JP5128461B2 - Wireless communication apparatus, wireless communication method and program - Google Patents

Description

  The present invention relates to a wireless communication apparatus that selects a base station and downloads data.

  Conventionally, in a wireless communication device that continues communication while moving, such as a mobile phone, a process called handoff that switches a base station to be connected according to a radio wave reception state in order to always ensure a good communication environment Is done. In such a wireless communication apparatus, the electric field strength of a neighboring base station notified from a base station in communication is measured, and base stations having a certain strength or higher are set as data reception destination candidates, that is, an active set (ActiveSet). to add. Then, the base station having the highest electric field strength among the base stations in the active set is selected as the data receiving destination, that is, the best active set (Best ASP).

  Here, when the electric field strength is an opportunity for handoff, as shown in FIG. 5, the radio communication device X communicates with a closer base station A. However, if there are many wireless communication apparatuses communicating with the base station A and traffic is concentrated, the reception data rate is kept low. On the other hand, since the neighboring base station B has a small number of wireless communication devices in communication, it can be expected that the reception data rate will be high. That is, the wireless communication device X can receive data more efficiently when handed off to the base station B having a low electric field strength.

Thus, in the data download process, the throughput may be reduced depending on the traffic situation of the communicating base station. Therefore, a method of handing off to a neighboring base station when a decrease in throughput due to traffic concentration is detected has been proposed (for example, Patent Document 1).
JP 2006-217495 A

  However, according to the method of Patent Document 1, there is a case where traffic is concentrated on the destination base station handed off due to a decrease in throughput in the same manner as or more than the original base station. Therefore, it is desired that the handoff can be reliably performed to a base station that can obtain a throughput higher than the expected value.

  An object of the present invention is to provide a wireless communication apparatus that can detect a congestion state in an active set and can select a base station that can obtain a throughput higher than an expected value.

  A radio communication apparatus according to the present invention is a radio communication apparatus that selects a communication destination from a plurality of base stations based on electric field strength, and includes a measurement unit that measures an index related to throughput when receiving data, and the base A signal receiving unit that receives a signal that regulates the data rate of the upstream band due to communication congestion, and an index measured by the measuring unit is less than a predetermined throughput, and the data receiving unit sets the data rate by the signal receiving unit. And a control unit that switches the data reception destination to a base station having the next highest electric field strength after the current data reception destination when a signal to be regulated is received.

  Moreover, it is preferable that the control unit repeats the switching process until the data reception destination is switched to a base station that can obtain the predetermined throughput.

  A radio communication method according to the present invention is a radio communication method of a radio communication device that selects a communication destination from a plurality of base stations based on electric field strength, and measures and measures an index related to throughput when receiving data. If the received index falls below a predetermined throughput and a signal is received from the base station that regulates the data rate of the upstream band due to communication congestion, the base having the next highest electric field strength after the current data receiving destination Switch the data reception destination to the station.

  A program according to the present invention is a program for causing a wireless communication apparatus to select a communication destination from a plurality of base stations based on electric field strength, and is an index related to throughput when the wireless communication apparatus receives data. And when the wireless communication apparatus receives a signal from the base station that regulates the data rate of the upstream band due to communication congestion, when the measured index falls below a predetermined throughput. The data receiving destination is switched to the base station having the next highest electric field strength after the data receiving destination.

  A radio communication apparatus according to the present invention is a radio communication apparatus that selects a communication destination based on electric field strength from a plurality of base stations, and a signal receiving unit that receives a Reverse Activity Bit from the base station, and a downlink throughput Is less than a predetermined throughput, and the Combined Busy Bit based on the Reverse Activity Bit received from the base station is a predetermined value, the data receiving destination is set to the base station having the next highest field strength after the current data receiving destination. A control unit for switching.

  A radio communication method according to the present invention is a radio communication method of a radio communication apparatus that selects a communication destination from a plurality of base stations based on electric field strength, receives a Reverse Activity Bit from the base station, and receives a downlink throughput. Is less than a predetermined throughput, and the Combined Busy Bit based on the Reverse Activity Bit received from the base station is a predetermined value, the data receiving destination is set to the base station having the next highest field strength after the current data receiving destination. Switch.

  A program according to the present invention is a program for causing a wireless communication device to select a communication destination from a plurality of base stations based on electric field strength, and receiving the Reverse Activity Bit from the base station to the wireless communication device. When the combined communication bit based on the Reverse Activity Bit received from the base station has a predetermined value, the downlink communication is next to the current data reception destination. The data receiving destination is switched to a base station having a high electric field strength.

  According to the present invention, it is possible to select a base station that can obtain a throughput higher than the expected value in the active set.

