JP2011061829A - Data retransmission control method, system and data retransmission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an efficient data retransmission control method when data errors occur due to poor radio wave environments of users (mobile station), so as to improve the total throughput of the plurality of users located in the sector of a radio system (especially, mobile radio system). <P>SOLUTION: The data retransmission control method that dynamically changes a retransmission interval or a retransmission slot interval when data errors occur in a radio system. A mobile station is informed in advance of a retransmission interval from a base station. Data retransmission control can be efficiently performed. A notification channel is released when a mobile error rate is low, and radio resources are effectively used. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technical field of a data retransmission control method for improving system throughput in a wireless system (particularly, a mobile wireless data communication system), and further, a system using the retransmission control method and an apparatus for performing retransmission control, The present invention relates to the technical field of base stations and mobile stations (mobile terminals) constituting the system.

Specifically, the slot timing (retransmission interval or retransmission time) for data retransmission from the transmitting side (mainly base station) to the receiving side (mainly mobile station) is dynamically controlled to efficiently use the slots. In particular, in the TDMA (Time Division Multiple Access) system, there is an effect of improving the system throughput.
Also in the CDMA (Code Division Multiple Access) system, by controlling the retransmission time interval, the quality of the radio channel is improved and the system throughput is improved.
In general, in a wireless system, traffic is managed for each sector, so improving the sector throughput is synonymous with improving the system throughput.

  In the current wireless system, the error data retransmission method of transmission data is a method for immediately transmitting a NAK signal (retransmission) when an error is detected on the mobile station side or when an error is detected but the error cannot be corrected. The control response signal is urged to be transmitted to the transmission side.

  Actually, the NAK signal arrives at the base station, that is, after the base station detects that there is an error in the received data of the mobile station, data retransmission is performed after a fixed time interval.

In the example of the CDMA2000 1xEV-DO system, data retransmission is performed after an interval of 4 slots.
Hereinafter, data retransmission from the transmission side (base station) to the reception side (mobile station) will be described by taking CDMA2000 1xEV-DO (Evolution Data Only) as an example.
The specifications of the EV-DO modulation method are as follows. QPSK, 8PSK, 16QAM is used for the downlink radio channel (from the base station to the mobile station), and BPSK, QPSK, 8PSK is used for the uplink radio channel (from the mobile station to the base station). The modulation method and the data transfer rate correspond to each other, and the strength of error tolerance is determined by the combination with the redundancy. The connection method is TDM (time division multiplexing) for downlink and CDMA (code division multiple access) for uplink.

  In each layer of EV-DO, various processes are performed in each layer in order to improve the quality of the radio channel. Layer 1 (physical layer) performs hybrid ARQ, acknowledgment (ACK), negative acknowledgment (NAK), error rate processing (channel quality information processing), and layer 2 (data link layer) performs retransmission control and radio link control. Layer 3 (network layer) performs control related to data reliability and radio resource control (radio channel control).

  In the EV-DO system, the radio service area is generally divided into a plurality of sectors, and the maximum transfer rate in each sector is about 2.4 Mbps (megabits per second). When there is one mobile station and the radio wave environment is good, the maximum transfer rate can be achieved. However, the transfer rate per unit decreases as the number of mobile stations increases. It goes without saying that the transfer rate decreases as the radio wave environment deteriorates. The deterioration of the radio wave environment will be described later.

  In the current EV-DO, TDM (Time Division Multiplexing) is adopted as the transmission method of the downlink radio channel, and therefore, in a certain sector, radio resources at a certain moment are concentrated on one mobile station (receiving side). For this reason, in the ARQ (automatic retransmission request) system in which an error in transmission data is detected at the reception side (mobile station) and retransmission is requested from the reception side (mobile station) to the transmission side (base station), the number of retransmission requests is If it increases, that is, if data errors occur frequently and the frequency at which the mobile station transmitting the NAK signal occupies the radio resource increases, the high-speed communication (reception) of other users (other mobile stations) will be hindered. In general, ARQ (Automatic Repeat Request) technology refers to a retransmission process in which data that could not be recovered by error correction in layer 1 is automatically sent again.

  In EV-DO, in order to further improve the efficiency of ARQ, hybrid-ARQ (combined automatic repeat request method) is adopted. EV-DO employs a method in which ARQ is incorporated between the base station and the mobile station in the process of iterative decoding of the error correction code (turbo code).

