JP2007281553A - Method of assigning channel, mobile communication system, and base station device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of assigning a channel for enabling appropriate scheduling according to an application that a user utilizes. <P>SOLUTION: The method includes: a step for setting a plurality of pieces of priority according to information for identifying the application; and a step for assigning channels by using the priority in a time sharing unit, based on information on communication quality and the information for identifying the application. The information for identifying the application is information based on a degree, where the application requests real-time properties. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a channel allocation method, a mobile communication system, and a base station apparatus that optimize scheduling for channel allocation to mobile terminals.

  Conventionally, downlink transmission of wireless data communication such as Cdma2000 1x Evolution Data Only system (1xEV-DO or High Rate Packet Data (HRPD) system) is time division, and allocation of each terminal to a time division slot is a mobile terminal. There is known a radio system that is made by scheduling in consideration of the reception state (reception field strength, carrier-to-interference ratio = CIR) of base station signals (such as pilot channel signals) in. The Cdma2000 1xEV-DO system is a system to which the Cdma2000 1x system is further applied to a system aimed at improving communication speed by specializing in data communication. In the Cdma2000 1xEV-DO system, the configuration of the radio interface in the direction from the mobile terminal to the base station (uplink direction) is almost the same as that of the Cdma2000 1x system, but the direction from the base station to the mobile terminal (downlink direction) is the same as that of Cdma2000 1x. Although the bandwidth (1.23 MHz) is used, the modulation method and multiplexing method are greatly different. The modulation scheme is Cdma2000 1x for QPSK and HPSK, and in 1xEV-DO, depending on the downlink reception state at the mobile terminal, the modulation scheme is switched to QPSK, 8-PSK or 16QAM, and the reception state is good. Is configured to use a transmission rate that is low in error tolerance but high in speed, and uses a transmission rate that is low in error but high in error tolerance when reception is poor.

  A multiplexing method for distinguishing and simultaneously performing communication from one base station to a plurality of mobile terminals is also CDMA (Code Division Multiple Access used in CdmaOne, Cdma2000 1x, assigning a spreading code to each mobile terminal, Rather than TDMA (time division multiple access; time is divided in units of 1/600 seconds) instead of communication to each mobile terminal spread with each code, communication with only one mobile terminal is performed within that time, Communicate with a plurality of mobile terminals by switching the mobile terminal of the communication partner according to time). The mobile terminal measures the CIR (carrier-to-interference ratio) of the downlink pilot signal, which is a value indicating the reception state in the downlink direction from the base station that is the communication partner, and the “predetermined error rate (system design) The maximum transmission rate that can be received at a rate below 1%). The base station receives notifications from a plurality of mobile terminals, determines which mobile terminal to communicate with each time division unit by a function called a scheduler, and the transmission rate is based on the transmission rate notified from the mobile terminal. Communicate with each mobile terminal using the highest possible transmission rate.

The scheduler used in the Cdma2000 1xEV-DO system calculates DRC / R from DRC (downlink communication speed request value) from each mobile terminal and the average data rate R in the downlink direction received by each mobile terminal so far. Then, data transmission is performed by assigning a downlink transmission slot to the mobile terminal having the maximum DRC / R value in each time division unit. The average data rate R is an actual value average of past data rates from a predetermined time (for example, 1000 slots; 1.66 seconds) to the present time. Transmission of downlink data to the mobile terminal having the maximum DRC / R value means that the current DRC is improved with respect to the past average received data rate (average of the downlink signal reception state in the past mobile terminal). This means that downlink data is transmitted to a mobile terminal having a large. On the other hand, since the average data rate R is a small value in a mobile terminal that is rarely assigned downlink transmission from the base station, it can finally be assigned downlink transmission even if the DRC is low. An attempt has been made to efficiently use radio communication resources while guaranteeing a certain degree of fairness by such scheduling (see, for example, Patent Document 1).
JP 2004-040786 A

  With the improvement of data communication performance in mobile communication systems such as mobile phones, it is expected that in the field of mobile communication, services such as streaming video playback and IP phone and IP-TV phone will be expanded. In particular, in the Cdma2000 1xEV-DO system, in order to expand these services, scheduling that considers the quality of service (QoS) such as data rate and real-time performance is required more than ever.

