JP2006042150A - Wireless communication terminal, program, and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication terminal, a program, and a communication method in a communication system wherein a communication speed is changed in response to a degree of congestion of a base station. <P>SOLUTION: The wireless communication terminal connected to a connected base station for storing information of surrounding base stations being objects of hand-off destinations includes: a reception means for receiving instruction information for instructing change of an upper limit of a communication speed from the surrounding base stations; a discrimination means for discriminating whether or not the instruction information received by the reception means includes instruction information for instructing decrease of the upper limit of the communication speed; a generating means for generating a signal for controlling the information of the surrounding base stations when a result of the discrimination by the discrimination means indicates that the received instruction information includes information for instructing decrease of the upper limit of the communication speed; and a transmission means for transmitting the signal generated by the generating means to the connected base station. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless communication terminal, a program, and a communication method, and more particularly, to a wireless communication terminal, a program, and a communication method in a communication system that varies the communication speed according to the congestion level of a base station.

  In a wireless communication system including a wireless communication terminal such as a cellular communication system and a plurality of base stations, a base station (hereinafter referred to as a connection base station) with which the wireless communication terminal is connected to perform communication, One or more base stations adjacent to each other and handoff destination candidates (hereinafter referred to as neighboring base stations) each instruct to increase or decrease the communication speed based on the degree of congestion, and based on this instruction, the wireless communication terminal A device that performs communication control by changing the communication speed has been proposed. In the present specification, handoff means switching of connected base stations.

  In this communication control, if all of the connected base stations and the peripheral base stations that are candidates for the handoff destination are low and all these base stations are instructed to increase the communication speed, the wireless communication terminal sets the communication speed. On the other hand, if at least one of the base stations is highly congested and instructed to reduce the communication speed, the wireless communication terminal operates in a direction to decrease the communication speed. . By controlling in this way, the communication speed is adjusted to the base station that is congested in the connected base station and all the neighboring base stations, so communication is performed from a base station with a low degree of congestion and a high communication speed. When handing off to a base station having a low speed, it is possible to prevent the occurrence of errors such as packet loss due to a sudden decrease in communication speed.

As an example of a communication system that performs such communication control, there is a CDMA2000 1xEVDO system that has been developed as a next-generation high-speed wireless communication system. This CDMA2000 1xEVDO system is a standardized version of the HDR (High Data Rate) system, which is an extension of the CDMA2000 1x system by Qualcomm, USA. In the radio wave industry ARIB, Std.T-64 IS-2000 CS0024 “CDMA2000 High Rate Packet It is standardized by the “Data Air Interface Specification”, and currently extends the CDMAOne system (ARIBT-53 in Japan, EIA / TIA / IS-95, etc. in North America, Korea, etc.) currently being serviced by KDDI 杜 in Japan. The CDMA2000 1x method corresponding to the third generation method (3G) is a method aimed at further improving communication speed by specializing in data communication. In CDMA2000 1xEVDO, “EV” means Evolution, and “DO” means DataOnly (see Patent Document 1).
JP 2002-300634 A

  However, if communication control as described above is performed, only one of the connected base stations and one or more neighboring base stations that are candidates for handoff destinations is congested, and how much other base stations are congested. Even if the degree is low, there is a problem that the communication speed does not increase and the throughput deteriorates.

  This is especially true when a user places a wireless communication terminal on a desktop or the like and receives a streaming video bit stream that requires real-time performance. There is no need to consider, but rather it is a problem when it is desired to increase the communication speed preferentially.

  1st invention is a radio | wireless communication terminal connected with the connection base station holding the information of the periphery base station used as the candidate of handoff destination, Comprising: Instruct | indicates to change the upper limit of communication speed from the said periphery base station Receiving means for receiving instruction information, determining means for determining whether or not the instruction information received by the receiving means includes instruction information for instructing to lower the upper limit of the communication speed, and the determination If the result of determination by the means includes instruction information for instructing to lower the upper limit value of the communication speed, generating means for generating a signal for controlling information on the neighboring base station, and the generated by the generating means Transmitting means for transmitting a signal to the connected base station.

