CN102958124B - By subscriber equipment from the first cell merge to the method and apparatus of the second community - Google Patents

Abstract

The invention discloses a method and apparatus subscriber equipment being switched to the second cell base station from the first cell base station.Described method comprises step: arrange for this subscriber equipment specific scope expansion bias, judge when described subscriber equipment is from after described first cell base station is switched to described second cell base station, whether its signal interference ratio experienced is not less than first threshold, and the power of the power of the reference symbol received from described second cell base station judging that described subscriber equipment measures and the reference symbol received from described first cell base station expanding for the specific scope of this subscriber equipment whether bias sum be greater than that described subscriber equipment measures; And when the result of above-mentioned judgement is affirmative, described subscriber equipment is switched to described second cell base station from described first cell base station.According to the present invention, effective ICIC can be realized, not there is huge or even not endurable expense.

Description

By subscriber equipment from the first cell merge to the method and apparatus of the second community

Technical field

The present invention relates to the communications field, more specifically, the present invention relates to a method and apparatus subscriber equipment being switched to the second cell base station from the first cell base station.

Background technology

When deploying multiple Microcell that can openly access in macrocell, some subscriber equipmenies can be served by Microcell, thus alleviate the burden of macrocell, realize load balance.Wherein macrocell is such as basic wireless cellular network community in LTE-A, 3G, GSM, and Microcell is such as pico community, femto community etc.

In lte-a system, base station (eNB) can send reference symbol, mutually orthogonal between the reference symbol that wherein each base station sends.Each subscriber equipment can measure the power of the reference symbol received from the base station around it.Further, if subscriber equipment is in connection mode, the reference symbol received power of measurement can be reported to its serving BS.

For any user equipment (UE) _j, use represent the set of its peripheral base station, if UE _jbe in connection mode, and when considering to switch, also comprise U E _jserving BS.Further, RSRP is used _ijrepresent UE _jthe power of the reference symbol from base station i reception measured, the so conventional cell association criterion based on the reference symbol received power measured can be expressed as follows:

$\mathrm{Cell}\_{\mathrm{ID}}_{\mathrm{serving}}=\arg {\max }_{\left\{i\right\}}\left\{{\mathrm{RSRP}}_{\mathrm{ij}}\right\},i\∈{\mathrm{\Λ}}_{\mathrm{surr}}^{\left(j\right)}---\left(1\right)$

The implication of above-mentioned criterion is, UE _jthat base station prominent of the reference symbol received from its peripheral base station that it is measured will be associated with.

When macrocell-picocell deployment, if still application is as cell association criterion given in (1), so compared to Microcell, more subscriber equipment will be had to be associated with macrocell, and reason is the transmitted power of transmitted power much larger than microcell base station of macro cell base station.In this case, the available resources of Microcell are not fully utilized, and in macrocell, the competition for available resources can be very fierce.In order to more effectively utilize the potential load balance function provided by Microcell, for the deployment scenario of macrocell-Microcell, for any UE _j, use following cell association criterion:

$\mathrm{Cell}\_{\mathrm{ID}}_{\mathrm{serving}}=\arg {\max }_{\left\{i\right\}}\{{\mathrm{RSRP}}_{\mathrm{ij}}+{\mathrm{bias}}_i\},i\∈{\mathrm{\Λ}}_{\mathrm{surr}}^{\left(j\right)}---\left(2\right)$

The implication of above-mentioned criterion is, UE _jits power of reference symbol received from its peripheral base station measured and bias (bias of peripheral base station will be associated with _i) with maximum that base station (macro cell base station or microcell base station).

In above-mentioned equation (2), for macrocell, bias is 0, and for each Microcell, bias is a nonnegative value, thus more subscriber equipment can be had to be served by Microcell.Use due to bias is equivalent to the ability of the scope giving Microcell extending user equipment association, and therefore this process is called scope expansion (RE) of Microcell, and above-mentioned bias is also called scope expansion bias.

For system, need correctly to design Microcell scope expansion bias, to realize good load balance, and do not cause the extra problem produced due to interference, the subscriber equipment being such as associated with the Microcell of scope expansion experiencings low signal interference ratio (SIR).

