CN1312869C - Method for measuring radio communication system propagation delay - Google Patents

Abstract

The present invention discloses a method for measuring the propagation delay of a radio communication system, which is applied to a communication system. The communication system at least is composed of a base station and a terminal. The present invention has the following steps: a wireless propagation loss mould of the base station is obtained by the estimation or a fitting way; the base station sends and broadcasts the propagation loss mould to terminals which are covered by the base station; a wireless propagation loss mould of the base station is obtained by the terminals which are demodulated; the terminals measure and receive the power, and compute the distance between the terminals and the base station and the propagation delay of air signals according to the received power and the propagation loss mould of the base station. The method increases the accuracy of the propagation delay time which is computed by the terminals so as to increase the covering radius of the base station by a before-hand emission way and exactly position the terminals.

Description

A kind of method of measuring the wireless communication system propagation delay

Technical field

The present invention relates to wireless communication system, especially measure the method that radio transmission postpones in the mobile communication system.

Background technology

Mobile communication system structure involved in the present invention comprises a CN (core net) as shown in Figure 1 at least, a RNC (wireless access net controller), a Node B (Node B), a just general said base station and a UE (terminal).

Between Node B and UE, have propagation delay, and this propagation delay increases and increases along with the distance of UE and Node B.Owing to have this propagation delay, when the signal of UE arrives Node B, just produced 2 times propagation delay.

The disclosed name of Patent Office of the People's Republic of China is called " equipment and the method for measuring propagation delay in the arrowband TDD CDMA mobile communication system ", and publication number is 1404668 patent, discloses a kind of propagation delay estimation approach commonly used.This method is that UE compares with the received power of UE according to the transmitting power of Node B, estimates the delay that comes and goes.Because the different residing wireless environment difference of Node B, under wireless environments such as city, suburb, rural area, the decay of Node B signal is along with the pace of change of distance is also inequality, the speed of city decay is fast, and the rural area decay is slow, so the method for this patent only compares estimated delay according to the transmitting power of Node B and the received power of UE, is not accurate enough, need allow travelling carriage adopt different methods of estimation according to different wireless environments.

Summary of the invention

The purpose of this invention is to provide a kind of method of measuring the wireless communication system propagation delay, solved UE the different radio in-the-environment propagation delay is estimated inaccurate technical problem, improved the accuracy that propagation delay is estimated.

Communication system involved in the present invention is made up of a Node B and a UE at least, and described Node B comprises a transmitter and a receiver at least, and described transmitting comprises an overhead channel at least; Described overhead channel is finished the transmission of public information; Described UE comprises a transmitter and a receiver at least, described UE obtains the state of described communication system by the overhead channel of demodulating system, as propagation characteristic of Node B wireless environment of living in etc., described UE obtains the state of current system by the overhead channel of demodulating system.

The method of measurement wireless system propagation delay of the present invention comprises the steps:

Step 1 estimation or match obtain the radio transmission loss model of base station;

The terminal broadcast transmission propagation loss model of step 2 base station in its area of coverage;

Step 3 terminal obtains the radio transmission loss model of base station by demodulation;

The power that the measurement of step 4 terminal receives;

Step 5 terminal is calculated the distance of itself and base station according to the propagation loss model of received power, base station;

Step 6 terminal is calculated the propagation delay of aerial signal.

In the described step 1, can be directly to utilize existing model, also can be that the user tests again with match and obtains model.

In the described step 2, described base station by broadcast synchronization channel or Common Control Channel the terminal broadcast transmission of propagation loss model in cell footprint.

Adopt the method for the invention, compared with prior art,, improved the accuracy in propagation delay time, thereby can further increase the covering radius of NodeB by emission in advance by considering the difference of different Node B environment of living in, or accurate positioning UE etc.

Description of drawings

Fig. 1 is a prior art mobile communication system structure chart involved in the present invention;

Fig. 2 is the inventive method flow chart;

Fig. 3 is the structure of time slot schematic diagram of the uplink and downlink link of prior art TD-SCDMA system;

Fig. 4 is a prior art TD-SCDMA system propagation delay sequential schematic diagram.

Embodiment

Specify embodiments of the invention below in conjunction with accompanying drawing.

Fig. 1 is the said common mobile communication system figure of the present invention, and radio network controller (RNC) is worked under the control of core net CN, and Node B then communicates by letter with UE under the control of RNC.Because different its residing wireless environment differences of Node B, its propagation model are also different, that is to say under the identical distance that the signal power of the Node B that UE receives is difference with seeing the residing wireless environment of Node B.

Fig. 2 is the inventive method flow chart, and concrete steps are as follows:

Step 1 estimation or match obtain the radio transmission loss model of Node B.

