JP4672029B2 - Communication means changing method and terminal device using the same - Google Patents

Description

  The present invention relates to a communication means changing method. In particular, the present invention relates to a communication means changing method for switching a plurality of different communication systems and a terminal device using the same.

  In recent years, a cdma2000 1x-EV DO (hereinafter referred to as “EV-DO”) system has been developed as a next-generation high-speed wireless communication system. The EV-DO method is a method in which the cdma2000 1x method, which is an extension of the cdmaOne method and is adapted to the third generation method, is further specialized in data communication to increase the transmission rate. Here, “EV” means Evolution, and “DO” means Data Only.

  In the EV-DO system, the configuration of the uplink radio interface from the radio communication terminal to the base station is almost the same as that of the cdma2000 1x system. Regarding the downlink radio interface configuration from the base station to the radio communication terminal, the bandwidth defined in 1.23 MHz is the same as that of the cdma2000 1x system. On the other hand, the modulation method, the multiplexing method, etc. are greatly different from the cdma2000 1x method. As for the modulation scheme, QPSK, 8-PSK, and 16QAM in the EV-DO scheme are switched according to the downlink reception state in the radio communication terminal, in contrast to QPSK and HPSK used in the cdma2000 1x scheme. As a result, when the reception state is good, a high transmission rate with low error resistance is used, and when the reception state is bad, a transmission rate with low error but high error resistance is used.

  In addition, a multiplexing method for simultaneously performing communication from one base station to a plurality of wireless communication terminals is not code division multiple access (CDMA) used in the cdmaOne method or the cdma2000 1x method. The time is divided in units of 1/600 seconds, and communication is performed with only one wireless communication terminal within that time. Further, the wireless communication terminals to be communicated are switched every unit time to communicate with a plurality of wireless communication terminals. Use time division multiple access (TDMA) to perform.

  The wireless communication terminal measures the carrier-to-interference wave ratio (hereinafter referred to as “CIR: Carrier to Interference power Ratio”) of the pilot signal as the reception state of the downlink from the base station to be communicated, The reception state at the reception timing is predicted, and the expected “maximum transmission rate that can be received at a predetermined error rate or less” is notified to the base station as a data rate control bit (hereinafter referred to as “DRC: Data Rate Control bit”). To do. Here, the predetermined error rate depends on the system design, but is usually about 1%. The base station receives DRCs from a plurality of radio communication terminals, and the scheduler function in the base station determines which radio communication terminal to communicate with in each time division unit. Therefore, the highest possible transmission rate is used based on the DRC from the wireless communication terminal.

The EV-DO system enables a maximum transmission rate of 2.4 Mbps (Mega-bit per second) per sector in the downlink with the above configuration. However, this transmission rate is the total amount of data communication with a plurality of wireless communication terminals to which one base station is connected in one frequency band and one of a plurality of sectors, which is usually a plurality of frequencies. If the band is used, the transmission rate also increases.
JP 2002-300634 A

  The wireless communication terminal has a communication function of another wireless communication system such as a wireless LAN system (hereinafter referred to as “W-LAN”) or a simplified mobile phone system in addition to the EV-DO system described above, and When one of these wireless communication systems is selected and actually used, in order to satisfy the general user requirement of “stable communication at a high transmission rate”, the wireless communication system to be used is switched. Judgment criteria for are becoming important. In particular, the wireless communication terminal can use the above-described W-LAN, EV-DO system, and simplified mobile phone system, and the maximum transmission rate is 11 Mbps of W-LAN conforming to IEEE802.11b. If the difference is about 100 times, such as 128 kbps, the actual transmission rate may vary greatly due to the difference in switching method. In order to satisfy the above-described requirements under such conditions, the reference for switching is changed when the transmission rate of the communication system currently in use is higher or lower than the transmission rate of the communication system to be switched. There is a need.

  In general, the transmission characteristics of a wireless communication system largely depend on the quality of the wireless transmission path (hereinafter referred to as “transmission path quality”), and therefore switching of the wireless communication system is determined based on the transmission path quality. If the transmission rate, the communication method, and the transmission output of the radio communication system to be switched are different in the upper and lower lines as in the EV-DO system, it is desirable to separately measure the transmission path quality of the upper and lower lines. On the other hand, the wireless communication terminal can measure the downlink transmission path quality, but cannot measure the uplink transmission path quality. Furthermore, in consideration of the ease of realization, unless a new control signal is added to the wireless communication system, the uplink transmission path quality is not notified from the base station apparatus, so that the acquisition of the uplink transmission path quality can be further improved. It becomes difficult. Further, when reciprocating between cover areas of different wireless communication systems, it is desirable that the wireless communication system does not switch over a short period of time and that there is hysteresis in the switching control, because of communication stability.

