JP4711821B2 - Wireless communication terminal and wireless communication method - Google Patents

Description

  The present invention relates to a wireless communication terminal and a wireless communication method for controlling a communication speed of uplink data by changing an upper limit value stepwise based on a probability.

  In the CDMA2000 1xEV-DO (hereinafter referred to as 1xEV-DO) system, the uplink data transmission rate of a wireless communication terminal such as a mobile phone is the upper limit of the uplink communication rate (transfer rate) transmitted at a given timing from the radio base station. Control is performed based on information “RAbit (Reverse Activity Bit)” instructing to increase or decrease the value and a threshold value determined when a session between the wireless communication terminal and the wireless base station is established.

FIG. 6 is a communication speed change test table used in the 1xEV-DO system. (See non-patent literature)
As shown in FIG. 6, in 1xEV-DO, the upper limit of the uplink 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 communication is started, communication is first started at the slowest communication speed (9.6 kbps). Thereafter, the radio communication terminal receives the RAbit given from the radio base station and adjusts the communication speed.

  The RAbit is a bit value that varies depending on the congestion level of the wireless base station to which the wireless communication terminal is currently connected and the neighboring base stations to be handed off. Also, the radio base station is congested when many radio communication terminals are connected to the radio base station in a concentrated manner or when a communication line is congested.

  When communication is not congested in the radio base station, that is, when the communication speed can be increased, RAbit is set to “0”. On the other hand, when it is determined that the radio base station is congested, that is, when it is not preferable to increase the communication speed, RAbit is set to “1”.

  FIG. 7 is a flowchart illustrating a data communication speed change process performed by a 1xEV-DO compatible wireless communication terminal.

  First, the 1xEV-DO compatible wireless communication terminal starts communication at the lowest communication speed (9.6 kbps) (step 9001).

  When the RAbit is received from the radio base station, it is determined whether or not the received RAbit is “0”. (Step 9002). If it is determined that RAbit is “0” (YES in step 9002), 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.

  First, a random number x (0 <x <1) is generated (step 9003). It is determined whether or not the generated random number x is smaller than a threshold value α for changing the communication speed (step 9004). Here, as shown in FIG. 6, 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 “48” divided by “255”. The obtained value is “48/255”. In this example, it is determined whether the random number x is larger or smaller than “48/255”.

  If it is determined that the random number x is smaller than the threshold value α (YES in step 9004), the upper limit value of the current communication speed is increased by one step (step 9005). For example, if the upper limit value of 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 9006). For example, if the current communication speed is 9.6 kbps, 9.6 kbps is maintained.

  On the other hand, when it is determined that RAbit is “1” (NO in step 9002), the operation is performed in a direction to lower the upper limit value of the current communication speed by one step. That is, first, a random number x (0 <x <1) is generated (step 9007), and the random number x and a threshold value α (hereinafter referred to as “α ′” in order to distinguish it from α when RAbit is “0”). Are compared (step 9008). If it is determined that the random number x is smaller than the threshold α ′ (YES in step 9008), the upper limit value of the current communication speed is lowered by one step (step 9009). 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 α ′ (NO in step 9008), the upper limit value of the current communication speed is maintained (step 9006). For example, if the current communication speed is 19.2 kbps, 19.2 kbps is maintained.

  Thus, in the 1xEV-DO system, the wireless communication terminal is based on the RAbit transmitted from the wireless base station at every predetermined timing and the threshold determined at the time of session establishment between the wireless communication terminal and the wireless base station, At least the upper limit value of the communication speed in uplink communication is controlled to be increased, decreased or maintained by one step.