  Hybrid ARQ is a transmission function in layer 1 (physical layer). When reception fails in all slots, retransmission control is performed in layer 2 (data link layer). Incidentally, the turbo code has a strong error correction capability for transmission data and is superior to the convolutional code.

  Further, an N-channel SAW (Stop and Wait) system is employed for speeding up data. SAW is a type of data ARQ that returns an ACK signal from the receiving side to the transmitting side when data from the transmitting side is correctly received at the receiving side, and returns a NAK signal when a data error occurs. Patent Document 2 relating to SAW discloses a method in which when a NAK signal is received on the transmitting side, priority is given to other receiving stations until an ACK signal is received on the transmitting side for a specific frame on the receiving side. ing.

  However, this method processes N processes in parallel and independently, and therefore the order of data between processes is not guaranteed. This is a method in which the base station transmits data with a serial number attached to the header, and the mobile station arranges the order of the data according to the serial number and increases the amount of transmission per unit time. Even if the above-described method is adopted, if DRC (data rate control) that requires a data transmission rate from the mobile station to the base station is adopted, a high throughput can be realized in a place where the reception environment is good. However, in a bad place, the throughput is significantly reduced.

  As described above, even if the hybrid ARQ or the N-channel SAW method is used, it is inevitable that radio resources are still concentrated on one mobile station (receiving side). Repeatedly allocating radio resources to mobile stations with poor reception environment reduces sector throughput. Further, if the data retransmission interval is not properly controlled, the waiting time of other mobile stations becomes long, and the sector throughput is further reduced.

  Below, a prior art is demonstrated based on the figure of patent document 1. FIG. 27 shows a block diagram on the data receiving side, and FIG. 28 shows a block diagram on the data transmitting side. 27, on the data receiving side, a line monitoring unit 116 that outputs either the SIR measurement result or the packet arrival rate, and a data storage unit 117 that stores data for comparing the measurement results (stores the correspondence table of FIG. 29). ) And the data read from the data storage unit 117 and the measurement result, the two inputs are compared and the control state is output as a comparison unit 115, and the control state storage unit 113 stores the control state. And a control data generation unit 114 that receives the output of the control state storage unit 113 as an input.

  On the data transmission side in FIG. 28, the control state storage unit 125 that stores the control state, and the control data and the data read from the data storage unit 126 (stores the correspondence table of FIG. 30) are used as inputs, and these two inputs are compared. In addition, a comparison unit 123 that outputs data of the retransmission control cycle and a retransmission control cycle control 124 that controls the window size of the retransmission control are provided.

  FIG. 25 shows a chart on the data receiving side, and FIG. 26 shows a chart on the data receiving side. When the number of received packets is greater than or equal to the threshold k and S65 on the receiving side in FIG. 25, the packet arrival rate is measured S66. The measured value is compared S67 with the packet arrival rate vs. packet retransmission control periodic table. The retransmission control periodic table is shown in FIG.

  If the number of received packets is not greater than or equal to the threshold value k in step 65, the SIR is measured S68, and the measured value is compared with the SIR versus packet retransmission control periodic table S69. After the processing of step S67 or step S69, the control state is updated S70. Next, the control data of the retransmission control cycle is transmitted S71.

  In FIG. 26, the period control data for retransmission control is received S72, and the control state is updated S73. The control data and the retransmission cycle pair control state table are compared S75, and the retransmission control cycle is updated S75.

  The retransmission control periodic table is shown in FIG. In the method of measuring the packet arrival rate and SIR as described above, and further changing the retransmission interval using the correspondence table of retransmission control periods created in advance, the presence of other mobile stations and the traffic that changes with time are taken into account. It was difficult to improve the sector throughput.

  None of the prior art has proposed a method for dynamically changing the error rate and the retransmission interval.

JP 2002-271303 A Republished W02003 / 032566

  In order to improve the total throughput of a plurality of users in a sector of a radio system (especially a mobile radio system), the present invention efficiently performs retransmission control when a data error occurs due to the poor radio wave environment of the user (mobile station). It is to be implemented. In EV-DO, a TDM (Time Division Multiplexing) method is adopted for the downlink radio channel, and therefore radio resources for a certain period of time are concentrated on one mobile station (receiving side) in a certain sector. For this reason, errors in transmission data are frequently detected at the mobile station (reception side), the number of requests for data retransmission from the mobile station (reception side) to the base station (transmission side) increases, and other mobile stations ( Interfering with high-speed communication (reception) of other users) has been a problem. In addition, the constant use of the control notification channel (frequency channel) is contrary to the effective use of radio resources, which degrades the radio wave environment in the sector (increases the noise level) and decreases the throughput. It was.