However, the scheduling method disclosed in Patent Document 1 is basically a best-effort scheduling method, and an application used in a mobile terminal is not considered in the scheduling algorithm. For this reason, when a user uses an application such as streaming video playback, IP phone, or IP-TV phone that requires real-time performance, there is a problem that usability may deteriorate depending on the result of scheduling.
On the other hand, when scheduling is performed so that only a part of the applications is prioritized, other disadvantages such as a channel being allocated with a small transmission capacity to other low priority applications occur.

  The present invention has been made in view of such circumstances, and provides a channel allocation method, a mobile communication system, and a base station apparatus capable of performing appropriate scheduling according to an application used by a user. For the purpose.

  The present invention includes a step of setting a plurality of priorities according to information for identifying an application, and a step of allocating a channel using priority in a time division unit based on information on communication quality and information for identifying an application It is characterized by having.

  The present invention is characterized in that the information for identifying the application is information based on a degree to which the application requires real-time property.

  According to the present invention, the priority in the time division unit for each priority according to the information for identifying the application passes through the time of the number of time division units greater than the number of terminals with a high priority, so that a plurality of time division units are obtained. The priority in is characterized by having an intersection.

  The present invention is characterized in that, when there are applications having different priorities based on information based on the applications, the priorities are switched in a certain time division unit.

  The present invention is characterized in that the information for identifying the application is information based on a delay time allowed for each of the plurality of applications using communication.

  The present invention is characterized in that the information based on the communication quality includes a value based on a communication speed that the terminal desires to transmit to the base station by referring to the communication quality.

  The present invention includes a step of storing the priority calculated for each terminal, the communication quality, and information for identifying the application, and a step of dynamically updating a value based on the time division unit; It is characterized by including.

  The present invention is a mobile communication system that performs communication with a base station by allocating communication channels to a plurality of terminals, and the terminal is used for communication with a base station. An application information grasping unit for identifying information for identifying the application being transmitted, a transmission unit for transmitting information identifying the communication quality requested to the base station and information for identifying the application to the base station, The base station receives a communication quality information requested by the terminal and information identifying the application transmitted from the terminal, the communication quality information requested by the terminal, and the terminal in the past A channel for identifying a terminal to which a channel is allocated based on information on the frequency with which the channel is allocated and information identifying the application Characterized by comprising a Ri abutting portion.

  The present invention is a base station apparatus that performs communication by assigning communication channels to a plurality of terminals, and that acquires information for identifying an application used for performing communication in the terminals. A communication quality acquisition unit that acquires information on communication quality requested by the terminal, information on the communication quality requested by the terminal, information on frequency of channel assignment to the terminal in the past, and the terminal And a channel allocation unit that identifies a terminal to which a channel is allocated based on information for identifying an application used in the network.

  According to the present invention, the frequency of channel assignment is changed according to the application used by the user, and the assignment of the application with a high priority is performed by assigning the priority according to a plurality of applications. Even in the case of channels that are allocated to low-priority applications with increasing frequency, it is possible to prevent the time-averaged transmission capacity from becoming extremely different and to optimize scheduling for channel allocation to terminals. Is obtained.

  Hereinafter, a channel allocation method, a mobile communication system, and a base station apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment. In this figure, symbols A, B, and C are mobile terminals that use the Cdma2000 1xEV-DO scheme (simply shown as terminals in the drawing). Reference numeral 1 denotes a base station that establishes a wireless communication line with each of the mobile terminals A, B, and C. Reference numeral 2 denotes a network to which a plurality of base stations 1 are connected. Reference numeral 3 denotes an information distribution server that is connected to the network 2 and distributes information to the mobile terminals A, B, and C.