Current, in LTE version-10 (Rel-10), recommend to arrange scope expansion bias in the specific mode in community.Further, considering the simplicity of realization, in LTE Rel-10, recommending all Microcells for disposing in a macrocell, identical scope expansion bias is set.

Based on a large amount of assessment report, following conclusion can be drawn:

For not supporting the situation that the scope of Microcell is expanded, for descending (DL) control channel (CCH), there is not problem of inter-cell interference, and for DL data channel, presence of intercell interference cancellation (ICIC) scheme of reusing Rel-8/9 just can solve problem of inter-cell interference well.

But, for the specific scope expansion bias setting of use community and for each Microcell, use the situation that the Current standards of identical scope expansion bias is recommended, observe increase scope expansion bias and can realize better load balance, but the subscriber equipment being associated with corresponding Microcell can be made to experience lower SIR, particularly for being in the subscriber equipment at edge, Microcell, therefore DL CCH can be caused to occur, and the risk of problem of inter-cell interference increases, and finally causes radio jink failure.

Propose a kind of time division multiplexing (TDM) ICIC technology, be called almost blank subframe (ABS) technology, solve DL CCH problem of inter-cell interference.In ABS technology, as the macro cell base station of interference source, the subframe of ABS is configured at some, transfer of data is not carried out in physics DLCCH (PDCCH), and only transmit cell specific reference symbol (CRS) and possibly, at other primary channel, Physical Broadcast Channel such as, carry out transfer of data.Obviously, in the subframe being configured to ABS, on Physical Downlink Shared Channel (PDSCH), do not carry out transfer of data, namely do not carry out transfer of data on a data channel.In the implementation procedure of ABS technology, the interfere information of time domain must via the communication link between certain base station, and such as the back haul link of X2-type, exchanges between neighbor cell.

But ABS technology still suffers the interference problem of " CRS is to control signal ", even if reason is in almost blank subframe, macro cell base station should keep transmitting CRS.More importantly, the inherent shortcoming of this TDM ICIC technology is reduction of time-domain resource available in macrocell, thus causes the throughput performance of subscriber equipment in macrocell to reduce.

Therefore, be importantly or for the scope expansion bias plan of establishment of current consideration, design more effective DL CCH ICIC technology, or the scope expansion bias plan of establishment of design improvement, its load balance that can realize, and good DL CCH ICIC effect can be realized.

Summary of the invention

According to an aspect of the present invention, propose an a kind of method subscriber equipment being switched to the second cell base station from the first cell base station, comprise step: arrange for this subscriber equipment specific scope expansion bias; Judge when described subscriber equipment is from after described first cell base station is switched to described second cell base station, whether its signal interference ratio experienced is not less than first threshold, and the power of the power of the reference symbol received from described second cell base station judging that described subscriber equipment measures and the reference symbol received from described first cell base station expanding for the specific scope of this subscriber equipment whether bias sum be greater than that described subscriber equipment measures; And when the result of above-mentioned judgement is affirmative, described subscriber equipment is switched to described second cell base station from described first cell base station.

According to another aspect of the present invention, propose an a kind of device subscriber equipment being switched to the second cell base station from the first cell base station, comprising: setting unit, for arranging for this subscriber equipment specific scope expansion bias; Judging unit, for judging when described subscriber equipment is from after described first cell base station is switched to described second cell base station, whether its signal interference ratio experienced is not less than first threshold, and the power of the power of the reference symbol received from described second cell base station judging that described subscriber equipment measures and the reference symbol received from described first cell base station expanding for the specific scope of this subscriber equipment whether bias sum be greater than that described subscriber equipment measures; And switch unit, for when the judged result of above-mentioned judging unit is affirmative, described subscriber equipment is switched to described second cell base station from described first cell base station.

According to the present invention, effective ICIC can be realized, not there is huge or even not endurable expense.

