JP4074197B2 - Receiver for mobile communication system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a receiver for a mobile communication system that performs predetermined processing including demodulation processing on received signals received by a plurality of antennas having different communication areas, and more particularly to a technique for detecting the position of a mobile communication terminal. .
[0002]
[Prior art]
Conventionally, the following techniques are already known as techniques for detecting the position of a mobile communication terminal.
[1] Position detection by GPS (Global Positioning System): By providing a GPS receiver in the mobile communication terminal, the position of the mobile communication terminal can be detected based on signals received from a plurality of GPS satellites (for example, (See Patent Document 1).
[2] Location detection based on base station ID: The base station ID included in the communication signal can detect the location where the mobile communication terminal exists in units of base stations.
[0003]
[Patent Document 1]
JP 2001-305210 A [Patent Document 2]
JP-A-5-268128 [0004]
[Problems to be solved by the invention]
However, the above [1] has a problem that position detection cannot be performed in an area where a signal from a GPS satellite cannot be received, such as in a building or an underground mall. As for [2] above, the radius of the communication area of one base station may be set as wide as, for example, about 1 to 10 kilometers. In such a case, the desired position detection accuracy cannot be ensured. There is.
[0005]
[Means for Solving the Problems]
A receiving apparatus according to the present invention is a receiving apparatus that performs predetermined processing including demodulation processing on reception signals received by a plurality of antennas having different communication areas, and each receiving signal received by each antenna has a different delay amount. A delay element that is delayed by the delay element, a synthesis processing unit that synthesizes a plurality of reception signals delayed by the delay element, a correlation value acquisition unit that acquires a correlation value between the synthesized signal and the known signal, and the acquired correlation A terminal position detection unit that identifies a communication area where a signal transmission terminal exists based on a peak timing of the value, and the delay amount of the delay element is different for each antenna in a time zone in which the peak of the correlation value appears The terminal position detection unit identifies a communication area where a signal transmission terminal exists from the time zone in which the peak appears.
[0006]
In this way, the position of the mobile communication terminal can be detected in units of antenna communication areas, and the position detection accuracy can be improved as compared with a conventional system that performs position detection in units of base stations. Further, the position of the mobile communication terminal can be detected even in a building or an underground mall where GPS signals do not reach.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of a mobile communication system 10 including a transmission / reception device 12 according to the present embodiment. FIG. 2 is a signal processing mechanism of a reception unit in a base station device (BTS) 20 included in the transmission / reception device 12. FIG. 3 is a diagram illustrating an example of a change in a signal waveform inside the transmission / reception device 12, and FIG. 4 is a diagram illustrating an example of a sequence relating to position detection of the mobile terminal 14.
[0008]
In the mobile communication system 10 of FIG. 1, the transmission / reception device 12 has jurisdiction over a plurality of communication areas Ai (i = 0, 1,..., N−1; n is an integer of 2 or more). Each mobile terminal 14 in the communication area Ai can exchange signals with another terminal (not shown) as a communication partner via the transmission / reception device 12 and the communication line network 16. . The communication area Ai is defined as a range in which the mobile terminal 14 can transmit and receive a wireless communication signal (uplink signal / downlink signal) with a predetermined power between each antenna 18-i. Further, the mobile communication system 10 can be configured as a mobile phone communication system of, for example, a CDMA (Code Division Multiple Access) system.
[0009]
The transmission / reception apparatus 12 according to the present embodiment broadly includes a base station apparatus (BTS) 20 and a relay mechanism 22. The relay mechanism 22 is interposed between the BTS 20 and the antenna 18-i, and repeater slave unit 26-i (i = 0, 1,... Corresponding to one repeater master unit 24 and each antenna 18-i. , N-1), and a plurality of delay elements 28-i (i = 0, 1,..., N-1). The repeater base unit 24 has a function of combining / distributing signals. When receiving, the repeater master 24 combines signals (received signals) from the respective antennas 18-i (that is, generates a combined signal), while transmitting signals. The signal from the BTS 20 is distributed to each antenna 18-i. That is, the repeater base unit 24 corresponds to a synthesis processing unit according to the present invention. The repeater master unit 24 and the repeater slave unit 26-i can be provided with an optical / electrical signal conversion function. In this case, communication between the repeater master unit 24 and the repeater slave unit 26-i is performed using an optical signal. Done.