  The present inventor has recognized the above situation and made the present invention. The object of the present invention is to change a communication means for switching to a wireless communication system suitable for transmission rate and stability among a plurality of wireless communication systems, and It is to provide a terminal device using it.

One embodiment of the present invention is a terminal device. This apparatus is replaced with a transmission path quality deriving means for deriving a transmission path quality value in the communication system in use, a first deriving means for deriving a throughput value of the communication system in use, and a communication system in use. second deriving means for deriving the throughput value of the communication system with different communication systems available, based on the throughput value throughput value and the second deriving means for first deriving means is derived is derived, teeth about the transmission path quality A communication system different from the communication system in use from the communication system in use based on the threshold value determining means for determining the threshold value and the derived channel quality value in the communication system in use derived from the determined threshold value. Change determining means for determining a change to

  The “first value corresponding to the throughput” and the “second value corresponding to the throughput” may be the throughput value itself, but may include the reception level, and the throughput value is estimated from the value. Be good. Further, these values may not be actually measured, and include cases where they are determined in advance.

“Derivation” may be actually measured or a value stored in a memory may be read out, that is, it is only necessary to obtain a target value.
With the above devices, the threshold for transmission path quality is changed in accordance with the communication system being used and the throughput of the communication system that is different from the communication system that can be used. It is possible to change the communication system.

  In the transmission path quality deriving means, the communication system in use may have different communication speeds and communication methods for the up and down lines. The transmission path quality deriving unit derives values of a plurality of types of transmission path quality, the threshold value determining unit determines a plurality of threshold values corresponding to the plurality of types of transmission path quality, and the change determining unit includes: If any one of the derived types of transmission path quality values satisfies the condition defined by the threshold corresponding to the transmission path quality, the communication system being used is changed to a communication system different from the communication system. The change may be determined.

  “Satisfied with the condition determined by the threshold” means that if the condition is satisfied if the threshold is exceeded, the threshold is exceeded, and if the threshold is less than the threshold, the condition is satisfied In this case, it indicates that the threshold value is not exceeded, and it is set according to the conditions.

  The transmission path quality deriving means may derive each of transmission path quality values corresponding to the upper and lower lines of the communication system in use as a plurality of types of transmission path quality values. If the second value is higher than the first value, the threshold value determining means is a change determining means that facilitates a change from a communication system in use to a communication system different from the communication system. A threshold may be determined for the value.

  “Transmission channel quality value corresponding to the uplink and downlink” naturally includes the transmission channel quality value of the uplink and downlink, but even if it is not, the transmission channel quality value of the uplink and downlink is estimated. Anything that can be done is acceptable.

Another aspect of the present invention is a communication means change determination method. In this method, a channel quality value and a throughput value in a communication system in use are derived, and a communication system different from the communication system that can be switched from the communication system in use in place of the communication system in use. derive a throughput value, and the threshold of transmission path quality determined from the throughput value of a communication system different from the throughput value of the communication system in use, the value of the transmission path quality of a communication system in the derived using Based on the communication system in use, a change to a communication system different from the communication system is determined.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  According to the present invention, it is possible to switch to a wireless communication system suitable for transmission rate and stability among a plurality of wireless communication systems.

(Embodiment 1)
The first embodiment relates to a terminal device that can be communicated by using a W-LAN, EV-DO system, or a simple mobile phone system, and switching one of them, but the maximum transmission rate among the three wireless communication systems. The EV-DO method will be described mainly with the difference between the communication methods of the upper and lower lines being the largest. That is, the priority of the EV-DO system is set high in advance by the user or the communication carrier, and the priority of other wireless communication systems including the W-LAN and the simplified mobile phone system is set low. When the terminal device in the present embodiment determines switching from the EV-DO system to another wireless communication system, that is, when determining switching from a wireless communication system with high priority to a low wireless communication system, first, Measure multiple types of transmission path quality (all or one of these transmission path quality values is referred to as “EV-DO quality value”) corresponding to the EV-DO system uplink / downlink . When the throughput of the wireless communication system to be switched is lower than the throughput of the EV-DO system, a predetermined threshold value for the EV-DO quality value (all or one of such threshold values is referred to as a “first threshold value”). ) Is set, and if any EV-DO quality value satisfies the first threshold value, switching is determined.

