandwidth negotiation process can be determined to be a non-bandwidth negotiation process. When the parameter DYN_BANDWIDTH_IN_NON_HT is indicated as 0 in the PPDU, it can be determined that the bandwidth negotiation process is a static bandwidth negotiation process; or when the parameter DYN_BANDWIDTH_IN_NON_HT is indicated as 1 in the PPDU, it can be determined that the bandwidth negotiation process is a dynamic bandwidth negotiation process. In some forms of the seventh aspect, the processing circuit is further configured to: if the bandwidth negotiation process is the dynamic bandwidth negotiation process, select a smaller candidate bandwidth from the plurality of candidate bandwidths. An eighth aspect of this disclosure provides a first device. The first device includes an input interface and a processing circuit. The input interface is configured to receive a PPDU from a second device, where the PPDU is used to determine a group of bits associated with bandwidth and located in a service field. The processing circuit is configured to: if a check error occurs in the bit group, determine a bandwidth for communication between the first and second devices based on a bandwidth negotiation process between them. In some forms of the eighth aspect, the processing circuit is further configured to: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, determine a preset bandwidth as the bandwidth for communication. In some modalities of the eighth aspect, the preset bandwidth is 20 MHz. In some eighth-aspect modes, the bit group is a third bit group; the PPDU is also used to determine a fourth bit group in an encoding sequence, and the third and fourth bit groups indicate bandwidth. The processing unit is further configured to determine the bandwidth for communication based on the bandwidth negotiation process and the fourth bit group. In some forms of the eighth aspect, the processing circuit is further configured to: if the fourth group of bits indicates a plurality of candidate bandwidths, determine the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process. In some forms of the eighth aspect, if the fourth group of bits indicates a unique candidate bandwidth, the first device can determine the unique candidate bandwidth as the bandwidth for communication. In some forms of the eighth aspect, the processing circuit is further configured to: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, select a smaller candidate bandwidth from the plurality of candidate bandwidths. In some forms of the eighth aspect, the processing circuit is further configured to: if the bandwidth negotiation process is a non-dynamic bandwidth negotiation process, determine the bandwidth for communication from the plurality of candidate bandwidths through blind detection, where the non-dynamic bandwidth negotiation process includes either a static bandwidth negotiation process or a non-bandwidth negotiation process. In some modalities of the eighth aspect, the bandwidth negotiation process is determined depending on whether the PPDU indicates a preset parameter or based on a value of a preset parameter indicated by the PPDU. In some forms of the eighth aspect, the PPDU is a PPDU in a non-HT format or a duplicated non-HT format. A ninth aspect of this disclosure provides a computer-readable storage medium. The computer-readable storage medium stores one or more computer instructions, and the computer instruction or instructions are used by a processor to perform a method. The method includes: A first device receives a PPDU from a second device, where the PPDU is used to determine an encoding sequence and a service field, and a first group of bits in the encoding sequence and a second group of bits in the service field indicate a bandwidth; and if a check error occurs in the second group of bits, it determines a bandwidth for communication between the first device and the second device based on the first group of bits. In some forms of the ninth aspect, determining a bandwidth for communication between the first device and the second device based on the first group of bits includes: if the first group of bits indicates a unique candidate bandwidth, determining the unique candidate bandwidth as the bandwidth for communication. In some forms of the ninth aspect, the determination of a bandwidth for communication between the first device and the second device based on the first group of bits includes: if a value of the first group of bits is 1, it indicates that the bandwidth for communication is a first bandwidth; if a value of the first group of bits is 2, it indicates that the bandwidth for communication is a second bandwidth; or if a value of the first group of bits is 3, it indicates that the bandwidth for communication is a third bandwidth. In some modalities of the ninth aspect, the first bandwidth is 40 MHz, the second bandwidth is 80 MHz, and the third bandwidth is 160 MHz. In some embodiments of the ninth aspect, the determination of a bandwidth for communication between the first device and the second device based on the first bit group includes: if the first bit group indicates a plurality of candidate bandwidths, determining the bandwidth for communication from the plurality of candidate bandwidths based on a bandwidth negotiation process between the first device and the second device. In some aspects of the ninth aspect, the bandwidth negotiation process is determined by whether the PPDU specifies a preset parameter (e.g., DYN_BANDWIDTH_IN_NON_HT) or by a preset parameter value specified by the PPDU. For example, when the parameter DYN_BANDWIDTH_IN_NON_HT is not specified in the PPDU, the bandwidth negotiation process can be determined to be a non-negotiation process; when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 0 in the PPDU, the bandwidth negotiation process can be determined to be a static bandwidth negotiation process; or when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 1 in the PPDU, the bandwidth negotiation process can be determined to be a dynamic bandwidth negotiation process. In some forms of the ninth aspect, determining the bandwidth for communication from the plurality of candidate bandwidths includes: if the bandwidth negotiation process is the dynamic bandwidth negotiation process, selecting a smaller candidate bandwidth from the plurality of candidate bandwidths. In some forms of the ninth aspect, determining the bandwidth for communication from the plurality of candidate bandwidths includes: if the bandwidth negotiation process is a non-dynamic bandwidth negotiation process, determining the bandwidth for communication from the plurality of candidate bandwidths through blind detection, where the non-dynamic bandwidth negotiation process includes the static bandwidth negotiation process or the no bandwidth negotiation process. In some aspects of the ninth aspect, the PPDU is a PPDU in a non-HT format or a duplicate non-HT format. A tenth aspect of this disclosure provides a means of storage IVIA / computer-readable. The computer-readable storage medium stores one or more computer instructions, and the instruction or instructions are used by a processor to perform a method. The method includes: A first device receives a PPDU from a second device, where the PPDU is used to determine a group of bits that are associated with a bandwidth and are in a service field; and if a check error occurs in the group of bits, it determines a bandwidth for communication between the first and second devices based on a bandwidth negotiation process between the first and second devices. In some forms of the tenth aspect, determining a bandwidth for communication between the first device and the second device includes: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, determining a preset bandwidth as the bandwidth for communication. In some modalities of the tenth aspect, the preset bandwidth is 20 MHz. In some tenth aspect modes, the bit group is a third bit group; the PPDU is also used to determine a fourth bit group in an encoding sequence, and the third and fourth bit groups indicate a bandwidth. Determining a bandwidth for communication between the first and second devices includes determining the bandwidth for communication based on the bandwidth negotiation process and the fourth bit group. In some forms of the tenth aspect, the determination of the bandwidth for communication based on the bandwidth negotiation process and the fourth bit group includes: if the fourth bit group indicates a plurality of candidate bandwidths, determining the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process. In some tenth aspect modes, if the fourth group of bits indicates a unique candidate bandwidth, the first device can determine the unique candidate bandwidth as the bandwidth for communication. In some forms of the tenth aspect, determining the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process includes: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, selecting a smaller candidate bandwidth from the plurality of candidate bandwidths. In some forms of the tenth aspect, the determination of bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process includes: whether the bandwidth negotiation process is IVIA / a non-dynamic bandwidth negotiation process, determining the bandwidth for communication from the plurality of candidate bandwidths through blind detection, where the non-dynamic bandwidth negotiation process includes either a static bandwidth negotiation process or a no bandwidth negotiation process. In some modalities of the tenth aspect, the bandwidth negotiation process is determined depending on whether the PPDU indicates a preset parameter or based on a value of a preset parameter indicated by the PPDU. In some tenth aspect forms, the PPDU is a PPDU in a non-HT format or a duplicate non-HT duplicate PPDU in a non-HT format. An eleventh aspect of this disclosure provides a computer program product. When the computer program product is executed on a computer, the computer is enabled to perform a method. The method includes: A first device receives a PPDU from a second device, where the PPDU is used to determine an encoding sequence and a service field, and a first group of bits in the encoding sequence and a second group of bits in the service field indicate a bandwidth; and if a check error occurs in the second group of bits, it determines a bandwidth for communication between the first device and the second device based on the first group of bits. In some forms of the