  In the method using the correspondence table (shown in FIG. 29 and FIG. 30) described in Patent Document 1 described in the technical background, when the radio wave environment of the mobile station (reception side) is bad (SIR is low), the downlink data The retransmission time interval has been shortened, the number of retransmissions has increased, and the probability that a large number of mobile stations have been waiting has increased. SIR represents a desired wave received power to interference power ratio. In addition, when the correspondence table of Patent Document 1 is used, when the electric field strength varies greatly due to fading or the like and the radio wave environment is bad, it is necessary to frequently notify the change of the retransmission time interval using the notification channel. Wireless resource usage efficiency was impaired. As described above, it is difficult to improve the sector throughput when the conventional technique is used.

  The present invention has been made in view of the above problems, and is intended to grasp parameters to be controlled and information and status of mobile stations at a base station, efficiently perform data retransmission control, and improve throughput. . In order to achieve the above object, the present invention is characterized in that when a data error occurs in a wireless system, a time interval of data retransmission is notified in advance from the base station to the mobile station.

  The time interval dynamically changes, for example, a slot interval, a packet interval, a frame interval, a block interval, and the like. Also included are sub-slot intervals, sub-packet intervals, sub-frame intervals, sub-block intervals, and the like that further dynamically change the time interval in detail. Further, a fine time interval other than the above-described interval may be used. This is because the various time intervals are freely defined by the wireless system and may be selected according to the wireless system.

  Subsequently, in order to notify the retransmission interval in advance, it is necessary to manage traffic on the base station side. The traffic is defined by the data amount per second in the sector including not only data but also packet data by error retransmission control such as ARQ. The unit is bps (bits per second). As an example, when the existing A mobile station, B mobile station, and C mobile station are performing data communication of 1.2 Mbps, 0.6 Mbps, and 0.3 Mbps without any data error in the sector, the sum of 2 .1Mbps is traffic. By using the traffic as a variable and calculating using a calculation formula, the retransmission interval can be dynamically determined.

  In addition to the above, in order to determine the retransmission interval in advance, there is also a method of notifying the retransmission interval from the base station to the mobile station according to a predetermined condition (standard or negotiation at the start of communication).

  A specific data retransmission control method uses a notification channel for retransmission control in an ARQ (automatic retransmission request) method in which an error in transmission data is detected on the reception side and retransmission is requested from the reception side to the transmission side. Retransmission interval (slot interval or time interval) is notified from the transmission side to the mobile station that newly entered the sector with the retransmission interval calculated based on the traffic in the sector, and an error occurred on the reception side In this case, in response to receiving a NAK signal (control response signal for prompting retransmission) from the reception side, the transmission side retransmits the same data as the transmission data after the retransmission interval previously notified to the reception side by the transmission side. .

  In FIG. 1, the transmission side and the reception side can be either a base station or a mobile station. However, in a mobile data communication system, the base station is frequently used as a transmission side and the mobile station is a reception side. I will explain. The EV-DO base station has a maximum transfer rate of 2.4 Mbps per sector with three sectors as service areas. In EV-DO, PER (packet error rate, hereinafter referred to as error rate) is used as the error rate at the mobile station (reception side).

  As the error rate, BER (bit error rate), BLER (block error rate), FER (frame error rate), and the like are used as an index of error rate by various wireless communication systems. When the error rate is below a predetermined level, the notification channel is released without notifying the retransmission interval from the transmission side to the reception side using the notification channel for retransmission control. Thereby, radio resources can be used effectively.

  When the error rate reaches a predetermined level or higher, transmission is performed at a lower transmission rate than the previous time. Next, when the error rate reaches a predetermined level or higher, the frequency channel is changed from the previous one. Changing the frequency channel corresponds to changing the distance between the base station and the mobile station, can improve fading due to multipath, and is effective in improving the error rate. Finally, power control is performed. Increasing transmission power improves the error rate and improves the throughput for a desired mobile station. However, since leakage radio wave energy to adjacent sectors and adjacent service areas is increased, it is necessary to increase power to a minimum.

