CN103327525A - PUCCH (physical uplink control channel)-based small cell discovering method - Google Patents

Abstract

The invention provides a PUCCH (physical uplink control channel)-based small cell discovering method which comprises the following steps that: macro eNB issues PUCCH parameters to UE (user equipment) and all small cells in a coverage area, and the small cells store the PUCCH parameters; the UE transmits a PUCCH according to the PUCCH parameters, and each small cell in the area covered by the macro eNB detects a CQI (channel quality indicator) in the PUCCH and computes sinr; the small cells compare a sinr value with a threshold value T, and transmit a nRNTI (n radio network temporary identity) of the UE to the macro eNB when the sinr is more than or equal to T; the macro eNB issues measurement configuration to the corresponding UE of the nRNTI, and the UE measures according to the measurement configuration and reports a measurement result; the macro eNB carries out corresponding operation according to the measurement result.

Description

Small cell discover method based on PUCCH

Technical field

The technical field that the present invention relates to is wireless communication system, and more specifically, what the present invention relates to is the method that small cell finds among the R12 of 3GPP LTE-A.

Background technology

Current 3GPP(the 3rd generation partner program) normal structure RAN2 group is for the LTE(Long Term Evolution) the Rel12 version, carrying out a research project: small cell(Microcell).This project strengthens macrocell edges cover and the demand that satisfies a large amount of indoor data services mainly in order to alleviate the huge flow pressure of current grand network.Through research, the several deployment scenario of small cell have been proposed, the UE(user terminal) how to find that the small cell industry affair offload that goes forward side by side is the problem that needs solve.

Small cell can effectively shift the flow of grand network, helps the flow unloading, and covering or the raising capacity of expansion macrocellular, so has proposed the research to small cell on the standard.Small cell scene has: whether grand covering is arranged, with grand station whether with frequently, the indoor and outdoor focus disposes, desirable or imperfect back haul link and several scenes such as sparse or intensive deployment.

In the LTE system, descending scheduling and uplink scheduling all are in the eNB(base station) side carries out, eNB needs channel condition information to dispatch, by the PDCCH(Physical Downlink Control Channel) inform UE.Up is to carry out channel estimating according to uplink reference signals to obtain the up channel state information, and descending then is to know downlink channel condition information by the UCI feedback information.

The PUCCH(Physical Uplink Control Channel) information of upper carrying has SR, ACK/NACK and CQI/PMI, and RI, corresponding to the format1 of PUCCH, format1a/1b and format2/2a/2b, related symbol is this area expression commonly used, can be referring to pertinent literature.Wherein be the indication of periodic report CQI(channel quality among the PUCCH format2/2a/2b).By L3(layer 3) parameter I _CQI/PMITwo important parameter N that indication periodicity CQI/PMI reports _P, N _{OFFSET, CQI}, its corresponding relation is as shown in table 1, and these two parameters have determined UE reports CQI/PMI in which subframe.

Table 1:

CQI/PMI is according to the configuration of layer 3, reports in the subframe that satisfies following formula according to the fixed cycle.

1) broadband reports:

Broadband CQI satisfies

2) subband reports:

Broadband CQI satisfies

Subband CQI satisfies

H=J*K+1 wherein, J is the subband group number, K is by upper-layer configured, n _fThe expression System Frame Number, n _sThe expression timeslot number, UE is satisfying periodic report CQI/PMI on the subframe of following formula.

According to the method in the present agreement, find small cell by measuring control, be UE eNB is to UE sending measuring configuration information when initially accessing, UE measures according to measurement configuration information, and triggers type according to reporting in the configuration information and come the reporting measurement result.This method, in order to find small cell, UE need to frequently measure, to greatly increase the power consumption of UE like this, and report the triggering type to be divided into reporting events and periodic report, reporting events only has when measurement result satisfies trigger condition and just reports, and periodic report only has and by the time arrives certain cycle and just report, and so also affects the promptness that UE finds smallcell.

Summary of the invention

For the power consumption and the timely small of the discovery cell that save UE, the present invention proposes the method that a kind of new small cell finds.

