JP5204192B2 - Base station apparatus, terminal movement estimation method and program - Google Patents

Description

  Embodiments described herein relate generally to a base station apparatus, a terminal movement estimation method, and a program for estimating a movement state of a wireless terminal.

  Along with the development of wireless broadband technology, communication speeds, higher functions, and multi-functions are increasing in the communication field.

  Conventionally, the base station has been mainly composed of a radio unit and a control unit, but recently, a base station that separates the radio unit and the control unit (hereinafter referred to as a separable base station) has been commercialized. Has been. Since the separation-type base station can accommodate a plurality of radio units with a single control unit, it is possible to realize various functions that were difficult with the integrated type. For example, macro diversity and high-speed handover are characteristic functions of the separated base station.

JP 2010-43996 A

  However, since the functions described above are effective when performed on a specific terminal, it is necessary to select the terminal appropriately. If a terminal that performs these functions cannot be selected properly, there is a possibility that the processing becomes enormous and a load is imposed on the entire base station system, and there is a problem of wasteful use of radio resources.

  An object of the present embodiment is to provide a base station apparatus, a terminal movement estimation method, and a program that simply estimate a movement state of a terminal without imposing a load on the base station system.

  The base station apparatus according to the present embodiment includes a radio unit that receives a radio signal arriving from a radio terminal by an antenna, a received power measuring unit that measures received power of a signal received by the radio unit, and the measured Change amount calculating means for calculating a change amount of received power in time units, movement direction estimating means for estimating the movement direction of the wireless terminal based on the sign of the change amount, and based on the absolute value of the change amount Moving speed estimating means for estimating the moving speed of the wireless terminal.

  The terminal movement estimation method according to the present embodiment is a method used for a base station apparatus including a radio unit that receives a radio signal arriving from a radio terminal by an antenna, and uses received power of a signal received by the radio unit. A received power measurement step for measuring, a change amount calculating step for calculating a change amount of the measured received power in a time unit, and a moving direction estimating step for estimating a moving direction of the wireless terminal based on a sign of the change amount And a moving speed estimating step for estimating the moving speed of the wireless terminal based on the absolute value of the change amount.

  The terminal movement estimation program according to the present embodiment is a program used for a base station apparatus including a radio unit that receives a radio signal arriving from a radio terminal by an antenna, and receives received power of a signal received by the radio unit. Received power measurement processing to measure, change amount calculation processing to calculate the amount of change of the measured received power in time units, and movement direction estimation processing to estimate the moving direction of the wireless terminal based on the sign of the change amount And a moving speed estimation process for estimating the moving speed of the wireless terminal based on the absolute value of the change amount.

The figure which shows the whole structure of the base station apparatus which concerns on this embodiment. The figure which shows the movement estimation process of the terminal in Example 1. FIG. 5 is a flowchart illustrating movement estimation processing according to the first embodiment. The figure which shows the movement estimation process of the terminal in Example 2. FIG. 10 is a flowchart illustrating movement estimation processing according to the second embodiment.

  Hereinafter, a base station apparatus, a terminal movement estimation method, and a program according to the present embodiment will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating an overall configuration of a base station apparatus according to the present embodiment.

  The base station apparatus is configured by a separation base station of, for example, wireless broadband (mobile phone, XGP, WiMAX, etc.). In the base station apparatus, the radio units 2-1 to 2-N and the control unit 1 are separated, and an optical cable is connected between them. The control unit 1 includes a power control unit 11 and a movement estimation unit 12, and a single control unit 1 can accommodate a plurality of radio units 2-1 to 2-N. Each of the wireless units 2-1 to 2-N is installed and operated at different locations away from the control unit 1.

  In FIG. 1, a plurality of radio units 2-1 to 2-N include an antenna, a power amplifier, and a frequency converter, and are connected to the control unit 1. Each of the radio units 2-1 to 2-N receives a radio signal coming from a radio terminal through an antenna. The signals received by the radio units 2-1 to 2-N are transmitted to the control unit 1, the received power (for example, RSSI: Received Signal Strength Indicator) is measured by the power control unit 11, and the received power information is obtained. Retained. The power control unit 11 and the movement estimation unit 12 are connected in the control unit 1, and receive power information is exchanged. The movement estimation unit 12 estimates the movement state of the terminal based on the received power information.

  Hereinafter, a method for estimating the movement state of the terminal will be described according to each embodiment.

Example 1
FIG. 2 is a diagram illustrating terminal movement estimation processing according to the first embodiment. In FIG. 2, in the state where one terminal A is communicating with one wireless unit 2-1, when the terminal A moves a distance l from a point a to a point b, The change of the received power Pr and the movement status are shown.

  FIG. 3 shows a flowchart of the movement estimation process in the first embodiment. In step S <b> 1, the base station apparatus measures the received power Pr of the received signal from the terminal A by the power control unit 11 at intervals of the period T, and transmits the obtained received power information to the movement estimating unit 12. The movement estimation unit 12 calculates a change amount α (= Pr_a−Pr_b) of the received power transmitted from the power control unit 11 per period T. In steps S2 and S3, the movement estimation unit 12 determines that the terminal A is moving away from the radio unit 2-1 when the received power change amount is α ≧ 0 (step S3a), and when α <0, the terminal It is determined that A is approaching the wireless unit 2-1 (step S3b). By this determination process, the moving direction of the terminal is estimated.

