Terminal

Abstract

This terminal comprises a management unit. The management unit manages transmission of an initial control frame such that the initial control frame is successively transmitted, at fixed intervals, to an access point that is in a power saving mode.

Description

terminal

[0001] The embodiment relates to a terminal.

[0002] A wireless LAN (Local Area Network) is a system that wirelessly connects an access point (AP), which acts as a radio station, with a terminal (STA). Through a wireless LAN, terminals located within the AP's communication range can access the network via the AP.

[0003] The IEEE 802.11bn Statement of Purpose (PAR), which is currently being standardized, includes provisions for enhancing the power-saving capabilities of access points (APs). Normally, APs operate according to their supported capabilities, such as transmit power, bandwidth, and MCS, so that they can always wait for communication from STAs (Site Activators). In recent years, wireless LANs have become more sophisticated, leading to an increase in power consumption. Therefore, especially for APs that cannot receive wired power supply, such as mobile APs, the increased power consumption in normal operating mode may reduce the available operating time. To address this reduction in available operating time due to increased power consumption, IEEE 802.11TGbn is discussing a power-saving mode in which the AP waits for communication from STAs by reducing its capabilities to the point where it cannot transmit frames but can still listen to media and receive frames. The AP then transitions to normal mode upon receiving an initial control frame (ICF), such as a trigger frame.

[0004] According to the IEEE 802.11 standard, when control frames such as trigger frames or RTS frames are used as ICFs, the AP must transmit an initial response (IR) to the ICF after receiving the ICF and after SIFS. On the other hand, a transition time is required to transition from power-saving mode to normal mode, which depends on the AP's equipment performance. This transition time is usually longer than SIFS. To account for this transition time, IEEE 802.11TGbn is considering pre-inserting padding bits into the ICF transmitted by the STA to account for the AP's transition time from power-saving mode to normal mode.

[0005] Neel Krishnan et al., “A Proposal For UHR Mobile-AP Power Save,” IEEE 802.11-24 / 450r3, March, 2024

[0006] The transition time depends on the device performance of the AP. In order to be able to transmit the IR after the SIFS from the reception of the ICF regardless of the different transition times for each AP, it is conceivable to estimate the bit length of the padding bits inserted into the ICF redundantly considering a sufficiently slow transition time. However, in this case, the frame length of the ICF may increase, the frequency utilization efficiency may decrease, and the delay may increase.

[0007] Embodiments provide a terminal that can realize a stable power save function of an AP while suppressing a decrease in frequency utilization efficiency and an increase in delay.

[0008] A terminal according to one aspect includes a management unit. The management unit manages the transmission of the initial control frame so that the initial control frame is transmitted continuously at intervals for an access point in the power saving mode.

[0009] According to the embodiments, a terminal is provided that can realize a stable power save function of an AP while suppressing a decrease in frequency utilization efficiency and an increase in delay.

[0010] FIG. 1 is a diagram showing an example of the configuration of a communication system according to an embodiment. FIG. 2 is a block diagram showing an example of the hardware configuration of an AP. FIG. 3 is a block diagram showing an example of the hardware configuration of a terminal. FIG. 4 is a block diagram showing an example of the functional configuration of an AP according to an embodiment. FIG. 5 is a block diagram showing an example of the functional configuration of a terminal according to an embodiment. FIG. 6 is a flowchart showing the operation of the terminal. FIG. 7 is a flowchart showing the operation of the AP. FIG. 8 is a timing chart showing the operation of the communication system according to FIGS. 6 and 7.

[0011] Embodiments will now be described with reference to the drawings. Figure 1 is a diagram showing an example of the configuration of a communication system according to the embodiment. As shown in Figure 1, the communication system 1 includes an access point (AP) 10, a terminal (STA) 20, and a network 30.