According to a second aspect, in the first aspect, the signal for controlling the information on the neighboring base station is a base station that transmits the instruction information that instructs to lower the upper limit value of the communication speed. The third invention is characterized in that, in the first invention, the signal for controlling the information of the neighboring base station is directed to lower the upper limit value of the communication speed. A value indicating communication quality between the base station that transmits the instruction information to be transmitted and the wireless communication terminal, and a value that is lower than a predetermined reference value.

  In a fourth aspect based on the first aspect, the apparatus further comprises derivation means for deriving a data amount of data to be communicated, and the transmission means instructs to lower the upper limit value of the communication speed as a result of the determination by the determination means. Only when the instruction information is included and the amount of data derived by the deriving means is greater than a predetermined value, a signal for controlling the information on the neighboring base stations is transmitted to the connected base station. It is characterized by.

  A fifth invention is a program used for a wireless communication terminal connected to a connection base station that holds information of a peripheral base station that is a candidate for a handoff destination, and the communication base station sets an upper limit value of the communication speed from the peripheral base station. It is determined whether or not the first procedure for receiving the instruction information for instructing to change and the instruction information for instructing to lower the upper limit value of the communication speed is included in the instruction information received by the receiving means. As a result of the determination by the second procedure and the determination means, if the instruction information for instructing to lower the upper limit value of the communication speed is included, a signal for controlling the information of the neighboring base station is sent to the connecting base station And a third procedure for transmitting.

According to a sixth invention, in the fifth invention,
The signal that controls the information on the neighboring base station includes information for excluding the base station that transmits the instruction information that instructs to lower the upper limit value of the communication speed from the information on the neighboring base station. A program characterized by

  In a fifth aspect based on the fifth aspect, the signal for controlling the information of the neighboring base station is a signal transmitted between the base station that transmits the instruction information for instructing to lower the upper limit value of the communication speed and the wireless communication terminal. It is a value indicating the communication quality during the period, and is a value lower than a predetermined reference value.

  An eighth invention according to the fifth invention includes a fourth procedure for deriving a data amount of data to be communicated, wherein the third procedure is the upper limit value of the communication speed as a result of the determination by the second procedure. Only when the amount of remaining data derived in the fourth procedure is greater than a predetermined value, the signal for controlling the information of the neighboring base stations is included in the signal. It transmits to a connection base station, It is characterized by the above-mentioned.

  A ninth invention is a communication method used for a wireless communication terminal connected to a connection base station that holds peripheral base station information of a peripheral base station that is a candidate for a handoff destination. The instruction information instructing to change the upper limit value of the communication is received, and it is determined whether or not the instruction information instructed to decrease the upper limit value of the communication speed is included in the instruction information received by the receiving means. If the result of determination by the determining means includes instruction information for instructing to lower the upper limit value of the communication speed, a signal for controlling information on the neighboring base stations is transmitted to the connected base station. It is characterized by.

  According to a tenth aspect, in the ninth aspect, the signal for controlling the information on the neighboring base station is a base station that transmits the instruction information that instructs to lower the upper limit value of the communication speed. It includes information for exclusion from the information.

  In an eleventh aspect based on the ninth aspect, the signal for controlling the information on the neighboring base station is a base station that transmits the instruction information that instructs to lower the upper limit value of the communication speed, and the wireless communication terminal. It is a value indicating the communication quality during the period, and is a value lower than a predetermined reference value.

  In a twelfth aspect based on the ninth aspect, when the result of the determination includes instruction information for instructing to lower the upper limit value of the communication speed, a further communication data amount is derived, and the derived data amount A signal for controlling the information on the neighboring base stations is transmitted to the connected base station only when is greater than a predetermined value.

  According to the present invention, the throughput of the wireless communication terminal can be increased.

  A first embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a wireless communication terminal 200 according to the first embodiment of this invention.

  The wireless communication terminal (mobile phone terminal) 200 according to the present embodiment uses a common antenna 10 to perform a CDMA2000 1x communication method (hereinafter referred to as “lx system”) and a 1xEVDO communication method (hereinafter referred to as “DO system”). And a base station 100 (100a, 100b, 100c) of the DO system or a base station 101 of the 1x system.

  Base stations 100 a, 100 b, and 100 c perform DO system communication with radio communication terminal 200, and base station 101 performs 1x system communication with radio communication terminal 200.