By the way, the study of CDMA2000 1xEV-DO rev.A (hereinafter referred to as 1xEV-DO rev.A), which is an extension of the above 1xEV-DO (hereinafter referred to as 1xEV-DO rev.0) communication method, is currently in progress. . QoS (Quality of Service) control is a new function added to 1xEV-DO rev.A. QoS control is a control in which a priority is set for a packet for each application executed on a wireless communication terminal, and the packet is transferred from a packet with a high priority. That is, instead of controlling the communication speed stepwise according to the probability as described above, it is possible to ensure the upstream communication speed required by the application executed on the wireless communication terminal from the start of communication, Even during communication, the upstream communication speed can be changed relatively freely according to the upstream communication speed required by the application.
“Cdma2000 High Rate Packet Data Air Interface 3GPP2 C.S0024 Version 4.0 section8.5.6.1.5.2 Rate Control”, 3GPP2, October 2002

  In the environment of 1xEV-DO rev.A, while executing an application that requires a certain uplink communication speed (transfer speed) on the wireless communication terminal, the wireless communication terminal is connected to the 1xEV-DO rev.0 wireless When handing off to the base station, communication is first started from 9.6 kbps, and the required uplink communication speed cannot be obtained unless the communication speed increase test based on the above probability is passed. However, in the above conventional technique, only one threshold value α is given for each upper limit value of each communication speed, so even communication that requires a certain upstream communication speed that does not allow delay can be executed at a low speed. Even in simple communication, the increase / decrease in the uplink communication speed of all communications is controlled with the same probability.

  For example, a case where an IP phone is executed will be described. This IP phone converts voice data into IP packets (VoIP) and delivers the voice to the other party via a normal IP network. Since a dedicated voice network (circuit-switched network) is not used, delay is likely to occur on the route. However, since it is a voice call, the delay is not allowed to exceed a certain time. In other words, generally a communication speed of about 70 to 80 kbps is required, but 1xEV-DO rev.0 always starts from 9.6 kbps, and the above communication speed increase test is required at least three times to meet the required speed It becomes. Actually, the above-mentioned communication speed increase test is governed by probability, and the probability that the communication speed increases as the communication speed increases becomes low. Therefore, if a considerable number of tests are not passed, the required speed cannot be obtained. Delay "occurs.

  In addition, IP phones use a method called “silence compression” that does not transmit data on the side that is not speaking, that is, silence is not transferred, so that the bandwidth is effectively used. Data transmission is not performed while listening to the other party's story, but data transmission is started when the conversation starts. In other words, when an IP phone is executed in a 1xEV-DO rev.0 environment, the uplink communication speed when starting to talk during a call always starts from 9.6 kbps, and the communication speed is set to a necessary and sufficient speed in the communication speed increase test described above. Since it takes time to go up, there will always be a delay at the beginning of the conversation.

  In order to solve the above-described problem, a first feature of the wireless communication terminal of the present invention is that a storage unit that stores a plurality of change rates according to an application for each upper limit value of uplink communication speed set in stages, and a predetermined A plurality of changes stored in the storage means based on information indicating whether to increase or decrease the upper limit of the uplink communication speed received from the radio base station at the timing of and a currently assigned uplink communication speed And a control unit that selects a change rate according to an application to be executed from the rate and controls a change in the upper limit value of the uplink communication speed based on the selected change rate.

  Further, the second feature of the radio communication terminal of the present invention is that the reception means for receiving, from the radio base station, a rate of change set for each upper limit value of the uplink communication speed in the radio base station, and the reception means And a notification means for transmitting to the radio base station a notification that the rate of change received by the control means is used for control by the control means.

  Further, the radio communication method of the present invention stores a plurality of change rates corresponding to communication applications for each upper limit value of the uplink communication speed set in stages, and the uplink communication speed is determined by the radio base station from the radio base station. A change rate set for each upper limit value is transmitted to the radio base station, and a notification that the received change rate is used for change control of the upper limit value of the uplink communication speed is transmitted to the radio base station. Depending on information to be executed from a plurality of change rates stored in the storage unit based on information indicating whether to increase or decrease the uplink communication speed received from the base station and the currently allocated uplink communication speed The change rate is selected, and the upper limit value of the uplink communication speed is changed based on the selected change rate.

  According to the present invention, it is possible to increase the uplink communication speed with high probability for communication that requires a high uplink communication speed that does not allow delay, and it is possible to prevent the deterioration of the service quality of the application.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a schematic block configuration diagram of a radio communication terminal and a radio base station according to an embodiment of the present invention.