[0012] AP10 and terminal 20 are, for example, radio stations with wireless communication capabilities based on the OSI (Open Systems Interconnection) reference model. In the OSI reference model, wireless communication capabilities are divided into seven layers (Layer 1: Physical Layer, Layer 2: Data Link Layer, Layer 3: Network Layer, Layer 4: Transport Layer, Layer 5: Session Layer, Layer 6: Presentation Layer, Layer 7: Application Layer). The data link layer includes the LLC (Logical Link Control) sublayer and the MAC (Media Access Control) sublayer. For example, the 2.4 GHz, 5 GHz, 6 GHz, 45 GHz, and 60 GHz bands may be used for wireless communication in communication system 1. Multiple channels are allocated to each frequency band. AP10 can communicate with terminal 20. Here, Figure 1 shows one terminal, but there can be one or more terminals.

[0013] Terminal 20 can exchange traffic with AP 10. Terminal 20 is, for example, a smartphone or a PC (personal computer), and is a wireless terminal compliant with the IEEE 802.11 standard.

[0014] Next, the hardware configuration of the AP and terminal in the communication system according to the embodiment will be described.

[0015] Figure 2 is a block diagram showing an example of the hardware configuration of an AP. As shown in Figure 2, the AP 10 includes, for example, a CPU (central processing unit) 11, ROM (read-only memory) 12, RAM (random access memory) 13, a wireless communication module 14, and a wired communication module 15.

[0016] The CPU 11 is a processing circuit that controls the overall operation of the AP 10. The ROM 12 is, for example, a non-volatile semiconductor memory. The ROM 12 stores programs and data for controlling the AP 10. The RAM 13 is, for example, a volatile semiconductor memory. The RAM 13 is used as a workspace for the CPU 11. The wireless communication module 14 is a circuit used for sending and receiving data via wireless signals. The wireless communication module 14 is connected to an antenna. The wired communication module 15 is a circuit used for sending and receiving data via wired signals. The wired communication module 15 is connected to the network 30.

[0017] Although the wired communication module 15 is described as a means of connecting AP 10 and network 30, alternatively, a wireless communication module different from the wireless communication module 14 may be used to connect AP 10 and network 30, or the wireless communication module 15 may communicate with network 30 during times when it is not communicating with terminal 20.

[0018] Figure 3 is a block diagram showing an example of the hardware configuration of a terminal. As shown in Figure 3, the terminal 20 includes, for example, a CPU 21, ROM 22, RAM 23, a wireless communication module 24, a display 25, and storage 26.

[0019] The CPU 21 is a processing circuit that controls the overall operation of the terminal 20. The ROM 22 is, for example, a non-volatile semiconductor memory. The ROM 22 stores programs and data for controlling the terminal 20. The RAM 23 is, for example, a volatile semiconductor memory. The RAM 23 is used as a workspace for the CPU 21. The wireless communication module 24 is a circuit used for sending and receiving data via wireless signals. The wireless communication module 24 is connected to an antenna. The display 25 is, for example, an LCD (liquid crystal display) or an EL (electro-luminescence) display. The display 25 displays a GUI (graphical user interface) etc. corresponding to the application software. The storage 26 is a non-volatile storage device. The storage 26 stores the system software etc. of the terminal 20.

[0020] Next, the functional configuration of the AP and terminal in the communication system according to the embodiment will be described.

[0021] Figure 4 is a block diagram showing an example of the functional configuration of an AP according to an embodiment. AP10 functions as a computer comprising a data processing unit 110, a frame processing unit 120, a management unit 130, and a wireless signal processing unit 140. The data processing unit 110 is a functional block that executes processing corresponding to the LLC sublayer of the second layer and layers 3 through 7. The frame processing unit 120 and the management unit 130 are functional blocks that execute processing corresponding to the MAC sublayer of the second layer. The wireless signal processing unit 140 is a functional block that executes processing corresponding to the first layer.

[0022] The data processing unit 110 outputs data received from the network 30 via the LLC layer to the frame processing unit 120. The data processing unit 110 also outputs data received from the frame processing unit 120 to the network 30 via the LLC layer.