eleventh aspect, determining a bandwidth for communication between the first device and the second device based on the first bit group includes: if the first bit group indicates a unique candidate bandwidth, determining the unique candidate bandwidth as the bandwidth for communication. In some forms of the eleventh aspect, the determination of a bandwidth for communication between the first device and the second device based on the first group of bits includes: if a value of the first group of bits is 1, it indicates that the bandwidth for communication is a first bandwidth; if a value of the first group of bits is 2, it indicates that the bandwidth for communication is a second bandwidth; or if a value of the first group of bits is 3, it indicates that the bandwidth for communication is a third bandwidth. In some modalities of the eleventh aspect, the first bandwidth is 40 MHz, the second bandwidth is 80 MHz, and the third bandwidth is 160 MHz. In some forms of the eleventh aspect, determining a bandwidth for communication between the first device and the second device based on the first group of bits includes: if the first group of bits indicates a plurality of candidate bandwidths, determining the bandwidth for communication from the plurality of IVIA / candidate bandwidths based on a bandwidth negotiation process between the first device and the second device. In some modalities of the eleventh aspect, the bandwidth negotiation process is determined by whether the PPDU specifies a preset parameter (e.g., DYN_BANDWIDTH_IN_NON_HT) or is based on a preset parameter value specified by the PPDU. For example, when the parameter DYN_BANDWIDTH_IN_NON_HT is not specified in the PPDU, the bandwidth negotiation process can be determined to be a non-negotiation process; when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 0 in the PPDU, the bandwidth negotiation process can be determined to be a static bandwidth negotiation process; or when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 1 in the PPDU, the bandwidth negotiation process can be determined to be a dynamic bandwidth negotiation process. In some forms of the eleventh aspect, the determination of bandwidth for communication from the plurality of candidate bandwidths includes: if the bandwidth negotiation process is the dynamic bandwidth negotiation process, selecting a smaller candidate bandwidth from the plurality of candidate bandwidths. In some forms of the eleventh aspect, determining the bandwidth for communication from the plurality of candidate bandwidths includes: if the bandwidth negotiation process is a non-dynamic bandwidth negotiation process, determining the bandwidth for communication from the plurality of candidate bandwidths through blind detection, where the non-dynamic bandwidth negotiation process includes the static bandwidth negotiation process or the no bandwidth negotiation process. In some forms of the eleventh aspect, the PPDU is a PPDU in a non-HT non-high-performance format or a duplicated non-HT non-high-performance PPDU. A twelfth aspect of this disclosure provides a computer program product. When the computer program product is executed on a computer, the computer is enabled to perform a method. The method includes: A first device receives a PPDU from a second device, where the PPDU is used to determine a group of bits that are associated with a bandwidth and are in a service field; and if a check error occurs in the group of bits, it determines a bandwidth for communication between the first device and the second device based on a bandwidth negotiation process between the first and second devices. In some modalities of the twelfth aspect, the determination of a bandwidth for communication between the first device and the second device includes: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, determining a preset bandwidth as the bandwidth for communication. In some twelfth aspect modalities, the preset bandwidth is 20 MHz. In some twelfth aspect modes, the bit group is a third bit group; the PPDU is also used to determine a fourth bit group in an encoding sequence, and the third and fourth bit groups indicate a bandwidth. Determining a bandwidth for communication between the first and second devices involves determining the bandwidth for communication based on the bandwidth negotiation process and the fourth bit group. In some forms of the twelfth aspect, the determination of the bandwidth for communication based on the bandwidth negotiation process and the fourth bit group includes: if the fourth bit group indicates a plurality of candidate bandwidths, determining the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process. In some twelfth aspect modes, if the fourth group of bits indicates a unique candidate bandwidth, the first device can determine the unique candidate bandwidth as the bandwidth for communication. In some forms of the twelfth aspect, the determination of bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process includes: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, selecting a smaller candidate bandwidth from the plurality of candidate bandwidths. In some forms of the twelfth aspect, determining the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process includes: if the bandwidth negotiation process is a non-dynamic bandwidth negotiation process, determining the bandwidth for communication from the plurality of candidate bandwidths through blind detection, where the non-dynamic bandwidth negotiation process includes a static bandwidth negotiation process or a no bandwidth negotiation process. In some modalities of the twelfth aspect, the bandwidth negotiation process is determined depending on whether the PPDU indicates a preset parameter or based on a value of a preset parameter indicated by the PPDU. In some twelfth aspect modalities, the PPDU is a PPDU in a non-HT non-high-performance format or a duplicated non-HT duplicated PPDU in a non-HT non-high-performance format. The brief description portion is provided to outline the selection of concepts in a simplified manner. The concepts are described more fully in the specific implementations that follow. The brief description is not intended to identify key features or essential characteristics of this disclosure or to limit its scope. BRIEF DESCRIPTION OF THE DRAWINGS The features, advantages, and other aspects described above and in this disclosure become clearer with reference to the accompanying drawings and the following detailed descriptions. In the accompanying drawings, identical or similar reference numbers represent identical or similar items. FIGURE 1 is a schematic block diagram of a communication environment for implementing modalities of this request; FIGURE 2 is a flowchart of a bandwidth determination process according to some modalities of this disclosure; FIGURE 3A and FIGURE 3B are example schematic diagrams of duplicate non-HT PPDU in accordance with some modalities of this disclosure; FIGURE 4 is a schematic diagram of a check of a second group of bits according to one modality of this request; FIGURE 5 is a flowchart of a bandwidth determination process according to some other modalities of this disclosure; FIGURE 6 is a schematic block diagram of a first device according to some modalities of this disclosure; FIGURE 7 is a schematic block diagram of a first device according to some other modality of this disclosure; and FIGURE 8 is a simplified block diagram of an example device suitable for implementing some modalities of this disclosure. In the various accompanying drawings, identical or similar reference numbers represent identical or similar elements. DETAILED DESCRIPTION OF THE INVENTION The following describes in detail the forms of this disclosure with reference to the accompanying drawings. Although the accompanying drawings illustrate some forms of this disclosure, it should be understood that this disclosure can be implemented in various ways and should not be interpreted as being limited to the forms described herein. Rather, these forms are provided for a more complete and comprehensive understanding of this disclosure. It should be understood that the accompanying drawings and the forms of this disclosure are used merely as examples and are not intended to limit the scope of protection of this disclosure. In the descriptions of the modalities in this disclosure, the term "include" and similar terms herein should be understood as non-exclusive inclusion, that is, they include but are not limited to. The term "based on" should be understood as at least partially based on. The terms "a modality" or "this modality" should be understood as at least one modality. The terms "first," "second," and similar terms may refer to different objects or the same object. Other explicit and implicit definitions may also be included below. Example of a communication environment IEEE 802.11 is one of the leading wireless access standards and has been widely used in commercial applications over the past decade. Figure 1 is a schematic diagram of a communication environment in which modalities of this disclosure can be implemented. As shown in Figure 1, in the communication environment, an access point (AP) accesses the Internet via wired or wireless connections. The access point (AP) can be associated with one or more stations (STA). The access point (AP) and the associated station (STA) perform uplink and downlink communication using a predefined protocol (for example, the IEEE 802.11 protocol). In some configurations, the AP 110 access point may be, for example, a wireless router. The STA 120 station may include a wireless mobile device, and an example of a wireless mobile device includes, but is not limited to, a smartphone, laptop, tablet, smart wearable, in-vehicle mobile device, or similar. In the IEEE 802.11a standard, only 20 MHz is supported. In subsequent standard evolutions, the bandwidth continues to increase. In the IEEE 802.11η standard, a maximum of 40 MHz is supported. In the IEEE 802.11ac / ax standard, a maximum of 160 (80+80) MHz is supported. In standards subsequent to IEEE 802.11a, to ensure backward compatibility, some MAC frames are sent in a non-high-throughput (HT) duplication manner on a channel with a bandwidth greater than 20 MHz. In other words, a frame in IEEE 802.11a format is sent on each 20 MHz channel, and the content is repeated on multiple 20 MHz channels. This allows an IEEE 802.11a station to smoothly analyze the frame. Because an IEEE 802.11a frame format