  In FIG. 1, a wireless communication terminal 100 is a terminal corresponding to both rev.A and rev.0, and includes an RF unit 110, a system control unit 120, a system storage unit 130, a display unit 140, and a key input unit 150.

  The RF unit 110 transmits and receives radio signals according to CDMA to and from the radio base station 200. The RF unit 110 demodulates the radio signal, transmits the demodulated reception data to the system control unit 120, modulates the data received from the system control unit 120, and transmits the data to the radio base station 200 as a radio signal. .

  The system control unit 120 controls various functions included in the wireless communication terminal 100. A more detailed functional block diagram of the system control unit 120 according to the present embodiment will be described later.

  The system storage unit 130 stores various types of information used in control and the like in the wireless communication terminal 100. More detailed functional blocks of the system storage unit 130 according to the present embodiment will be described later.

  The display unit 140 displays image content received via the RF unit 110 and the system control unit 120, and displays operation details (such as an input telephone number and an address).

  The key input unit 150 is configured by a numeric keypad, function keys, and the like, and is an interface used for inputting user operation details.

  The radio base station 200 is a base station that supports only rev.0, and includes an RF unit 210, a system control unit 220, and a system storage unit 230.

  The RF unit 210 transmits and receives radio signals according to CDMA to and from the radio communication terminal 100. In addition, the RF unit 210 performs conversion between the radio signal and the baseband signal, and transmits and receives the baseband signal to and from the system control unit 220.

  The system control unit 220 controls various functions included in the radio base station 200. A more detailed functional block diagram of the system control unit 220 relating to the present embodiment will be described later.

  The system storage unit 230 stores various types of information used for control in the radio base station 200. More detailed functional blocks of the system storage unit 230 relating to the present embodiment will be described later.

  FIG. 2 is a detailed functional block configuration diagram of the system control unit 120 and the system storage unit 130 of the wireless communication terminal 100.

  As shown in FIG. 2, the system control unit 120 includes a data communication unit 121, a communication speed setting unit 122, and a random number generation unit 123.

  The system storage unit 130 includes a communication speed change test table storage unit 131 and a communication level storage unit 132.

  The data communication unit 121 receives RAbits periodically transmitted from the radio base station 200.

  The communication speed setting unit 122 sets the communication speed according to the application to be executed, as will be described later.

  The random number generator 123 periodically generates a random number x (0 <x <1) at a predetermined timing.

  The communication speed change test table storage unit 131 stores a communication speed change test table 350 described later.

  The communication level storage unit 132 stores a communication level corresponding to an application.

  Here, a communication speed change test table 350 stored in the communication speed change test table storage unit 131 is shown in FIG.

  In FIG. 4A, the communication speed change test table 350 associates a plurality of communication levels with each upper limit value of each uplink communication speed, and provides the above-described probability test threshold value for each communication level. This is different from the conventional communication speed change test table.

  The communication level is a value stored according to the application in the communication level storage unit 132, that is, a value stored based on the uplink communication speed required by the application (see FIG. 4B). .

  According to the communication speed change test table 350, when the communication level of the application is determined to be “1” (for example, VoIP or the like) and RAbit = 0 (that is, the communication speed can be increased), for example, , The threshold α corresponding to the communication level “1” at 9.6 kbps is “255/255”, and α> x (0 <x <1) (100% probability), so the upper limit of the communication speed is always It is raised to 19.2kbps which is the stage. Similarly, even at 19.2 kbps and 38.4 kbps, the threshold α when the communication level is “1” is “255/255”, so it is always raised to the next stage.

  That is, according to the communication speed change test table 350, the upper limit value of the communication speed is reliably increased to 76.8 kbps in three change tests for an application for which the communication level is set to “1”.

  Even when RAbit = 1 (that is, when it is not preferable to increase the communication speed), if the communication level of the application is “1”, for example, the threshold corresponding to the communication level “1” at 76.8 kbps α is “0/255”, and since α <x (0 <x <1) (100% probability), the communication speed can be maintained at 76.8 kbps.