  On the other hand, when the throughput of the wireless communication system to be switched is higher than the throughput of the EV-DO system and the quality of the wireless communication system is lower than a predetermined standard, basically the first threshold value with respect to the EV-DO quality value. Set thresholds that can be more easily satisfied (all or one of these thresholds is referred to as a “second threshold”), and any EV-DO quality value satisfies the second threshold. If so, the switching is determined. Further, when the throughput of the wireless communication system to be switched is higher than the throughput of the EV-DO system and the quality of the wireless communication system is equal to or higher than a predetermined reference, switching is determined regardless of the EV-DO quality value.

  Further, the terminal device in the present embodiment determines when switching from another wireless communication system to the EV-DO system, that is, when determining switching from a low priority wireless communication system to a high wireless communication system. Set a predetermined threshold value for EV-DO quality value (all or one of such threshold values is referred to as “third threshold value”), and all EV-DO quality values have a third threshold value. If satisfied, switch is determined. Since all EV-DO quality values do not satisfy the third threshold value, they cannot be switched, so that the EV-DO system is switched only when the quality of the EV-DO system is more stable.

  FIG. 1 shows a communication system 200 according to the first embodiment. The communication system 200 includes a terminal device 10, a W-LAN base station device 12, a simplified mobile phone base station device 14, an EV-DO base station device 16, a center facility 18, a network 20, and a server 22. The terminal device 10 includes a W-LAN communication unit 24, a W-LAN compatible antenna 30, a simple mobile phone communication unit 26, a simple mobile phone compatible antenna 32, an EV-DO communication unit 28, and an EV-DO compatible antenna 34. The W-LAN base station apparatus 12 includes a W-LAN base station antenna 36, the simplified mobile phone base station apparatus 14 includes a simplified mobile phone base station antenna 38, and the EV-DO base station apparatus 16 Includes an EV-DO base station antenna 40, and the center facility 18 includes a first router 42, a second router 44, a third router 46, and a switch server 48.

  The terminal device 10 is a mobile terminal having a communication function, and here includes a W-LAN communication unit 24, a simplified mobile phone communication unit 26, and an EV-DO communication unit 28 as a plurality of communication means. Further, the terminal device 10 does not communicate simultaneously by the W-LAN communication unit 24, the simplified mobile phone communication unit 26, and the EV-DO communication unit 28, and monitors these transmission line qualities, and is an autonomously optimal one. Select to communicate. The terminal device 10 may be configured as a single device, and a communication card having the functions of the W-LAN communication unit 24, the simplified mobile phone communication unit 26, and the EV-DO communication unit 28 may be used. It may be configured by being inserted into a PC. In the latter case, the selection of the communication means is executed by a software program installed in the PC. In addition, the W-LAN communication unit 24, the simple mobile phone communication unit 26, and the EV-DO communication unit 28 have a W-LAN compatible antenna 30, a simple mobile phone compatible antenna 32, and an EV-DO compatible antenna 34, respectively.

  The W-LAN base station apparatus 12 is a base station apparatus compatible with the W-LAN communication system, and communicates with the W-LAN communication unit 24 via the W-LAN base station antenna 36. The simple mobile phone base station device 14 is a base station device compatible with a simple mobile phone system, and communicates with the simple mobile phone communication unit 26 via the simple mobile phone base station antenna 38. The EV-DO base station apparatus 16 is a base station apparatus compatible with the EV-DO system, and communicates with the EV-DO communication unit 28 via the EV-DO base station antenna 40.

  The switch server 48 has a function of switching between the W-LAN base station device 12, the simplified mobile phone base station device 14, and the EV-DO base station device 16 in response to the selection of communication means by the terminal device 10. Depending on the selection by the switch server 48, any one of the first router 42, the second router 44, and the third router 46 is connected to the W-LAN base station device 12, the simplified mobile phone base station device 14, the EV-DO base station. Routing is performed based on the IP address assigned to each of the devices 16. In addition, between the switch server 48 and the W-LAN communication unit 24, the simplified mobile phone communication unit 26, and the EV-DO communication unit 28, processing such as IPsec (IP security protocol) is performed as necessary to improve security. May be raised. The switch server 48 is connected to the server 22 via the network 20.

