Communication device, communication method, and program

Abstract

To make it possible to receive frames transmitted from other communication devices more reliably.SOLUTION: A communication device operates by transitioning between a first state and a second state in which the power consumption is lower than the first state and is capable of concurrently operating a function of participating in a first communication network for communication and a function of participating in a second communication network for communication. The communication device controls to transition the communication device from the second state to the first state to receive a frame from a first other communication device and to transition the communication device to the second state after a predetermined period of time has elapsed, initiates a process to establish a connection with a second other communication device when receiving the frame from the second other communication device within the predetermined period of time, and does not initiate a process to establish a connection with the second other communication device when receiving the frame from the second other communication device outside of the predetermined period of time.SELECTED DRAWING: Figure 3

Description

Technical Field

[0005]

[0001] The present invention relates to a communication device that performs wireless communication.

Background Art

[0002] Conventionally, in a wireless communication device compatible with the IEEE802.11 standard and the Wi-Fi standard, a communication device that operates the station (hereinafter, STA) function and the access point (hereinafter, AP) function in parallel has been proposed. Here, IEEE is an abbreviation for Institute of Electrical and Electronics Engineers. While establishing a connection with an AP through the STA function and executing communication, the communication device can establish a connection with a STA through the AP function and execute communication.

[0003] Similarly, a communication device having a plurality of STA functions and capable of operating the first STA function and the second STA function in parallel has been proposed. For example, the communication device can establish a connection with an AP in the first STA function and execute communication, and at the same time, establish a connection with a GO (Group Owner) through the client function of the Wi-Fi Direct standard in the second STA function and perform communication.

[0004] Also, in the IEEE8o2.11 standard, there is a power save function as a function for suppressing the battery consumption of a STA. In Patent Document 1 and Patent Document 2, technologies for controlling the power save mode and communicating with lower power consumption have also been proposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] A communication device having multiple STA functions as described above can operate by transitioning between a first state and a second state with lower power consumption than the first state, in accordance with the IEEE 802.11 standard. However, in the case of a communication device having multiple STA functions, including a first STA and a second STA, the following problem arises. That is, after receiving a frame from the first AP, which is the destination of the first STA, and transitioning to the second state, a frame from the second AP may arrive while the device is in the process of transitioning back to the first state to receive a frame from the second AP, which is the destination of the second STA. In the above situation, a communication device having multiple STA functions, including the first and second STAs, may not be able to receive the frame from the second AP, and packet loss may occur.

[0007] In view of the above issues, the present invention aims to more reliably receive frames transmitted from other communication devices. [Means for solving the problem]

[0008] To achieve the above objective, the present invention provides a communication device that operates by transitioning between a first state and a second state having lower power consumption than the first state, and is capable of operating in parallel a function of participating in a first communication network and communicating and a function of participating in a second communication network and communicating, comprising: receiving means for receiving frames from a first other communication device that constitutes the first communication network and a second other communication device that constitutes the second communication network; and control means for transitioning the communication device from the second state to the first state, and then transitioning to the second state after a predetermined period of time has elapsed, in order to receive the frames from the first other communication device. A receiving means for receiving a user selection to establish a connection with both the first other communication device and the second other communication device, or to establish a connection with either the first other communication device or the second other communication device,The control means, when it receives the frame from the second other communication device within the predetermined period, starts processing to establish a connection with the second other communication device, and when it receives the frame from the second other communication device outside the predetermined period, it starts processing to establish a connection with the second other communication device. stomach . [Effects of the Invention]

[0009] According to the present invention, it becomes possible to receive frames transmitted from other communication devices more reliably. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram shows the network configuration in this embodiment. [Figure 2] This diagram shows the hardware configuration of the communication device 103. [Figure 3] This is a flowchart relating to the processing of the communication device 103 in Embodiment 1. [Figure 4] This is a flowchart relating to the processing of the communication device 103 in Embodiment 2. [Figure 5] This diagram shows the state transitions of communication device 103 when communication devices 101 and 102 transmit Beacon frames. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the embodiments described below are examples, and various forms of devices, systems, methods, programs, media, etc., configured to realize the functions described are included within the scope of the present invention.

