JP5301616B2 - HANDOVER METHOD AND RADIO COMMUNICATION DEVICE - Google Patents

Description

  The present invention relates to a handover method and a wireless communication apparatus for switching a connection destination between a mobile communication network and a wireless LAN in a wireless communication apparatus connectable to a mobile communication network and a wireless LAN.

  Here, the wireless communication apparatus may be a mobile terminal having two interfaces (IF) that can be connected to both the mobile communication network and the wireless LAN, or relays between the mobile terminal and the mobile communication network or the wireless LAN. Communication function unit on the WAN side of the wireless relay device (a communication function unit for the wireless relay device to communicate with a mobile communication network or a wireless LAN. Note that a communication functional unit for the wireless relay device to communicate with a mobile terminal is a LAN. May be referred to as a communication function unit on the side).

  The mobile communication network is, for example, a 3rd generation, 3.5th generation, or 3.9th generation mobile phone network, and the standards include, for example, HSPA (High speed packet access), WCDMA (Wide band code division multiple access), EDGE (Enhanced data rates for GSM evolution), LTE (Long Term Evolution), etc.

  When comparing a mobile communication network and a wireless LAN, the mobile communication network generally has a wide cover area but a low communication speed, and the wireless LAN has a feature that the cover area is narrow but the communication speed is high. Therefore, as a wireless communication device that can make use of the characteristics of the mobile communication network and the wireless LAN, the wireless communication device includes two IFs that can be connected to both the mobile communication network and the wireless LAN. There is a wireless communication device that switches to a wireless LAN when the connection becomes possible (Patent Document 1).

FIG. 3 shows a configuration example of a conventional wireless communication apparatus.
In FIG. 3, the wireless communication device includes a wireless LAN IF unit 11, a mobile communication network IF unit 12, a reception level detection unit 13 that is connected to the wireless LAN IF unit 11 and detects a reception level (RSSI) of the wireless LAN, A control unit 14 that controls the wireless LAN and handover of the mobile communication network according to the RSSI of the LAN is provided.

FIG. 4 shows an example of a conventional handover processing procedure.
In FIG. 4, it is determined whether the wireless LAN is currently connected to the mobile communication network (S10). If the wireless LAN is connected, the wireless LAN detected by the reception level detection unit 13 is determined. It is determined whether or not the RSSI is less than or equal to the threshold (S11). If the RSSI is less than or equal to the threshold, handover to the mobile communication network is performed (S12). If the RSSI exceeds the threshold, the RSSI threshold determination is repeated while connecting to the wireless LAN.

  If the mobile communication network is connected, it is determined whether or not the RSSI of the wireless LAN detected by the reception level detector 13 exceeds a threshold (S13). When the RSSI exceeds the threshold, handover to the wireless LAN is performed (S14). When the RSSI is equal to or less than the threshold, the RSSI threshold determination is repeated while connecting to the mobile communication network.

  Thereby, if the RSSI of the wireless LAN is equal to or less than the threshold, the mobile communication network can be connected, and if the RSSI exceeds the threshold, the wireless LAN can be connected. For example, when the wireless LAN area is locally present in the mobile communication network area and the wireless communication device is in the mobile communication network area and outside the wireless LAN area, the RSSI of the wireless LAN is less than the threshold value. If the wireless communication device is connected to the mobile communication network, enters the wireless LAN area, and the RSSI of the wireless LAN exceeds a threshold, the wireless LAN can be connected to the wireless LAN.

JP 2010-021878 A

  In the handover between the mobile communication network and the wireless LAN, the reception level (RSSI) of the wireless LAN is compared with a threshold value, and if the reception level of the wireless LAN exceeds the threshold value while connected to the mobile communication network, the handover is performed to the wireless LAN. If the reception level falls below the threshold during connection to the wireless LAN, a handover to the mobile communication network has been performed.

  However, although the reception level and throughput of a wireless LAN generally have a high correlation, the wireless LAN uses a frequency band (ISM band) with many interference waves, so even if the reception level is high, the actual throughput decreases due to interference. There is a case. Therefore, even if the reception level of the wireless LAN is higher than the threshold, the throughput may be higher in the mobile communication network. For this reason, when the reception level of the wireless LAN exceeds a threshold value while connecting to the mobile communication network, the throughput may be lowered when handed over to the wireless LAN. Also, if the reception level exceeds the threshold value while connected to the wireless LAN, handover to the mobile communication network may not be possible even if the throughput decreases.