is 20 MHz, a PPDU in a format other than non-HT duplicated or non-HT duplicated cannot carry bandwidth information.Therefore, a receiving end cannot accurately learn a bandwidth currently used by a transmitting end. Because a hidden node typically exists in a wireless local area network, a channel is usually reserved using an RTS (Request to Send) / CTS (Ready to Send) interaction. An RTS frame and a CTS frame are sent in a non-HT (non-HT) manner, duplicated, over a bandwidth greater than 20 MHz. Since a transmitting station and a receiving station are in different wireless channel environments, it is very useful for data communication if available bandwidth for both parties can be obtained through negotiation based on their current channel availability before data communication begins. However, when neither the RTS frame nor the CTS frame can carry bandwidth information, bandwidth negotiation cannot occur when reserving a channel. To resolve this issue, the IEEE 802.11ac standard places two bits, B5 and B6, in the first seven bits of a scrambling sequence into a field called CH_BANDWIDTH_IN_NON_HT to indicate bandwidth information. However, four states of the CH_BANDWIDTH_IN_NON_HT field are fully utilized, and consequently, B5 and B6 cannot indicate a bandwidth greater than 160 MHz. In one form of bandwidth expansion, one or more bits in B7 to B15 in a SERVICE field in a data part are used together with B5 and B6 in the encoding sequence to indicate a bandwidth. The first seven bits of the encoding sequence are a non-zero random sequence. In the IEEE 802.11ac standard, the bandwidths indicated by different values ​​of B5 and B6 are shown in Table 1. Table 1 B5B6 value Indicated bandwidth 0 CBW 20 1 CBW 40 2 CBW 80 3 CBW 160 (80+80) CBW20, CBW40, CBW80 and CBW160 in the table represent bandwidths of 20 MHz, 40 MHz, 80 MHz and 160 MHz respectively. Furthermore, to allow the receiving station to learn whether the transmitting station includes CH_BANDWIDTH_IN_NON_HT information in the encoding sequence, the transmitting end uses a signaling TA (transmit address) for indication. The signaling TA means that a unicast / multicast bit in the address TA of The IVIA / transmission bit is set to 1 to indicate that the PPDU encoding sequence carries the CH_BANDWIDTH_IN_NON_HT information. If the unicast / multicast bit in the TA is set to 0, it indicates that the encoding sequence for sending the PPDU does not carry the CH_BANDWIDTH_IN_NON_HT information. The unicast / multicast bit (bO) is also known as an individual / group bit in the standard. In the IEEE 802.11be standard, to support a bandwidth of 320 MHz, one or more bits (for example, B7) in the SERVICE field are used in conjunction with B5 and B6 in the encoding sequence to indicate a bandwidth. Table 2 shows an example of one specific indication method. Table 2 Value of B5B6 Value of B7 Indicated bandwidth 0 0 CBW 20 1 0 CBW 40 2 0 CBW 80 3 0 CBW 160 (80+80) 0 1 CBW 320 CBW 20, CBW 40, CBW 80, CBW 160 and CBW 320 in the table respectively represent bandwidths of 20 MHz, 40 MHz, 80 MHz, 160 MHz and 320 MHz. However, a conventional receiving end lacks a bit-checking mechanism for one or more bits (e.g., B7) in the service field. As a result, the receiving end cannot determine if a transmission error has occurred in one or more bits. Once a bit-checking mechanism is added, based on a common design, the receiving end assumes that the information was received incorrectly and does not perform any further processing. This results in retransmission or channel contention at the transmitting end. It should be noted that bits B5 and B6 in the current encoding sequence correspond to a parameter called CH_BANDWIDTH_IN_NON_HT. Since B7 in the service field is used in conjunction with B5 and B6 in the encoding sequence to indicate bandwidth, there are two ways to describe it. In one way, the three bits including B5 and B6 in the encoding sequence and B7 in the service field, together correspond to the parameter CH_BANDWIDTH_IN_NON_HT. In this way of describing it, B5 and B6 correspond to two bits in CH_BANDWIDTH_IN_NON_HT, and B7 corresponds to the other bit in CH_BANDWIDTH_IN_NON_HT. In other words, B5 and B6 in the encoding sequence correspond to the parameter CH_BANDWIDTH_IN_NON_HT. When the values ​​of B7 are different, the same CH_BANDWIDTH_IN_NON_HT value corresponds to different bandwidths. The implementation solutions of this patent are not limited to any of the methods described. First application of this disclosure An example of a modality in this disclosure provides an improved solution for a first device to determine bandwidth. Specifically, in some modalities, the first device receives a PPDU from a second device. The PPDU is used to determine an encoding sequence and a service field, and the first set of bits in the encoding sequence and the second set of bits in the service field indicate bandwidth. Then, if a check error occurs in the second set of bits, the first device determines bandwidth for communication between the first and second devices based on the first set of bits. In this way, according to the modalities in this disclosure, when the check error occurs in the second set of bits, the bandwidth determination for communication is not abandoned. This avoids unnecessary retransmission or channel contention. Examples of embodiments of this disclosure are described in detail below with reference to the accompanying drawings. FIGURE 2 is a flowchart of a bandwidth determination process 200 according to some embodiments of this disclosure. As shown in FIGURE 2, in block 202, a first device receives a PPDU from a second device, where the PPDU is used to determine an encoding sequence and a service field, and a first group of bits in the encoding sequence and a second group of bits in the service field indicate a bandwidth. In some configurations, the first device may include, for example, the STA 120 station shown in FIGURE 1. Accordingly, the second device may include the AP 110 access point shown in FIGURE 1. According to the solution in this disclosure, the STA 120 can determine a bandwidth for communication between the STA 120 and the AP 110 access point based on a PPDU sent from the AP 110 access point. In another implementation, the first device may alternatively include, for example, the access point AP 110 shown in FIGURE 1. Accordingly, the second device may include the station STA 120 shown in FIGURE 1. According to the solution in this disclosure, the access point AP 110 can determine a bandwidth for communication between the access point AP 110 and the station STA 120 based on a PPDU received from the station STA 120. In another implementation, the first device may alternatively include, for example, a station STA 1 shown in FIGURE 1. Accordingly, the second device may include a station STA 2 shown in FIGURE 1. According to the solution in this disclosure, STA 1 can determine a bandwidth for communication between STA 1 and station 2 based on a PPDU received from station 2. In some modes, the PPDU received by the first device may carry a control frame or a management frame. In some modes of the first aspect, the received PPDU is a non-HT format PPDU or a duplicate non-HT format PPDU. Examples of the control frame carried include, but are not limited to, an RTS (Request to Send) frame, a CTS (Ready to Send) frame, a PS-Poll (Power Saving Poll) frame, a CF-end (No Contention End) frame, a BAR (Request to Block Acknowledge) frame, or an NDP (Null Data PPDU Advertisement) frame. Figure 3A and Figure 3B are example schematic diagrams 300A and 300B of a duplicate non-HT PPDU according to some modalities of this disclosure. Figure 3A is an entity diagram 300A of the transmission of a duplicate non-HT PPDU on an 80 MHz channel. The duplicate non-HT PPDU is transmitted on each 20 MHz channel using an IEEE 802.11a frame format and specifically includes four parts: an L-STF, an LLTF, an L-SIG, and data. The data further includes four parts: a service field, a PSDU (encoded PSDU), a tail bit, and a padding bit. The duplicate non-HT PPDU is transmitted on four 20 MHz channels of the 80 MHz network in a full-repeat manner. Figure 3B is a schematic diagram of the transmission of a duplicate non-HT PPDU on a channel, for example, 320 MHz, which is larger than 160 MHz. The principle of transmitting the duplicate non-HT PPDU is similar to that of transmitting the duplicate non-HT PPDU on 80 MHz shown in Figure 3A, except that the number of duplicate copies increases as the bandwidth increases. The duplicate non-HT PPDU includes a Physical Layer Preamble (PHY Preamble), a Signal field (SIGNAL), and a Data portion (DATA). The Signal portion carries a Signal Indication and a Parity bit, both of which are required for the Data portion. If the Parity bit check is successful, the Data portion continues to be parsed using the Signal field's Indication information. Conversely, if the Parity bit check is unsuccessful, it indicates that the Physical Layer signaling is being received incorrectly, and the subsequent Data portion is not parsed. The Data portion includes a Service field, a PSDU field, a Tail field, and a Padding bit. The PSDU field carries the contents of a MAC layer frame. The MAC layer frame includes an FCS field used to check if the PSDU contents are correct. If the FCS field is correct, it indicates that the frame was received correctly. In this case, a receiving station proceeds to make a response based on the MAC frame contents according to a protocol procedure. If the FCS field is incorrect, it indicates that the frame was received incorrectly. In this case, a receiving station discards the frame. Parity bit errors are explained herein. The parity bit in the signal field is used to check the first 17 bits (a SPEED field, a reserved bit, and a LENGTH field). An even parity check is used.Specifically, when a transmitting end sends the signal field, it is guaranteed that the number of bits set to 1 in the parity bit and the first 17 bits is an even number. If a receiving end finds that the number of bits set to 1 in the received parity bit and the first 17 received bits is an odd number, it indicates a check error. If the number is even, it indicates no check error. In an FCS (Frame Check Sequence) check, the receiving station generates a check sequence based on the content to be checked in a received PSDU and an FCS algorithm to determine if the check sequence is the same as a received FCS check sequence. If the check sequence is the same as the