Technical scheme of the present invention is a kind of Small cell discover method based on PUCCH, and described PUCCH is ascending control channel, and described small cell is Microcell, it is characterized in that, may further comprise the steps:

Step 1, macro eNB issues the PUCCH parameter to all small cell in UE and the area of coverage, each small cell storage PUCCH parameter; Described macro eNB is macro base station, and described UE is user terminal;

Step 2, UE sends PUCCH according to the PUCCH parameter, and each small cell detects the CQI among the PUCCH and calculates sinr in the macro eNB area of coverage; Described CQI information is channel quality indication (CQI) information, and described sinr value is Signal to Interference plus Noise Ratio;

Each small cell compares judgement with obtaining the sinr value in the step 2 with the threshold T of presetting respectively in the step 3, the macro eNB area of coverage,

If the comparative result of all small cell is sinr＜T in the macro eNB area of coverage, then waits a PUCCH to send all after dates and return step 2;

If having the comparative result of small cell in the macro eNB area of coverage is sinr 〉=T, corresponding small cell is with the wireless network identification n in the PUCCH parameter _RNTISend to macro eNB;

Step 4, macro eNB receives the wireless network identification n that small cell sends _RNTIAfter, give wireless network identification n _RNTIThe configuration of corresponding UE sending measuring, UE measures and the reporting measurement result according to measuring configuration;

Step 5, macro eNB operates accordingly according to measurement result.

And in the step 1, macro eNB sends to the PUCCH parameter by X2 interface all small cell of the macro eNB area of coverage.

And in the step 3, small cell is with the wireless network identification n in the PUCCH parameter _RNTISend to macro eNB by X2 interface.

Technical scheme of the present invention realizes that by the CQI that detects UE periodic report in existing signal PUCCH small cell finds, dispose macro cell(macrocell at small cell) the area of coverage in, under the scene of macro cell with frequency, UE can find in time that small cell is to carry out professional offload.

Description of drawings

Fig. 1 is the flow chart of the embodiment of the invention;

Fig. 2 is that the small cell of the embodiment of the invention finds schematic diagram.

Embodiment

Describe technical solution of the present invention in detail below in conjunction with drawings and Examples.

In order to save UE power consumption, and agreement is changed minimum principle, utilize the mechanism of UE periodic report CQI on PUCCH, the present invention proposes a kind of small cell detects UE and sends to macro eNB(macrocell) existing signal be the CQI information of the upper carrying of PUCCH, then calculate Signal to Interference plus Noise Ratio sinr value, itself and threshold T are compared and judge, to find small cell.As shown in Figure 1, the specific implementation step of embodiment is as follows:

Step 1: macro eNB issues the PUCCH parameter to all small cell in UE and the area of coverage, and small cell stores these PUCCH parameters.

Among the embodiment, macro eNB is to UE configuration distributing ascending control channel PUCCH parameter, namely

n _RNTI,

I _CQI/PMI,

Then macro eNB sends to all small cell of its area of coverage by base-station interface (being generally X2 interface) with these parameters, and small cell stores these PUCCH parameters, wherein

Residential quarter ID, n _RNTIThe wireless network identification C-RNTI of UE,

Form 2/2a/2b(format2/2a/2b) take total RB(Resource Block) number, The cyclic shift number of determining to be used among mixed format 1/1a/1b and the 2/2a/2b form 1/1a/1b, I _CQI/PMIBe high-rise configuration be used for calculating the subframe numbers that CQI reports,

It is the initial index of form 2/2a/2b mapping RB.Like this, CQI information is carried on the form 2/2a/2b of PUCCH, passes through I _CQI/PMIKnow the subframe numbers that CQI reports,

Know the initial RB index of CQI mapping,

Total RB number of CQI mapping, according to above-mentioned other parameter generating CQI signal.

Step 2: UE sends PUCCH, and each small cell detects the CQI among the PUCCH in the macro eNB area of coverage, and calculates sinr.

Among the embodiment, according to present mechanism, after UE receives the PUCCH parameter, report CQI according to these parameter generating PUCCH and in corresponding subframe.When UE sent PUCCH to macro eNB, each smallcell monitored respectively PUCCH and solves UE in the CQI information that corresponding subframe reports in the macro eNB area of coverage, then calculates the sinr value.Concrete account form is prior art, provides for the sake of ease of implementation as follows:

$\sin r=\frac{\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{\left|\right|d\_{\mathrm{hard}}_n\left|\right|}^2}{\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{\left|\right|d_n-d\_{\mathrm{hard}}_n\left|\right|}^2}$

D wherein _nDemodulation symbol, d_hard _nBe the decoding Output rusults, N is the data symbol number in the subframe.For format2a/2b, N=10, the value of data symbol sequence number n is 1,2 ... N;

Step 3: each small cell compares obtaining sinr value and threshold T in the step 2 respectively in the macro eNB area of coverage, and is as follows according to the comparative result processing,

If the comparative result of all small cell is sinr＜T in the macro eNB area of coverage, think that then UE is from the position of small cell away from, do not need to send toward macro eNB the information of UE, UE does not need to measure, send all after dates Deng a PUCCH and return step 2, be that UE resends PUCCH, each small cell carries out the calculating of new sinr;

If having the comparative result of small cell in the macro eNB area of coverage is sinr 〉=T, think that then corresponding small cell detects the CQI information that UE reports, expression has UE near small cell.Judge sinr 〉=the small cell of T is the n in the PUCCH parameter _RNTISend to macro eNB by X2 interface, T is threshold value here, can according to circumstances set voluntarily value by those skilled in the art, and span is generally 280dB～320dB.