  In order to solve such a problem, as shown in FIG. 5, it is conceivable to control the throughput while measuring the throughput while connected to the wireless LAN, and handing over to the mobile communication network when the throughput falls below the throughput threshold. However, when connected to the mobile communication network, the reception level (RSSI) of the wireless LAN can be confirmed, but the throughput cannot be confirmed. Therefore, the control is based on the reception level of the wireless LAN. As a result, since the throughput is used as a reference when connected to a wireless LAN and the reception level is used as a reference while connected to a mobile communication network, parameters serving as a reference for handover differ. Therefore, when the reception level of the wireless LAN exceeds the threshold value and the throughput is lower than the threshold value, “flapping” that frequently repeats handover between the wireless LAN and the mobile communication network occurs. Such “flapping” means frequent interruption of communication associated with handover, and service quality is significantly deteriorated.

  An object of the present invention is to provide a handover method and a wireless communication apparatus capable of performing a stable handover between a mobile communication network and a wireless LAN while considering the throughput of the wireless LAN.

  According to the first aspect of the present invention, the first communication network and the second communication network can be switched and connected, and wireless communication is performed between the first communication network and the second communication network according to a predetermined standard. In the communication apparatus, a reception level detecting means for detecting the reception level of the first communication network, a throughput calculation means for calculating the throughput during connection to the first communication network, and the first communication from the second communication network RSSI threshold management means for managing an RSSI threshold used for controlling handover to the network, and the first communication if the throughput calculated by the throughput calculation means falls below a predetermined throughput threshold while connected to the first communication network. A handover from the network to the second communication network is performed, and an RSSI threshold value obtained by adding a predetermined value to the reception level of the first communication network at that time is set in the RSSI threshold value management means and connected to the second communication network. Control means for performing handover from the second communication network to the first communication network if the reception level of the first communication network detected by the reception level detection means exceeds the RSSI threshold managed by the RSSI threshold management means With.

  The throughput calculation means in the wireless communication apparatus of the first invention periodically transmits dummy data for throughput measurement to the first communication network while connected to the first communication network, and receives a response signal from the data transmission. The round trip time until reception of the first communication network is measured, and the throughput of the first communication network is calculated by dividing the data size of the dummy data by the round trip time.

  In the wireless communication apparatus of the first invention, the first communication network is a wireless LAN, and the second communication network is a mobile communication network.

  According to a second aspect of the present invention, the first communication network and the second communication network can be switched to be connected, and wireless communication is performed between the first communication network and the second communication network according to a predetermined standard. In the handover method of the communication device, the reception level detection unit of the wireless communication device detects the reception level of the first communication network, the throughput calculation unit of the wireless communication device calculates the throughput during connection to the first communication network, The RSSI management means of the wireless communication apparatus manages the RSSI threshold used for controlling the handover from the second communication network to the first communication network, and the throughput calculated by the throughput calculation means while connected to the first communication network Is set to a predetermined throughput threshold or less, the handover from the first communication network to the second communication network is performed, and the RSSI threshold obtained by adding a predetermined value to the reception level of the first communication network at that time is set to RS If the reception level of the first communication network detected by the reception level detection unit exceeds the RSSI threshold managed by the RSSI threshold management unit while being set in the I threshold management unit and connected to the second communication network Handover from the second communication network to the first communication network is performed.

  The throughput calculation means in the handover method of the second invention periodically transmits dummy data for throughput measurement to the first communication network while connected to the first communication network, and from the data transmission, the reception response signal The round trip time until reception is measured, and the throughput of the first communication network is calculated by dividing the data size of the dummy data by the round trip time.

  In the handover method of the second invention, the first communication network is a wireless LAN, and the second communication network is a mobile communication network.