  Hereinafter, an example of a preferred embodiment of the present invention will be described. In the present embodiment, a mobile phone 1 will be described as an example of a wireless communication device. Note that the wireless communication device of the present invention is not limited to this, and can be applied to various wireless communication devices such as a PHS (Personal Handyphone System), a PDA (Personal Digital Assistant), a communication module attached to an in-vehicle device or a personal computer. Applicable.

  FIG. 1 is an external perspective view of a mobile phone 1 (wireless communication apparatus) according to the present embodiment. FIG. 1 shows a so-called foldable mobile phone, but the mobile phone according to the present invention is not limited to this. For example, a sliding type in which one casing is slid in one direction from a state in which both casings are overlapped, or a rotary type in which one casing is rotated around an axis along the overlapping direction ( Turn type), or a type (straight type) in which the operation unit and the display unit are arranged in one housing and does not have a connecting unit.

  The mobile phone 1 includes an operation unit side body 2 and a display unit side body 3. The operation unit side body 2 includes a key input unit 11 and a microphone 12 to which a voice uttered by a user of the mobile phone 1 is input on the surface unit 10. The key input unit 11 includes a function setting operation button 13 for operating various functions such as various setting functions, a phone book function, and a mail function, and an input operation button 14 for inputting a telephone number and mail characters. And a determination operation button 15 for performing determination and scrolling in various operations.

  The display unit side body 3 includes a display unit 21 for displaying various types of information on the surface unit 20 and a receiver 22 for outputting the voice of the other party of the call.

  Further, the upper end portion of the operation unit side body 2 and the lower end portion of the display unit side body 3 are connected via a hinge mechanism 4. In addition, the mobile phone 1 relatively rotates the operation unit side body 2 and the display unit side body 3 which are connected via the hinge mechanism 4, so that the operation unit side body 2 and the display unit side body 3 are rotated. The body 3 can be in an open state (open state), or the operation unit side body 2 and the display unit side body 3 can be folded (folded state).

  FIG. 2 is a block diagram showing functions of the mobile phone 1 according to the present embodiment. The mobile phone 1 includes a display unit 21, a CPU 30, a communication control unit 31, an antenna 32, a voice control unit 33, a microphone 12, a receiver 22, a key input unit 11, and a memory 34.

  The CPU 30 controls the entire mobile phone 1, and performs predetermined control on the display unit 21, the communication control unit 31, the voice control unit 33, and the like, for example. In addition, the CPU 30 receives input from the key input unit 11 or the like and executes various processes. Then, the CPU 30 controls the memory 34 to execute reading of various programs and data and writing of data when executing processing.

  In particular, in this embodiment, the CPU 30 compares the electric field strength for each base station and monitors the throughput in data download. Specifically, the throughput uses the received data rate as an index. For example, when the value of the reception data rate is less than a predetermined value or the ratio of the actual reception data rate to the request rate determined based on the current reception quality is less than the predetermined value, the CPU 30 Judge that it is below the expected throughput. When the CPU 30 determines that the throughput is below the expected throughput, the CPU 30 attempts a handoff to another base station (details of the process will be described later).

  The display unit 21 performs predetermined image processing according to the control of the CPU 30. Then, the processed image data is stored in the frame memory and output to the screen at a predetermined timing.

  The communication control unit 31 communicates with an external device (base station) in a predetermined use frequency band (for example, 2 GHz band, 800 MHz band, etc.). Then, the communication control unit 31 demodulates the signal received from the antenna 32, supplies the processed signal to the CPU 30, modulates the signal supplied from the CPU 30, and transmits the signal from the antenna 32 to the external device. .

  In particular, in this embodiment, the communication control unit 31 transmits and receives signals related to voice calls, mails, and the like, as well as a signal that regulates the data rate of the upstream band from the base station due to network congestion (Reverse described later). (Activity Bit) is received, and based on this signal, a comprehensive result (CombinedBusyBit described later) indicating whether or not there is a base station that regulates the data rate in the active set is acquired.

  The audio control unit 33 performs predetermined audio processing on the signal supplied from the communication control unit 31 under the control of the CPU 30 and outputs the processed signal to the receiver 22. The receiver 22 outputs the signal supplied from the audio control unit 33 to the outside. This signal may be output from a speaker (not shown) instead of or together with the receiver 22.

  The voice control unit 33 processes a signal input from the microphone 12 according to the control of the CPU 30 and outputs the processed signal to the communication control unit 31. The communication control unit 31 performs predetermined processing on the signal supplied from the audio control unit 33 and outputs the processed signal from the antenna 32.

  The memory 34 includes, for example, a working memory and is used for arithmetic processing by the CPU 30. Further, in the present embodiment, a program for executing processing to be described later, a threshold value for determining a decrease in throughput, a flag value indicating a congestion state in the active set, and the like are stored. Note that the memory 34 may also serve as a removable external memory.