  FIG. 2 shows the configuration of the terminal device 10. The terminal device 10 includes a W-LAN communication unit 24, a simple mobile phone communication unit 26, an EV-DO communication unit 28, a data processing unit 72, a throughput measurement unit 74, a condition setting unit 76, a threshold storage unit 78, a W A LAN quality measurement unit 80, an EV-DO quality measurement unit 82, a communication determination unit 84, a selection unit 90, an interface unit 92, and a device control unit 100 are included. The W-LAN communication unit 24 includes a radio unit 50, a baseband processing unit 52, a control unit 54, and a control signal IF unit 56. The simplified mobile phone communication unit 26 includes a radio unit 58 and a baseband processing unit 60. The EV-DO communication unit 28 includes a radio unit 64, a baseband processing unit 66, a control unit 68, and a control signal IF unit 70. The communication determination unit 84 includes a first determination unit 86, a first determination unit 86, and a control unit IF. 2 determination unit 88, and interface unit 92 includes display unit 94, operation unit 96, and external IF unit 98.

The wireless unit 50 has a frequency conversion function that converts a W-LAN radio frequency signal and a baseband signal, an amplification function that amplifies the signal, and a function that performs AD conversion and DA conversion.
The baseband processing unit 52 performs modulation / demodulation processing on the baseband signal. When W-LAN is compliant with IEEE802.11b, it has a diffusion processing function and a despreading function. When W-LAN is compliant with IEEE802.11a and IEEE802.11g, it has a fast Fourier transform function and a reverse high-speed function. Has a Fourier transform function.

  The control signal IF unit 56 outputs a predetermined control signal processed by the W-LAN communication unit 24 as a value of transmission path quality described later. The control unit 54 performs timing control of the W-LAN communication unit 24 and generation of control signals.

  The radio unit 58, the baseband processing unit 60, and the control unit 62 perform processing corresponding to the radio unit 50, the baseband processing unit 52, and the control unit 54 on the simple mobile phone system. For example, 60 is modulated / demodulated with π / 4 shift QPSK.

  The radio unit 64, the baseband processing unit 66, the control signal IF unit 70, and the control unit 68 perform processing corresponding to the radio unit 50, the baseband processing unit 52, the control signal IF unit 56, and the control unit 54 for the EV-DO system. Do. For example, the baseband processing unit 66 executes processing based on CDMA for the uplink and TDMA for the downlink. The control signal IF unit 70 outputs the EV-DO quality value. The EV-DO quality value will be described later.

  The data processing unit 72 converts data between any of the baseband processing unit 52, the baseband processing unit 60, and the baseband processing unit 66 and the interface unit 92.

  The display unit 94 corresponds to a display that displays predetermined data, the operation unit 96 corresponds to a keyboard or the like for a user to input predetermined processing, and the external IF unit 98 inputs and outputs data with an external device. It is an interface for.

  The W-LAN quality measurement unit 80 detects a value corresponding to RSSI (Receive Signal Strength Indicator), which is received power, among the control signals output from the control signal IF unit 56, and determines the transmission path quality of the W-LAN. Value (hereinafter referred to as “W-LAN-RSSI”).

  The EV-DO quality measurement unit 82 periodically acquires the EV-DO quality value output from the control signal IF unit 70. Here, as the EV-DO quality value, SINR (Signal to Interference and Noise Ratio), DRC (Data Rate Control) information, RSSI, transmission output, and DRC Lock information are targeted. In order to acquire these pieces of information, the EV-DO quality measurement unit 82 sends a log acquisition request to the control signal IF unit 70. Further, the EV-DO quality value composed of these five elements is parameterized and stored at predetermined intervals, and statistical processing such as averaging is performed on each value.

  Of the EV-DO quality values, the downlink transmission path quality can be determined by SINR, DRC information, and RSSI. The SINR represents the reception level ratio of the desired wave to the interference wave or noise, and the DRC information is the downlink requested to the EV-DO base station apparatus 16 based on the past CIR and RSSI fluctuation as described above. The transmission rate. On the other hand, the transmission line quality of the uplink can be determined from the transmission output and DRC Lock information. Since the transmission output generally increases as the distance from the EV-DO base station device 16 increases, the transmission path quality tends to deteriorate as the transmission output increases. From the statistics of the DRC Lock information, the ratio of error-free packets received by the EV-DO base station apparatus 16 is known.

  The throughput measuring unit 74 wraps back an echo command having a data length of 1000 bytes defined as an access control command with the switch server 48 for each of the W-LAN, the simple mobile phone system, and the EV-DO system. RTT (Round Trip Time) is measured and the measured value is made to correspond to the throughput. Further, a predetermined conversion may be performed on the measured RTT. Hereinafter, the throughput and the RTT are used in the same manner without particular distinction.