  Reference numeral 11 denotes a control unit that performs overall control of processing operations of the base station, and exchanges data with the network 2, transmission / reception data encoding / decoding processing, transmission / reception timing control, application information acquisition, channel assignment Etc. The code | symbol 11a is an application information acquisition part which acquires the application information grasped | ascertained in the mobile terminal from the demodulated received signal. Reference numeral 11b denotes a channel allocation unit that allocates a channel including an uplink / downlink slot from a scheduler to a mobile terminal. Reference numeral 12 denotes a transmitter that transmits a downlink signal to the mobile terminal. Reference numeral 13 denotes a receiving unit that receives an uplink signal from a mobile terminal. Reference numeral 14 denotes a scheduler that determines to which mobile terminal data is transmitted in which time division unit by executing a scheduling process. Reference numeral 15 denotes an average data rate calculation unit that calculates the average data rate R of the mobile terminals A, B, and C that are communicating with each other within their own communication area. Reference numeral 16 denotes a DRC / R value based on DRC (downlink communication speed request value) from each mobile terminal A, B, and C and the average data rate R of downlink data received by each mobile terminal so far. It is a DRC / R calculation unit to calculate. Reference numeral 17 denotes a DRC / R comparison unit that compares the DRC / R values calculated by the DRC / R calculation unit 16 and identifies the mobile terminal having the maximum DRC / R value. Reference numeral 18 denotes a terminal information storage unit that stores information related to a mobile terminal that is communicating in its own communication area. Details of the information stored in the terminal information storage unit 18 will be described later. Reference numeral 19 denotes a sector throughput monitoring unit that monitors the throughput of each sector. Reference numeral 20 denotes an interface unit that performs information communication with the information distribution server 3 via the network 2.

  Reference numeral 21 denotes a CPU that performs overall control of processing operations of the mobile terminal C. Reference numeral 22 denotes an application information grasping unit that identifies an application activated and processed by the CPU 21 and outputs identification information of the activated application. Reference numeral 23 denotes a duplexer that distributes a received signal and a transmitted signal. Reference numeral 24 denotes a demodulator that demodulates the received signal. Reference numeral 25 denotes a decoder that decodes (despreads) the demodulated signal. Reference numeral 26 denotes a predictor that predicts the CIR value at the next reception slot timing based on the decoded CIR. The code | symbol 27 is a CIR-DRC conversion table for converting into the value of DRC based on a CIR prediction value. Reference numeral 28 denotes a GPS receiver that receives a GPS (Global Positioning System) signal. Reference numeral 29 denotes a MUX (multiplexer) that synthesizes the transmission data with the DRC value and the like. Reference numeral 30 denotes an encoder that encodes data to be transmitted. The code | symbol 31 is a modulator which modulates the encoded signal. Reference numeral 32 denotes a memory for storing an application program executed by the CPU 21 and downloaded data. Reference numeral 33 denotes a display unit constituted by a liquid crystal display device or the like. Reference numeral 34 denotes an operation unit configured by a key panel on which numeric keys and function keys are arranged.

When the application used in the mobile terminal as described above is an application that requires real-time performance such as streaming video or IP-TV phone, communication is performed by preferentially allocating a channel to the mobile terminal. A method for ensuring continuity is conceivable.
However, with such a method using a single priority, channel assignment to mobile terminals using applications other than the priority application is reduced or interrupted.

Therefore, in the present invention, in order to avoid such a problem, allocation is performed according to a plurality of priorities according to the real-time property of the application. Establish time division unit priority for allocating channels for each mobile terminal that uses the application, increase the priority for each time division unit by time division unit, and obtain the time division unit priority for each time division unit The channel is allocated to the mobile terminal based on the priority in the time division of the allocation timing. The setting value of the priority of the time division unit can be determined based on, for example, the DRC for each mobile terminal, and the rising slope is determined based on the allocation frequency required by the application used by the mobile terminal. At this time, it is important to determine the setting value and the inclination so that the priorities of the time division units having different allocation frequencies required by the application have intersections.
In this way, a high-frequency assignment is performed to a mobile terminal with a high priority according to the real-time property of the application, while a mobile terminal with a low priority is also reliably assigned.
Hereinafter, the specific method will be described.