[0023] When data is input from the data processing unit 110 or the management unit 130, the frame processing unit 120 adds a MAC header to the input data to generate a MAC frame. The frame processing unit 120 then outputs the MAC frame to the wireless signal processing unit 140. Furthermore, when a MAC frame is input from the wireless signal processing unit 140, the frame processing unit 120 extracts data from the MAC frame and outputs the extracted data according to the type of MAC frame to the data processing unit 110 or the management unit 130. Specifically, if the MAC frame is a data frame, the frame processing unit 120 inputs the data to the data processing unit 110. If the MAC frame is a management frame or a control frame, the frame processing unit 120 inputs the data to the management unit 130.

[0024] The management unit 130 controls the logical wireless connection between the AP 10 and the terminal 20. For example, the management unit 130 executes wireless connection processing in response to an association request from the terminal 20. The management unit 130 has a mode switching unit 131. The mode switching unit 131 switches the operating mode of the AP 10 related to power saving. In this embodiment, the AP 10 has two operating modes related to power saving: Normal Operation Mode and Power Save Mode. Normal Operation Mode is the normal operating mode in which the AP operates according to its supported capabilities, such as transmit power, bandwidth, and MCS. On the other hand, Power Save Mode is a power saving mode in which power saving is achieved by reducing capabilities to the extent that frames cannot be transmitted but media listening and frame reception are still possible. The mode switching unit 131 switches the operating mode from Power Save Mode to Normal Operation Mode upon receiving an ICF in Power Save Mode. The mode switching unit 131 then instructs the frame processing unit 120 to send an initial response (IR) to the terminal 20. After the frame exchange in Normal Operation Mode is completed following the transmission of the IR, the mode switching unit 131 switches the operating mode from Normal Operation Mode to Power Save Mode.

[0025] The wireless signal processing unit 140 generates a wireless frame by adding a preamble and the like to the MAC frame input from the frame processing unit 120. The wireless signal processing unit 140 converts the generated wireless frame into a wireless signal. The wireless signal processing unit 140 then transmits the converted wireless signal via the antenna. The conversion process from wireless frame to wireless signal includes, for example, error correction coding, interleaving, subcarrier modulation, inverse fast Fourier transform, OFDM modulation, and frequency conversion. The wireless signal processing unit 140 also converts the wireless signal received via the antenna into a wireless frame. The conversion process from wireless signal to wireless frame includes, for example, frequency conversion, OFDM demodulation, fast Fourier transform, subcarrier demodulation, deinterleaving, and error correction decoding. The wireless signal processing unit 140 extracts the MAC frame from the converted wireless frame. The wireless signal processing unit 140 then outputs the extracted MAC frame to the frame processing unit 120.

[0026] Figure 5 is a block diagram showing an example of the functional configuration of a terminal according to the embodiment. The terminal 20 functions as a computer comprising a data processing unit 210, a frame processing unit 220, a management unit 230, a wireless signal processing unit 240, and an application execution unit 250. The data processing unit 210 is a functional block that executes processing corresponding to the LLC sublayer of the second layer and layers 3 through 7. The frame processing unit 220 and the management unit 230 are functional blocks that execute processing corresponding to the MAC sublayer of the second layer. The wireless signal processing unit 240 is a functional block that executes processing corresponding to the first layer. The application execution unit 250 is a functional block that executes processing corresponding to layer 7.

[0027] The data processing unit 210 outputs data received from the application execution unit 250 via the LLC layer to the frame processing unit 220. The data processing unit 210 also outputs data received from the frame processing unit 220 to the application execution unit 250 via the LLC layer.

[0028] When data is input from the data processing unit 210 or the management unit 230, the frame processing unit 220 adds a MAC header to the input data to generate a MAC frame. The frame processing unit 220 then outputs the MAC frame to the wireless signal processing unit 240. Furthermore, when a MAC frame is input from the wireless signal processing unit 240, the frame processing unit 220 extracts data from the MAC frame and outputs the extracted data according to the type of MAC frame to the data processing unit 210 or the management unit 230. Specifically, if the MAC frame is a data frame, the frame processing unit 220 inputs the data to the data processing unit 210. If the MAC frame is a management frame or a control frame, the frame processing unit 220 inputs the data to the management unit 230.