received FCS check sequence, no FCS check error occurs.Otherwise, an FCS check error occurs. In some modes, when the second device is going to send a duplicate or non-HT PPDU, the second device can encode a portion of the data using an encoding sequence, thus including that encoded data portion in the PPDU to be sent. Consequently, upon receiving the PPDU, the first device can determine, based on the encoded data portion, the encoding sequence used by the transmitting end, and decrypt the encoded data portion using that encoding sequence to obtain the data portion. In the data portion, a service field comprises 16 bits, designated as bits 0 through 15 (represented as B0 through B15). Bit 0 is transmitted first in terms of time. Bits 0 through 6 in the service field are set to 0, allowing the receiving end to synchronize decoding. The remaining nine bits (B7 through B15) in the service field are reserved and are also set to 0. Bits B7 through B15 in the service field can be ignored for a station using a standard predating IEEE 802.11be. The service field is present in all PPDUs transmitted in a non-HT or duplicated non-HT format. Therefore, the service field is not limited by a specific MAC frame structure and is universal. The service field was originally designed to assist with a physical layer encoding operation. This is a common operation for all MAC frames. Consequently, the service field exists in all MAC frames.In some modes, the second device can use the first group of bits (for example, bits B5 and B6) in the encoding sequence and the second group of bits (for example, bit B7) in the service field to indicate a bandwidth, so that more bandwidths can be specified. In some modes, the first bit group and / or the second bit group may include one or more bits. For example, as shown in Table 3, the first bit group may include bits B5 and B6 in the encoding sequence, and the second bit group may include bit B7 in the service field. Table 3 B5B6 in the encoding sequence B7 in the SERVICE field Indicated bandwidth 0 0 20 MHz 1 0 40 MHz 2 0 80 MHz 3 0 160 MHz 0 1 320 MHz 1 to 3 1 Reserved It should be understood that the bandwidth indicated in Table 3 is merely an example. For instance, 480 MHz may be indicated later using B5, B6, and B7, both of which are 1. This disclosure is not intended to limit how the first and second bit groups can be used to indicate bandwidth. In block 302, if no FCS check error occurs in the PPDU, the first device checks the second group of bits to determine if a check error occurred there. In some modes, for example, the first device can check the second group of bits by using one or more bits in the service field. For example, as shown in Figure 4, bits B7 through B9 can be checked based on B10 in the service field using a parity check method. It should be understood that the second group of bits can alternatively be checked using any other suitable bit and / or any other suitable form of checking. This disclosure is not intended to limit any specific method of checking the second group of bits. In block 304, if a check error occurs in the second group of bits, the first device determines a bandwidth for communication between the first device and the second device based on the first group of bits. In some modes, if the first group of bits indicates a single candidate bandwidth, that single candidate bandwidth is determined as the bandwidth for communication. In the example in Table 3, when a value of B5B6 is 1, 2, or 3, it can indicate a single candidate bandwidth, regardless of a value of B7. Conversely, when a value of B5B6 is 0, it indicates two candidate bandwidths, namely 20 MHz and 320 MHz. Therefore, when the value of B5B6 is determined to be 1, 2, or 3, the first device can uniquely determine the bandwidth for communication, regardless of whether a check error occurs in B7. For example, the first device can determine the bandwidth based on a predefined mapping relationship between the first group of bits and a corresponding bandwidth. See the example in Table 3. When the check error occurs at B7, for example, the first device can determine the bandwidth based on the first group of bits (B5-B6 in the encoding sequence) according to Table 4. Table 4 B5B6 in the encoding sequence. Indicated bandwidth: 1 40 MHz, 2 80 MHz, 3 160 MHz In some modes, if the first group of bits indicates a plurality of candidate bandwidths, the first device can further determine the bandwidth for communication from the plurality of candidate bandwidths based on a bandwidth negotiation process between the first device and the second device. The bandwidth negotiation process determines whether bandwidth negotiation is accepted between the first and second devices. In some modes, the bandwidth negotiation process may include a dynamic bandwidth negotiation process. The dynamic bandwidth negotiation process is as follows: When sending an RTS frame, a station that supports dynamic bandwidth negotiation sets B4 (indicating DYN_BANDWIDTH_IN_NON_HT) in the first seven bits of the encoding sequence to 1 (indicating a dynamic mode). After a receiving station receives the RTS frame, if a NAV (Network Allocation Vector) indicates idle, and a candidate bandwidth less than or equal to the bandwidth of the RTS frame meets the following condition, the receiving station sends a CTS (Ready To Send) frame using the candidate bandwidth. Otherwise, no CTS is returned.The condition that must be met is that a CCA (Clear Channel Assessment) detection result for a candidate bandwidth secondary channel is idle within a PIFS (Point Coordination Function Interframe Space) time before the RTS is sent. In some modes, the bandwidth negotiation process may include a static bandwidth negotiation process. The static bandwidth negotiation process is as follows: When sending an RTS frame, a station that does not support dynamic bandwidth negotiation sets B4 (indicating DYN_BANDWIDTH_IN_NON_HT) in the first seven bits of the encoding sequence to 0 (indicating a static mode). After a receiving station receives the RTS frame, if a NAV indicates idle, and the bandwidth of the RTS frame meets the following condition, the receiving station sends a CTS frame using the same bandwidth as the RTS frame. Otherwise, no CTS is returned. The condition that must be met is that a CCA detection result for a subchannel of the RTS bandwidth is idle within a PIFS time before the RTS is sent. In some modes, the bandwidth negotiation process may also include a bandwidth-free process. The bandwidth-free process is as follows: When a station sends a non-HT or non-HT PPDU carrying content that is not an RTS frame, a DYN_BANDWIDTH_IN_NON_HT indication is not used. In other words, B4 in the first seven bits of the encoding sequence can be randomly generated, provided that the first seven bits of the encoding sequence are not all 0. In this case, a receiving station must return a response frame using the same bandwidth as the received frame. In this specification, considering that both the static bandwidth negotiation process and the bandwidth-free negotiation process require the receiving station to accurately identify the bandwidth of the received frame, in order to set the bandwidth of the response frame to be the same as the bandwidth of the received frame, the static bandwidth negotiation process and the bandwidth-free negotiation process are collectively referred to as the non-dynamic bandwidth negotiation process. In some variations of the first aspect, the bandwidth negotiation process is determined by whether the PPDU specifies a preset parameter (e.g., DYN_BANDWIDTH_IN_NON_HT) or is based on a preset parameter value specified by the PPDU. For example, when the parameter DYN_BANDWIDTH_IN_NON_HT is not specified in the PPDU, the bandwidth negotiation process can be determined to be the no-bandwidth-negotiation process; when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 0 in the PPDU, the bandwidth negotiation process can be determined to be the static bandwidth negotiation process; or when the parameter DYN_BANDWIDTH_IN_NON_HT is specified as 1 in the PPDU, the bandwidth negotiation process can be determined to be the dynamic bandwidth negotiation process. In some modes, if the bandwidth negotiation process is dynamic bandwidth negotiation, the first device can select a smaller candidate bandwidth from the plurality of candidate bandwidths. However, see the example in Table 3. If the first device determines that the value of B5B6 is 0, and the bandwidth negotiation process between the first and second devices is dynamic bandwidth negotiation, the first device can select a smaller bandwidth (for example, 20 MHz) from the two candidate bandwidths (for example, the 20 MHz bandwidth and the 320 MHz bandwidth) indicated by B5B6 as the bandwidth for communication between the first and second devices. In another example, if the value of B5B6 is 1 and the value of B7 is 0, it indicates 40 MHz; or if the value of B5B6 is 1 and the value of B7 is 1, it indicates 480 MHz. In this case, if the check error occurs in B7, and the value of B5B6 is 1, the first device can use a smaller bandwidth of 40 MHz across both bandwidths as the bandwidth for communication between the first and second devices. In this way, although some bandwidth may be lost, the first device can successfully establish data communication between itself and the second device, instead of simply assuming a PPDU check failure and failing to generate a response. This can prevent retransmission or channel contention at the transmitting end, conserve valuable air interface resources, and improve system efficiency. In some modes, alternatively, the first device can directly determine, based on the pre-established mapping relationship between the first group of bits and a corresponding bandwidth, the bandwidth corresponding to the first group of bits. For example, a mapping table (e.g., Table 5) corresponding to the dynamic bandwidth negotiation process can be pre-established, so that the first device can directly determine, based on the mapping table, the bandwidths corresponding to different values ​​of the first group of bits in the dynamic bandwidth negotiation process. Table 5 B5B6 in the encoding sequence Indicated bandwidth 0 20 MHz 1 40 MHz 2 80 MHz 3 160 MHz IVIA / In some modes, if the bandwidth negotiation process is the non-dynamic bandwidth negotiation process, the first device can determine the bandwidth for communication from the plurality of candidate bandwidths through blind