Accompanying drawing explanation

By below in conjunction with the description of the drawings, and understand more comprehensively along with to of the present invention, other objects of the present invention and effect will become clearly and easy to understand, wherein:

Fig. 1 shows the environment 100 that the present invention can realize wherein;

Fig. 2 shows a flow chart subscriber equipment being switched to the method for the second cell base station from the first cell base station according to an embodiment of the invention;

Fig. 3 shows a block diagram subscriber equipment being switched to the device of the second cell base station from the first cell base station according to an embodiment of the invention.

In all above-mentioned accompanying drawings, identical label represents to have identical, similar or corresponding feature or function.

Embodiment

In execution mode as described below of the present invention, pay close attention to for subscriber equipment specific scope expansion bias scheme.According to the embodiment of the present invention, effective ICIC can be realized, and not there is huge or even not endurable expense.

Fig. 1 shows the environment 100 that the present invention can implement wherein.

As shown in Figure 1, this environment 100 comprises the base station 110 corresponding to community 111, corresponding to base station 120 and multiple subscriber equipment 130-1,130-2,130-3,130-4,130-5 and 130-6 of community 112.

Base station 110 provides coverage 110-a, and base station 120 provides coverage 120-a.

Subscriber equipment can move in environment 100, and can enter or exit coverage 110-a and 120-a.Therefore, subscriber equipment is communicated with base station 110 by wireless link 140.Or subscriber equipment is communicated with base station 120 by wireless link 150.In addition, communicated by back haul link 160 between base station 110 and base station 120.Back haul link 160 can be wired, also can be wireless.

Here, assuming that base station 110 is macro cell base station, base station 120 is microcell base stations, and wherein macro cell base station is such as basic wireless cellular network base station in LTE-A, 3G, GSM etc., and microcell base station is such as that pico base station, femto base station, via node or remote radio frequency are first-class.In describing the invention, base station and community are relations one to one.Ji Yige only has community a base station, and a community is only served in a base station.

As shown in Figure 1, coverage 110-a comprises coverage 120-a completely.Certainly, those skilled in the art will appreciate that coverage 110-a partly can comprise coverage 120-a.Even coverage 110-a and coverage 120-a does not intersect.

Here, for simplicity and clear for the purpose of, merely illustrate a Microcell and 6 subscriber equipmenies in FIG, it will be understood by those of skill in the art that the present invention be applicable to be deployed with multiple Microcell in a macrocell and the number of subscriber equipment greater or less than the scene of 6.

More generally, use represent and be associated with the second cell base station before handover, namely microcell base station k (k ∈ 1 ..., K}) the number of current user equipment.With represent and be associated with the first cell base station before handover, the namely number of the current user equipment MUE of macro cell base station.

Any one is associated with before handover to the subscriber equipment MUE of macro cell base station _j, measure the power of the reference symbol received from its peripheral base station (comprising macro cell base station and microcell base station).

At subscriber equipment MUE _jthe power of the reference symbol received from the microcell base station around it measured, maximum that is expressed as [dBm], is expressed as from the power of the reference symbol of other K-1 microcell base stations receptions (l=1 ..., K-1) [dBm].In addition, for MUE _j, the power of the reference symbol received from its macro cell base station measured is expressed as [dBm].

In order to outstanding basic thought of the present invention, ignore the impact of noise in the following description.

After carrying out RSRP measurement, this MUE _jwill to its serving BS, namely macro cell base station reports its RSRP measured and corresponding cell identifier ID.

In the following description, mainly pay close attention to the switching of subscriber equipment from macro cell base station to microcell base station, that is, in the following description, the first cell base station refers to macro cell base station; Second cell base station refers to microcell base station.

Certainly, it will be understood by those of skill in the art that general principle of the present invention is also applicable to the switching of subscriber equipment from microcell base station to microcell base station.

Therefore, the first cell base station in detail in the claims both can refer to macro cell base station, also can refer to microcell base station.

In addition, in the following description, mainly pay close attention to from macro cell base station to the switching of that microcell base station causing maximum reference symbol received power at subscriber equipment.