Hereinafter, details of processing in the CPU 30 of the mobile phone 1 will be described.
FIG. 3 is a diagram showing a configuration of a communication channel according to the present embodiment.

  The downlink channel of EV-DO (Evolution Data Only) communication in CDMA2000_1x includes a pilot channel, a MAC channel, a control channel, and a traffic channel. When the CPU 30 controls the communication control unit 31 and establishes EVDO communication with the base station synchronized with the pilot channel using the control channel, the CPU 30 downloads data through the traffic channel. The MAC channel is a channel including parameters for maintaining and managing communication, and further includes a plurality of subchannels. The RA channel, which is one of the subchannels, is a physical channel that transmits a RAB (Reverse Activity Bit) indicating the congestion level of the base station.

  Here, RAB is set to “0” when the base station is not congested and the uplink communication speed can be increased, and is set to “1” when the base station is congested. Bit value. The RAB is transmitted in units of base stations, and the CPU 30 monitors RAB notified from all active sets at a predetermined period. At this time, the CPU 30 cannot detect each RAB notified from each base station in the active set, and is set to “1” if even one RAB in the active set is “1”. The congestion state is determined based on the Combined Busy Bit.

  Then, the mobile phone 1 that has determined the congestion state adjusts the uplink communication rate in accordance with a predetermined rule (for example, EV-DO standard specifications). For example, in an active set in a congested state, congestion can be eliminated by reducing the uplink data rate from the wireless communication apparatus with a predetermined probability. Conversely, in an active set that is not in a congested state, the uplink data rate from the wireless communication apparatus can be increased with a predetermined probability.

  As described above, the CPU 30 can determine the presence or absence of a congestion state in the active set using the Combined Busy Bit. Therefore, the CPU 30 can determine that there is a possibility that the current receiving destination (Best ASP) is congested if the active set is in a congested state upon detecting a decrease in throughput. Thereby, CPU30 suppresses the fall of a throughput by handing off a receiving destination to another base station.

  However, the determination of the congestion state by the Combined Busy Bit cannot determine which base station in the active set is in the congestion state. Therefore, the expected throughput can be obtained more reliably by determining the throughput even at the handoff destination.

  FIG. 4 is a flowchart showing processing of the CPU 30 according to the present embodiment.

  In step S1, the CPU 30 determines whether or not EV-DO communication is being performed. If this determination is YES, since the above-mentioned Combined Busy Bit can be acquired, the process proceeds to step S2 and the process is continued. On the other hand, if the determination is NO, the Combined Busy Bit necessary for the subsequent process cannot be acquired, and the process ends.

  In step S2, the CPU 30 determines whether or not the throughput is lower than the expected value in the process of downloading data from the current receiving destination. If this determination is YES, the process proceeds to step S3 in order to determine the cause of the decrease in throughput. If the determination is NO, the process ends because there is no need for handoff.

  In step S3, the CPU 30 refers to the Combined Busy Bit and determines whether or not it is “1”. If this determination is YES, it is determined that there is a congestion state in any of the base stations in the active set, and that the cause of the decrease in the throughput at the current receiving destination is this congestion. Move. On the other hand, if the determination is NO, it is not a decrease in throughput due to congestion, and the process is terminated.

  In step S4, the CPU 30 determines whether or not two or more base stations are held in the active set. If this determination is YES, there is a candidate to be a handoff destination, and the process proceeds to step S5. On the other hand, if the determination is NO, the handoff cannot be performed, and the process is terminated.

  In step S5, the CPU 30 performs handoff so as to switch the receiving destination to the base station having the highest electric field strength among the base stations in the active set other than the current receiving destination. At this time, the expected throughput is not always obtained in the handoff destination base station, and the process moves to step S6.

  In step S6, the CPU 30 determines whether or not the throughput is below the expected value in the process of downloading data from the current receiving destination (handoff destination base station). If this determination is YES, the expected throughput could not be obtained even by handoff, and the process proceeds to step S7. On the other hand, if the determination is NO, the expected throughput is obtained by handoff, and the process is terminated.

  In step S <b> 7, the CPU 30 determines whether or not there is a base station that has not attempted a handoff (not a Best ASP) in the current active set. If this determination is YES, there is a candidate to be a handoff destination, and the process proceeds to step S8. On the other hand, if the determination is NO, since handoff cannot be performed, the process proceeds to step S9.

  In step S8, the CPU 30 performs handoff so as to switch the reception destination to the base station having the highest electric field strength among the base stations not attempting handoff in the active set. At this time, the expected throughput is not always obtained in the handoff destination base station, so the CPU 30 returns to step S6 to determine the throughput.

  In step S9, since there is no base station capable of obtaining the expected throughput in the active set, the CPU 30 determines a base station having the highest electric field strength in the active set as a receiving destination, and performs handoff.