  In the present embodiment, in the communication speed change test table 350, four levels from 1 to 4 are set as the communication level for each upper limit value of the communication speed. However, the method of setting the communication level is not limited to this, and can be set in three steps for each upper limit value of each communication speed. Further, different steps for each upper limit value of the communication speed (for example, at 9.6 kbps) It may be set to 4 levels, 3 levels for 19.2kbps, etc.). Of course, the value of the threshold value α is not limited to the value used in the present embodiment.

  FIG. 3 is a functional block configuration diagram of the system control unit 220 and the system storage unit 230 of the radio base station 200.

  As shown in FIG. 3, the system control unit 220 includes a data communication unit 221 and a RAbit generation unit 222.

  The system storage unit 230 includes a communication speed change test table storage unit 231.

  The data communication unit 221 executes processing related to communication such as image content and music content, and transmission / reception of various control information.

  The RAbit generator 222 generates an RAbit having a value of “0” or “1” depending on the congestion level of the radio base station 200 and the neighboring base stations.

  The communication speed change test table storage unit 231 stores and holds a conventional communication speed change test table 350 '.

  That is, in the present embodiment, the communication speed change test table held by the radio communication terminal 100 and the communication speed change test table held by the radio base station 200 are thresholds set for each upper limit value of the uplink communication speed. The number and value are different.

  FIG. 5 is a flowchart showing details of the operation of the wireless communication terminal 100.

  When creating a session with the radio base station 200, the radio communication terminal 100 matches the communication speed change test table. That is, when the wireless communication terminal 100 receives an instruction from the wireless base station 200 to use the communication speed change test table 350 ′ (threshold) (step 1001), a signal indicating that the instruction has been accepted is transmitted to the wireless base station. 200 (step 1002).

  However, actually, the wireless communication terminal 100 performs control using the communication speed change test table 350 (threshold value) held in its own communication speed change test table storage unit 131.

  Thereafter, the wireless communication terminal 100 first starts communication at the lowest communication speed (9.6 kbps) (step 1003).

  The communication speed setting unit 122 determines a communication level appropriate for the application to be executed based on the communication level storage unit 132 (step 1004).

  Subsequently, when the RAbit is received from the radio base station 200, the communication speed setting unit 122 determines whether or not the received RAbit is “0”. (Step 1005).

  If it is determined that RAbit is “0” (YES in step 1005), the upper limit value of the current uplink communication speed is set based on the communication speed change test table 350 stored in the communication speed change test table 131. Operates in the direction of increasing levels.

  That is, the random number generation unit 123 generates a random number x (0 <x <1) and supplies it to the communication speed setting unit 122 (step 1006), and the communication speed setting unit 122 sets the upper limit (communication speed) of the current uplink communication speed. A threshold value α corresponding to the communication level determined in step 1004 and the communication level determined in step 1004 is acquired from the communication speed change test table 350, and the acquired threshold value α is compared with the random number x (step 1007).

  As a result, if it is determined that the random number x is smaller than the threshold value α (YES in step 1007), the radio base station 200 is notified that “x <α” (step 1008), and the current uplink communication speed is determined. The upper limit is increased by one step (step 1009).

  On the other hand, if it is determined that the random number x is greater than or equal to the threshold value α (NO in step 1007), the radio base station 200 is notified that “x ≧ α” (step 1010), and the upper limit of the current uplink communication speed is reached. The value is maintained (step 1011).

  If it is determined that RAbit is “1” (NO in step 1005), the upper limit value of the current uplink communication speed based on the communication speed change test table 350 stored in the communication speed change test table 131. It moves in the direction of lowering.

  That is, the random number generation unit 123 generates a random number x (0 <x <1) and supplies it to the communication speed setting unit 122 (step 1012). The communication speed setting unit 122 sets the upper limit of the current uplink communication speed and the step. The threshold value α corresponding to the communication level determined in 1004 is acquired from the communication speed change test table 350 and is distinguished from the acquired threshold value α (the threshold value α when RAbit is “0”. (referred to as α ′) and the random number x (step 1013).

  As a result, when it is determined that the random number x is smaller than the threshold value α (YES in step 1013), the radio base station 200 is notified that “x <α” (step 1014), and the current uplink communication speed is determined. The upper limit value is lowered by one step (step 1015).