  The condition setting unit 76 sets a condition for selecting one of the W-LAN communication unit 24, the simplified mobile phone communication unit 26, and the EV-DO communication unit 28. First, the throughputs measured by the throughput measuring unit 74 are compared. In order to set the comparison criteria, that is, the communication system switching criteria in detail, the conditions are classified as follows. Depending on whether the currently used communication means is the EV-DO communication section 28 or other communication means, the communication means is roughly classified into two, and the communication means currently in use is the EV-DO communication section 28, that is, communication with high priority. In the case of means, the area fringe determination condition is used, and when the communication means currently in use is another communication means, that is, in the case of a communication means with a low priority, the in-area determination condition is used. Further, in the case of the area fringe determination condition, the switching candidate is classified according to whether it is the W-LAN communication unit 24 or the simple mobile phone communication unit 26, that is, the high-speed or low-speed than the EV-DO method, This is called a fringe judgment condition and a low speed area fringe judgment condition.

  That is, based on the throughput measured by the throughput measuring unit 74 and the priority of the communication means currently in use, the switching criterion to be determined from now is the high-speed area fringe determination condition, the low-speed area fringe determination condition, One of the judgment conditions is met. If the EV-DO communication unit 28 is used and both the W-LAN communication unit 24 and the simplified mobile phone communication unit 26 can be used, the W-LAN communication unit 24 with higher throughput can be used. Select to meet the high-speed area fringe determination condition. Although details will be described later, the judgment logic is different between the area fringe judgment condition and the in-area judgment condition, and the high-speed area fringe judgment condition, the low-speed area fringe judgment condition, and the in-area judgment condition are thresholds related to the EV-DO quality value. The value is different.

  The threshold value storage unit 78 stores threshold values, and its data structure is shown in FIG. Here, “Case” corresponds to the above-mentioned conditions, “Case 1” is the low-speed area fringe determination condition, “Case 2” and “Case 3” are the high-speed area fringe determination conditions, and “Case 4”. Corresponds to the in-area determination condition. For each of these cases, EV-DO quality values, RTT, W-LAN RTT (hereinafter referred to as “W-LAN-RTT”), and threshold values corresponding to W-LAN-RSSI are stored. Here, the threshold value of “Case 1” is the above-mentioned first threshold value, the threshold value of “Case 3” is the above-mentioned second threshold value, and the threshold value of “Case 4” is the above-mentioned threshold value. Corresponds to the third threshold. The threshold value selection based on the case is made by the condition setting unit 76.

  The first determination unit 86 compares W-LAN-RTT and W-LAN-RSSI with the threshold values G and H of “Case 2” in the case of the high-speed area fringe determination condition. If W-LAN-RTT is less than or equal to the threshold and W-LAN-RSSI is greater than or equal to the threshold, that is, if it can be estimated that the communication state of W-LAN is good, switching to W-LAN with higher throughput is possible. decide.

  The second determination unit 88 compares the EV-DO quality value with a threshold value. In the case of the low-speed area fringe determination condition, the EV-DO quality value is compared with the threshold value of “Case 1”, and if any of the threshold values satisfies the threshold value, switching to the simplified mobile phone system is determined. In the case of the high-speed area fringe determination condition, the EV-DO quality value is compared with the threshold value of “Case 3”, and if any of the threshold values satisfies the threshold value, switching to the W-LAN is determined. Here, in the high-speed area fringe determination condition, the throughput increases due to the switching of the wireless communication system, and in the low-speed area fringe determination condition, the throughput decreases. Switching is desired. Therefore, the threshold value of “Case 3” is set to a value that can be more easily satisfied than the threshold value of “Case 1”. In the case of the in-area judgment condition, the EV-DO quality value and the EV-DO system RTT are compared with the threshold values of “Case 4”, and if all satisfy the threshold values, the switch to the EV-DO system is determined. To do.

The selection unit 90 switches the W-LAN communication unit 24, the simplified mobile phone communication unit 26, and the EV-DO communication unit 28 according to the switching determination by the first determination unit 86 or the second determination unit 88.
The device control unit 100 performs timing control, control signal generation, and the like.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of an arbitrary computer, and in terms of software, it is realized by a program having a reservation management function loaded in memory. The functional block realized by those cooperation is drawn. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  FIGS. 4A and 4B show the concept of switching timing when moving from the EV-DO area to an area of another wireless communication method. Here, for ease of explanation, the EV-DO base station device 16 and the W-LAN base station device 12 or the simplified mobile phone base station device 14 are arranged on a one-dimensional straight line, and the terminal device 10 is connected to the EV. -The case where it moves to the direction away from DO base station apparatus 16 is assumed. The transmission output and minimum reception sensitivity of the EV-DO base station device 16, the W-LAN base station device 12, and the simplified mobile phone base station device 14 are different from each other. These conditions are assumed to be uniform.