For any one given MUE _j, use

${\mathrm{SIR}}_{\mathrm{ifbeco}\min \mathrm{gPUE}}^{\left(j\right)}=Y_{P,0}^{\left(j\right)}-Y_M^{\left(j\right)}-{\mathrm{\Σ}}_{l=1~K-1}{Y}_{P,l}^{\left(j\right)}\left[\mathrm{dB}\right]$

Represent this MUE of supposition _jgeneration is switched to from macro cell base station microcell base station, become the subscriber equipment of this microcell base station, namely after PUE, the descending signal interference ratio of estimation.For the switching in connection mode, this parameter is utilized from MUE by macro cell base station _jreport each corresponding base station (comprising macro cell base station and microcell base station) RSRP and estimate to obtain.

Fig. 2 shows a flow chart subscriber equipment being switched to the method for the second cell base station from the first cell base station according to an embodiment of the invention.

Method 200 comprises step S205, arranges for this subscriber equipment specific scope expansion bias; Step S210, judge when subscriber equipment is from after the first cell base station is switched to the second cell base station, whether its signal interference ratio experienced is not less than first threshold, and the power of the power of the reference symbol received from the second cell base station judging that subscriber equipment measures and the reference symbol received from the first cell base station expanding for the specific scope of this subscriber equipment whether bias sum be greater than that subscriber equipment measures; And

Step S220, when the result of above-mentioned judgement is affirmative, is switched to the second cell base station by subscriber equipment from the first cell base station.

Wherein, in an embodiment of the invention, first threshold is the target signal interference ratio SIR of down control channel _{cCH target}.

Certainly, those skilled in the art will appreciate that first threshold also can be other values.Such as, in yet another embodiment of the present invention, first threshold is the maximum in the minimum value of the target signal interference ratio of down control channel and the target signal interference ratio of downstream data channel, and namely first threshold is wherein the latter is the minimum value of the target signal interference ratio of downstream data channel.

Wherein, as mentioned above, the second cell base station is except macro cell base station, causes that microcell base station of maximum reference symbol received power at subscriber equipment place.

Said method 200 is such as performed by macro cell base station.

From MUE _jafter obtaining the RSRP measured value of each base station, whether the following inequality 3 and 4 of detection is set up by macro cell base station:

${\mathrm{SIR}}_{\mathrm{ifbeco}\min \mathrm{gPUE}}^{\left(j\right)}\≥{\mathrm{SIR}}_{\mathrm{CCHt}\arg \mathrm{et}}---\left(3\right)$

$Y_{P,0}^{\left(j\right)}+{\mathrm{\β}}_j>Y_M^{\left(j\right)}$ (that is, $Y_{P,0}^{\left(j\right)}-Y_M^{\left(j\right)}>-{\mathrm{\β}}_j$ )(4)

Wherein SIR _{cCH target}for the target signal interference ratio of down control channel, β _j[dB] represents MUE _juser equipment (UE) particular range expansion bias, wherein β _jit is a nonnegative value.

If inequality 3 and 4 is set up, so macro cell base station will contact with this microcell base station, to switch, by MUE _jmicrocell base station is switched to from macro cell base station.

If be false, that is, if set up, clearly, in this case, MUE _jshould remain under being associated with macro cell base station, should not be switched to microcell base station.

If set up, from the view point of ICIC, via switching MUE _jbecome under being associated with microcell base station and be fine.

Present discussion UE particular range expansion RE bias β _jdesign.

Below, if will set up this situation and be expressed as situation 1; If will set up this situation and be expressed as situation 2.

If in case 1, from the view point of ICIC, via switching MUE _jbecome to be associated with under microcell base station cannot, therefore do not need to design β _j.

Situation 2 is divided into two sub cases: situation 2.1 and situation 2.2.

If wherein so belong to situation 2.1; If so belong to situation 2.2.

Situation 2.1 times, according to the traditional cell association standard based on RSRP shown in equation 1, even if do not perform scope expansion in microcell level, be also recommend MUE _jby being switching to PUE.When using the correlation rule shown in inequality 4, regardless of nonnegative value β _jarrange and why be worth, such as, by β _jbe set to 0, thus in fact do not support RE, inequality 4 also always can be set up, thus MUE _jwill by being switching to PUE.