  The base station to which the wireless communication terminal 200 is connected and performing communication is hereinafter referred to as a “connection base station”, and one or more base stations that are adjacent to the connection base station and are candidates for handoff destinations. A. Hereinafter, it is referred to as “neighboring base station”.

  The antenna 10 converts a high-frequency signal from either the 1xRF unit 20 or the DO RF unit 30 into a radio wave and transmits the radio wave to the base stations 100 and 101, and receives a radio wave from the base stations 100 and 101 to receive the 1xRF unit 20. Alternatively, it is sent to the DO RF unit 30 as a high frequency signal.

  The 1xRF unit 20 converts data or a voice signal to be transmitted in the 1x system into a high-frequency signal and sends it to the antenna 10. Moreover, the high frequency signal sent from the antenna 10 is converted into a data signal or an audio signal.

  The DO RF unit 30 converts data to be transmitted by the DO system into a high-frequency signal and sends it to the antenna 10. Moreover, the high frequency signal sent from the antenna 10 is converted into a data signal. The DO RF unit 30 functions as a receiving unit and a transmitting unit.

  The RF control unit 40 is a control unit that controls communication between the two systems of the DO system and the 1x system. In addition, the RF control unit 40 measures the strength (such as RSSI) of radio waves from the base station 100 received by the antenna 10.

  The system control unit 50 is a control unit that performs overall control of each unit of the wireless communication terminal 200. The system control unit 50 controls the RF control unit 40 to control switching between the two systems of the DO system and the 1x system. The system control unit 50 functions as a generation unit and a determination unit.

  The system storage unit 60 is configured by a memory such as a RAM, and stores applications, temporary data, and the like.

  Next, the operation of radio communication terminal 200 according to the embodiment of the present invention will be described.

  First, fluctuations in the upper limit value of the communication speed in data communication in the DO system according to the first embodiment of this invention will be described with reference to FIGS.

  First, in the uplink communication in the DO system, the upper limit value of the communication speed is divided into five stages of 9.6 kbps, 19.2 kbps, 38.4 kbps, 76.8 kbps, and 153.6 kbps.

  When the radio communication terminal 200 starts uplink communication with the base station 100a, communication is first started at the lowest communication speed (9.6 kbps), and thereafter, the base station 100a that is a connected base station and the base stations around the base station 100a Then, the upper limit value of the communication speed is changed according to the degree of congestion of the base stations 100b and 100c that are handoff destination candidates.

  Specifically, the connecting base station 100a has, as “Activeset”, information indicating the peripheral base stations 100b and 100c that are handoff destination candidates. Then, the connected base station 100a and the neighboring base stations 100b and 100c registered in the Activeset respectively receive RABit (ReverseActivityBit) that is information instructing to increase or decrease the upper limit of the communication speed according to the congestion level of the own base station. Send. The wireless communication terminal 200 receives this RABit and adjusts the communication speed. “RABit” is a bit value that varies depending on the congestion level of the base station. A base station is congested when many wireless communication terminals are concentrated and connected to the base station or when a communication line is congested. When there is no congested base station, that is, when the communication speed can be increased, RABit is set to “0”. When there is one or more congested base stations, that is, when it is not preferable to increase the communication speed, RABit is set to “1”. This RABit functions as instruction information for instructing the upper limit value of the communication speed of the wireless communication terminal 200 (fluctuating or lowering the upper limit value).

  FIG. 3 is a flowchart of communication rate change performed by the system control unit 50 of the wireless communication terminal 200.

  When the wireless communication terminal 200 starts uplink communication with the DO system, communication is first started at the lowest communication speed (9.6 kbps).

  Thereafter, when the antenna 10 receives a RABit from each of the connected base station 100a and the neighboring base stations 100b and 100c registered in the Activeset, it is determined whether or not a RABit indicating “1” exists in the RABit ( Step 1001). When it is determined that all the RABits are “0”, the operation is performed to increase the upper limit value of the current communication speed by one step. In this case, the communication speed is configured to be increased probabilistically rather than absolutely. That is, first, a random number x (x is a range of 0 <x <1) is generated (step 1002). Then, it is determined whether or not the generated random number x is smaller than a threshold value α for changing the communication speed (step 1003). Here, as shown in FIG. 2, the threshold value α differs depending on the current communication speed. For example, when the threshold value α is to be increased by one step from 9.6 kbps to 19.2 kbps, the threshold value α is “0x30” (hexadecimal notation). That is, a value obtained by dividing “48” by 255, that is, 48/255 is the value of α. In this example, in step 1003, it is determined whether the random number x is larger or smaller than 48/255.