  Further, in order to improve the radio wave environment in the sector, when the error rate is below a predetermined value, the notification channel is released without notifying the retransmission interval from the transmission side to the reception side. When the error rate reaches a predetermined level or more, the retransmission interval is notified using the notification channel.

  Next, depending on the data rate requested from the receiving side to the transmitting side, different retransmission intervals are defined in advance using a calculation formula, and when a data error occurs, the DRC (data rate control) signal at that time is defined. The retransmission data is transmitted after the corresponding retransmission interval.

  Next, when the mobile station (reception side) is BUSY (busy: for example, when using Internet browsing, games, etc.), the data transmission side, after the BUSY state ends, the mobile station NACK signal is transmitted from the base station to the base station.

  Finally, when an error is detected on the data receiving side and the data is retransmitted from the transmitting side, it is retransmitted at a lower data rate than the previous transmission, or retransmitted with a modulation scheme that is stronger in error tolerance than the previous transmission. Or is retransmitted on a frequency channel different from the previous time, or transmitted with higher power than the previous time. In EV-DO, the data rate substantially corresponds to the modulation method, and is 16QAM, 8PSK, and QPSK in order from the highest efficiency.

  According to the data retransmission control method of the present invention configured as described above, the following effects can be obtained.

  First, the number of steps during retransmission control can be reduced by notifying the mobile station of the retransmission interval (retransmission timing, retransmission cycle) in advance.

  That is, when a retransmission request is notified to the base station, data can be retransmitted promptly. It is possible to reduce the waiting time until the specified retransmission interval timing, and it is possible to eliminate the waiting time when the traffic is low or when there is no other user (mobile station). Furthermore, since the retransmission timing is known, processing other than data communication can be performed on the mobile station side.

  Further, when the error rate is low, the radio resource can be used effectively by releasing the notification channel or omitting the notification of the retransmission interval. Further, since the retransmission interval is managed by the base station, the probability of overlapping with the data retransmission request of other users (mobile stations) can be reduced, the radio wave environment can be kept good, and the throughput can be further improved.

  The reason why the radio wave environment can be improved by opening the notification channel is as follows. The notification channel belongs to a frequency channel, and the frequency channel has a band. Similarly, the communication channel has a bandwidth. A notification channel and a communication channel are arbitrarily assigned from the base station to the mobile station. When the channel is used, electromagnetic wave energy at both ends of the channel leaks to adjacent frequency channels.

  Opening the notification channel temporarily increases the number of vacant channels, can reduce radio waves leaking to the communication channel, and improve the radio wave environment.

FIG. 2 is a system configuration diagram of a base station and a mobile station in the best mode for carrying out the present invention. In the best mode for carrying out the present invention, it is a chart for reporting a retransmission interval to a base station or a plurality of mobile stations using a notification channel. In the best mode for carrying out the present invention, a retransmission control apparatus provided in a base station. In the best mode for carrying out the present invention, the receiving side receives data at the notified retransmission interval. It is the best form which implements this invention, and is a chart which transmits data by the retransmission interval notified from the transmission side. 5 is a chart showing a method for determining a retransmission interval in the best mode for carrying out the present invention. 5 is a chart showing a method for releasing a notification channel in the first embodiment of the present invention. It is a chart which shows the transmission rate change method in Example 1 of this invention. It is a chart which shows the modulation system change method in Example 1 of this invention. It is a chart which shows the method of changing and transmitting the frequency channel in Example 1 of this invention. It is a chart which shows the electric power control method in Example 1 of this invention. It is a chart of the retransmission interval according to the data request rate in Example 2 of the present invention. It is a chart which shows the change method of the NAK signal transmission timing in Example 2 of this invention. It is a chart which shows the frequency channel, data rate, and power control method in Example 3 of this invention. It is a figure which shows the structure of the frequency channel common to the best form and each implementation item. It is a figure which shows the structure of the notification channel common to the best form and each implementation item. It is a figure which shows the structure of the data channel common to the best form and each implementation item. It is a figure of the mobile station which carried out location registration or the hand-over in the service area in Example 3 of this invention. It is a figure of the mobile station when the error rate exceeds a predetermined level in the service area in Embodiment 3 of the present invention. It is a figure in Example 3 of this invention that a BUSY state is complete | finished within a service area, and a mobile station performs resending operation | movement. [Fig. 10] Fig. 10 is a diagram in which a mobile station notifies an error rate to a base station and a mobile station receives data corresponding to the error rate in Embodiment 3 of the present invention. It is a figure which shows the traffic and retransmission interval in the best embodiment of this invention. It is a figure which shows the error rate and retransmission interval in the best embodiment of this invention. It is a figure which shows the data rate and retransmission interval in Example 1 of this invention. It is a figure which shows the chart by the side of a data transmission in a prior art. It is a figure which shows the chart by the side of a data reception in a prior art. It is a block diagram on the data receiving side in the prior art. It is a block diagram by the side of a data transmission in a prior art. It is a figure of the correspondence table which the data storage part 117 of the transmission side of a prior art memorize | stores. It is a figure of the correspondence table which the data storage part 126 of the receiving side of a prior art memorize | stores.