  Next, terminal information stored in the terminal information storage unit 18 shown in FIG. 1 will be described with reference to FIG. FIG. 2 is an explanatory diagram showing a table structure of a terminal information table stored in the terminal information storage unit 18 shown in FIG. The terminal information table includes data for the past 20 slots (k = 1 to 20) for all mobile terminals with which the base station 1 is currently communicating (here, only terminal A, terminal B, and terminal C are shown). It has a field in which the rate value is stored. k = 20 means the oldest slot, the smaller the value of k, the closer it is to the present, and k = 1 means the most recent slot. In FIG. 2, the value of the data rate is blank, but the value stored in each field is updated dynamically by the scheduler 14. Further, for each terminal, there are stored fields in which the average data rate R calculated in the scheduler 14, the DRC that is a required value of the downlink communication speed, and identification information that identifies an application activated in the mobile terminal are stored. Have. These values are also dynamically updated by the scheduler 14.

  The identification information for identifying the application activated in the mobile terminal includes real-time (high priority) applications such as streaming video playback, IP phone, IP-TV phone, and the like. It is information that can identify an application that does not need to be connected. Here, it is assumed that identification information of an application that does not require real-time property is “1”, and identification information of an application that requires real-time property is “2”.

  Also, the weighted average coefficients α and β are related to each of k = 1-20. The weighted average coefficients α and β are coefficients used when calculating the average data rate R from the data rate value for 20 slots, and α is applied when the application identification information is “1”. , Β is applied when the identification information of the application is “2”. The weighted average coefficient β is associated with a value only for k (time division unit) of 1 to 5, but k of 6 to 20 means that the value is “0”. The weighted average coefficient α is defined such that the most recent value is the largest and decreases linearly as it becomes the past. When all values are added together, the weighted average coefficient α is “1”. Similarly to α, the weighted average coefficient β is defined such that the most recent value is the largest and linearly decreases in the past, and when all values are added, the value becomes “1”. . However, in the case of the weighted average coefficient β, the coefficient is “0” for k of 6-20.

  The number of data rate values in the past slots stored in the terminal information storage unit 18 is 20 slots for simplicity of explanation, but in actuality, 20 or more slots (for example, 1000 slots, 1.66 seconds) is no problem. However, when the number of past data rate values to be stored is increased, the number of weighted average coefficients α and β must be increased in proportion to this.

  Next, basic operations of the base station 1 and the mobile terminal C will be described with reference to FIGS. First, the downlink pilot signal from the base station 1 received by the mobile terminal C is demodulated and decoded (despread) by the demodulator 24 and the decoder 25, and Ec / lo (pilot signal strength vs. total) in the course of the decoding process. Received signal strength) is obtained, and CIR is obtained from the relationship of CIR = (Ec / lo) / (1-Ec / lo). The obtained CIR value is input to the predictor 26, and the predictor 26 predicts and outputs the CIR value at the next reception slot timing. The predicted CIR value is converted into a DRC value with reference to the CIR-DRC table 27 and notified to the CPU 21. The DRC value and the identification information of the currently activated application output from the application information grasping unit 22 are multiplexed with the data to be transmitted by the MUX 29, and encoded by the encoder 30 and the modulator 31. Modulated and transmitted to the base station 1. As a result, the mobile terminal C is notified of information identifying the currently used application to the base station 1 at the start of communication with the base station 1 or whenever DRC transmission to the base station 1 is performed.

  On the other hand, when receiving the application identification information with the DRC value notified from each of the communicating mobile terminals A, B, and C existing in its own communication area, the control unit 11 receives The application identification information and the DRC value are stored in the terminal information storage unit 18 via the scheduler 14. In the terminal information storage unit 18, information for identifying applications used in all mobile terminals (here, mobile terminals A, B, and C) currently communicating with the base station 1 is registered. When the communication is completed, the information regarding the mobile terminal is discarded. Each mobile terminal communicating with the base station 1 transmits to the base station 1 the DRC value obtained for each time division slot based on the downlink reception state. In the base station 1, the scheduler 14 calculates DRC / R based on the DRC from each mobile terminal, and downlink transmission in the next time division slot is assigned to the mobile terminal having the maximum DRC / R.