  On the other hand, if it is determined that the random number x is greater than or equal to the threshold value α (NO in step 1013), the radio base station 200 is notified that “x ≧ α” (step 1016), and the upper limit of the current uplink communication speed is set. The value is maintained (step 1011).

  In steps 1008, 1010, 1014, 1016, radio communication terminal 100 does not notify radio base station 200 of the values of “x” and “α”, but only notifies the magnitude relationship. That is, for example, “x / α” (a value obtained by dividing x by α), “x−α” (a value obtained by subtracting α from x), or the like indicating a magnitude relationship between “x” and “α”. To be notified.

  When receiving the value indicating the magnitude relationship between “x” and “α” from the wireless communication terminal 100, the wireless base station 200 changes the upper limit value of the uplink communication speed based on the value.

  That is, for example, when RAbit is “0”, the radio base station 200 operates to increase the upper limit value of the current uplink communication speed by one step, and the magnitude relationship between “x” and “α” from the radio communication terminal 100. For example, when a value of “x / α” is notified as a value indicating “1”, if “1> (x / α)” (that is, x <α), the upper limit value of the uplink communication speed is increased by one step. If ≦ (x / α) ”(that is, x ≧ α), the upper limit value of the current uplink communication speed is maintained. When RAbit is “1”, radio base station 200 operates in a direction to lower the upper limit value of the current uplink communication speed by one step, and is a value indicating the magnitude relationship between “x” and “α” from radio communication terminal 100. For example, when the value of “x / α” is notified, if “1> (x / α)” (that is, x <α), the upper limit value of the uplink communication speed is lowered by one step, and “1 ≦ (x / Α) ”(ie, x ≧ α), the upper limit value of the current uplink communication speed is maintained.

  In the above embodiment, the radio communication terminal 100 is configured to notify the radio base station 200 of the magnitude relationship between the random number x and the threshold value α. However, the present invention is not limited to this, and the upper limit value of the uplink communication speed is simply set to one. The radio base station 200 may be configured to instruct whether to raise, lower, or maintain the level. The radio base station 200 changes the upper limit value of the uplink communication speed according to the instruction from the radio base station 100.

  As described above, according to the present embodiment, the radio communication terminal 100 controls the upper limit value of the uplink communication speed according to the application without changing the uplink communication control of the radio base station 200 as the rev.0 base station. It becomes possible to do.

It is a schematic block block diagram of the radio | wireless communication terminal and radio | wireless base station which concern on embodiment of this invention. It is a detailed functional block diagram of the system control part and system memory | storage part of the radio | wireless communication terminal which concerns on embodiment of this invention. It is a detailed functional block diagram of a system control unit and a system storage unit of the radio base station according to the embodiment of the present invention. It is a figure which shows an example of the table for a communication speed change test which concerns on embodiment of this invention. It is a figure which shows the operation | movement flow of the radio | wireless communication terminal which concerns on embodiment of this invention. It is a figure which shows the table for a conventional communication speed change test. It is a figure which shows the operation | movement flow of the communication speed change in the conventional radio | wireless communication terminal.

Explanation of symbols

100: wireless communication terminal, 200: wireless base station

Claims (2)

Storage means storing a plurality of probabilities of raising the upper limit value of the communication speed according to the application to the next stage for each upper limit value of the uplink communication speed set in stages ,
Based on information indicating whether to increase or decrease the upper limit of the uplink communication speed received from the radio base station at a predetermined timing and the currently assigned uplink communication speed, a plurality of data stored in the storage means control means for selecting a probability corresponding to the application to be executed from the probability, controls the change of the upper limit of the uplink transmission rate based on the probabilities the selected,
A wireless communication terminal comprising: For each upper limit of uplink communication speed set in stages, memorize multiple probabilities of raising the upper limit of communication speed according to the application to the next stage ,
Based on information indicating whether to increase or decrease the upper limit of the uplink communication speed received from the radio base station at a predetermined timing and the currently assigned uplink communication speed, a plurality of data stored in the storage means radio communication method characterized by selecting a probability depending on the applications that run from the probability, controls the change of the upper limit of the uplink transmission rate based on the probabilities said selected.

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