  In FIG. 4A, the terminal apparatus 10 is moving in the direction of the W-LAN base station apparatus 12, that is, it corresponds to a high-speed area fringe determination condition. On the other hand, in FIG. 4B, the terminal device 10 is moving in the direction of the simplified mobile phone base station device 14, that is, it corresponds to the low-speed area fringe determination condition. As is clear from comparison between FIGS. 4A and 4B, FIG. 4A is switched from the EV-DO system to another communication system earlier. 4A, the EV-DO area is shorter than the W-LAN area, whereas in FIG. 4B, the EV-DO area is longer than the area of the simple mobile phone. FIG. 4A quickly switches to a higher-speed W-LAN, and FIG. 4B can use a higher-speed EV-DO scheme for a long period. This is because the threshold values are different between “Case 2 and 3” and “Case 1”.

  FIG. 5 is a flowchart showing a switching procedure when moving from the EV-DO area to an area of another wireless communication method. The throughput measuring unit 74 measures the throughput of the W-LAN communication unit 24, the simple mobile phone communication unit 26, and the EV-DO communication unit 28 (S10). The condition setting unit 76 compares them, and if the EV-DO system does not have a higher throughput than other systems (N in S12), the second determination unit 88 executes the determination based on the low-speed area fringe determination condition (S14). . On the other hand, when EV-DO has a higher throughput than the other system (Y in S12), the quality of the other system is not higher than the threshold value or the RTT is not lower than the threshold value by the first determination unit 86 ( The second determination unit 88 executes determination based on the high-speed area fringe determination condition (S18). If the quality of the other system is equal to or higher than the threshold value and the RTT is equal to or lower than the threshold value (Y in S16), the communication state of the other system can be estimated to be good, and the system is switched to another system (S20). ).

  FIG. 6 is a flowchart showing a determination procedure based on the low-speed area fringe determination condition. As a premise, the threshold value of “Case 1” in the threshold value storage unit 78 is selected. The EV-DO quality measurement unit 82 acquires SINR, DRC information, RSSI, transmission output, and DRC Lock information (S30). SINR is A1 or less (Y in S32), DRC information is B1 or less (Y in S34), RSSI is E1 or less (Y in S36), and the transmission output is C1 or more (Y in S38). If any one of the conditions that DRC Lock is D1 or less (S40) is satisfied, the communication system is switched to another communication system (S44). On the other hand, when all are not satisfied (N of S32 to N of S40), it is determined to maintain the communication by the EV-DO system (S42). The determination procedure for the high-speed area fringe determination condition is the same flowchart as in FIG. 6 except that the threshold value is “Case 3”.

  FIGS. 7A to 7C show the concept of switching timing in the case of reciprocating between the EV-DO area and other wireless communication system areas. Here, as shown in FIG. 7A, it is assumed that the EV-DO base station device 16 and the simplified mobile phone base station device 14 are arranged on a one-dimensional straight line. In FIG. 7B, the terminal apparatus 10 is moving from the EV-DO base station apparatus 16 toward the simplified mobile phone base station apparatus 14, that is, it corresponds to the low-speed area fringe determination condition. On the other hand, in FIG. 7C, the terminal device 10 is moving in the direction from the simplified mobile phone base station device 14 to the EV-DO base station device 16, that is, it corresponds to the in-area determination condition. As is clear from comparison between FIGS. 7B and 7C, the area of the EV-DO system is longer in FIG. 7A. That is, when switching from the EV-DO system to another communication system, use the EV-DO system for as long as possible, and when switching from another system to the EV-DO system, use until the EV-DO system becomes more stable. do not do. By such processing, even if the terminal device 10 makes a round trip between the position indicated as “switch” in FIG. 7B and the position indicated as “switch” in FIG. It is not changed and more stable operation is possible.

  FIG. 8 is a flowchart showing a determination procedure based on the in-area determination condition. As a premise, the threshold value of “Case 4” in the threshold value storage unit 78 is selected. The EV-DO quality measurement unit 82 acquires SINR, DRC information, RSSI, transmission output, and DRC Lock information, and the throughput measurement unit 74 acquires RTT (S50). SINR is greater than or equal to A3 (Y in S52), DRC information is greater than or equal to B3 (Y in S54), RSSI is greater than or equal to E3 (Y in S56), and the transmission output is less than or equal to C3 (Y in S58). If DRC Lock is equal to or greater than D3 (Y in S60) and RTT is equal to or greater than F (Y in S62), the EV-DO system is switched (S64). On the other hand, if either of them is not satisfied (N in S52 to N in S62), it is determined to maintain communication by the current system (S66).