  Here, the operation in which the average data rate calculation unit 15 calculates the value of the average data rate R of each mobile terminal will be described. First, when the average data rate calculation unit 15 receives the average data rate calculation timing signal output from the control unit 1, the average data rate calculation unit 15 reads the values of the downlink data rates for the past 20 slots stored in the terminal information storage unit 18. At the same time, the value of the weighted average coefficient is read out. At this time, the average data rate calculation unit 15 selects the weighted average coefficient α or β based on the identification information of the activated application of the mobile terminal for which the average data rate is calculated, and reads the selected weighted average coefficient. That is, when the identification information of the activated application is “1”, the weighted average coefficient α is read, and when the identification information of the activated application is “2”, the weighted average coefficient b is read. Then, if the identification information of the startup application is “1”, the average data rate calculation unit 15 calculates the average data rate R according to the following equation (1), and if the identification information of the startup application is “2”: For example, the average data rate R is calculated by the following equation (2).

  When the average data rate R is calculated by the formula (2) when the identification information of the activated application is “2”, the average data rate R is calculated by using all weighted average coefficients as in the formula (1). However, by omitting the calculation of the term whose weighted average coefficient is “0” and calculating only the term whose weighted average coefficient β is not “0” (that is, k is 1 to 5). The calculation time of the average data rate R is shortened. The average data rate calculation unit 15 performs this calculation for all mobile terminals currently communicating with the base station 1 and stores the obtained average data rate R value in the terminal information storage unit 18. As a result, the value of the average data rate R is updated for each mobile terminal currently communicating.

  In this way, the weighted average coefficient to the average data rate R to be obtained is performed according to the real-time property required for the application, and the priority of the application with high frequency for each time division unit of the application with high priority is high. Be sure to exceed the priority of the low time division unit. Even in a terminal with a low application priority, the priority of the time division unit will increase and the probability of allocation will increase.

  In this way, in the base station 1, the scheduler 14 determines to which mobile terminal the next slot is used for transmission, and the transmission rate in this transmission is as high as possible based on the DRC notified from the mobile terminal. Is used to communicate with mobile terminals. The Cdma2000 1xEV-DO system enables downlink data transmission of up to 2.4 Mbps per sector, but this is only the maximum value per sector, and actually this sector is connected to a plurality of mobile terminals currently connected. It will be shared and used. For this reason, in order to make use of the capability of the 1xEV-DO system, it is important to perform scheduling that is efficient and convenient for the user.

  Next, an operation in which the base station 1 shown in FIG. 1 performs scheduling will be described with reference to FIG. First, the control unit 11 receives the request value (DRC) of the downlink communication speed and the identification information of the activated application via the receiving unit 13 (step S1). The control unit 11 stores the received DRC and activation application identification information in the terminal information storage unit 18 via the scheduler 14. The operation of storing the DRC and the identification information of the activated application in the terminal information storage unit 18 is performed for all mobile terminals that are currently communicating within the own communication area.

  Next, the average data rate calculation unit 15 calculates the average data rate R based on the application activated in each mobile terminal by using the above-described method for calculating the average data rate R, and obtains the obtained result. The information is stored in the terminal information storage unit 18 (step S2). In response to this, the DRC / R calculation unit 16 reads the average data rate R and DRC from the terminal information storage unit 18, calculates the DRC / R value, and selects the mobile terminal for this DRC / R value. The identification information to be specified is assigned and notified to the DRC / R comparison unit 17 (step S3). For example, in the example illustrated in FIG. 2, if the calculation target is the mobile terminal A, the average data rate R is “R−A”, and the DRC is “DRC-A”. It is calculated by “DRC-A” / “R-A”. Then, the average data rate calculation unit 15 determines whether or not the average data rate R has been calculated for all mobile terminals currently communicating (step S4), and there is a mobile terminal that has not calculated the average data rate R. For example, the process returns to step S2 to calculate the average data rate and DRC / R.

  Next, when the DRC / R comparison unit 17 is notified of the DRC / R values from the DRC / R calculation unit 16 for all mobile terminals currently in communication, the notified DRC / R value is the maximum. A certain mobile terminal is specified (step S5). Then, the DRC / R comparison unit 17 notifies the identification information of the specified mobile terminal to the control unit 11. In response to this, the channel assignment unit 11b of the control unit 11 assigns the next downlink transmission slot to the identified mobile terminal (step S6), and each mobile terminal stored in the terminal information storage unit 18 The value of the downlink data rate is updated (step S7). Then, the downlink communication speed request value (DRC) and the activation application identification information are received again (step S1), and the processes of steps S2 to S7 are repeatedly executed.