[0010]
The delay element 28-i delays the received signal received by each of the plurality of antennas 18-i by different delay amounts. The setting of the delay amount by each delay element 28-i will be described later. When optical communication is performed between the repeater master unit 24 and the repeater slave unit 26-i, the delay element 28-i is, for example, the optical cable itself between the repeater master unit 24 and the repeater slave unit 26-i. Can be configured. That is, a desired delay amount and delay difference can be given by adjusting the length of each cable between the repeater master unit 24 and the repeater slave unit 26-i. However, this is merely an example, and it may be delayed at the stage of the electric signal, or a predetermined element or circuit may be used as the delay element 28-i. Means for delaying at the stage of the electrical signal include a coaxial cable (for example, a leaky coaxial cable), a SAW delay element, and the like.
[0011]
As shown in FIG. 2, the reception processing unit (RX) 30 performs amplification, filtering, frequency conversion processing, and the like, and generates I of complex baseband signals orthogonal to each other from the synthesized signal generated by the repeater master unit 24. Extract signal and Q signal. The correlator 32 acquires a complex correlation value based on the I signal, the Q signal, and the known signal. The searcher 34 acquires the timing (or phase) at which the complex correlation value peaks. Note that FIG. 2 shows only the components related to position detection, and the BTS 20 actually includes other components. The reception processing unit 30, the correlator 32, and the searcher 34 themselves do not require significant changes to the known device configuration, and are also used for normal signal processing (that is, signal processing for various services). .
[0012]
Now, from the timing when the complex correlation value acquired by the searcher 34 becomes a peak, the position detection unit 36 identifies the communication area Ai where the mobile terminal 14 exists. Here, the principle will be described with reference to FIG. 3 shows waveforms of received signals received by three antennas (18-0, 18-1, 18-2) corresponding to different communication areas (A0, A1, A2). It is a schematic diagram which shows how it changes with elements. 3A shows the waveforms (R ₀ , R ₁ , R ₂ ) of the received signals before being input to the delay elements (28-0, 28-1, 28-2), and FIG. The waveforms (Rl ₀ , Rl ₁ , Rl ₂ ) of the received signals after being output from the delay elements (28-0, 28-1, 28-2), FIG. 3 (c) are shown in FIG. FIG. 3D shows a waveform (Cz) of the correlation value acquired by the correlator 32. FIG. Note that (a) to (d) in FIG. 3 are drawn with the same reference timing (that is, the left end of the horizontal axis), but the actual times of these reference timings are different in each figure (each process). Please note that. Note that FIG. 3C shows only a portion based on the waveform shown in FIG. 3B and is different from the actual waveform.
[0013]
As shown in FIGS. 3A and 3B, delay amounts (τ ₀ , τ ₁ , τ ₂ ) with respect to received signals received by the plurality of antennas (18-0, 18-1, 18-2), respectively. ) Are set to different values. In the example of FIG. 3, the delay amount tau ₀ for the received signal R _0, so that the delay amounts tau ₂ for delay tau _1, and the received signal R ₂ for a received signal R ₁ becomes τ ₀ <τ ₁ <τ ₂ Is set. Here, as described above, when adjusting the delay amount by the length of the cable, the received signal the length of the cable through the R ₀ L _0, the received signal R ₁ L ₁ the length of the cable through the, when the length of cable through which the received signal R ₂ a and L _2, may be set to _{L 0 <L 1 <L 2} . The delayed received signals (Rl ₀ , Rl ₁ , Rl ₂ ) are combined into one signal (combined signal Rt) by the repeater master unit 24 (FIG. 3 (c)) and correlated from the combined signal Rt. The correlation value Cz is acquired in the device 32 (FIG. 3 (d)).