[0029] The management unit 230 controls the logical wireless connection between the terminal 20 and the AP 10. For example, the management unit 230 generates an association request based on a beacon frame from the AP 10. The management unit 230 also has an ICF transmission management unit 231. The ICF transmission management unit 231 manages the transmission of initial control frames (ICFs) to the AP 10. Specifically, the ICF transmission management unit 231 manages the operation of the frame processing unit 220 so that ICFs are transmitted continuously at regular intervals. The ICF transmission management unit 231 then initiates communication with the AP 10 if it receives an IR from the AP 10 before the number of ICF transmissions reaches the maximum number of transmissions. On the other hand, if the ICF transmission management unit 231 does not receive an IR from the AP 10 even after the number of ICF transmissions reaches the maximum number of transmissions, it determines that communication with the AP 10 has failed. Here, the ICF may be sent to AP10 at times such as when an association request is made to AP10 or when a frame is sent to AP10. Various control frames may be used as ICFs, such as trigger frames, RTS (request to send) frames, MU-RTS (multi-user RTS) frames, MU-RTS TXS trigger frames, and BSRP (buffer status report poll) frames.

[0030] The wireless signal processing unit 240 generates a wireless frame by adding a preamble and the like to the MAC frame input from the frame processing unit 220. The wireless signal processing unit 240 converts the generated wireless frame into a wireless signal. Then, the wireless signal processing unit 240 transmits the converted wireless signal via the antenna. When transmitting the wireless signal, the wireless signal processing unit 240 transmits the wireless signal using individual resources determined by the management unit 230. The conversion process from wireless frame to wireless signal includes, for example, error correction coding, interleaving, subcarrier modulation, inverse fast Fourier transform, OFDM modulation, and frequency conversion. The wireless signal processing unit 240 also converts the wireless signal received via the antenna into a wireless frame. The conversion process from wireless signal to wireless frame includes, for example, frequency conversion, OFDM demodulation, fast Fourier transform, subcarrier demodulation, deinterleaving, and error correction decoding. The wireless signal processing unit 240 extracts the MAC frame from the converted wireless frame. The wireless signal processing unit 240 then outputs the extracted MAC frame to the frame processing unit 220.

[0031] The application execution unit 250 executes an application based on data input from the data processing unit 210. The application execution unit 250 also inputs data to the data processing unit 210. For example, the application execution unit 250 can display application information on the display 25. Furthermore, the application execution unit 250 can operate based on operations on the input interface.

[0032] Next, the operation of the communication system will be explained. Figure 6 is a flowchart showing the operation of terminal 20. Prior to the operation shown in Figure 6, terminal 20 is requested by AP 10 to transmit an ICF when communicating. After this, AP 10 switches its operating mode to Power Save Mode.

[0033] In step S1, terminal 20 transmits an ICF. In this embodiment, the transmitted ICF may be the same various control frames as before, without padding or the like inserted.

[0034] In step S2, terminal 20 waits for an IR from AP 10 for a certain period of time. The IR waiting time may be, for example, IFS which is longer than SIFS. Possible IR waiting times include PIFS and DIFS. If no IR is received during the period in step S2, the process moves to step S3. If an IR is received during the period in step S2, the process moves to step S4.

[0035] In step S3, terminal 20 determines whether the number of ICF transmissions has reached a predetermined maximum number of ICF transmissions. The maximum number of transmissions can be fixedly determined considering the transition time for switching from AP10's Power Save Mode to Normal Operation Mode. In practice, the transition time depends on the equipment performance of each AP10. Therefore, the maximum number of transmissions is determined to have redundancy considering the equipment performance of each AP10. For example, the maximum number of transmissions can be determined such that (transmission time for the maximum number of ICF transmissions) + (IR waiting time for each ICF) is longer than (a sufficiently slow transition time considering equipment performance). In step S3, if the number of ICF transmissions has not reached a predetermined maximum number of ICF transmissions, the process returns to step S1. In this case, terminal 20 retransmits the ICF. In step S3, if the number of ICF transmissions has reached a predetermined maximum number of ICF transmissions, the process in Figure 6 ends. In this case, terminal 20 determines that communication has failed.