  As described above, when the scheduler 14 calculates the average data rate R for each mobile terminal, the scheduler 14 reads the activation application identification information for each mobile terminal stored in the terminal information storage unit 18 to perform streaming video or IP-TV telephone. If an application that requires real-time performance is used, the number of slots for calculating the average data rate R of the mobile terminal is reduced. The frequency at which transmission slots are assigned can be increased, and real-time performance at the time of application execution can be maintained. For example, if the number of slots for calculating the average data rate R of the target mobile terminal is set to the past 5 slots, even if no downlink transmission slot is assigned to the mobile terminal in the past 5 slots, this movement is performed at the 6th slot. The average data rate R of the terminal is “0”, and the possibility that the downlink transmission slot is allocated to this mobile terminal at the sixth slot by the scheduler 14 is dramatically increased. If there is no other mobile terminal that starts communication in that slot, the downlink transmission slot is assigned to the target mobile terminal. That is, for example, even if a downlink transmission slot for the target mobile terminal is not allocated for 5 slots, the possibility that a downlink transmission slot is allocated to this mobile terminal is very high in the 6th slot. can do. If the frequency with which the downlink transmission slot is assigned by the scheduler 14 is increased, it is possible to improve the usability of an application that requires real-time performance.

On the other hand, the number of slots for calculating the average data rate R of the mobile terminal is read if the application identification information for each terminal is read and an application that does not require real-time property is used, such as browsing a Web page that does not include mail or streaming information By increasing the number of slots, the allocation to applications having real-time characteristics is not hindered. On the other hand, when the number of slots for calculating R elapses, the average data rate R of this mobile terminal approaches “0”. In contrast, the possibility of assigning a downlink transmission slot greatly increases. As a result, the probability of unilateral allocation even in an application that does not require real-time performance is not reduced.
In this way, the allocation frequency is divided according to the degree to which the real-time property of the application is required, and the frequency of assigning the priority application that requires the real-time property is increased. It will be.

  As described above, for a mobile terminal using an application that requires real-time performance (hereinafter referred to as a priority mobile terminal), a weighted average in which the average data rate R is always “0” in a desired cycle. Set the number of coefficients to be the preferred mobile terminal by setting it less than the number of mobile terminals using applications that do not require real-time performance (applications such as downloading data without displaying in real time). It is possible to increase the probability that downlink transmission slots are assigned in a cycle. However, there is no problem when the ratio of the priority mobile terminals to the total number of mobile terminals in communication with the base station 1 is low, but when the ratio of the priority mobile terminals is large, mobile terminals other than the priority mobile terminals (hereinafter referred to as normal mobile terminals). It is necessary to consider so that the downlink transmission slot allocation frequency (probability) does not decrease. This point will be described with reference to FIG.

  FIG. 4 is an explanatory diagram showing the relationship between the weighted average coefficients α and β shown in FIG. In FIG. 4, the number of weighted average coefficients αk for obtaining the average data rate R of the normal mobile terminal (the number of past slots when obtaining the average data rate R) is S, and the average data rate R of the priority mobile terminal is obtained. The number of weighted average coefficients βk is represented by T. For example, when S = 1000 and T = 60, k> 57 and αk> βk, so that a priority mobile terminal is more easily selected than a normal mobile terminal (R in DRC / R with the same DRC becomes smaller) and setting The possibility that the downlink transmission slot is allocated to the priority mobile terminal at a cycle shorter than the above cycle becomes high. In other words, if the number of priority mobile terminals is close to the set cycle (downlink transmission slot allocation cycle), the frequency (probability) assigned to a normal mobile terminal is significantly reduced, which may hinder the use of normal mobile terminal users. There is.