  If it is determined in step 1003 that the random number x is smaller than the threshold value α, the upper limit value of the current communication speed is increased by one level (step 1004). For example, if the current communication speed is 9.6 kbps, it is changed to 19.2 kbps, which is one step higher. On the other hand, if it is determined that the random number x is greater than or equal to the threshold value α, the upper limit value of the current communication speed is maintained (step 1005). For example, if the current communication speed is 9.6 kbps, 9.6 kbps is maintained.

  On the other hand, if it is determined in step 1001 that there is at least one base station whose RABit is “1”, the operation is performed to lower the upper limit value of the current communication speed by one step. That is, first, a random number x (x is a range of 0 <x <1) is generated (step 1006), and the random number x is compared with a threshold value α (step 1007). If it is determined that the random number x is smaller than the threshold value α, the upper limit value of the current communication speed is lowered by one step (step 1008). For example, if the current communication speed is 19.2 kbps, it is changed to 9.6 kbps, which is one step lower. On the other hand, if it is determined that the random number x is greater than or equal to the threshold value α, the upper limit value of the current communication speed is maintained (step 1005). For example, if the current communication speed is 19.2 kbps, 19.2 kbps is maintained.

  As described above, the radio communication terminal 200 performs a probabilistic and stepwise process based on the RABit transmitted at each predetermined timing from each of the connected base station 100a and the neighboring base stations 100b and 100c registered in the Activeset. Therefore, the upper limit value of the communication speed can be changed. On the other hand, when there is one of the neighboring base stations registered in Activeset, the wireless communication terminal 200 operates in the direction of lowering the upper limit value of the communication speed. When handoff is performed from the connected base station 100a to the peripheral base station 100b that is crowded and can only perform low-speed communication, it is possible to prevent a communication error such as packet loss due to a sudden drop in the communication speed.

  The Activeset possessed by the connected base station 100a is updated based on the communication quality between the wireless communication terminal 200 and the base station 100. FIG. 5 is a sequence diagram showing the update processing of the Activeset according to the present embodiment. FIG. 5A shows the addition of the base station to the Activeset, and FIG. 5B shows the base station from the Activeset. Each exclusion is shown.

  In FIG. 5A, the radio communication terminal 200 performs communication using the base station 100a as a connection base station. At this time, it is assumed that the peripheral base station 100b is not registered in Activeset. Here, the radio communication terminal 200 measures the signal strength (RSSI value) of the pilot signal of the neighboring base station 100b, and transmits a “RouteUpdate message” including this measurement value to the connected base station 100a. The connected base station 100a that has received the RouteUpdate message registers the neighboring base station 100b in the Activeset if the measured value is equal to or greater than a predetermined threshold ζ (ζ is a threshold for registering the base station in the Activeset). Then, a “TCA (Traffic Channel Assignment) message” including that fact is transmitted to the wireless communication terminal 200. The wireless communication terminal 200 obtains information on the peripheral base station 100b added to the Activeset by this TCA message.

  On the other hand, in FIG.5 (b), the radio | wireless communication terminal 200 is communicating using the base station 100b as a connection base station. At this time, it is assumed that the peripheral base station 100a is registered in Activeset. Here, the radio communication terminal 200 measures the signal strength of the pilot signal of the neighboring base station 100a, and transmits a RouteUpdate message including this measured value to the connecting base station 100b. The connected base station 100b that has received the RouteUpdate message excludes the neighboring base station 100a from the Activeset when the measured value is less than a predetermined threshold ζ (ζ is a threshold for registering a base station in the Activeset). Then, a TCA message including that is transmitted to the wireless communication terminal 200. The wireless communication terminal 200 obtains information on the neighboring base station 100a excluded from Activeset by this TCA message.