[0036] In step S4, terminal 20 performs the necessary frame exchange with AP 10. After the frame exchange is complete, the process shown in Figure 6 is terminated.

[0037] Figure 7 is a flowchart illustrating the operation of AP10. Prior to the operation shown in Figure 7, AP10 switches its operating mode to Power Save Mode. The operation shown in Figure 7 is initiated periodically while in Power Save Mode.

[0038] In step S101, AP10 determines whether or not an ICF has been received. If an ICF has not been received in step S101, the process shown in Figure 7 ends. If an ICF has been received in step S101, the process proceeds to step S102.

[0039] In step S102, AP10 switches the operating mode from Power Save Mode to Normal Operation Mode. After the switch to Normal Operation Mode is complete, the process proceeds to step S103.

[0040] In step S103, AP10 sends an IR to terminal 20. In the subsequent step S104, AP10 exchanges the necessary frames with terminal 20. After the frame exchange is complete, the process proceeds to step S105.

[0041] In step S105, AP10 switches the operating mode from Normal Operation Mode to Power Save Mode. After the switch to Power Save Mode is complete, the process shown in Figure 7 is terminated. Here, the switch from Normal Operation Mode to Power Save Mode does not necessarily have to be performed immediately after the completion of the frame replacement. For example, the switch from Normal Operation Mode to Power Save Mode may be performed after a certain period of time has elapsed since the completion of the frame replacement.

[0042] Figure 8 is a timing chart showing the operation of communication system 1 according to Figures 6 and 7. In Figure 8, STA represents terminal 20, and AP represents AP 10. The timing chart for AP also shows the AP's operation and its operating mode. Prior to the operation in Figure 8, STA is requested by AP to transmit an ICF during communication, and after this request, AP switches its operating mode to Power Save Mode. In the example in Figure 8, the maximum number of ICF transmissions is assumed to be 3.

[0043] When communication with the AP is required, such as when traffic to be transmitted to the AP occurs, the STA transmits an ICF to the AP. As the ICF, various control frames such as a trigger frame, an RTS (request to send) frame, a MU-RTS (multi-user RTS) frame, a MU-RTS TXS trigger frame, and a BSRP (buffer status report poll) frame can be used. The control frame transmitted as the ICF may be transmitted in the frame format defined in the IEEE 802.11 standard. That is, these control frames do not need to include padding. The STA waits for reception of an IR from the AP for a certain period from the transmission of the ICF. In FIG. 8, an example of PIFS (= SIFS + 1 slot) is shown, but as described above, the certain period may be a time longer than SIFS. For example, the certain period may be DIFS or the like.

[0044] Upon receiving the ICF, the AP switches its operation mode from the Power Save Mode to the Normal Operation Mode in order to return an IR for the ICF. In practice, when switching the operation mode from the Power Save Mode to the Normal Operation Mode, a transition time depending on the device performance of the AP is required. Since this transition time is usually longer than PIFS, it is difficult for the AP whose operation mode is the Power Save Mode to return an IR immediately after receiving the first ICF.

[0045] The STA that has not received an IR during a certain period determines whether the transmission count of the ICF has reached the maximum transmission count. Then, when the transmission count of the ICF has not reached the maximum transmission count, the STA transmits the ICF again. At the current time, since the transmission count of the ICF has not reached 3, which is the maximum transmission count, the STA transmits the ICF again.

[0046] In the example of FIG. 8, during the transmission period of the second ICF, the AP has completed switching the operation mode. Therefore, the AP immediately transmits an IR to the STA, for example, after the elapse of SIFS. Upon receiving the IR, the STA performs the necessary communication with the AP without transmitting the third ICF. Although not shown in FIG. 8, the necessary communication with the AP includes, for example, data frame exchange and association.