detection. In some modes, blind detection can be performed based on information obtained by the physical layer during a receive process. For example, in a PPDU receive process, an EHT receiving station records the received signal strength in each 20 MHz subchannel within 320 MHz, performs cross-correlation on the receive channels in each 20 MHz subchannel, or separately performs frame header synchronization in each 20 MHz subchannel. In this way, it is determined whether there is a received signal only in the primary 20 MHz or whether there is a received signal in each 20 MHz within 320 MHz. It should be understood that any suitable blind detection technology may be used, and this disclosure is not intended to limit any specific form of blind detection. It should be understood that a difference with respect to a conventional method for directly determining a bandwidth based on blind detection lies in the fact that, for example, the selection is made from 20 MHz and 320 MHz through blind detection, because the first device only needs to identify the two types of bandwidths: 20 MHz and 320 MHz, and the difference between the values ​​of the two types of bandwidths is huge, the accuracy of blind detection is considerably improved. Similar to the dynamic bandwidth negotiation process, in some modes, the first device can alternatively determine the bandwidth corresponding to the first bit group directly, based on the pre-established mapping relationship between the first bit group and a corresponding bandwidth. For example, a mapping table (e.g., Table 6) corresponding to the non-dynamic bandwidth negotiation process can be pre-established, so that the first device can directly determine, based on the mapping table, the bandwidths corresponding to different values ​​of the first bit group in the non-dynamic bandwidth negotiation process. Table 6 B5B6 in the encoding sequence. Indicated bandwidth: 0 20 MHz or 320 MHz as identified by blind detection; 1 40 MHz; 2 80 MHz; 3 160 MHz In some modes, to reduce bandwidth waste caused in the dynamic bandwidth negotiation process where the smallest bandwidth is used directly as the bandwidth for communication between the first and second devices, a correspondence between the first bit group, the second bit group, and a bandwidth can be further regulated at the transmitting and receiving ends. An example where B5B6 in the encoding sequence and B7 in the service field indicate a bandwidth mode is still used, and a mapping relationship between B5B6, B7 and a bandwidth can be represented, for example, as shown in Table 7. One difference from the mapping relationship in Table 3 is that 320 MHz can be indicated using a B5B6 value of 3 and a B7 value of 1. Table 7 B5B6 in the encoding sequence B7 in the SERVICE field Indicated bandwidth 0 0 20 MHz 1 0 40 MHz 2 0 80 MHz 3 0 160 MHz 0 a2 1 Reserved 3 1 320 MHz Consequently, the mapping relationship in the dynamic bandwidth negotiation process described above can be represented as that in Table 8, and the mapping relationship in the non-dynamic bandwidth negotiation process can be represented as that in Table 9. Table 8 B5B6 in the encoding sequence Indicated bandwidth 0 20 MHz 1 40 MHz 2 80 MHz 3 160 MHz Table 9 B5B6 in the encoding sequence Indicated bandwidth 0 20 MHz 1 40 MHz 2 80 MHz 3 The bandwidth is identified as 160 MHz or 320 MHz through blind detection It can be learned that in the dynamic bandwidth negotiation process, if the check error occurs at B7 and the value of B5B6 is 3, the first device can determine that the bandwidth is 160 MHz, that is, formulate a response using 160 MHz instead of 20 MHz. In this way, bandwidth loss can be reduced. Second application of this disclosure An example of a modality in this disclosure provides an improved solution for a first device to determine a bandwidth for communication between itself and a second device. Specifically, in some modalities, the first device receives a PPDU from the second device. This PPDU is used to determine a group of bits associated with a bandwidth, located in a service field. If a bit-check error occurs within this bit group, the first device determines the bandwidth for communication between itself and the second device based on a bandwidth negotiation process between the two. Thus, according to the modalities in this disclosure, even if a bit-check error occurs, the bandwidth determination process is not abandoned.This prevents unnecessary retransmission or channel congestion. Examples of embodiments of this disclosure are described in detail below with reference to the accompanying drawings. FIGURE 5 is a flowchart of a bandwidth determination process 500 according to some embodiments of this disclosure. As shown in FIGURE 5, in block 502, a first device receives a PPDU from a second device, where the PPDU is used to determine a group of bits that are associated with a bandwidth and are in a service field. In some configurations, the first device may include, for example, the STA 120 station shown in FIGURE 1. Accordingly, the second device may include the AP 110 access point shown in FIGURE 1. According to the solution in this disclosure, the STA 120 can determine a bandwidth for communication between the STA 120 and the AP 110 access point based on a PPDU sent from the AP 110 access point. In another implementation, the first device may alternatively include, for example, the access point AP 110 shown in FIGURE 1. Accordingly, the second device may include the station STA 120 shown in FIGURE 1. According to the solution in this disclosure, the access point AP 110 can determine a bandwidth for communication between the access point AP 110 and the station STA 120 based on a PPDU received from the station STA 120. In another implementation, the first device may alternatively include, for example, a station STA 1 shown in FIGURE 1. Accordingly, the second device may include a station STA 2 shown in FIGURE 1. According to the solution in this disclosure, STA 1 can determine a bandwidth for communication between STA 1 and station 2 based on a PPDU received from station 2. In some modes, the PPDU received by the first device may carry a control frame or a management frame. In some modes of the first aspect, the received PPDU is a non-HT PPDU or a duplicate non-HT PPDU. Examples of the control frame carried include, but are not limited to, an RTS (Request to Send) frame, a CTS (Ready to Send) frame, a PS-Poll (Power Saving Survey) frame, a CF-end (No Contention End) frame, a BAR (Request to Block Acknowledge) frame, or an NDP (Null Data PPDU Advertisement) frame. For specific structures of a non-HT frame and a duplicate non-HT frame, see the descriptions above regarding FIGURE 3. These details are not described again here. In some modes, when the second device is going to send a duplicate or non-HT PPDU, the second device can encode a portion of the data using an encoding sequence, thus including that encoded data portion in the PPDU to be sent. Consequently, upon receiving the PPDU, the first device can determine, based on the encoded data portion, the encoding sequence used by the transmitting end, and decrypt the encoded data portion using that encoding sequence to obtain the data portion. In the data portion, a service field comprises 16 bits, designated as bits 0 through 15. Bit 0 is transmitted first in terms of time. Bits 0 through 6 in the service field are set to 0, allowing the receiving end to synchronize decoding. The remaining nine bits (bits B7 through B15) in the service field are reserved and are also set to 0. Bits B7 through B15 in the service field can be ignored for a station using a standard predating IEEE 802.11be. The service field is present in all PPDUs transmitted in a non-HT or duplicated non-HT format. Therefore, the service field is not limited by a specific MAC frame structure and is universal. The service field was originally designed to assist with a physical layer encoding operation. This is a common operation for all MAC frames. Consequently, the service field exists in all MAC frames.In some modes, the second device can use a group of bits (for example, bits B5 and B6) in the encoding sequence and the group of bits (for example, bit B7) in the service field to indicate a bandwidth, so that more bandwidths can be specified. IVIA / Table 10 B5B6 in the encoding sequence B7 in the SERVICE field Indicated bandwidth 0 0 20 MHz 1 0 40 MHz 2 0 80 MHz 3 0 160 MHz 0 1 320 MHz 1 to 3 1 Reserved In some modes, the bit group in the service field may include one or more bits. For example, as shown in Table 10, the bit group in the encoding sequence may include bits B5 and B6 in the encoding sequence, and the bit group in the service field may include bit B7 in the service field. It should be understood that the bandwidth indicated in Table 10 is merely an example. For instance, 480 MHz can be indicated later using B5, B6, and B7, both of which are 1. This disclosure is not intended to limit how a bit can be used to indicate bandwidth. In block 504, if no FCS check error occurs in the PPDU, the first device checks the bit group to determine if a check error has occurred. In some modes, for example, the first device can check the bit group by using one or more bits in the service field. Similarly, as described with reference to Figure 4, the first device can check B7 to B9 based on B10 in the service field using a parity check method. It should be understood that the bit group can be alternatively verified using any other suitable bit and / or any other suitable method of verification. This disclosure is not intended to limit any specific method of verifying the bit group. In block 506, if a check error occurs in the bit group, the first device determines a bandwidth for communication between the first device and the second device based on a bandwidth negotiation process between the first device and the second device. The bandwidth negotiation process determines whether bandwidth negotiation is accepted between the first and second devices. In some modes, the bandwidth negotiation process may include a dynamic bandwidth negotiation process. The dynamic bandwidth negotiation process is as follows: When sending an RTS frame, a station that supports dynamic bandwidth negotiation sets B4 (indicating DYN_BANDWIDTH_IN_NON_HT) in the first seven bits of the encoding sequence to 1 (indicating a dynamic mode). After a receiving station receives the RTS frame, if a NAV (Network Allocation Vector) indicates idle, and a candidate bandwidth less