  In the present invention, during connection to the first communication network (wireless LAN), if the throughput falls below the throughput threshold, the handover to the second communication network (mobile communication network) is performed regardless of the RSSI of the first communication network. Can be implemented. Also, during connection to the second communication network (mobile communication network), the RSSI threshold value obtained by adding a predetermined value to the RSSI of the first communication network at the time of handover from the first communication network to the second communication network is managed. If the RSSI exceeds the RSSI threshold, the handover to the first communication network can be performed. As described above, the handover from the second communication network (mobile communication network) to the first communication network (wireless LAN) is controlled on the basis of the RSSI threshold, so that the handover to the first communication network (wireless LAN) is performed. The flutter just after is eliminated and stable handover can be realized.

It is a figure which shows the Example of the radio | wireless communication apparatus of this invention. 5 is a flowchart illustrating an example of a handover processing procedure according to the present invention. It is a figure which shows the structural example of the conventional radio | wireless communication apparatus. It is a flowchart which shows the example of the conventional handover processing procedure. It is a flowchart which shows the example of the conventional handover processing procedure.

FIG. 1 shows an embodiment of a wireless communication apparatus of the present invention.
In FIG. 1, a wireless communication apparatus includes a wireless LAN IF unit 11, a mobile communication network IF unit 12, a reception level detection unit 13 that is connected to the wireless LAN IF unit 11 and detects a reception level (RSSI) of the wireless LAN, A control unit 14 that controls handover between a LAN and a mobile communication network, a throughput calculation unit 15 and an RSSI threshold management unit 16 connected to the control unit 14 are provided.

  This configuration may be a single wireless terminal or a communication function unit on the WAN side of the wireless relay device. In the case of a wireless relay device, a LAN-side wireless LANIF that communicates with a wireless terminal is connected to the control unit 14, and the control unit 14 is connected to the LAN-side wireless LANIF unit, and the wireless LANIF unit 11. It is configured to perform relay processing with the wireless LAN connected to the mobile communication network connected to the mobile communication network IF unit 12.

  The throughput calculation unit 15 periodically transmits dummy data for throughput measurement from the control unit 14 via the wireless LAN IF unit 11 while connected to the wireless LAN, and the round trip time (time from data transmission to ACK reception). ) And the average throughput of the wireless LAN is calculated by dividing the data size of the dummy data by the round trip time. Here, the dummy data for measuring the round trip time is transmitted by, for example, the TCP protocol, and the time until the TCP-ACK for the dummy data is received is measured as the round trip time. The destination of the dummy data may be a base station of a mobile communication network or a base station of a wireless LAN and a server on the network to which the base station is connected.

  The RSSI threshold management unit 16 acquires the RSSI of the wireless LAN when performing handover from the wireless LAN to the mobile communication network under the control of the control unit 14, and manages the RSSI threshold obtained by adding a predetermined value to the RSSI.

  The control unit 14 receives the RSSI of the wireless LAN from the reception level detection unit 13. Further, the control unit 14 outputs the dummy data for throughput measurement input from the throughput calculation unit 15 to the wireless LANIF unit 11 and outputs the ACK signal input from the wireless LANIF unit 11 to the throughput calculation unit 15 to calculate the throughput. The average throughput of the wireless LAN is acquired from the unit 15. Then, the handover to the mobile communication network is controlled according to the average throughput of the wireless LAN while the wireless LAN is connected, and the handover to the wireless LAN is controlled based on the RSSI of the wireless LAN and the RSSI threshold during the connection of the mobile communication network. To do. Hereinafter, the handover control processing procedure in the control unit 14 will be described with reference to FIG.

  In FIG. 2, it is determined whether the wireless LAN is currently connected to the mobile communication network (S0). If the wireless LAN is connected, the average of the wireless LANs acquired from the throughput calculation unit 15 is determined. It is determined whether the throughput is equal to or less than the throughput threshold (S1). When the average throughput is equal to or less than the throughput threshold, an RSSI threshold obtained by adding a predetermined value to the RSSI acquired at that time is set in the RSSI threshold management unit 16 (S2), and a handover to the mobile communication network is performed (S3). If the throughput exceeds the throughput threshold value, the throughput threshold determination is repeated while connecting to the wireless LAN.