  First, a channel configuration common to all the embodiments will be described.

  The configuration of the notification channel for retransmission control will be described with reference to FIGS. 15 to 17 as common items in the best mode and each embodiment.

 In FIG. 15, the frequency channel 80 is divided into a common channel 81 and an individual channel 82. The frequency channel 80 corresponds to each frequency in the TDMA system, and corresponds to a spread spectrum frequency in the CDMA. The common channel 81 is a channel used in common for all mobile stations in the sector.

  The dedicated channel 82 is a channel used for control or communication after the mobile station establishes call setting, and is generally a channel that is continuously used until the call is terminated.

  The common channel 81 is further divided into a common control channel 83 and a common communication channel 84. The common control channel 83 can notify control information to mobile stations in a sector all at once.

  The common communication channel is a channel that can be used for information transmission by all mobile stations and base stations in the sector.

  The dedicated channel 82 is further divided into a dedicated control channel 85 and a dedicated communication channel 86. The dedicated control channel 85 controls only one mobile station in the sector. The dedicated communication channel 86 is used when communicating with a mobile station in a sector. The individual channel 82 can be used efficiently by multiplexing even the same frequency channel 80 by time division processing or encoding processing.

  The notification channel 87 in FIG. 16 is a generic term for the common control channel 83 and the dedicated control channel, and is a channel for notifying the mobile station of the retransmission interval, data rate, modulation method, transmission power, and the like. The notification channel 87 to be released during communication is mainly the individual control channel 85. By releasing the channel according to the error rate, it is possible to effectively use radio resources.

  If the error rate reaches a predetermined level or more while using the dedicated communication channel 86, the common control channel 86 or the dedicated control channel is set to control the retransmission interval. The data channel 90 is a general term for communication channels, and includes a common communication channel 84 and an individual communication channel 86. Each application is the same as that described for the frequency channel 80. This completes the description of the channel.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  1 includes a data transmission device 5, a retransmission control device 6, and a data reception device 7. The data transmission device 5 transmits data at a variable data rate, a variable modulation scheme, and a variable transmission power. The data receiving device 7 receives data from the mobile station 2 and performs demodulation / decoding. The retransmission control device 6 classifies the data from the data receiving device 7 and performs traffic calculation, retransmission method determination, retransmission interval calculation, and the like. Details will be described later as the retransmission control device 6 in FIG.

  The mobile station in FIG. 1 includes a data receiving device 8, a retransmission control device 9, and a data transmitting device 10, and the data receiving unit 8 receives data from the base station, demodulates and decodes, and detects data errors. , Correct errors. The retransmission control device 9 calculates the error rate and notifies the base station 1 of the result. Also, a retransmission method is determined, and a data rate request is made to the base station 1. The data transmitter 10 transmits data at the variable data rate, modulation scheme, and variable power finally determined by the base station 1.

  From here, the retransmission control device 6 will be described with reference to FIG. The retransmission control device 6 includes a mobile station management unit 143, an error rate management unit 146, a data rate management unit 147, a transmission buffer 142, a traffic management unit 144, and a retransmission interval management unit 145. The mobile station management unit 143 counts the mobile stations registered in the sector and the number of mobile stations flowing into and out of the sector, and always knows the current number of mobile stations. Further, the mobile station grasps and manages whether or not the mobile station is BUSY. The error rate management unit 146 sequentially holds the latest error rate for each mobile station based on the notification from the mobile station. The data rate management unit 147 manages the data rate for each mobile station and the amount of data to be transmitted, which are determined by a request from the mobile station or the judgment of the base station. The transmission buffer 14 holds data to be transmitted to each mobile station according to an instruction from the data rate management unit 147.