  As described above, by registering / excluding the base station in / from the Activeset, the communication quality between the radio communication terminal 200 and the base station 100 is good (the signal strength of the pilot signal is equal to or higher than the threshold ζ). By actively setting the station 100 as a handoff destination candidate, it is possible to always perform communication with good communication quality. On the other hand, the communication quality between the wireless communication terminal 200 and the base station 100 is not good (the signal strength of the pilot signal is less than the threshold ζ), and the neighboring base stations are excluded from the handoff destination candidates, thereby improving the communication quality. Even if the connection is poor, it is possible to prevent unnecessary hand-down to the base station, which may cause a communication interruption immediately.

  Here, when there is a base station that is congested at least one of the base stations registered in Activeset, and the base station indicates RABit = “1”, the connected base station and other neighboring base stations 3 is not congested and indicates RABit = “0”, the upper limit value of the communication speed does not increase according to the processing of FIG. Therefore, the wireless communication terminal 200 according to the present embodiment performs the following process when performing communication using the DO system.

  FIG. 6 is a flowchart at the time of uplink data transmission in the DO system performed by the wireless communication terminal 200.

  It is assumed that the connecting base station 100a registers the peripheral base stations 100b and 100c in Activeset.

  The radio communication terminal 200 starts uplink data communication using the base station 100a as a connection base station. During uplink data communication, the DO RF unit 30 (reception unit) of the wireless communication terminal 200 receives RABits transmitted by the neighboring base stations 100b and 100c registered in Activeset at predetermined timings (step 2001). .

  When receiving the RABit, the system control unit 50 determines whether or not a plurality of neighboring base stations registered in the Activeset are registered (step 2002). If there is only one neighboring base station registered in Activeset, if the base station is excluded from Activeset, there will be no base station to perform handoff. Therefore, the process proceeds to step 2005 and data is transmitted as it is. .

  If it is determined in step 2002 that a plurality of neighboring base stations are registered in Activeset, the system control unit 50 (determination means) sets RABit = “1” among the neighboring base stations registered in Activeset. It is determined whether there is at least one neighboring base station to be shown, that is, one neighboring base station that is congested and difficult to increase the communication speed (step 2003). As a result of this determination, when there is no peripheral base station indicating RABit = “1” in Activeset, that is, when all peripheral base stations indicate RABit = “0” and the communication speed can be increased. In step S2005, data is transmitted as it is.

  If it is determined in step 2003 that there is at least one neighboring base station indicating RABit = “1” in Activeset, for example, the neighboring base station 100b is congested among a plurality of neighboring base stations, and RABit = When “1” is indicated, the system control unit 50 (generating unit) generates a RouteUpdate message for removing the neighboring base station 100b from Activeset, and the DO RF unit 30 (transmitting unit) transmits the antenna unit 10 Is transmitted to the connected base station 100a via (step 2004).

  The RouteUpdate message for removing the neighboring base station 100b from the Activeset does not transmit the signal strength of the actual pilot signal of the neighboring base station 100b, but the signal strength of the pilot signal of the neighboring base station 100b is less than the threshold ζ. A value indicating “false pilot signal strength” is included. As described above with reference to FIG. 5, the threshold ζ is a threshold of signal strength for the base station 100a to register another base station in Activeset.

  The base station 100a that has received the RouteUpdate message including the “false pilot signal strength” determines that the pilot signal strength is less than the threshold ζ, and performs a process of removing the peripheral base station 100b indicating the pilot signal strength from the Activeset. Do. This result is notified to the wireless communication terminal 200.

  The wireless communication terminal 200 performs data transmission (step 2005). During data transmission, as described above with reference to FIG. 3, the communication speed is changed at a predetermined timing, and the upper limit of the communication speed is changed probabilistically. In this case, since the neighboring base stations indicating RABit = “1” in Activeset are excluded in step 2004, the communication base is changed to increase the upper limit of the communication speed. This process is repeated until the data transmission is completed (step 2006).

  If it is determined that the data transmission is completed, the base station 100b excluded from the Activeset for data transmission in Step 2004 is registered again in the Activeset (Step 2007). That is, the RouteUpdate message including the “correct” pilot signal strength between the neighboring base station 100b and the radio communication terminal 200 is transmitted instead of the “false” pilot signal strength generated and transmitted in step 2004. If this “correct” pilot strength is equal to or greater than the threshold value ζ, the connecting base station 100a registers the neighboring base station 100b in Activeset again.