than or equal to the bandwidth of the RTS frame meets the following condition, the receiving station sends a CTS (Ready To Send) frame using the candidate bandwidth. Otherwise, no CTS is returned.The condition that must be met is that a CCA (Clear Channel Assessment) detection result for a candidate bandwidth secondary channel is idle within a PIFS (Point Coordination Function Interframe Space) time before the RTS is sent. In some modes, the bandwidth negotiation process may include a static bandwidth negotiation process. The static bandwidth negotiation process is as follows: When sending an RTS frame, a station that does not support dynamic bandwidth negotiation sets B4 (indicating DYN_BANDWIDTH_IN_NON_HT) in the first seven bits of the encoding sequence to 0 (indicating a static mode). After a receiving station receives the RTS frame, if a NAV indicates idle, and the bandwidth of the RTS frame meets the following condition, the receiving station sends a CTS frame using the same bandwidth as the RTS frame. Otherwise, no CTS is returned. The condition that must be met is that a CCA detection result for a subchannel of the RTS bandwidth is idle within a PIFS time before the RTS is sent. In some modes, the bandwidth negotiation process may also include a bandwidth-free process. The bandwidth-free process is as follows: When a station sends a non-HT or non-HT PPDU carrying content that is not an RTS frame, a DYN_BANDWIDTH_IN_NON_HT indication is not used. In other words, B4 in the first seven bits of the encoding sequence can be randomly generated, provided that the first seven bits of the encoding sequence are not all 0. In this case, a receiving station must return a response frame using the same bandwidth as the received frame. In this specification, considering that both the static bandwidth negotiation process and the bandwidth-free negotiation process require the receiving station to accurately identify the bandwidth of the received frame, in order to set the bandwidth of the response frame to be the same as the bandwidth of the received frame, the static bandwidth negotiation process and the bandwidth-free negotiation process are collectively referred to as the non-dynamic bandwidth negotiation process. In some modalities, the bandwidth negotiation process is determined depending on whether the PPDU indicates a preset parameter (for example, IVIA / DYN_BANDWIDTH_IN_NON_HT) or based on a preset parameter value indicated by the PPDU. For example, when the DYN_BANDWIDTH_IN_NON_HT parameter is not indicated in the PPDU, the bandwidth negotiation process can be determined to be the non-bandwidth negotiation process; when the DYN_BANDWIDTH_IN_NON_HT parameter is indicated as 0 in the PPDU, the bandwidth negotiation process can be determined to be the static bandwidth negotiation process; or when the DYN_BANDWIDTH_IN_NON_HT parameter is indicated as 1 in the PPDU, the bandwidth negotiation process can be determined to be the dynamic bandwidth negotiation process. In some configurations, if the bandwidth negotiation process is dynamic, a preset bandwidth is determined as the bandwidth for communication. For example, the preset bandwidth might be 20 MHz. This way, if a check error occurs in the bit group within the service field, the first device can directly determine 20 MHz as the bandwidth for communication between the first and second devices. This prevents situations where the first device does not respond directly to the PPDU and reduces the processing complexity for the first device. In some configurations, the first device can further determine the bandwidth for communication between the first and second devices with reference to both the bandwidth negotiation process and the bit group in the encoding sequence. For ease of description, in this implementation, the bit group in the service field is referred to as a third bit group (e.g., B7 in the service field), and the bit group in the encoding sequence is referred to as a fourth bit group (e.g., B5B6 in the encoding sequence). Consequently, if the fourth group of bits indicates a plurality of candidate bandwidths, the first device determines the bandwidth for communication from among these candidate bandwidths based on the bandwidth negotiation process. Conversely, if the fourth group of bits indicates a single candidate bandwidth, the first device can determine that single candidate bandwidth as the bandwidth for communication. In some modes, if the bandwidth negotiation process is dynamic bandwidth negotiation, the first device can select a smaller candidate bandwidth from the plurality of candidate bandwidths. However, see the example in Table 10. If the first device determines that a B5B6 value is 0, and the bandwidth negotiation process between the first and second devices is dynamic bandwidth negotiation, the first device can select a smaller bandwidth (for example, 20 MHz) from the two candidate bandwidths (for example, 20 MHz and 320 MHz) indicated by B5B6 as the bandwidth for communication between the first and second devices. In another example, if B5B6 is 1 and B7 is 0, it indicates 40 MHz; or if B5B6 is 1 and B7 is 1, it indicates 480 MHz. In this case, if a check error occurs in B7, and B5B6 is 1, the first device can use a smaller 40 MHz bandwidth for communication between the first and second devices. In this way, although some bandwidth may be lost, the first device can successfully establish data communication between itself and the second device, instead of simply assuming a PPDU check failure and failing to generate a response. This can prevent retransmission or channel contention at the transmitting end, conserve valuable air interface resources, and improve system efficiency. In some modes, alternatively, the first device can directly determine, based on a pre-established mapping relationship between the fourth bit group and a corresponding bandwidth, the bandwidth corresponding to the fourth bit group. For example, a mapping table (e.g., Table 11) corresponding to the dynamic bandwidth negotiation process can be pre-established, so that the first device can directly determine, based on the mapping table, the bandwidths corresponding to different values ​​of the fourth bit group in the dynamic bandwidth negotiation process. Table 11 B5B6 in the encoding sequence Indicated bandwidth 0 20 MHz 1 40 MHz 2 80 MHz 3 160 MHz In some modes, if the bandwidth negotiation process is the non-dynamic bandwidth negotiation process, the first device can determine the bandwidth for communication from the plurality of candidate bandwidths through blind detection. In some modes, blind detection can be performed based on information obtained by the physical layer during a receive process. For example, in a PPDU receive process, an EHT receiving station records the received signal strength in each 20 MHz subchannel within 320 MHz, performs cross-correlation on the receive channels in each 20 MHz subchannel, or separately performs frame header synchronization in each 20 MHz subchannel. In this way, it is determined whether there is a received signal only in the primary 20 MHz or whether there is a received signal in each 20 MHz within 320 MHz. It should be understood that any suitable blind detection technology may be used, and this disclosure is not intended to limit any specific form of blind detection. It should be understood that a difference with respect to a conventional method for directly determining a bandwidth based on blind detection lies in the fact that, for example, the selection is made from 20 MHz and 320 MHz through blind detection, because the first device only needs to identify the two types of bandwidths: 20 MHz and 320 MHz, and the difference between the values ​​of the two types of bandwidths is huge, the accuracy of blind detection is considerably improved. Similar to the dynamic bandwidth negotiation process, in some modes, the first device can alternatively determine the bandwidth corresponding to the fourth bit group directly, based on the pre-established mapping relationship between the fourth bit group and a corresponding bandwidth. For example, an allocation table (e.g., Table 12) corresponding to the non-dynamic bandwidth negotiation process can be pre-established, so that the first device can directly determine, based on the mapping table, bandwidths corresponding to different values ​​of the fourth bit group in the non-dynamic bandwidth negotiation process. Table 12 B5B6 in the encoding sequence Indicated bandwidth 0 The bandwidth is identified as 20 MHz or 320 MHz via blind detection 1 40 MHz 2 80 MHz 3 160 MHz In some modes, to reduce bandwidth waste caused in the dynamic bandwidth negotiation process where the smallest bandwidth is used directly as the bandwidth for communication between the first and second devices, a correspondence between the third bit group, the fourth bit group, and a bandwidth can be regulated at the transmitting and receiving ends. An example where B5B6 in the encoding sequence and B7 in the service field indicate a bandwidth mode is still used, and a mapping relationship between B5B6, B7 and a bandwidth can be represented, for example, as shown in Table 13. One difference from the mapping relationship in Table 3 is that 320 MHz can be indicated using a B5B6 value of 3 and a B7 value of 1. Table 13 B5B6 in the encoding sequence B7 in the SERVICE field Indicated bandwidth 0 0 20 MHz 1 0 40 MHz 2 0 80 MHz 3 0 160 MHz 0 a2 1 Reserved 3 1 320 MHz Consequently, the mapping relationship in the dynamic bandwidth negotiation process described above can be represented as that in Table 14, and the mapping relationship in the non-dynamic bandwidth negotiation process can be represented as that in Table 15. Table 14 B5B6 in the encoding sequence Indicated bandwidth 0 20 MHz 1 40 MHz 2 80 MHz 3 160 MHz Table 15 B5B6 in the encoding sequence Indicated bandwidth 0 20 MHz 1 40 MHz 2 80 MHz 3 The bandwidth is identified as 160 MHz or 320 MHz through blind detection It can be learned that in the dynamic bandwidth negotiation process, if the check error occurs at B7 and the value of B5B6 is 3, the first device can determine that the bandwidth is 160 MHz, that is, formulate a response using 160 MHz instead of 20 MHz. In this way, bandwidth loss can be reduced. Example of apparatus and example of device Figure 6 is a schematic block diagram of a first device 600 according to some embodiments of this disclosure. As shown in Figure 6, the first device 600 includes a receiving unit 610 and a processing unit 