  As described above, there are various error rates depending on various wireless communication systems, but since EV-DO performs data communication in units of packets, the relationship between the packet error rate and the retransmission interval in FIG. Will be described as an example. The traffic managed by the traffic management unit 147 includes not only data but also a packet by data retransmission control such as hybrid AQR.

  In the present invention, with reference to the correspondence table of FIG. 29 of the prior art and the correspondence table of FIG. 30, steps such as changing the control state are not performed, and the retransmission interval is dynamically determined using a calculation formula. Basically, the calculation formula may be such that the retransmission interval does not become zero.

  This is because it takes a finite time from when the mobile station transmits the NAK until the signal reaches the base station and the retransmission data reaches the mobile station. In the traffic and retransmission interval of FIG. 22, the calculation formula y = [7 / x] -1 is exemplified. [] Is a Gaussian symbol and represents the largest integer. The constants 7 and 1 in the calculation formula can be appropriately changed so that the calculation result becomes a value larger than 0. FIG. 6 shows a chart of a method for determining a retransmission interval.

  First, the intra-sector traffic is calculated S29, and then the retransmission interval corresponding to the traffic is calculated. The mobile station is notified of the calculated retransmission interval. The notified mobile station stays in the sector with the mobile station that newly entered the sector, and is notified to the mobile station that is not performing data communication using the notification channel 87.

  FIG. 23 shows a calculation formula y = [2.5x] +1 of the packet error rate and the retransmission interval. The calculation formula can also be appropriately changed so that the calculation result becomes a value larger than 0, similarly to the calculation formula of FIG.

  Although the packet error rate is shown in FIG. 23, other error rates may be used as appropriate. In each of the above two expressions, a constant is selected so that the retransmission interval is about 1 to several tens.

  The retransmission intervals in FIGS. 22, 23, and 24 are in units of slots. However, since one EV-DO slot is 1.666 ms (milliseconds), the number of slots is multiplied by 1.666 ms to be converted into time. It ’s fine.

  FIG. 2 is a chart for notifying the retransmission interval from the base station 1 to the mobile station A3 and the mobile station B4 using the notification channel. For simplicity, it is assumed that the amount of data to be transmitted from the base station has changed (traffic has changed) without considering the inflow mobile station and the outflow mobile station. The base station 1 notifies the retransmission interval T to the mobile station A3 and the mobile station B4.

  In FIG. 2, the horizontal axis is the time axis, and the common control channel 83 is used as the notification channel 87. (Thick arrow) The timing at which packet data (thin arrow) is sent from the base station 1 to each mobile station is shown. The NAK signal and the corresponding packet data are indicated by dotted lines.

  Data (1), (3), (5), (6), and (8) are packet data transmitted from the base station 1 to the mobile station A3, and data (5) of these data failed to receive data. Thus, it is received again at the retransmission interval S. Data (2), (4), and (7) are packet data transmitted from the base station 1 to the base station B4. The data (2) fails to receive data and is received again at the retransmission interval T. .

  In the example of FIG. 2, using the common control channel 83 as the notification channel 87, the same retransmission interval is notified to the two mobile stations at the same timing. However, if the dedicated control channel 85 is not released, Different retransmission intervals may be notified using the dedicated control channel. Different retransmission intervals may be notified from the base station 1 to the mobile station A3 and the mobile station B4 in advance.

  Next, FIGS. 4 and 5 show detailed operations of the mobile station 1 and the base station 2. First, the base station 1 transmits a retransmission interval notification to the mobile station 2 in advance S19, and the mobile station 2 receives a retransmission interval notification S12. The mobile station 2 transmits a data request S13 to the base station 1, and the base station receives S20 the data request. The base station 1 transmits data S21 to the mobile station 2. The data causes an error due to propagation failure, and the mobile station receives the error data S14. Therefore, the mobile station transmits a NAK signal to the base station S15. The base station that receives the NAK signal S22 transmits S23 at the retransmission interval in which the request data is notified in advance. At this time, the mobile station waits for a retransmission interval S16. The mobile station that correctly receives the request data S17 transmits an ACK signal to the base station S18. The base station receives the ACK signal S24, and the series of data retransmission ends. The best mode for carrying out the present invention has been described above with reference to FIGS. 1 to 6, 22, and 23.

  As a first embodiment, a method for changing various parameters will be described. 7 to 11 are all effective methods for improving the throughput.