  By the processing of FIG. 6, data communication is performed by excluding peripheral base stations that cannot increase the communication speed due to congestion during data communication (indicating RABit = “1”) from the active set of the connected base station. Therefore, the upper limit value of the uplink data communication speed is changed in the direction of increasing according to the process of FIG. By doing so, the throughput of uplink data communication can be increased.

  FIG. 7 is a sequence diagram at the time of uplink data transmission in the DO system performed by the wireless communication terminal 200.

  The wireless communication terminal 200 starts communication with the connected base station 100a.

  Here, if the base station 100b among the neighboring base stations registered in Activeset cannot be increased because of the congestion, and if RABit = “1”, the neighboring base station In order to remove 100b from Activeset, a RouteUpdate message including “false pilot signal strength” is generated and transmitted to the connecting base station 100a.

  The base station 100a that has received the RouteUpdate message including the “false pilot signal strength” determines that the pilot signal strength is less than the threshold ζ, and performs a process of removing the peripheral base station 100b indicating the pilot signal strength from the Activeset. Do. The fact that the base station 100b is excluded from the Activeset is notified to the radio communication terminal 200 by a TCA message.

  The wireless communication terminal 200 performs data communication in this state, that is, in a state where a base station that cannot increase the communication speed due to congestion (RABit = “1” is indicated) is excluded.

  Then, when it is determined that the data transmission is completed, in order to register the base station 100b excluded from the Activeset in the Activeset again, instead of the “false” pilot signal strength, “ Send a RouteUpdate message containing the “correct” pilot signal strength. If this “correct” pilot strength is greater than or equal to the threshold ζ, the connecting base station 100a registers the neighboring base station 100b in Activeset again. The fact that the base station 100b is registered in Activeset is notified to the wireless communication terminal 200 by a TCA message.

  In the first embodiment of the present invention configured as described above, at the time of data communication, the communication speed cannot be increased because of the congestion among the base stations registered in Activeset (RABit = Since the peripheral base station (showing “1”) is excluded from the Activeset and performs data communication, it is stochastically changed in a direction to increase the upper limit of the uplink data communication speed. By doing so, the throughput of uplink data communication can be increased.

  Next, a second embodiment of the present invention will be described.

  In the second embodiment, as in the first embodiment, the base station is excluded from Activeset during data communication. Note that the wireless communication system according to the second embodiment is the same as that of the first embodiment shown in FIG.

  FIG. 8 is a flowchart at the time of uplink data transmission in the DO system performed by the wireless communication terminal 200 according to the second embodiment. Steps 2001 to 2007 are the same as the processing of the first embodiment shown in FIG. 6, and thus the same reference numerals are given and description thereof is omitted.

  In step 2001, during uplink data communication, the DO RF unit 30 (reception unit) of the wireless communication terminal 200 receives RABits transmitted by the peripheral base stations 100b and 100c registered in Activeset at each predetermined timing. .

  Next, the system control unit 50 (derivation unit) derives the data amount of data that is the target of uplink communication by referring to, for example, a buffer in the system storage unit 60, and the derived data amount is a threshold value. It is determined whether or not β is greater than or equal to (step 2008).

  As a result of the determination, if the derived data amount is less than the threshold value β, the process proceeds to step 2005 and data transmission is continued as it is.

  On the other hand, if it is determined in step 2008 that the derived data amount is equal to or greater than the threshold value β, the processes in steps 2002 to 2007 are executed.

  That is, it is determined whether or not a plurality of neighboring base stations registered in Activeset are registered (step 2002). If it is determined that a plurality of neighboring base stations are registered in Activeset, the system control unit 50 ( Judgment means) is one of the peripheral base stations registered in Activeset that indicate RABit = “1”, that is, one that is congested and it is difficult to increase the communication speed. It is determined whether or not to perform (step 2003). When it is determined that there is at least one neighboring base station indicating RABit = “1” in the Activeset, the system control unit 50 (generating means) “false pilot signal strength for removing the neighboring base station 100b from the Activeset” ”Is generated and transmitted from the DO RF unit 30 (transmission means) to the connected base station 100a via the antenna unit 10 (step 2004). As a result, the base station 100b is excluded from Activeset. The wireless communication terminal 200 performs data transmission (step 2005), and when the data transmission is completed, transmits a RouteUpdate message including the “correct” pilot signal strength between the neighboring base station 100b and the wireless communication terminal 200 (step 2007). ).