[0012] Figure 1 shows the network configuration of the communication system according to this embodiment. In Figure 1, communication devices 1101 and 2102 are Access Points (APs) that play a role in building a communication network, and AP1101 and AP2102 in Figure 1 are similar to AP101 and AP102, respectively, which will be described later. Also in Figure 1, communication device 103 is a Station (STA) that participates in the communication network built by the APs and performs communication. Communication device 103 is a personal computer (hereinafter referred to as PC). Communication device 103 is capable of operating two STA functions and can establish connections with two APs and perform communication.

[0013] Furthermore, the communication device 103 can establish a connection with the AP and perform communication in the first STA function, and in parallel, establish a connection with the GO (Group Owner) using the Wi-Fi Direct standard client function in the second STA function and perform communication.

[0014] Furthermore, communication devices 101 to 103 are capable of performing power-saving functions compliant with the IEEE 802.11 standard series. When operating in power-saving mode, communication device 103 regularly transitions between the Awake state and the Doze state, which operates with lower power consumption than the Awake state. Here, the Awake state is a state in which power is supplied to the circuit and frames can be transmitted and received, while the Doze state is a state in which frames cannot be transmitted or received.

[0015] Figure 2 shows the hardware configuration of the communication device 103. The communication device 103 consists of a wireless transceiver unit 201, a Beacon confirmation unit 202, a Beacon reception determination unit 203, an electric field strength measurement unit 204, a connection control unit 205, a user notification unit 206, a user input unit 207, a storage unit 208, and a control unit 209.

[0016] The wireless transceiver unit 201 transmits and receives wireless signals such as Beacon frames. Furthermore, when the communication device 103 operates in power-saving mode, the receiving circuit switches the power supply ON / OFF.

[0017] The Beacon confirmation unit 202 confirms the information of the Beacon received by the wireless transceiver unit 201. In this embodiment, the DTIM (Delivery Traffic Indication Message) interval included in the Beacon is confirmed.

[0018] The Beacon reception determination unit 203 predicts the timing of receiving the Beacon based on the information confirmed by the Beacon confirmation unit 202. Also, in this embodiment, for Beacons received from the same AP, the determination of the Beacon reception timing is performed only once for the first time, but it may be configured to perform the determination every time a Beacon is received.

[0019] The electric field strength reception unit 204 measures the radio wave strength of the signal received by the wireless transceiver unit 201. <​​​​​​​​​​The user input unit 207 receives various operations from the user. The user input unit 207 is an interface for the user to input various information, and in this embodiment, it also serves as an interface used by the connection control unit 205 to contact the user. Here, since the communication device 103 is a PC, the user input unit 207 is represented as a mouse, but any interface that allows the user to input information is acceptable. Furthermore, both the user input unit 207 and the user notification unit 206 may be implemented in a single module, such as a touch panel. Also, the user input unit 207 and the user notification unit 206 may be integrated with STA103 or they may be separate components.

[0023] The storage unit 208 is composed of memory such as ROM and RAM, and stores programs for various processing operations described later, as well as various information. ROM stands for Read Only Memory, and RAM stands for Random Access Memory. In addition to memory such as ROM and RAM, the storage unit 208 may also use storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs. Furthermore, the storage unit may have multiple memories or the like.

[0024] The control unit 209 is composed of, for example, a processor such as a CPU or MPU, an ASIC, a DSP, or an FPGA. CPU stands for Central Processing Unit, MPU for Micro Processing Unit, and ASIC for Application Specific Integrated Circuit. DSP stands for Digital Signal Processor, and FPGA stands for Field Programmable Gate Array.

[0025] The control unit 209 controls the entire AP and STA by executing a program stored in the memory unit 208. Alternatively, the control unit 209 may control the entire AP and STA in cooperation with the OS (Operating System) and the program stored in the memory unit 208.

[0026] <Embodiment 1> Figure 3 is a flowchart showing the processing flow when the control unit 209 executes a program stored in the memory unit 208 of STA103. This flowchart shows the connection processing flow when STA103 is instructed to connect to multiple APs.

[0027] This flowchart is initiated when the user operates the input unit 207 to select the SSID of the target AP, etc. Furthermore, during user input, if the user makes an input error or if connection is not possible for any other reason, the system may be configured to prompt the user for further input after a timer timeout.