620. The receiving unit 610 is configured to receive a PPDU from a second device, where the IVIA / PPDU is used to determine an encoding sequence and a service field. The first group of bits in the encoding sequence and the second group of bits in the service field indicate a bandwidth. The 620 processing unit is configured to: if a check error occurs in the second group of bits, determine a bandwidth for communication between the device and the second device based on the first group of bits. It should be understood that the receiving unit 610 and the processing unit 620 in the first device 600 can be further configured to implement another process or step in bandwidth determination as described in the first implementation above. For specific details, refer to the related descriptions above. Details are not described again herein. Figure 7 is a schematic block diagram of a first device 700 according to some other embodiments of this disclosure. As shown in Figure 7, the first device 700 includes a receiving unit 710 and a processing unit 720. The receiving unit 710 is configured to receive a PPDU from a second device, where the PPDU is used to determine a group of bits that are associated with a bandwidth and are in a service field. The processing unit 720 is configured to: if a check error occurs in the bit group, determine a bandwidth for communication between the first and second devices based on a bandwidth negotiation process between the first and second devices. It should be understood that the receiving unit 710 and the processing unit 720 in the first device 700 can be further configured to implement another process or step in bandwidth determination, as described in the second implementation above. For specific details, refer to the related descriptions above. Details are not described again herein. It should be understood that the first 600 device and / or the first 700 device may be implemented using an application-specific integrated circuit, one or more FPGAs (field-programmable gate arrays), a PLD (programmable logic device), a controller, a state machine, gate logic, a discrete hardware component, any other suitable circuit, or any combination of circuits capable of performing various processes in this disclosure, a chip, a board, a communication device, or the like. The figure is a simplified block diagram of an example 800 device suitable for implementing the modalities of this disclosure. The 800 device can be configured to implement the first device in this disclosure. As shown in the figure, the 800 device includes one or more 810 processors and an 840 transceiver coupled to the 810 processor. The 840 transceiver is configured to implement the functions of the receiving units shown in FIGURE 6 and FIGURE 7. For further details, please refer to the descriptions above. No further details are described herein. The 810 processor is configured to implement the functions of the processing units shown in FIGURE 6 and FIGURE 7. For further details, refer to the descriptions above. No further details are described herein. Optionally, the first 800 device also includes an 820 memory coupled to the 810 processor. The 820 memory is configured to store instructions executed by the processor. When instructions are executed by the processor, the processor can implement the functions of the processing units shown in Figure 6 and Figure 7. For further details, see the preceding descriptions. No further details are described herein. The 840 transceiver can be configured for bidirectional communication. The 840 transceiver can have at least one communication interface used for communication. The communication interface can include any interface necessary to communicate with another device. The 810 processor can be of any type suitable for a local technical network and may include, but is not limited to, one or more general-purpose computers, dedicated computers, microcontrollers, digital signal processors (DSPs), and controller-based multi-core architectures. The 800 device may have a plurality of processors, for example, application-specific integrated circuit chips, where the chips belong, in terms of timing, to a clock synchronized with a main processor. Memory 820 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memory include, but are not limited to, read-only memory (ROM) 824, erasable programmable read-only memory (EPROM), flash memory, a hard disk drive, a compact disc (CD), a digital video disc (DVD), and other magnetic and / or optical storage. Examples of volatile memory include, but are not limited to, random-access memory (RAM) 822 and other volatile memory that does not persist through a power outage. A computer program 830 includes computer-executable instructions executed by the associated processor 810. The program 830 can be stored in ROM 824. The processor 810 can perform any appropriate action and processing by loading the program 830 into RAM 822. The modalities of this disclosure can be implemented using program 830, so that device 800 can perform any process described with reference to FIGURE 2 to FIGURE 6. The modalities of this disclosure can alternatively be implemented by using hardware or a combination of software and hardware. In some embodiments, program 830 can be physically contained on a computer-readable medium. The computer-readable medium can be contained on device 800 (for example, in memory 820) or another storage device accessible from device 800. Program 830 can then be loaded from the computer-readable medium into RAM 822 for execution. The computer-readable medium can include any type of non-volatile physical memory, such as a ROM, EPROM, flash memory, hard disk, or DVD. In general, various embodiments of this disclosure can be implemented using dedicated hardware or circuitry, software, logic, or any combination thereof. Some aspects may be implemented using hardware, and other aspects may be implemented using firmware or software, or may be executed by means of a controller, a microprocessor, or another computing device. Although various aspects of the embodiments of this disclosure are shown and illustrated as block diagrams, flowcharts, or other diagrams, it should be understood that the blocks, devices, systems, technologies, or methods described in this specification may be implemented as, for example, in place of a limitation, hardware, software, firmware, dedicated circuitry, logic, general-purpose hardware, controllers, other computing devices, or a combination thereof. This disclosure also provides at least one computer program product tangibly stored on a non-transient, computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions contained within a program module. These instructions are executed on a device, either on a real or virtual target processor, to perform the process / method described above. Typically, the program module includes a routine, program, library, object, class, component, data structure, or similar item that performs a particular task or implements a particular abstract data structure. In various configurations, the functions of program modules can be combined, or a function within a program module can be divided as needed.The machine-executable instructions for the program module can be executed locally or within a distributed device. On the distributed device, the program module can be located either locally or on a remote storage medium. The computer program code used to implement the method disclosed in this disclosure may be written in one or more programming languages. The computer program code may be provided for a general-purpose computer processor, a dedicated computer, or other programmable data processing device, such that when the program code is executed by the computer or other programmable data processing device, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The program code may be executed entirely on one computer, partially on one computer as a standalone software package, partially on one computer and partially on a remote computer, or entirely on one computer or remote server. In the context of this disclosure, computer program code or related data may be transported via any suitable carrier medium, enabling a device, apparatus, or processor to perform the various processes and operations described above. Examples of carrier mediums include signals, computer-readable media, and the like. Examples of signals may include propagating signals in electrical, optical, radio, sound, or other forms, such as an infrared carrier and a similar signal. A computer-readable medium can be any tangible medium that includes or stores a program used by or related to an instruction execution system, apparatus, or device. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof.More detailed examples of computer-readable storage media include an electrical connection with one or more wires, a laptop disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, an optical storage device, a magnetic storage device, or any suitable combination thereof. Furthermore, although the operations of the method disclosed in this disclosure are described in a particular order in the accompanying drawings, this does not require or imply that these operations must be performed in that particular order or that all the operations shown must be performed to achieve a desired result. Instead, the order of execution of the steps depicted in the flowchart may be changed. Additionally, or optionally, some steps may be omitted, multiple steps may be combined into one step for execution, and / or one step may be broken down into multiple steps for execution. It should be further noted that the features and functions of two or more devices, in accordance with this disclosure, may be specified in one device. Conversely, the features and functions of a device described above may be further specified in multiple devices through classification. The implementations of this disclosure are described above. The descriptions above are examples, not exhaustive, and are not limited to the disclosed implementations. Many modifications and variations are clear to a person skilled in the art without departing from the scope and spirit of the described implementations. The selection of terms used in this specification is intended to clearly explain the implementation principles, the actual application or enhancements to technologies in the market, or to enable another person skilled in the art to understand the implementations disclosed in this specification.