  When the transmission data amount is equal to or larger than the predetermined threshold β by the processing of FIG. 8, the communication speed cannot be increased due to congestion (RABit = “1” is shown). Therefore, the upper limit of the uplink data communication speed is changed in the direction of increasing according to the process of FIG. By doing so, the throughput of uplink data communication can be increased.

  FIG. 9 is a sequence diagram when uplink data is transmitted in the DO system performed by the wireless communication terminal 200.

  The wireless communication terminal 200 starts communication with the connected base station 100a.

  Here, among the neighboring base stations registered in Activeset, the base station 100b is in a state where the communication speed cannot be increased because it is congested, and when RABit = “1” is indicated, the wireless communication terminal 200 determines whether the transmission data amount is equal to or greater than the threshold value β. When transmitting data that is equal to or higher than the threshold β, a RouteUpdate message including “false pilot signal strength” is generated to remove the peripheral base station 100b indicating RABit = “1” from the Activeset, and the connected base station 100a Send.

  The base station 100a that has received the RouteUpdate message including the “false pilot signal strength” determines that the pilot signal strength is less than the threshold ζ, and performs a process of removing the peripheral base station 100b indicating the pilot signal strength from the Activeset. Do. The fact that the base station 100b is excluded from the Activeset is notified to the radio communication terminal 200 by a TCA message.

  The wireless communication terminal 200 performs data communication in this state, that is, in a state where a base station that cannot increase the communication speed due to congestion (RABit = “1” is indicated) is excluded.

  Then, when it is determined that the data transmission is completed, in order to register the base station 100b excluded from the Activeset in the Activeset again, instead of the “false” pilot signal strength, “ Send a RouteUpdate message containing the “correct” pilot signal strength. If this “correct” pilot strength is greater than or equal to the threshold ζ, the connecting base station 100a registers the neighboring base station 100b in Activeset again. The fact that the base station 100b is registered in Activeset is notified to the wireless communication terminal 200 by a TCA message.

  In the second embodiment of the present invention configured as described above, only the base station registered in Activeset is congested only when data exceeding a predetermined threshold β is transmitted during data communication. Therefore, the neighboring base stations that cannot increase the communication speed (indicating RABit = “1”) are excluded from the Activeset. This produces the following effects. That is, in the case of a small amount of data transmission that completes transmission in a short time, the effect of setting the direction to increase the communication speed by spending time for the process of changing the Activeset (steps 2002 to 2007 in FIG. 8). Because it is thin, only change the Activeset when sending a large amount of data. By doing so, the throughput of uplink data communication can be increased.

  In the embodiment of the present invention, the pilot signal strength (RSSI value) is used for the determination of the radio wave state with the base station 100, but this is used using the carrier-to-interference wave ratio (C / I value) of the pilot signal. Also good.

  In the embodiment of the present invention, the hybrid system in which the CDMA2000 1x system and the 1xEV DO system perform wireless communication using a common antenna is described. However, the present invention is not limited to this, and separate antennas are used. It may be used to perform wireless communication.

  In the embodiment of the present invention, the hybrid system of the CDMA2000 1x system and the 1xEVDO system has been described. However, the present invention is not limited to this, and the communication system varies the communication speed according to the congestion level of the base station. If it exists, the kind of communication system is not ask | required.

It is a block diagram showing the structure of the radio | wireless communication terminal of the 1st Embodiment of this invention. It is a flowchart which shows the change process of the communication rate of the 1st Embodiment of this invention. It is a table | surface which shows the relationship between the change of the communication rate of 1st Embodiment of this invention, and threshold value (alpha). It is explanatory drawing which showed the relationship between the change of the communication rate of the 1st Embodiment of this invention, and the base station of Activeset. It is explanatory drawing which showed the change of the communication rate of the 1st Embodiment of this invention on the time-axis. It is a flowchart at the time of the uplink data transmission of the 1st Embodiment of this invention. It is a sequence diagram at the time of the uplink data transmission of the 1st Embodiment of this invention. It is a flowchart at the time of the uplink data transmission of the 2nd Embodiment of this invention. It is a sequence diagram at the time of the uplink data transmission of the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Antenna 20 1xRF part 30 DO RF part 40 RF control part 50 System control part 60 System storage part 100a, 100b, 100c, 101 Base station 200 Wireless communication terminal