[0028] Furthermore, in this embodiment, the connection sequence is guaranteed to start after a predetermined time has elapsed since the AP's SSID and security settings were entered.

[0029] In S301, it is determined whether or not there is an AP that has already established a connection. In this embodiment, it is determined whether or not a connection has been established with AP101. If it is determined in S301 that a connection has already been established with an AP, it is checked whether or not the power save (hereinafter referred to as PS) function of STA103 is enabled (S302). Alternatively, the Beacon confirmation unit 202 may be controlled to automatically perform PS control if it is confirmed that the PS function of AP101 is available.

[0030] When the PS function of STA103 is enabled, the receiving circuit of STA103 is periodically controlled, and STA103 regularly transitions between the Awake state and the Doze state, which operates in a lower power state than the Awake state. Here, STA103 establishes a connection with AP101 and controls the receiving circuit so that it can receive Beacon frames from AP101.

[0031] Figures 5(A) and 5(B) show the timing of receiving Beacon frames from AP101 and AP102 and the state transitions of STA103. As shown in Figure 5, STA103 regularly transitions between the "receivable" state and the "unreceivable" state. Here, the "receivable" state is the Awake state, and STA103 transitions to the Awake state in order to receive Beacon frames transmitted from AP101 and AP102. The "unreceivable" state is the Doze state, which operates in a lower power consumption state than the Awake state. As shown in Figure 5, when the PS function of STA103 is enabled, STA103 operates by regularly transitioning between the Awake state and the Doze state. That is, STA103 operates by transitioning between the Awake state and the Doze state, transitioning from the Doze state to the Awake state in order to receive Beacon frames from the AP, and then transitioning to the Doze state after a predetermined time has elapsed.

[0032] Figure 5(A) shows an example where the Beacon transmission timings of AP101 and AP102 are relatively close. In Figure 5(A), it is possible to receive a Beacon frame from AP102 while AP101 is in the Awake state to receive a Beacon frame from AP101.

[0033] On the other hand, Figure 5(B) shows an example where the Beacon transmission timings of AP101 and AP102 are relatively far apart. In the example in Figure 5(B), the Beacon frame of AP102 is transmitted while STA103 is in the Doze state, while STA103 is in the Awake state. Therefore, when STA103 is in the Awake state to receive the Beacon frame from AP101, it cannot receive the Beacon from AP102.

[0034] If it is determined in S302 that the PS function is enabled, the system transitions to the Awake state to receive a Beacon frame from AP101, and it is determined in S303 whether or not a Beacon was received from AP102 within a predetermined period. The determination in S303 is made by the Beacon reception determination unit 203. However, since STA103 has the PS function enabled, there is a period during which reception is not possible.

[0035] If a Beacon frame is received from AP102 in S303, it is understood that STA103, which has transitioned to the Awake state to receive Beacons from AP101, can receive Beacons from AP102. Therefore, while maintaining the connection with AP101, the process to establish a connection with AP102 is initiated (S304).

[0036] If, in S303, a Beacon frame from AP102 is not received within a predetermined period, i.e., if a Beacon frame from AP102 is received outside the predetermined period, the number of connected APs is controlled so that the number of connected APs is one or less. This is because, when the PS function of STA103 is enabled, it is unable to receive a Beacon from AP102 while in the Awake state in order to receive a Beacon from AP101. In this embodiment, the number of connected APs is controlled using the Received Signal Strength Indicator (RSSI), which is the received signal strength of the Beacon.

[0037] In S306, PS control is temporarily suspended, the Beacon from AP101 and the Beacon from AP102 are received, and the RSSI of AP101 and AP102 are compared. If the RSSI of the Beacon frame received from AP101 in S306 is strong, PS control is restored, and in S305, a decision is made as to whether or not to establish a connection with a further AP. If a connection with a further AP is to be established in S305, the process proceeds to S301; otherwise, this flowchart is terminated.

[0038] If the RSSI of the Beacon frame received from AP102 is strong in S306, a disconnection process is performed between AP101 and AP101 (S307). After disconnecting from AP101, the process to establish a connection with AP102 is started (S304). In S305, if a connection with a further AP is to be established, the process proceeds to S301; otherwise, this flowchart is terminated.