  7 is a notification channel releasing method, FIG. 8 is a transmission rate changing method, FIG. 9 is a modulation method changing method, FIG. 10 is a frequency channel changing method, and FIG. 11 is a power control method.

  First, a method for releasing the notification channel 87 will be described with reference to FIG. First, the error rate is measured S32 at the mobile station and notified to the base station 1. When the error rate is not below the predetermined level S33, the base station 1 notifies the mobile station of the retransmission interval via the notification channel S35. When the error rate is below a predetermined level S33, the notification channel is released S34 without notifying the retransmission interval. Thereby, the radio channel is released and the radio wave environment in the sector is improved.

  Next, a method for changing the transmission rate will be described with reference to FIG. An error rate is notified from the mobile station to the base station S40. When the error rate is not lower than the predetermined level S41, the transmission rate is lowered from the previous time, and the transmission S42 is performed. When the error rate is lower than the predetermined level S41, the same as the previous time. Transmission S43 is performed at the transmission rate.

  Next, a modulation method changing method will be described with reference to FIG. The error rate is notified from the mobile station to the base station S44, and when the error rate is not lower than the predetermined level S45, transmission S46 is performed with a modulation method having a stronger error resistance than the previous time. When the error rate is below a predetermined level, transmission S47 is performed using the same modulation method as the previous time.

  Next, a frequency channel changing method will be described with reference to FIG. An error rate is notified from the mobile station to the base station S48, and when the error rate is not less than a predetermined value S49, the error rate is transmitted on a frequency channel different from the previous one. When the error rate is below a predetermined level, transmission S51 is performed at the same frequency as the previous time.

  Finally, a power control method will be described with reference to FIG. An error rate is notified from the mobile station to the base station S52. When the error rate is not lower than a predetermined level S53, transmission is performed at a transmission power higher than the previous time S54, and when the error rate is lower than a predetermined level S53, the same power as the previous time is transmitted. Then, transmission S55 is performed.

  As described above, it is possible to improve the radio wave environment and improve the throughput by controlling various parameters with the threshold of the error rate.

  As a second embodiment, a retransmission method at a retransmission interval corresponding to a data request rate and a retransmission method at the timing of a NAK signal will be described based on FIG.

  First, in FIG. 12, the base station receives the data request rate from the mobile station S56, and transmits data S57 from the base station to the mobile station. When the base station receives the NAK signal S58, it retransmits data S59 to the mobile station at a predefined retransmission interval. The retransmission interval notification from the base station to the mobile station is omitted. FIG. 24 is a calculation formula showing the data rate and the retransmission interval. Formula y = [2.4 / x] The above formula does not become 0 because the denominator is the data rate.

  Whether or not the base station responds to the data request rate from the mobile station considers the error rate of the mobile station and the requested data amount. If the error rate is low, the request from the mobile station is accepted, but if the error rate is extremely high, the request is rejected.

  Next, the NAK signal transmission timing change will be described with reference to FIG. When data is transmitted from the base station to the mobile station but an error occurs in the mobile station S60, if the mobile station is not BUSY, the mobile station immediately transmits a NAK signal S62. When the mobile station is BUSYS 61, the mobile station holds the NAK signal S63. When the BUSY state ends, the mobile station transmits a NAK signal S64. As a result, the mobile station can receive data while it is ready for reception, without the base station transmitting data unnecessarily. Therefore, waste of radio resources can be prevented and the radio wave environment can be kept good.

  As Example 3, a case where various parameters are comprehensively used will be described with reference to FIG. In EV-DO, the data rate substantially corresponds to the modulation method, and therefore, description will be made using the data rate. When considering the modulation method, the data rate is associated with the modulation method.

  In step S105, transmission is performed at a data rate lower than the previous time with a modulation method having a stronger error resistance than the previous time. First, an error rate is notified from the mobile station to the base station S100, and when the error rate is not equal to or lower than a predetermined level, S101 is transmitted on a frequency channel different from the previous one. When the error rate is equal to or lower than S101, transmission S103 is performed using the same frequency channel as the previous time. If the error rate does not become equal to or lower than the predetermined S104 even if the frequency channel is changed in step S102, transmission is performed at a transmission rate S105 lower than the previous time. When the error rate is less than or equal to a predetermined value S104, transmission is performed at the same transmission rate S106 as the previous time. If the error rate does not become equal to or lower than S107 even when the transmission rate is lowered in step S105, transmission S108 is performed with higher power than the previous time. . This embodiment is an example in which parameters are managed strictly in detail.