  As described above, according to this embodiment, when it is detected that a congestion state has occurred in any of the base stations in the active set, a base station that can obtain a throughput higher than expected is searched for and handoff is performed. Thereby, since the base station selected based on the electric field strength is congested, it is possible to avoid a situation in which sufficient throughput in data download cannot be obtained. And since the mobile telephone 1 can select the base station which is not congested (the throughput more than expected is obtained) within the active set with favorable electric field strength, it can improve a throughput.

  As mentioned above, although embodiment of this invention was described, this invention is not restricted to embodiment mentioned above. The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

  In the above-described embodiment, the base station having the highest electric field strength is selected if the throughput is equal to or higher than the expected value. However, the present invention is not limited to this. For example, you may hand off to the base station with the highest throughput in the active set. That is, after measuring the throughput of all the base stations in the active set, the handoff destination is determined. Even when there is no base station that can obtain the expected throughput, the base station with the highest throughput is determined as the handoff destination. Thereby, the throughput can be further improved.

  In the above-described embodiment or modification, handoff candidates are targeted for all base stations in the active set. However, the present invention is not limited to this, and a predetermined number of base stations having a higher electric field strength or a predetermined number of base stations or higher You may limit to the base station of electric field strength.

1 is an external perspective view of a mobile phone according to an embodiment of the present invention. It is a block diagram which shows the function of the mobile telephone which concerns on embodiment of this invention. It is a figure which shows the structure of the communication channel which concerns on embodiment of this invention. It is a flowchart which shows the process of CPU which concerns on embodiment of this invention. It is a figure explaining the subject in the conventional handoff.

Explanation of symbols

1 Mobile phone (wireless communication device)
DESCRIPTION OF SYMBOLS 10 Surface part 11 Key input part 12 Microphone 21 Display part 22 Receiver 30 CPU (measurement part, control part)
31 Communication controller (signal receiver)
32 Antenna 33 Voice control unit 34 Memory

Claims (7)

A wireless communication device that selects a communication destination based on electric field strength from a plurality of base stations,
A measurement unit that measures an index related to throughput when receiving data;
From the base station, a signal receiving unit that receives a signal that regulates the data rate of the upstream band due to communication congestion; and
When the index measured by the measurement unit falls below a predetermined throughput and the signal receiving unit receives a signal that regulates the data rate, the data reception is performed to the base station having the next highest electric field strength after the current data receiving destination. A wireless communication device comprising: a control unit that switches the destination.   The wireless communication apparatus according to claim 1, wherein the control unit repeats switching processing until a data reception destination is switched to a base station that can obtain the predetermined throughput.   A wireless communication method of a wireless communication device for selecting a communication destination based on electric field strength from a plurality of base stations,
  Measure the throughput index when receiving data,
  When the measured index is lower than a predetermined throughput and a signal is received from the base station that regulates the data rate of the upstream band due to communication congestion, the electric field strength is next to the current data receiving destination. A wireless communication method of a wireless communication apparatus for switching a data reception destination to a base station.   A program for causing a wireless communication device to select a communication destination from a plurality of base stations based on electric field strength,
  Causing the wireless communication device to measure an index related to throughput when receiving data;
  When the wireless communication apparatus receives a signal from which the measured index falls below a predetermined throughput and regulates the data rate of the upstream band due to communication congestion from the base station, the current data receiving destination Next, a program for switching the data reception destination to a base station with the highest electric field strength.   A wireless communication device that selects a communication destination based on electric field strength from a plurality of base stations,
  A signal receiving unit for receiving a Reverse Activity Bit from the base station;
  When the downlink throughput is lower than the predetermined throughput and the Combined Busy Bit based on the Reverse Activity Bit received from the base station is a predetermined value, the data is transmitted to the base station having the next highest field strength after the current data receiving destination. And a control unit that switches a receiving destination.   A wireless communication method of a wireless communication device for selecting a communication destination based on electric field strength from a plurality of base stations,
  Receives Reverse Activity Bit from the base station,
  When the downlink throughput is lower than the predetermined throughput and the Combined Busy Bit based on the Reverse Activity Bit received from the base station is a predetermined value, the data is transmitted to the base station having the next highest field strength after the current data receiving destination. A wireless communication method of a wireless communication apparatus for switching a receiving destination.   A program for causing a wireless communication device to select a communication destination from a plurality of base stations based on electric field strength,
  Causing the wireless communication device to receive a Reverse Activity Bit from the base station;
  When the wireless communication device has a downlink throughput lower than a predetermined throughput and a Combined Busy Bit based on the Reverse Activity Bit received from the base station has a predetermined value, the electric field strength next to the current data reception destination A program for switching the data reception destination to a base station with a high level.

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