  For this problem, by setting the number of weighted average coefficients for the priority mobile terminals so that the point where αk and βk in FIG. 4 intersect (number of samples k = L) is equal to or greater than the number N of mobile terminals that can communicate. It is possible to avoid it. The number of mobile terminals managed by one scheduler increases or decreases depending on the usage status of the user, but the maximum value specified is 1xEV-DORev. 0, 59 units, Rev. In A, it is 114 units. The lower limit of the number T of the weighted average coefficient β in the priority mobile terminal that minimizes the influence on the normal mobile terminal even in the situation where the number of priority mobile terminals is large even in the situation where the number of users is maximum and L is the maximum number of users Nmax (59 or 114) or more, and T can be obtained as a function of L and N.

αk = (2 (S−k + 1) −1) / S ² (3)
βk = (2 (T−k + 1) −1) / T ² (4)
If T is obtained from (3) and (4), βk = αk,
T = (2S ² −√ (4S ⁴ −4 (2S−2k + 1) (2k−1) S ² )) / 2 (2S−2k + 1) (5)
It becomes.

  For example, for 59 units (k = L = N = 59, S = 1000 is substituted into equation (5)), T = 62.135, and T = 63 rounded up is the weighted average coefficient β in the priority mobile terminal. The minimum value of the number of. For the case where the maximum number of users Nmax = 59, if T is greater than this, a decrease in the frequency of assigning downlink transmission slots to normal mobile terminals regardless of the total number of sectors and the number of priority mobile terminals is prevented. be able to. Here, the value of T is obtained from the maximum number of users, but T is obtained from the total number of mobile terminals in communication with the base station at that time, and the value of T is switched according to the increase or decrease of the total number of mobile terminals. Also good. Further, when it is desired to shorten the cycle from T obtained from the number of mobile terminals, the number of priority mobile terminals may be limited.

  In the above description, one of the two types of weighted average coefficients α and β stored in advance in the terminal information storage unit 18 based on whether or not the application being used requires real-time performance. In the above description, the average data rate R is calculated, but the weighted average coefficients corresponding to all the applications that can be executed in the mobile terminal are stored in the terminal information storage unit 18 by the number of application types. The average data rate R may be calculated by selecting a weighted average coefficient corresponding to the application used in the mobile terminal. In this way, it is possible to control the frequency with which downlink transmission slots are allocated corresponding to the application being used.

  In addition, by assigning priorities according to each of a plurality of applications, the allocation frequency of high priority applications increases, but there is an extreme difference in time-averaged transmission capacity even in channels allocated to low priority applications. Can prevent sticking.

  In addition, although the number of weighted average coefficients is five in the case of the coefficient β, the number of weighted average coefficients for each application is determined based on an allowable delay time during application execution, and is stored in the terminal information storage unit 18. It may be stored. For example, when the number of coefficients is 5, even if no downlink transmission slot is assigned to the target mobile terminal for 5 slots, a downlink transmission slot can be assigned to this mobile terminal in the sixth slot. Therefore, if the number of weighted average coefficients is calculated based on the value obtained by dividing the application allowable delay time by the execution time per slot, downlink transmission slots are allocated within the application allowable delay time. It is possible to increase the possibility of being

  Further, although the downlink communication speed value (DRC) requested by the mobile terminal is used as the communication quality index for identifying the mobile terminal to which the downlink transmission slot is allocated, the index indicating the communication quality is not limited to this, Value of signal quality (for example, CIR, SIR, CNR, CINR, SINR, etc.) received by the base station or mobile terminal, value of received power (including RSSI) received by the base station or mobile terminal, base station or mobile terminal The error rate (for example, FER, PER, etc.) at the time of reception may be used.

  As described above, downlink transmission of wireless data communication such as the Cdma2000 1xEV-DO system is time division, and the allocation of each mobile terminal to the time division slot is a reception state of a base station signal (such as a pilot channel signal) in the mobile terminal. In a radio system made by scheduling considering (received field strength, carrier-to-interference ratio = CIR), the DRC / R value referred to when specifying the mobile terminal to which the next downlink transmission slot is assigned is used in the mobile terminal. Therefore, the user-friendliness of the application can be improved and the satisfaction of the user can be improved. In particular, when there is a mobile terminal that uses an application that requires real-time characteristics, the scheduling result is obtained by controlling the calculation method of the average data rate R for the mobile terminal so as to select a method according to the application. Since it becomes possible to periodically secure opportunities for downlink transmission slots to be allocated to mobile terminals that require real-time characteristics, it is convenient for users to use streaming video playback, IP phones, IPTV phones, etc. It becomes possible to improve. In addition, it is possible for network operators to introduce new services and increase the added value of the communication network that they own, so that an increase in profits can be expected.