[0039] In this embodiment, connection control was performed by comparing the RSSI of the received Beacon frames. However, if the Beacon of AP102 is not received in S304, the connection with AP102 may not be established, and the connection with AP101 may be maintained. Furthermore, if the Beacon of AP102 is not received in S304, the connection with AP101 may be disconnected, and the number of connected devices may be set to 0. In that case, it is possible to disable the PS control of STA103 and establish connections with the two APs.

[0040] If it is determined in S302 that the PS function of STA103 is disabled, the user notification unit 206 will ask the user whether PS control is disabled and whether to proceed with the connection process with AP102 (S308). If the response in S308 is affirmative, the process to establish a connection with AP102 will start (S304). If a connection with a further AP is to be established in S305, the process will proceed to S301. If a connection with a further AP is not to be established, this flowchart will end.

[0041] If a negative response is received in S308, the connection with AP101 is disconnected (S309), and the user is prompted to input a connection to another AP in S305. The sequence of steps from S308 to S309 may be determined, for example, by whether STA103 is externally powered or by the remaining battery level.

[0042] In this embodiment, the connection process for AP101 was performed first. However, it is also possible to predict whether the Beacon of AP102 can receive signals even when AP101 is performing PS control, determine the number of connected devices, and then perform connection control according to that determination.

[0043] In this embodiment, when the PS function is enabled and a connection is established with the first AP, the process for establishing a connection is started when a Beacon frame is received from the second AP within a predetermined period, and not started when it is received outside the predetermined period. This control makes it possible to suppress situations where a Beacon frame from either AP cannot be received when the PS function is enabled and the system is instructed to communicate with both the first AP and the second AP. Furthermore, when establishing a connection with either AP, the STA103 can continue communication more stably by comparing the RSSI of the Beacon frames received from each AP to determine which AP to establish a connection with.

[0044] <Embodiment 2> Embodiment 1 showed an example of establishing a connection with an AP that has a higher RSSI by comparing the RSSI of Beacon frames. This embodiment shows an example of establishing a connection with an AP that has a high PS effect by comparing the DTIM interval of Beacon frames.

[0045] Figure 4 is a flowchart showing the processing flow when the control unit 209 executes a program stored in the memory unit 208 of STA103. This flowchart shows the connection processing flow when STA103 is instructed to connect to multiple APs.

[0046] Steps S301 to S303 in Figure 4 are as described in Embodiment 1.

[0047] In S406, the Beacon frames received from AP101 and AP102 are compared to compare the PS effect on STA103. Here, the longer the DTIM interval, which is information contained in the Beacon frame, the less time STA103 is in the Awake state, and therefore the higher the PS effect on STA103. For this reason, in S406, the DTIM interval is compared from the received Beacon frames.

[0048] If it is determined in S406 that establishing a connection with AP101 would result in a higher PS effect for STA103, then in S305, a decision is made as to whether or not to establish a connection with a further AP. If a connection with a further AP is to be established in S305, the process proceeds to S301; otherwise, this flowchart ends. If it is determined in S406 that establishing a connection with AP102 would result in a higher PS effect for STA103, a disconnection process is performed with AP101 (S307). After disconnecting AP101, the connection process sequence with AP102 is started (S304). If a connection with a further AP is to be established in S305, the process proceeds to S301; otherwise, this flowchart ends.

[0049] S308 to S309 are as described in Embodiment 1.

[0050] In this embodiment, when a connection is established with the first AP while the PS function is enabled, the process to establish a connection is started when a Beacon frame is received from the second AP within a predetermined period, and not started when it is received outside the predetermined period. This control makes it possible to suppress situations where a Beacon frame from either AP cannot be received when the PS function is enabled and the system is instructed to communicate with both the first and second APs. Furthermore, when establishing a connection with either AP, the PS function of STA103 is enhanced by comparing the DTIM intervals of each AP to determine which AP to establish a connection with.

[0051] The STA103 described in this embodiment may be a printer having printing means. When operating as a printer, it is possible to print data acquired by communicating with a remote device, for example.

[0052] Furthermore, the STA103 described in this embodiment may be a camera having an imaging means. When operating as a camera, it is possible to transmit the captured data by communicating with a remote device, for example.