Operator at first will carry out the network planning when mobile communications network of design, determine the position of each base station transmit antennas.In case determined the position of base station transmit antennas, just can estimate the radio transmission model of this base station.The method of this estimation is a lot, is mature technique already.Can directly use existing model, such as famous Hata model, be exactly on the result that Okumura measures, and carries out match and obtained the propagation model of 800MHz electric wave under landform such as city, suburb and rural area.But directly use this Hata model, for a concrete base station, accurate not enough.So in order to improve accuracy, the user can also self testing and match.

The method of user's self testing is to use the transmitter of a constant power to send the test signal of standard, utilize field intensity meter to measure the signal power of the each point in the base station overlay area then, the power of representing with a logarithm and the relation of distance are carried out linear match again, obtain one and belong to the distinctive propagation model of this website.If the transmitting power of transmitter is Pt, use omnidirectional antenna, establishing the power that field intensity meter receives on distance r is Pr, has so:

$\mathrm{Pr}=A\frac{\mathrm{Pt}}{r^{\mathrm{\μ}}}---\left(1\right)$

Here A is a constant, and μ is the exponential factor of delegated path loss along with variable in distance,

The expression of taking the logarithm of (1) formula, have:

10logPr＝10logPt+10logA-10μlogr (2)

If power represents so just have with logarithm:

P _r＝P _t+α-10μlogr (3)

Make r=1, use p _R1Represent 1 kilometer signal power that place's travelling carriage receives, have:

P _r1＝p _t+α (4)

(4) formula substitution (3) formula, obtain:

P _r＝P _r1-10μlogr(5)

Wherein, the concrete expression travelling carriage received power signal of μ is along with the exponential depth of variable in distance.

From (5) formula as can be seen, the received power of travelling carriage and p _R1, μ and travelling carriage be relevant apart from r with the base station.

Utilize and measure, can obtain one group of p _R1, μ is along with the value that r changes, and can match obtain μ and p by the principle of least square like this _R1, just obtained with μ and p _R1The propagation model (5) of the Node B of expression.

Introduce the most brief propagation loss representation formula (5) though it should be noted that this paper, also can adopt the parameter and the formula of other expressions Node B propagation loss model.

Step 2 will be μ and p _R1The propagation model (5) of the base station of expression sends to travelling carriage, and concrete realization depends on different communication systems, and generally broadcast channel or the Common Control Channel by the base station sends.

Step 3, travelling carriage is through demodulation, μ that comprises in the receiving common control channels and p _R1, step 4 then, measure the received power p of self _r, step 5 utilizes (5) to obtain r,

$r={10}^{\frac{P_{r1}-P_r}{10\mathrm{\μ}}}---\left(6\right)$

(6) unit of r is a kilometer in.If the light velocity is c, then have

r＝cΔt (7)

Step 6 according to (6) and (7), obtains travelling carriage and to the propagation path delay of base station is:

$\mathrm{\Δt}=\frac{{10}^{\frac{P_{r1}-P_r}{10\mathrm{\μ}}}}{C}---\left(8\right)$

Know Δ t, travelling carriage just can shift to an earlier date 2 Δ t emission, eliminates because the mobile station signal that propagation delay causes may drop on the situation outside the search window.

Embodiment one:

Adopt the mobile communication system of TDD (Time Division Duplex) mode as the duplex communication mode, as TD-SCDMA, PHS (Personal Handset System) etc., down link and up link are worked on same frequency range, but use this frequency range according to timesharing between certain mode up-downgoing.Fig. 3 is the pattern that timesharing is used between the subframe up-downgoing of TD-SCDMA system, and subframe is the time interval of a burst transfer minimum.Time slot 0 generally is a common signal channel, and descending pilot frequency is that Node B sends to UE, to allow UE according to the descending pilot frequency and the system synchronization that receive.Boundary belt GP is the protection period, and is overlapping to prevent ascending pilot frequency and descending pilot frequency.Time slot 1--time slot 6 is user's time slots, is used for transporting speech or data service.When switching between the system transmissions generation uplink and downlink, be called transfer point, a subframe 2 conversions between the uplink and downlink are arranged, so 2 transfer points are arranged.

System generally sends broadcast on a common signal channel, the current configuring condition of illustrative system, as TD-SCDMA on the basic Common Control Channel P-CCPCH and auxiliary Common Control Channel S-CCPCH of TSO, the transmitting system configuration information.In the TD-SCDMA system, travelling carriage receiving downlink pilot time slot channel, acquisition is synchronous with system, sends uplink synchronizing signals to Node B then in uplink pilot time slot, attempts connecting system.Node B will search for the uplink synchronizing signals that UE sends in boundary belt GP and ascending pilot frequency.