  The mobile terminal of the present invention includes a mobile phone using mobile communication, a personal digital assistant (PDA) having a mobile communication function, a mobile mobile terminal, a car navigation device, and the like.

  Note that the program for realizing the function of the processing unit in FIG. 1 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into the computer system and executed to perform scheduling processing. May be. The “computer system” here includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

It is a block diagram which shows the structure of one Embodiment of this invention. It is explanatory drawing which shows the table structure of the terminal information table memorize | stored in the terminal information storage part 18 shown in FIG. It is a flowchart which shows operation | movement of the base station 1 shown in FIG. It is explanatory drawing which shows the relationship between the weighted average coefficients (alpha) and (beta) shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base station, 11 ... Control part, 12 ... Transmission part, 13 ... Reception part, 14 ... Scheduler, 15 ... Average data rate calculation part, 16 ... DRC / R calculation unit, 17 ... DRC / R comparison unit, 18 ... terminal information storage unit, 19 ... sector throughput monitoring unit, 20 ... interface unit, 2 ... network, 3 ... information Distribution server, A, B, C ... mobile terminal, 21 ... CPU, 22 ... application information grasping unit, 23 ... shared unit, 24 ... demodulator, 25 ... decoder, 26 ... Predictor, 27 ... CIR-DRC conversion table, 28 ... GPS receiver, 29 ... MUX, 30 ... Encoder, 31 ... Modulator, 32 ... Memory, 33... Display unit, 34.

Claims (9)

Setting multiple priorities according to information identifying the application;
A channel allocating method comprising: allocating a channel using priority in a time division unit based on communication quality information and information for identifying an application.   2. The channel allocation method according to claim 1, wherein the information for identifying the application includes information based on a degree to which the application requests real-time property.   The priority in the time division unit for each priority according to the information for identifying the application passes through the time of the number of time division units greater than the number of high priority terminals, so that the priority in the plurality of time division units is increased. 3. The channel allocation method according to claim 1, wherein the channel allocation method has an intersection.   The channel allocation method according to claim 1 or 2, further comprising: when there are applications having different priorities based on information based on the applications, the priorities are switched in a certain time division unit.   The channel according to any one of claims 1 to 4, wherein the information for identifying the application includes information based on a delay time allowed for each of the plurality of applications using communication. Assignment method.   The information based on the communication quality includes a value based on a communication speed that the terminal desires to transmit to the base station by referring to the communication quality. Channel assignment method. Storing the priority calculated for each terminal, the communication quality, and information for identifying the application;
The channel allocation method according to claim 1, further comprising a step of dynamically updating values based on these time division units. A mobile communication system that performs communication with a base station by assigning communication channels to a plurality of terminals,
The terminal
An application information grasping unit that identifies information for identifying an application used to communicate with a base station;
A transmission unit that transmits information on communication quality requested to the base station and information for identifying the application to the base station;
The base station
A receiving unit that receives communication quality information requested by the terminal and information identifying the application transmitted from the terminal;
A channel allocation unit that identifies a terminal to which a channel is allocated based on information on the communication quality requested by the terminal, information on frequency of channel allocation to the terminal in the past, and information identifying the application; A mobile communication system comprising: A base station apparatus that performs communication by assigning communication channels to a plurality of terminals,
An application information acquisition unit for acquiring information for identifying an application used for communication in the terminal;
A communication quality acquisition unit that acquires information of communication quality requested by the terminal;
A terminal for allocating a channel based on information on the communication quality requested by the terminal, information on frequency of channel allocation to the terminal in the past, and information for identifying an application used in the terminal; A base station apparatus comprising: a channel assigning unit that identifies the base station apparatus.

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