[0053] Alternatively, a recording medium containing program code for software that implements the above-described functions may be supplied to a system or device, and the computer (CPU, MPU) of the system or device may read and execute the program code stored on the recording medium. In this case, the program code read from the storage medium itself will implement the functions of the above-described embodiment, and the storage medium containing that program code will constitute the above-described device.

[0054] For storing program code, storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, ROMs, and DVDs can be used.

[0055] Furthermore, the above-mentioned functions may be realized not only by the computer executing the program code it reads, but also by the operating system (OS) running on the computer performing some or all of the actual processing based on the instructions of that program code. OS stands for Operating System.

[0056] Furthermore, the program code read from the storage medium is written to the memory of a function expansion board inserted into the computer or a function expansion unit connected to the computer. Then, based on the instructions of that program code, the CPU of the function expansion board or function expansion unit may perform some or all of the actual processing to realize the above-mentioned functions.

[0057] The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions. [Explanation of symbols]

[0058] 201 Wireless Transceiver Unit 202 Beacon Verification Section 203 Beacon reception determination unit 204 Electric field strength measurement unit 205 Connection Control Unit 206 User Notification Section 207 User Input Section 208 Storage section 209 Control Unit

Claims

1. A communication device that operates by transitioning between a first state and a second state having lower power consumption than the first state, and that can operate in parallel a function of participating in a first communication network and performing communication and a function of participating in a second communication network and performing communication, Receiving means for receiving frames from a first other communication device that constructs the first communication network and a second other communication device that constructs the second communication network, Control means for transitioning the communication device from the second state to the first state, and then transitioning it back to the second state after a predetermined period of time has elapsed, in order to receive the frame from the first other communication device, The system includes a receiving means for receiving a user selection to choose whether to establish a connection with both the first other communication device and the second other communication device, or to establish a connection with either the first other communication device or the second other communication device, The control means, when it receives the frame from the second other communication device within the predetermined period, starts the process of establishing a connection with the second other communication device, and when it receives the frame from the second other communication device outside the predetermined period, does not start the process of establishing a connection with the second other communication device. A communication device characterized by the following features.

2. The communication device according to claim 1, characterized in that, if the control means receives the frame from the second other communication device outside the predetermined period, the receiving means starts a process to establish a connection with the other communication device that has a higher radio wave intensity of the frame received by the receiving means.

3. The communication device according to claim 2, characterized in that, if the control means receives the frame from the second other communication device outside the predetermined period, the communication device starts a process to establish a connection with the other communication device in which the second state will last longer, based on the information contained in the frame.

4. The communication device according to any one of claims 1 to 3, characterized in that the frame is a Beacon frame compliant with the IEEE 802.11 standard.

5. The communication device according to any one of claims 1 to 4, characterized in that the information contained in the frame is a DTIM (Delivery Traffic Indication Message) interval compliant with the IEEE 802.11 standard.

6. The communication device according to any one of claims 1 to 5, characterized in that the communication device operates in a power-saving mode compliant with the IEEE 802.11 standard.

7. The communication device according to any one of claims 1 to 6, characterized in that the first other communication device and the second other communication device operate as APs (Access Points) compliant with the IEEE 802.11 standard series.

8. A communication method for a communication device that operates by transitioning between a first state and a second state having lower power consumption than the first state, and that can operate in parallel a function of participating in a first communication network and communicating and a function of participating in a second communication network and communicating, A receiving step of receiving frames from a first other communication device that constructs the first communication network and a second other communication device that constructs the second communication network, A control step of transitioning the communication device from the second state to the first state, and then transitioning it back to the second state after a predetermined period of time has elapsed, in order to receive the frame from the first other communication device, The system includes a receiving step for receiving a user selection to choose whether to establish a connection with both the first other communication device and the second other communication device, or to establish a connection with either the first other communication device or the second other communication device, The control step, when it receives the frame from the second other communication device within the predetermined period, starts a process to establish a connection with the second other communication device, and when it receives the frame from the second other communication device outside the predetermined period, does not start a process to establish a connection with the second other communication device. A communication method for a communication device characterized by the following features.

9. A program for causing a computer to function as one of the means of a communication device described in any one of claims 1 to 7.

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