Claims

1. A method for determining bandwidth, characterized in that it comprises: receiving, through a first device, a physical layer protocol data unit (PPDU) from a second device, wherein the PPDU is used to determine an encoding sequence and a service field, and a first group of bits in the encoding sequence and a second group of bits in the service field indicate a bandwidth; and if a check error occurs in the second group of bits, determining a bandwidth for communication between the first device and the second device based on the first group of bits.

2. The method according to claim 1, characterized in that the determination of a bandwidth for communication between the first device and the second device based on the first group of bits comprises: if the first group of bits indicates a unique candidate bandwidth, determining the unique candidate bandwidth as the bandwidth for communication.

3. The method according to claim 1, characterized in that the determination of a bandwidth for communication between the first device and the second device based on the first group of bits comprises: if a value of the first group of bits is 1, it indicates that the bandwidth for communication is a first bandwidth; if a value of the first group of bits is 2, it indicates that the bandwidth for communication is a second bandwidth; or if a value of the first group of bits is 3, it indicates that the bandwidth for communication is a third bandwidth.

4. The method according to claim 3, characterized in that the first bandwidth is 40 MHz, the second bandwidth is 80 MHz, and the third bandwidth is 160 MHz.

5. The method according to claim 1, characterized in that the determination of a bandwidth for communication between the first device and the second device based on the first group of bits comprises: if the first group of bits indicates a plurality of candidate bandwidths, determining the bandwidth for communication from the plurality of candidate bandwidths based on a bandwidth negotiation process between the first device and the second device.

6. The method according to claim 5, characterized in that the determination of the bandwidth for communication from the plurality of candidate bandwidths comprises: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, selecting a smaller candidate bandwidth from the plurality of candidate bandwidths.

7. The method according to claim 5, characterized in that the determination of the bandwidth for communication from the plurality of candidate bandwidths comprises: if the bandwidth negotiation process is a non-dynamic bandwidth negotiation process, determining the bandwidth for communication from the plurality of candidate bandwidths through blind detection, wherein the non-dynamic bandwidth negotiation process comprises a static bandwidth negotiation process or a non-bandwidth negotiation process.

8. The method according to claim 5, characterized in that the bandwidth negotiation process is determined depending on whether the PPDU indicates a preset parameter or based on a value of a preset parameter indicated by the PPDU.

9. The method according to claim 1, characterized in that the PPDU is a PPDU in a non-high-performance (non-HT) format or a PPDU in a non-high-performance (non-HT) duplicate format.

10. A bandwidth determination method, characterized in that it comprises: receiving, through a first device, a physical layer protocol data unit (PPDU) from a second device, wherein the PPDU is used to determine a group of bits that are associated with a bandwidth and are in a service field; and if a check error occurs in the group of bits, determining a bandwidth for communication between the first device and the second device based on a bandwidth negotiation process between the first device and the second device.

11. The method according to claim 10, characterized in that the determination of a bandwidth for communication between the first device and the second device comprises: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, determining a preset bandwidth as the bandwidth for communication.

12. The method according to claim 11, characterized in that the preset bandwidth is 20 MHz.

13. The method according to claim 10, characterized in that the bit group is a third bit group, the PPDU is further used to determine a fourth bit group in an encoding sequence, and the third bit group and the fourth bit group indicate a bandwidth; and the determination of a bandwidth for communication between the first device and the second device comprises: determining the bandwidth for communication based on the bandwidth negotiation process and the fourth bit group.

14. The method according to claim 13, characterized in that the determination of the bandwidth for communication based on the bandwidth negotiation process and the fourth bit group comprises: if the fourth bit group indicates a plurality of candidate bandwidths, determining the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process.

15. The method according to claim 14, characterized in that the determination of the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process comprises: if the bandwidth negotiation process is a dynamic bandwidth negotiation process, selecting a smaller candidate bandwidth from the plurality of candidate bandwidths.

16. The method according to claim 14, characterized in that the determination of the bandwidth for communication from the plurality of candidate bandwidths based on the bandwidth negotiation process comprises: if the bandwidth negotiation process is a non-dynamic bandwidth negotiation process, determining the bandwidth for communication from the plurality of candidate bandwidths through blind detection, wherein the non-dynamic bandwidth negotiation process comprises a static bandwidth negotiation process or a non-bandwidth negotiation process.

17. The method according to claim 10, characterized in that the bandwidth negotiation process is determined depending on whether the PPDU indicates a preset parameter or based on a value of a preset parameter indicated by the PPDU.

18. The method according to claim 10, characterized in that the PPDU is a PPDU in a non-high-performance (non-HT) format or a PPDU in a non-high-performance (non-HT) duplicate format.

19. A first device, characterized in that it comprises a unit configured to perform the method in accordance with any of claims 1 to 18.

20. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, and IVIA / when the computer program is executed by a processor, the method is implemented in accordance with any one of claims 1 to 18.

21. A computer program product, comprising computer-executable instructions, characterized in that, when the computer-executable instructions are executed by a processor, the method is implemented in accordance with any one of claims 1 to 18.

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