Claims (12)

A wireless communication terminal connected to a connection base station that holds information on neighboring base stations that are handoff destination candidates,
Receiving means for instructing to change the upper limit value of the communication speed from the neighboring base station;
Determining means for determining whether or not the instruction information received by the receiving means includes instruction information for instructing to lower the upper limit of the communication speed;
As a result of determination by the determination means, when instruction information for instructing to lower the upper limit value of the communication speed is included, generation means for generating a signal for controlling the information of the neighboring base station,
Transmitting means for transmitting the signal generated by the generating means to the connected base station;
A wireless communication terminal comprising: The wireless communication terminal according to claim 1,
The signal that controls the information on the neighboring base station includes information for excluding the base station that transmits the instruction information that instructs to lower the upper limit value of the communication speed from the information on the neighboring base station. A wireless communication terminal characterized by the above. The wireless communication terminal according to claim 1,
The signal for controlling the information of the neighboring base stations is a value indicating the communication quality between the base station that transmits the instruction information that instructs to lower the upper limit value of the communication speed and the wireless communication terminal, A wireless communication terminal having a value lower than a predetermined reference value. The wireless communication terminal according to claim 1,
Derivation means for deriving the amount of data to be communicated,
The transmission means includes, as a result of the determination by the determination means, instruction information for instructing to lower the upper limit value of the communication speed, and the amount of data derived by the derivation means is greater than a predetermined value Only, a signal for controlling information on the neighboring base stations is transmitted to the connecting base station. A program used for a wireless communication terminal connected to a connected base station that holds information on neighboring base stations that are handoff destination candidates,
A first procedure for receiving instruction information for instructing to change the upper limit value of the communication speed from the neighboring base station;
A second procedure for determining whether or not the instruction information received by the receiving means includes instruction information for instructing to lower the upper limit of the communication speed;
As a result of the determination by the determination means, when instruction information for instructing to lower the upper limit value of the communication speed is included, a signal for controlling the information on the neighboring base stations is transmitted to the connected base station. Procedure and
A program comprising: The program according to claim 5,
The signal that controls the information on the neighboring base station includes information for excluding the base station that transmits the instruction information that instructs to lower the upper limit value of the communication speed from the information on the neighboring base station. A program characterized by The program according to claim 5,
The signal for controlling the information of the neighboring base stations is a value indicating the communication quality between the base station that transmits the instruction information that instructs to lower the upper limit value of the communication speed and the wireless communication terminal, A program characterized in that the value is lower than a predetermined reference value. The program according to claim 5,
Including a fourth procedure for deriving the amount of data to be communicated;
The third procedure includes instruction information for instructing to lower the upper limit value of the communication speed as a result of the determination by the second procedure, and the remaining data amount derived in the fourth procedure is determined in advance. A program for transmitting a signal for controlling information on the neighboring base stations to the connected base station only when the number is larger than a predetermined value. A communication method used for a wireless communication terminal connected to a connection base station that holds peripheral base station information of a peripheral base station that is a handoff destination candidate,
From the neighboring base station, receiving instruction information instructing to change the upper limit value of the communication speed,
Determine whether the instruction information received by the receiving means includes instruction information for instructing to lower the upper limit of the communication speed;
As a result of the determination by the determining means, when instruction information for instructing to lower the upper limit value of the communication speed is included, a signal for controlling the information on the neighboring base stations is transmitted to the connected base station. A characteristic communication method. The communication method according to claim 9, wherein
The signal that controls the information on the neighboring base station includes information for excluding the base station that transmits the instruction information that instructs to lower the upper limit value of the communication speed from the information on the neighboring base station. A communication method characterized by the above. The communication method according to claim 9, wherein
The signal for controlling the information of the neighboring base stations is a value indicating the communication quality between the base station that transmits the instruction information that instructs to lower the upper limit value of the communication speed and the wireless communication terminal, A communication method characterized in that the value is less than a predetermined reference value. The communication method according to claim 9, wherein
As a result of the determination, when the instruction information instructing to lower the upper limit value of the communication speed is included, the data amount to be further communicated is derived, and only when the derived data amount is larger than a predetermined value, A communication method, comprising: transmitting a signal for controlling information on the neighboring base station to the connecting base station.

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