[0047] As described above, according to the embodiment, when communicating with the AP10 in the Power Save Mode, the terminal 20 intermittently and continuously transmits the ICF at regular intervals. Since it takes a transition time depending on the device performance of the AP when switching from the Power Save Mode to the Normal Operation Mode, the AP10 may not be able to return an IR with a single transmission of the ICF. In contrast, with intermittent and continuous transmission of the ICF, the AP can immediately return an IR after switching to the Normal Operation Mode. Therefore, the terminal 20 can transmit the ICF without considering different transition times for each AP10.

[0048] Furthermore, the terminal 20 does not need to insert padding or the like depending on the device performance of the AP10 into the transmitted ICF. Therefore, a decrease in frequency utilization efficiency and an increase in delay can be suppressed. That is, in the embodiment, a terminal that can realize a stable power save function of the AP while suppressing a decrease in frequency utilization efficiency and an increase in delay can be provided. Also, the ICF may be used for various functions such as NPCA (Non Primary Channel Access) and TXOP Sharing, in addition to the power save function. In the embodiment, padding for the ICF specialized for the power save function is unnecessary. That is, the ICF of the embodiment can be directly applied to other functions other than the power save function.

[0049] Furthermore, in this embodiment, the number of ICF transmissions is limited by the maximum number of transmissions. This suppresses an increase in communication time beyond what is necessary. In addition, by determining the maximum number of transmissions to have redundancy considering the equipment performance of each AP 10, a stable power saving function that takes into account the equipment performance of AP 10 can be realized while suppressing an increase in communication time beyond what is necessary.

[0050] In this embodiment, it is stated that no padding is inserted into the ICF, but padding may be inserted into the ICF. In other words, the intermittent continuous transmission of the ICF and the insertion of padding into the ICF in this embodiment may be used in combination.

[0051] Furthermore, in this embodiment, the maximum number of ICF transmissions is determined to have redundancy, taking into account the equipment performance of each AP 10. Alternatively, the maximum number of ICF transmissions may be determined after receiving notification of equipment performance information from AP 10.

[0052] Furthermore, the processes in AP10 and terminal 20 shown in the flowcharts described above can also be stored as programs that can be executed by a computer processor. In addition, they can be stored and distributed on external storage media such as magnetic disks, optical disks, and semiconductor memory. The processors of AP10 and terminal 20 can then read the programs stored on the external storage media and execute various processes by being controlled by the read programs.

[0053] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways during implementation without departing from its essence. Furthermore, each embodiment may be combined as appropriate, and in that case, the combined effects can be obtained. Moreover, the above embodiments include various inventions, and various inventions can be extracted by selecting combinations from the multiple constituent elements disclosed. For example, if the problem can be solved and effects obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiment, then the configuration with these deleted constituent elements can be extracted as an invention.

[0054] 1...Communication system 10...Access point (AP) 11...CPU 12...ROM 13...RAM 14...Wireless communication module 15...Wired communication module 20...Terminal 21...CPU 22...ROM 23...RAM 24...Wireless communication module 25...Display 26...Storage 30...Network 110...Data processing unit 120...Frame processing unit 130...Management unit 131...Mode switching unit 140...Wireless signal processing unit 210...Data processing unit 220...Frame processing unit 230...Management unit 231...ICF transmission management unit 240...Wireless signal processing unit 250...Application execution unit

Claims

1. A terminal equipped with a management unit that manages the transmission of initial control frames to an access point in power-saving mode so that the initial control frames are transmitted continuously at regular intervals.

2. The terminal according to claim 1, wherein the initial control frame does not include padding.

3. The terminal according to claim 1, wherein the aforementioned period is longer than the SIFS period.

4. The terminal according to claim 3, wherein the aforementioned period is PIFS or DIFS.

5. The terminal according to claim 1, wherein the initial control frame includes a trigger frame, an RTS frame, a MU-RTS frame, a MU-RTS TXS trigger frame, and a BSRP frame.

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