  18 to 21 are diagrams for explaining a wireless system according to the present invention.

  FIG. 18 shows a state where the second mobile station 136 has flown into the first sector 133 in the service area due to location registration or handover. Since the number of mobile stations in the sector has increased, the retransmission control device provided in the base station 131 calculates the traffic and notifies the second mobile station and the mobile station 132 originally in the first sector of the retransmission interval.

  FIG. 19 is a diagram showing a state in which the mobile station 132 in data communication in the first sector 133 moves, enters the shadow of the obstacle 137, and the error rate increases. In this case, the data rate of the mobile station may be managed by the method described in the first and third embodiments.

  FIG. 20 shows a mobile station that is being browsed, and shows a state in which a NAK signal is transmitted to the base station 131 and desired data is immediately received upon completion of the BUSY state.

  FIG. 21 is a diagram in which the mobile station 132 notifies the base station 131 of the error rate, and the mobile station 132 receives data corresponding to the error rate.

  The present invention is mainly aimed at improving the system throughput in a mobile radio communication system, but can also be applied to a satellite mobile radio communication system, a mobile optical communication system, and the like.

1: base station (transmitting side) 2: mobile station (receiving side) 3: mobile station A4: mobile station B5: base station data transmitter 6: base station retransmission controller 7: base station data receiver 8: Mobile station data receiver 9: Mobile station data retransmission controller 10: Mobile station data transmitter 87: Notification channel 131: Base station 132: Mobile station 136: Second mobile station 133: First sector 134: Second sector 135: Third sector 136: Second mobile station 137: Obstacle 142: Transmission buffer 143: Mobile station manager 144: Traffic manager 145: Retransmission interval manager 146: Error rate manager 147: Data rate management department

Claims (9)

In a data retransmission control method for detecting a transmission data error on the receiving side and requesting retransmission from the receiving side to the transmitting side, a retransmission interval corresponding to the traffic is received in advance from the transmitting side using a notification channel for retransmission control. When an error occurs on the receiving side, the transmitting side sends the same data as the transmission data after the retransmission interval previously notified to the receiving side by the transmitting side in response to receiving the NAK signal from the receiving side. A data retransmission control method characterized by performing retransmission. The data retransmission control method according to claim 1, wherein the retransmission interval is a slot interval or a time interval. When the error rate on the receiving side is lower than the predetermined level on the transmitting side, the notification channel is released without notifying the retransmission interval from the transmitting side to the receiving side using the notification channel for retransmission control. 2. The data retransmission control method according to claim 1, wherein a retransmission interval according to a condition is used, and when the error rate reaches a predetermined level or more, the retransmission interval is notified using the notification channel. A different retransmission interval is defined in advance according to a data rate of transmission data, and when a data error occurs, retransmission data is transmitted after the retransmission interval according to the transmission data rate at that time. 2. The data retransmission control method according to 1. A data retransmission control method characterized in that when data is retransmitted, a data rate, a modulation scheme, a frequency channel, and transmission power at the time of retransmission according to an error rate on the receiving side are selected and retransmitted on the transmitting side. A retransmission control system comprising a base station and at least one mobile station and notifying a retransmission interval using a notification channel for retransmission control, wherein a data retransmission interval is set based on traffic in the service area of the base station. A data retransmission control system that calculates and notifies in advance the data retransmission interval to a second mobile station that has newly registered or handed over a location within the service area. When the error rate in the mobile station has reached a predetermined level or lower, the notification channel is released, and a retransmission interval is used according to a predetermined condition, and when the error rate has reached a predetermined level or higher, The data retransmission control system according to claim 6, wherein the retransmission interval is notified using a notification channel. In a retransmission control apparatus provided in a base station for performing retransmission control of data, a data retransmission interval is calculated based on traffic in the service area of the base station, and a location registration or handover is newly performed in the service area A data retransmission control apparatus that notifies a station in advance of the data retransmission interval. When the error rate in the mobile station in the service area reaches a predetermined level or less, the notification channel is released, and a retransmission interval according to a predetermined condition is used, and the error rate reaches a predetermined level or more. In this case, the data retransmission control apparatus according to claim 8, wherein a retransmission interval is notified using the notification channel.

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