  If the mobile communication network is connected, it is determined whether the RSSI of the wireless LAN detected by the reception level detector 13 has exceeded the RSSI threshold (S4). When the RSSI exceeds the RSSI threshold, a handover to the wireless LAN is performed (S5). When the RSSI is equal to or less than the RSSI threshold, the RSSI threshold determination is repeated while connecting to the mobile communication network.

  As a result, during connection to the wireless LAN, handover to the mobile communication network is controlled based on the average throughput of the wireless LAN, and if the average throughput falls below the throughput threshold, the handover to the mobile communication network is performed regardless of the RSSI of the wireless LAN. Can be implemented. Further, during connection to the mobile communication network, the handover to the wireless LAN is controlled based on the RSSI threshold obtained by adding a predetermined value to the RSSI of the wireless LAN at the time of handover to the mobile communication network, and if the RSSI exceeds the RSSI threshold, Assuming that the throughput of the wireless LAN is better than that before the handover, the handover to the wireless LAN can be performed. That is, by controlling the handover from the mobile communication network to the wireless LAN based on the RSSI threshold, the fluttering immediately after the handover to the wireless LAN is eliminated, and a stable handover can be realized.

  As described above, the handover between the wireless LAN and the mobile communication network has been described as an embodiment. However, the handover processing method of the present invention can be applied even to handover control between two other communication networks.

DESCRIPTION OF SYMBOLS 11 Wireless LANIF part 12 Mobile communication network IF part 13 Reception level detection part 14 Control part 15 Throughput calculation part 16 RSSI threshold value management part

Claims (6)

In a wireless communication apparatus that is connectable by switching between a first communication network and a second communication network and performs a handover according to a predetermined standard between the first communication network and the second communication network,
Reception level detection means for detecting the reception level of the first communication network;
Throughput calculating means for calculating the throughput during connection to the first communication network;
RSSI threshold management means for managing an RSSI threshold used for controlling handover from the second communication network to the first communication network;
During connection to the first communication network, if the throughput calculated by the throughput calculation means falls below a predetermined throughput threshold, a handover from the first communication network to the second communication network is performed, and The RSSI threshold value management means is set to the RSSI threshold value management means obtained by adding a predetermined value to the reception level of the first communication network, and is detected by the reception level detection means while connected to the second communication network. Control means for performing a handover from the second communication network to the first communication network if the reception level of the first communication network exceeds the RSSI threshold managed by the RSSI threshold management means. A wireless communication device. The wireless communication device according to claim 1,
The throughput calculation means periodically transmits dummy data for throughput measurement to the first communication network while connected to the first communication network, and a round trip from the data transmission to reception of a reception response signal. A wireless communication apparatus characterized by measuring time and dividing the data size of dummy data by a round trip time to calculate the throughput of the first communication network. The wireless communication device according to claim 1,
The wireless communication apparatus, wherein the first communication network is a wireless LAN, and the second communication network is a mobile communication network. In a handover method of a wireless communication apparatus that is connectable by switching between a first communication network and a second communication network, and performs handover according to a predetermined standard between the first communication network and the second communication network ,
Detecting the reception level of the first communication network by the reception level detection means of the wireless communication device;
Calculating the throughput being connected to the first communication network by the throughput calculating means of the wireless communication device;
Managing an RSSI threshold used for controlling handover from the second communication network to the first communication network by the RSSI management means of the wireless communication device;
During connection to the first communication network, if the throughput calculated by the throughput calculation means falls below a predetermined throughput threshold, a handover from the first communication network to the second communication network is performed, and The RSSI threshold value management means is set to the RSSI threshold value management means obtained by adding a predetermined value to the reception level of the first communication network, and is detected by the reception level detection means while connected to the second communication network. A handover method comprising: performing handover from the second communication network to the first communication network if a reception level of the first communication network exceeds an RSSI threshold managed by the RSSI threshold management means. The handover method according to claim 4, wherein
The throughput calculation means periodically transmits dummy data for throughput measurement to the first communication network while connected to the first communication network, and a round trip from the data transmission to reception of a reception response signal. A handover method characterized by measuring time and calculating the throughput of the first communication network by dividing the data size of dummy data by a round trip time. The handover method according to claim 4, wherein
The handover method, wherein the first communication network is a wireless LAN, and the second communication network is a mobile communication network.

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