[0014]
It should be noted here that the correlation values corresponding to the received signals received by the antennas (18-0, 18-1, 18-2) do not overlap each other as shown in FIG. Appearing in different time zones (T ₀ , T ₁ , T ₂ ). Those skilled in the art can easily understand that such correlation values can be separated by appropriately setting the delay amounts (τ ₀ , τ ₁ , τ ₂ ). Specifically, when the maximum radius of the communication area Ai is 30 [m (meter)] and the signal propagation speed is 3 × 10 ⁸ [m / s], the maximum delay time difference Tlmax of the mobile terminal 14 in the communication area Ai. Tlmax = 30 / (3 × 10 ⁸ ) × 2 = 200 [ns] (round trip delay). Further, the resolution of path separation in the BTS 20 is considered to be about one chip time length (for example, 260 [ns], which is Tchip). Therefore, if each delay amount (τ ₀ , τ ₁ , τ ₂ ) is set stepwise in steps larger than the sum of Tlmax and Tchip, for example, 500 [ns] (= 0.5 [μs]) (ie, In the example of FIG. 3, τ ₀ = 0.5 [μs], τ ₁ = 1 [μs], and τ ₂ = 1.5 [μs] are set), and the correlation values corresponding to the antennas 18-i are separated on the time axis. It becomes possible to do. In that case, the time from the reference timing of each time zone (T ₀ , T ₁ , T ₂ ) is as follows: time zone T ₀ : 0.5 to 1 [μs], time zone T ₁ : 1 to 1.5 [μs], time zone T ₂ : 1.5 to 2 [μs].
[0015]
It is easy to specify the communication area Ai to which the mobile terminal 14 belongs from the peak of the correlation value Cz separated in time. That is, the position detection unit 36 is within a predetermined time range, that is, within a predetermined time from the reference timing of the received signal to be processed (in the example of FIG. 3D, from the reference timing to the end of the time zone T ₂ ). A peak timing tp at which the correlation value Cz is maximized is detected, and further, a time zone in which the timing tp is included is detected. 3 For (d), the peak timing of the correlation value Cz is maximized is in the time zone T _1. Then, the position detection unit 36 refers to information indicating the correspondence relationship between the time zone stored in the storage unit 38 and the communication area Ai, and performs communication corresponding to the time zone including the peak timing at which the correlation value Cz is maximum. Area Ai is acquired. In the case of FIG. 3, the time zone T ₀ and the communication area A 0 (identification code), the time zone T ₁ and the communication area A 1, and the time zone T ₂ and the communication area A 2 are stored in the storage unit 38 in association with each other. and it has a position detector 36, as a communication area Ai Field of the mobile terminal 14 obtains the communication area A1 corresponding to the time zone T _1. That is, the identification of the communication area Ai according to the present embodiment is based on the idea that the mobile terminal 14 exists in the communication area Ai corresponding to the antenna 18-i that has received the received signal having the highest correlation value with the known signal. ing.
[0016]
Furthermore, the position detection unit 36 determines the delay time δt _i (i = _i ) from the reference timing of the peak timing of each correlation value Cz (here, the timing at which the correlation value Cz peaks when the transmission / reception signal propagation delay = 0). By acquiring (0, 1,..., N-1), the position of the mobile terminal 14 can be acquired with higher accuracy. That is, since the delay time δt _i is proportional to the distance between the mobile terminal 14 and the antenna 18-i, if the signal propagation speed is v (≈3 × 10 ⁸ [m / s]), the mobile terminal 14 moves from each antenna 18-i. The distance l _i (i = 0,1,..., N−1) to the terminal 14 is set as l _i = 0.5 × v × δt _i considering that δt _i is observed as a round-trip propagation delay. Can be acquired. Therefore, for example, a circle having a radius l _i centering on the location of each corresponding antenna 18-i is acquired from the larger one of the plurality of correlation values Cz, and position coordinates that are the intersections of the two circles are obtained. It can be regarded as the location of the mobile terminal 14. In addition, for example, the circle is acquired for each of three or more antennas 18-i (in this case, it is preferable to select a predetermined number from the one having a larger correlation value Cz), and a plurality of position coordinates serving as intersections of the circles are obtained. The location of the mobile terminal 14 may be acquired based on (for example, the position where the sum of the distances to the plurality of position coordinates is minimized). In these cases, information indicating the position coordinates (for example, latitude and longitude) of each antenna 18-i is further stored in the storage unit 38, and the position detection unit 36 determines the position of the mobile terminal 14 based on the information. What is necessary is just to acquire a coordinate.
[0017]
Information (eg, communication area identification code or latitude / longitude) indicating the communication area Ai or the position coordinates where the mobile terminal 14 exists thus obtained is included in an appropriate position of a predetermined uplink signal, for example, from the BTS 20 to the mobile terminal. 14 is transmitted to a higher-level terminal location management server (not shown) that knows the location of 14. More detailed location information of each mobile terminal 14 stored in the terminal location management server is effectively used in various services or controls.