  The operation of the terminal device 10 having the above configuration will be described. It is assumed that the user moves from an EV-DO area to a W-LAN area. The throughput measuring unit 74 measures the throughput of the W-LAN communication unit 24, the simplified mobile phone communication unit 26, and the EV-DO communication unit 28. The condition setting unit 76 compares them, confirms that the throughput of the W-LAN is higher than the throughput of the EV-DO method, and obtains the threshold values of “cases 2 and 3” in the threshold value storage unit 78. The W-LAN quality measurement unit 80 measures the RSSI of the W-LAN, and in the first determination unit 86, the RSSI is lower than the threshold value of “Case 2” and the RTT of the W-LAN is higher than the threshold value. The result was obtained. The second determination unit 88 compares the EV-DO quality value measured by the EV-DO quality measurement unit 82 with the threshold value of “Case 3”. To switch to. The selection unit 90 selects the operation of the W-LAN communication unit 24.

  According to the present embodiment, since the value of the transmission path quality corresponding to the uplink and downlink is measured, the transmission path quality is improved even in a system such as cdma2000 1x-EV DO in which signals transmitted through the uplink and downlink are greatly different. Accurate judgment is possible. Since the transmission path quality value measured by the EV-DO method is calculated for other purposes, it can be realized with almost no change in the current system. Since multiple channel quality is parameterized and each is compared with a threshold value, switching control is possible with limited channel quality even in different situations by changing the decision logic and threshold value. It is. In addition, since a plurality of types of threshold values can be set, switching control considering the throughput of the communication system currently in use or the communication system to be changed can be performed. Further, only by changing the determination logic, the switching control is provided with hysteresis, and the communication system can be stabilized.

(Embodiment 2)
The second embodiment is a terminal device that is used while switching one of a plurality of wireless communication systems, as in the first embodiment, but is used for setting the first threshold value and the second threshold value. A preset value is used without measuring the throughput of a plurality of wireless communication systems. That is, regardless of the actual throughput, the throughput is set and the processing is simplified.
As the terminal device 10 according to the second embodiment, the one shown in FIG. 2 is effective. However, since the throughput is not measured, the throughput measuring unit 74 is unnecessary.

  FIG. 9 shows the data structure of the stored throughput according to the second embodiment, which is stored in the condition setting unit 76, for example. In this case, a value of “throughput” corresponding to “system” is defined, but the value of “throughput” is set to an arbitrary value within a feasible range and does not necessarily need to be the maximum throughput. According to this data, it is determined that the EV-DO system and the W-LAN are faster than the W-LAN regardless of the actual throughput, and the EV-DO system and the simplified mobile phone system are related to the actual throughput. The EV-DO method is judged to be faster.

  The operation of the terminal device 10 having the above configuration will be described. It is assumed that the user moves from an EV-DO area to a W-LAN area. Since it has been confirmed that the W-LAN communication unit 24 can receive the W-LAN signal, the condition setting unit 76 acquires the threshold values of “Case 2 and 3” in the threshold value storage unit 78. The W-LAN quality measurement unit 80 measures the RSSI of the W-LAN, and the first determination unit 86 obtains a result that the RSSI is lower than the threshold value of “Case 2”. The second determination unit 88 compares the EV-DO quality value measured by the EV-DO quality measurement unit 82 with the threshold value of “Case 3”. To switch to. The selection unit 90 selects the operation of the W-LAN communication unit 24.

According to the present embodiment, since a value stored in advance for the throughput is used, the processing can be simplified.
The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  In Embodiments 1 and 2, the EV-DO quality measurement unit 82 derives five types of values of SINR, DRC information, RSSI, transmission output, and DRC Lock information as values of the transmission path quality, and the second determination unit 88 Then, they are compared with a threshold value. However, the present invention is not limited to this. For example, any one of these may be used. According to this modification, the process can be simplified. That is, the type of transmission line quality may be selected according to the required accuracy and the allowable processing amount.

  In Embodiments 1 and 2, the EV-DO quality measurement unit 82 derives five types of values of SINR, DRC information, RSSI, transmission output, and DRC Lock information as EV-DO transmission path quality values. For example, W-LAN transmission path quality may be derived. That is, the priority of a communication system with a high throughput may be increased according to the communication standard. According to this modification, switching processing optimized for a communication system with high throughput is possible.