  Further, in step S4, the moving speed of the terminal is determined from the absolute value of the received power change amount α when the speed is | α | <X dB (steps S4a and S4d), and when XdB <| α | , S4e) and YdB <| α |, the estimation is performed separately for high speed (steps S4c, S4f). With the above processing, the movement estimation unit 12 estimates the movement state of the terminal such as “the terminal is“ high speed ”and“ has moved away ”from the radio unit 2-1” (step S5).

  Here, the period T for measuring the received power and the condition for case classification such as low speed, medium speed, and high speed can be set in a form suitable for each wireless communication system. Moreover, the method of Example 1 is applicable not only to a separation type base station but also to a base station apparatus in which the control unit 1 and the radio unit 2-1 are integrated.

(Example 2)
FIG. 4 is a diagram illustrating terminal movement estimation processing according to the second embodiment. FIG. 4 shows a state in which one terminal A is communicating with the wireless unit 2-1, and the wireless unit 2-1 and the wireless unit when the terminal A moves a distance l from the point a to the point b. The change of the received power Pr and the movement state in 2-2 are shown.

  FIG. 5 shows a flowchart of the movement estimation method in the second embodiment. In step S <b> 11, the base station apparatus measures the received power of the received signals from the terminals A and B at the power control unit 11 at intervals of the period T, and transmits the measured received power information to the movement estimation unit 12. The movement estimation unit 12 calculates the change amounts α (= Pr_a 1 −Pr_b 1) and β (= Pr_a 2 −Pr_b 2) per cycle T of the received power transmitted from the power control unit 11.

  If the received power change amount is α> 0 and β <0 in steps S12 and S13, it is determined that the terminal A is moving from the radio unit 2-1 toward the radio unit 2-2 (step S13a). When <0 and β> 0, it is determined that the terminal A is moving from the radio unit 2-2 toward the radio unit 2-1 (step S13b). If α> 0 and β> 0, the absolute values are compared. If | α | ≧ | β |, the terminal A is moving from the radio unit 2-2 toward the radio unit 2-1. If it is determined (step S13b) and | α | <| β |, it is determined that the terminal A is moving from the wireless unit 2-1 toward the wireless unit 2-2 (step S13a). Similarly, when α <0 and β <0, the absolute values are compared. If | α | ≧ | β |, the terminal A moves from the radio unit 2-1 toward the radio unit 2-2. If | α | <| β |, it is determined that the terminal A is moving from the radio unit 2-2 toward the radio unit 2-1 (step S13b). By this process, the moving direction of the terminal is estimated.

  Thereafter, in step S14, the movement estimation unit 12 compares the absolute values of the received power change amounts α and β. If | α | ≧ | β |, the movement estimation unit 12 compares the received power change amount α with the wireless unit 2-1. The moving speed is estimated (step S15). If | α | <| β |, the moving speed is estimated based on the received power change amount β of the radio unit 2-2 (step S16). The movement speed estimation process in step S17 is performed by the same method as the movement speed estimation process (step S4) in FIG. With the above processing, the movement estimation unit 12 estimates the movement state of the terminal such as “the terminal is“ high speed ”and“ moving from the radio unit 2-1 toward the radio unit 2-2 ”” ( Step S18).

  Here, the period T for measuring the received power and the condition for case classification such as low speed, medium speed, and high speed can be set in a form suitable for each wireless communication system. 4 and 5 show two examples of the radio unit, but the present invention can also be applied to a configuration having two or more radio units.

  As described above, according to the present embodiment, it is possible to easily estimate the movement state of the terminal based on the received power measured by the base station apparatus. Further, in the separated base station, it is possible to identify the movement state with higher accuracy than in the integrated base station. The information on the movement state estimated in this way is an effective index for selecting a terminal when performing macro diversity or handover. Thereby, it is possible to effectively use radio resources without imposing a load on the base station system.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Control part, 11 ... Power control part, 12 ... Movement estimation part, 2-1 to 2-N ... Radio | wireless part.

Claims (3)

Are arranged at different positions, a plurality of radio units for receiving radio terminal or found no line signal,
A received power measuring section that measures reception power of the radio signal the wireless unit receives,
A change amount calculating means for calculating a change amount of the received power measured by the received power measuring means in a time unit;
A moving direction estimating means for estimating a moving direction of the wireless terminal based on a positive and negative sign and an absolute value of the change amount for each wireless unit ;
A base station apparatus comprising: a moving speed estimating unit that estimates a moving speed of the wireless terminal based on an absolute value of the change amount. Are arranged at different positions, a method used in a base station apparatus having a plurality of radio unit for receiving a wireless terminal or found no line signal,
A received power measuring step of measuring the received power of the radio signal the wireless unit receives,
A change amount calculating step for calculating a change amount of the received power measured in the received power measurement step in a time unit;
A moving direction estimation step of estimating a moving direction of the wireless terminal based on a positive and negative sign and an absolute value of the change amount for each wireless unit ;
And a moving speed estimating step of estimating a moving speed of the wireless terminal based on an absolute value of the change amount. Are arranged at different positions, a program used for a base station apparatus having a plurality of radio unit for receiving a wireless terminal or found no line signal,
A reception power measurement process of measuring the received power of the radio signal the wireless unit receives,
A change amount calculation process for calculating a change amount of the received power measured in the received power measurement process in a time unit;
A moving direction estimation process for estimating a moving direction of the wireless terminal based on a positive and negative sign and an absolute value of the change amount for each wireless unit ;
A terminal movement estimation program for causing a computer to execute a movement speed estimation process for estimating a movement speed of the wireless terminal based on an absolute value of the change amount.

Images