[0018]
By the way, in the conventional general mobile communication system, the location information is not normally updated unless the mobile terminal 14 passes the boundary of the location registration area composed of a plurality of base station areas. On the other hand, in the mobile communication system 10 according to the present embodiment, a control signal for performing position detection is transmitted from the BTS 20 to the mobile terminal 14, and a position detection signal is transmitted to the mobile terminal 14 as a response to the control signal. In order to transmit, the above-described position detection can be performed as necessary at a desired timing. A specific example will be described with reference to FIG. 4. When the BTS 20 receives a location information request from the host device 40 (for example, the above-described terminal location management server) (step S 10), the BTS 20 sends a location detection signal to the mobile terminal 14. A control signal (downstream signal) requesting the transmission of is transmitted (step S11). Then, the mobile terminal 14 transmits a position detection signal (uplink signal) as a response (step S12). Here, the position detection signal may be a predetermined signal including the identification ID of the mobile terminal 14, for example. And BTS20 detects the communication area Ai to which the mobile terminal 14 belongs by the method mentioned above (step S13), and transmits the positional notification information containing the detection result to the high-order apparatus 40 (step S14). By adopting such a polling method, the mobile communication system 10 according to the present embodiment can acquire the position of the mobile terminal 14 at a desired timing.
[0019]
By the way, Patent Document 2 discloses a system in which delay elements having different delay amounts are added to a plurality of antennas connected to a base station apparatus. However, the delay element used in the system of Patent Document 2 is not used for the purpose of detecting the position of the mobile terminal, but to achieve a completely different purpose, that is, to construct an artificial frequency selective fading environment. However, it is used to reduce short-period fading by promoting the path diversity function. This Patent Document 2 does not suggest any “position detection of a mobile terminal” as an object of the present invention, nor does it disclose any device configuration or procedure essential for position detection. That is, the description in Patent Document 2 cannot be a motivation for the technical idea characteristic of the present invention.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a mobile communication system and a transmission / reception device according to an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a main part of the base station apparatus according to the embodiment of the present invention.
FIG. 3 is a diagram illustrating an example of a change in a time waveform of a reception signal in the transmission / reception apparatus according to the embodiment of the present invention.
FIG. 4 is a sequence diagram regarding position detection of a mobile terminal in the mobile communication system according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Mobile communication system, 12 Transmission / reception apparatus, 14 Mobile terminal, 16 Communication line network, 18-i (i = 0, 1, 2, ..., n-1) Antenna, 20 Base station apparatus (BTS), 22 Relay Mechanism, 24 repeater master unit, 26-i (i = 0, 1, 2,..., N-1) Repeater slave unit, 28-i (i = 0, 1, 2,..., N-1) ) Delay element, 30 reception processing unit, 32 correlator, 34 searcher, 36 position detection unit, 38 storage unit.

Claims (3)

A receiving device that performs predetermined processing including demodulation processing on reception signals received by a plurality of antennas having different communication areas,
A delay element that delays a received signal received by each antenna by a different delay amount;
A synthesis processing unit that synthesizes a plurality of received signals delayed by the delay element;
A correlation value acquisition unit for acquiring a correlation value between the synthesized signal and the known signal;
A terminal position detection unit that identifies a communication area where a signal transmission terminal exists based on the peak timing of the acquired correlation value;
With
The delay amount of the delay element is set so that the time zone in which the peak of the correlation value appears is different for each antenna,
The receiving apparatus according to claim 1, wherein the terminal position detecting unit specifies a communication area where a signal transmitting terminal exists from a time zone in which the peak appears. A signal processing mechanism for a receiving device according to claim 1,
The correlation value acquisition unit for acquiring a correlation value between the synthesized signal and the known signal;
The terminal position detection unit for identifying a communication area where a signal transmission terminal exists based on the peak timing of the acquired correlation value;
A signal processing mechanism comprising: A relay mechanism for a receiving device according to claim 1,
The delay element for delaying the received signal received by each antenna by a different delay amount;
The synthesis processing unit for synthesizing a plurality of received signals delayed by the delay element;
A relay mechanism comprising:

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