  In Embodiments 1 and 2, EV-DO, W-LAN, and a simple mobile phone system are used as a wireless communication system. However, the present invention is not limited to this, and may be, for example, PDC (Personal Digital Cellular) or W-CDMA (Wide-band CDMA). What is necessary is just to measure the value of transmission line quality. This modification can be applied to many wireless communication systems.

1 is a configuration diagram showing a communication system according to Embodiment 1. FIG. It is a figure which shows the structure of the terminal device of FIG. It is a figure which shows the data structure of the threshold value memory | storage part of FIG. FIGS. 4A and 4B are diagrams illustrating the concept of switching timing when moving from the EV-DO area of FIG. 1 to an area of another wireless communication method. It is a flowchart which shows the switching procedure in the case of moving to the area of another radio | wireless communication system from the EV-DO area of FIG. It is a flowchart which shows the determination procedure by the area fringe conditions for low speeds of FIG. FIGS. 7A to 7C are diagrams showing the concept of switching timing when the EV-DO area of FIG. 1 and other areas of the wireless communication method are reciprocated. It is a flowchart which shows the determination procedure by the determination condition in area of FIG. FIG. 10 is a diagram illustrating a data structure of stored throughput according to the second embodiment.

Explanation of symbols

  10 terminal devices, 12 W-LAN base station devices, 14 simple mobile phone base station devices, 16 EV-DO base station devices, 18 center facilities, 20 networks, 22 servers, 24 W-LAN communication units, 26 simple mobile phones Telephone communication unit, 28 EV-DO communication unit, 30 W-LAN compatible antenna, 32 Simple mobile phone compatible antenna, 34 EV-DO compatible antenna, 36 W-LAN base station antenna, 38 Simple mobile phone base station antenna, 40 EV-DO base station antenna, 42 first router, 44 second router, 46 third router, 48 switch server, 50 radio unit, 52 baseband processing unit, 54 control unit, 56 control signal IF unit, 58 radio unit , 60 baseband processing unit, 62 control unit, 64 radio unit, 6 6 baseband processing unit, 68 control unit, 70 control signal IF unit, 72 data processing unit, 74 throughput measurement unit, 76 condition setting unit, 78 threshold value storage unit, 80 W-LAN quality measurement unit, 82 EV-DO Quality measurement unit, 84 communication determination unit, 86 first determination unit, 88 second determination unit, 90 selection unit, 92 interface unit, 94 display unit, 96 operation unit, 98 external IF unit, 100 device control unit, 200 communication system .

Claims (6)

A transmission path quality deriving means for deriving a transmission path quality value in the communication system in use;
First derivation means for deriving a throughput value of the communication system in use;
Second derivation means for deriving a throughput value of a communication system different from the communication system that can be replaced with the communication system in use;
Threshold value determining means for determining a threshold value for transmission path quality based on the throughput value derived by the first deriving means and the throughput value derived by the second deriving means ;
A change determination for determining a change from the communication system in use to a communication system different from the communication system based on the determined threshold value and the derived value of the channel quality in the communication system in use. Means,
The terminal device characterized by including.   2. The terminal apparatus according to claim 1, wherein, in the transmission path quality deriving unit, the communication system in use has different communication speeds and communication methods in the up and down lines. The transmission path quality deriving means derives a plurality of types of transmission path quality values,
The threshold value determining means determines a plurality of threshold values corresponding to the plurality of types of transmission path quality,
If any one of the derived plural types of transmission path quality values satisfies the condition defined by the threshold value corresponding to the transmission path quality, the change determination means, from the communication system in use, The terminal apparatus according to claim 1, wherein a change to a communication system different from the communication system is determined.   4. The transmission path quality deriving unit derives transmission path quality values corresponding to upper and lower lines of the communication system in use as the plurality of types of transmission path quality values, respectively. Terminal equipment.   If the second value is higher than the first value, the threshold value determining means changes the communication system in use to a communication system different from the communication system. 5. The terminal device according to claim 1, wherein the threshold value is determined to a value that facilitates the processing. Deriving a link quality value and throughput value of the communication system in use, further wherein instead of the communication system in use can place the communication system in the use of the communication system with different throughput value of the communication system , And a threshold value relating to the transmission path quality determined from the throughput value in the communication system in use and the throughput value in the different communication system, and the derived value of the transmission path quality in the communication system in use And determining a change from the communication system in use to a communication system different from the communication system.

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