Step 4: receive the n that small cell sends _RNTIAfter, macro eNB is n to wireless network identification _RNTIUE sending measuring configuration information, UE measures according to measurement configuration information, UE reports trigger condition to macro eNB reporting measurement reports according to measuring in the configuration after measure finishing.During implementation, because the comparative result that may have a plurality of small cell in the step 3 in the macro eNB area of coverage is sinr 〉=T, each comparative result is sinr 〉=the small cell of T is with the n in the PUCCH parameter _RNTISend to macro eNB by X2 interface, it is n that macro eNB only needs to wireless network identification _RNTIUE issue the one-shot measurement configuration information, need not to repeat to send.

Step 5: macro eNB operates accordingly according to measurement result.General by measurement report, macro eNB judges around the UE whether small cell is arranged, and determines whether need the business of UE is carried out offload or no the switching.

Step 4 and five specific implementation are prior art, and it will not go into details in the present invention.

As shown in Figure 2, when UE from place A(location A) move to place B(location B) time, according to the step of front its process is illustrated.

As UE during at location A.

Step 1, macro eNB is to UE configuration PUCCH parameter, namely

n _RNTI,

I _CQI/PMI,

And by X2 interface the PUCCH parameter of UE being sent to small cell, small cell will receive the PUCCH Parameter storage;

Step 2, UE sends the PUCCH signal toward macro eNB, and small cell monitors PUCCH and separates CQI information according to the PUCCH parameter in corresponding subframe, calculates the sinr value;

Step 3, because UE is far away apart from small cell, the sinr value of calculating does not need to UE sending measuring configuration information less than threshold T;

It is mobile that UE does not stop, when sending the cycle through a PUCCH, when UE moves to location B.

Repeating step two, the sinr value is then thought UE near small cell greater than threshold T at this moment, finds the n of this UE according to the PUCCH parameter of storage _RNTI, and send it to macro eNB by X2 interface;

Step 4, macro eNB is to this UE sending measuring configuration information, and UE measures according to measurement configuration information, measures and finishes rear past macro eNB reporting measurement reports;

Step 5, whether macro eNB determines professional offload with this UE to small cell or whether this UE is issued handover request according to measurement report.

Specific embodiment described herein only is to the explanation for example of the present invention's spirit.Those skilled in the art can make various modifications or replenish or adopt similar mode to substitute described specific embodiment, but can't depart from spirit of the present invention or surmount the defined scope of appended claims.

Claims (3)

1. small cell discover method based on PUCCH, described PUCCH is ascending control channel, described small cell is Microcell, it is characterized in that, may further comprise the steps:

Step 1, macro eNB issues the PUCCH parameter to all small cell in UE and the area of coverage, each small cell storage PUCCH parameter; Described macro eNB is macro base station, and described UE is user terminal;

Step 2, UE sends PUCCH according to the PUCCH parameter, and each small cell detects the CQI among the PUCCH and calculates sinr in the macro eNB area of coverage; Described CQI information is channel quality indication (CQI) information, and described sinr value is Signal to Interference plus Noise Ratio;

Each small cell compares judgement with obtaining the sinr value in the step 2 with the threshold T of presetting respectively in the step 3, the macro eNB area of coverage,

If the comparative result of all small cell is sinr＜T in the macro eNB area of coverage, then waits a PUCCH to send all after dates and return step 2;

If having the comparative result of small cell in the macro eNB area of coverage is sinr 〉=T, corresponding small cell is with the wireless network identification n in the PUCCH parameter _RNTISend to macro eNB;

Step 4, macro eNB receives the wireless network identification n that small cell sends _RNTIAfter, give wireless network identification n _RNTIThe configuration of corresponding UE sending measuring, UE measures and the reporting measurement result according to measuring configuration;

Step 5, macro eNB operates accordingly according to measurement result.

2. described small cell discover method based on PUCCH according to claim 1, it is characterized in that: in the step 1, macro eNB sends to the PUCCH parameter by X2 interface all small cell of the macro eNB area of coverage.

3. described small cell discover method based on PUCCH according to claim 1, it is characterized in that: in the step 3, small cell is with the wireless network identification n in the PUCCH parameter _RNTISend to macro eNB by X2 interface.

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