As seen from Figure 4, because there are transmission delay in Node B and UE, indicate with Td among the figure, if not adding any processing, UE do not compensate this transmission delay, the reference time of the moment that receives Node B signal as oneself, as the zero-time of back emitted signal, the time of UE signal arrival Node B is always met together and postpones 2Td so.Node B generally detects the up access signal that UE sends in the time interval of " boundary belt GP+ ascending pilot frequency ", if 2Td＞ascending pilot frequency has so just dropped on outside the detection window of Node B, can not be detected by Node B.This has also just limited the coverage of Node B.

In order to overcome the deficiencies in the prior art, we wish that UE can estimate Td, UE just can shift to an earlier date the 2Td emission so, and the UE signal has just just in time dropped on the original position of ascending pilot frequency like this, remedies because the signal that aerial delay may cause can not be detected situation by Node B.The specific implementation step is as follows:

The first step in the network planning of TD-SCDMA system, is utilized existing propagation model, perhaps through measuring, obtains the shape of each Node B such as the propagation model of formula (5).It should be noted that for measure accurately, use the power of downlink pilot frequency channel here because the power of descending pilot frequency launches continuously, and power invariability, can make things convenient for UE to measure like this;

In second step,, arrive each UE in the Node B overlay area by Common Control Channel CCCH broadcast transmission the propagation model parameter prl and the u that obtain;

In the 3rd step, UE demodulation CCCH channel obtains prl and u, thereby obtains the radio transmission loss model of Node B;

In the 4th step, UE measures the power of downlink pilot frequency channel, obtains pr:

The 5th step, UE according to formula (6) calculate itself and Node B apart from r;

In the 6th step, UE calculates the propagation delay Td of itself and Node B according to formula (8);

At last, utilize above-mentioned steps obtain propagation delay Td, UE shifts to an earlier date 2Td emission, finally eliminates the influence of propagation delay.

Embodiment two:

In the IS95A system, often pass through the access signal of a fixing window search travelling carriage.Sometimes, because travelling carriage is too far away apart from the base station, it inserts signal and has dropped on outside the search window of base station, so just can not be found that causing can't connecting system by the base station.

By in the synchronizing channel of base station, launching the propagation model of the shape of current base station pilot channel as (5), travelling carriage is by the power of measurement pilot, calculate distance and propagation delay with the base station, by certain hour emission in advance, can allow remote mobile station signal drop within the search window of base station.Performing step is as follows:

The first step in the network planning of IS95A system, is utilized existing propagation model, perhaps through measuring, obtains the shape of each Node B such as the propagation model of formula (5).It is accurate for what measure to it should be noted that, uses the power of downlink pilot frequency channel here, constant because downlink pilot frequency channel power keeps, and is higher than general Traffic Channel, can make things convenient for UE to measure like this;

In second step,, arrive each UE in the Node B overlay area by the synchronizing channel broadcast transmission the propagation model parameter prl and the u that obtain;

In the 3rd step, UE demodulation synchronizing channel obtains prl and u, thereby obtains the radio transmission loss model of Node B;

In the 4th step, UE measures the power of downlink pilot frequency channel, obtains pr;

The 5th step, UE according to formula (6) calculate itself and Node B apart from r;

In the 6th step, UE calculates the propagation delay Td of itself and Node B according to formula (8);

At last, utilize above-mentioned steps obtain propagation delay Td, UE shifts to an earlier date 2Td emission, solves air propagation delay and causes the access signal of UE to drop on problem outside the Node B search window, eliminates the influence of propagation delay.

Claims (2)

1, a kind of method of measuring the wireless communication system propagation delay, related communication system are made up of a base station and a terminal at least, it is characterized in that, comprise the steps:

Step 1 estimation or match obtain the radio transmission loss model of base station;

Described radio transmission loss model is: p _r=p _R1-10 μ logr

Wherein, the power that field intensity meter receives on distance r is Pr, and μ is the exponential factor of delegated path loss along with variable in distance, p _R1The signal power that expression r=1 kilometer place travelling carriage receives;

The terminal broadcast transmission propagation loss model of step 2 base station in its area of coverage;

Step 3 terminal obtains the radio transmission loss model of base station by demodulation;

The power that the measurement of step 4 terminal receives;

Step 5 terminal is calculated the distance of itself and base station according to the propagation loss model of received power, base station;

Step 6 terminal is calculated the propagation delay of aerial signal.

2, method according to claim 1 is characterized in that, in the described step 2, described base station by broadcast synchronization channel or Common Control Channel the terminal broadcast transmission of propagation loss model in cell footprint.

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