At macro cell base station place, based on the RSRP measurement report of current acquisition, determine that the number of the MUE meeting situation 2.1 is n (n is non-negative).This n MUE will become PUE by switching, and what value the specific RE bias of UE regardless of them arranges.That is, n represents in the current user equipment being associated with the first cell base station before handover, if suppose that being switched to this situation in base station, switching target small area from the first cell base station occurs, its signal interference ratio experienced is not less than first threshold, and the power of the reference symbol received from base station, switching target small area is greater than the number of the subscriber equipment of the power of the reference symbol received from the first cell base station.

More specifically, this n MUE will be switched to different microcell base stations, because for two different MUE in this n MUE, the microcell base station producing the RSRP of maximum measurement is likely different.

Use n _k(n _k>=0) represent and fall into situation 2.1, and after the handover will by microcell base station k (k ∈ 1 ..., K}) number of MUE of serving.That is, for n _keach in individual MUE, microcell base station k is the base station producing maximum RSRP.

Obviously, ∑ _{k=1 ~ K}n _k=n.

Situation 2.2 times, for MUE _j, whether can be transformed to PUE by means of RE and mainly will rely on β _jspecial setting.

For the MUE dropped in the case _j, remain MUE and become PUE by the impact different on the generation of system load balance with by switching, and therefore have different impacts to throughput performance.

Next, will first provide the relevant analysis of some throughputs, then utilize the analysis that throughput is relevant, carry out β _jdesign.

In macro cell base station, based on the current RSRP measurement report obtained, determine that the number of the MUE of the situation that falls into 2.2 is m (m >=0).That is, m represents in the current user equipment being associated with the first cell base station before handover, if suppose that being switched to this situation in base station, switching target small area from the first cell base station occurs, its signal interference ratio experienced is not less than first threshold, and the power of the reference symbol received from base station, switching target small area is not more than the number of the subscriber equipment of the power of the reference symbol received from the first cell base station.Each of this m MUE depends on the specific RE bias of UE for they are arranged respectively, or remains MUE or by being switching to PUE.

Use m _k(m _k>=0) and if represent drop on situation 2.2 to its RE bias be arranged to switch generation will by microcell base station k (k ∈ 1 ..., K}) number of MUE of serving.That is, for this m _keach in individual MUE, microcell base station k is the microcell base station causing maximum RSRP.Obvious ∑ _{k=1 ~ K}m _k=m.

Use SIR ^(j)[dB] represents MUE _jdescending SIR experienced before handover, this descending SIR is by MUE _jestimate, and be reported to macro cell base station.

If MUE _jlikely become the PUE served by microcell base station k, i.e. this MUE by switching _jthe m of previous definition _kindividual MUE (wherein m _k>=0) one in, as this MUE of supposition _jremain MUE, so this MUE _jminimum and maximum possible throughput can be estimated as follows respectively:

$C_{M,\min }^{\left(j\right)}=\frac{B}{N_{\mathrm{MUE}}^{\left(\mathrm{curr}\right)}-n}\·{\log }_2(1+{10}^{{\mathrm{SIR}}^{\left(j\right)}/10})---\left(5.1\right)$

$C_{M,\max }^{\left(j\right)}=\frac{B}{N_{\mathrm{MUE}}^{\left(\mathrm{curr}\right)}-n-(m-1)}\·{\log }_2(1+{10}^{{\mathrm{SIR}}^{\left(j\right)}/10})---\left(5.2\right)$

Shown in (5.1) corresponding to following scene, in this scenario, all m the MUE dropped in situation 2.2 are still served by macro cell base station.

Shown in (5.2) corresponding to following scene, drop in all m MUE in situation 2.2, only have this MUE _jremain and served by macro cell base station

In (5.1) and (5.2), deducting n is the specific RE bias of UE arranging them because of n the MUE dropped in situation 2.1 howsoever, all will become PUE by switching.

If MUE _jlikely become the PUE served by microcell base station k, i.e. this MUE by switching _jthe m of previous definition _kindividual MUE (wherein m _k>=0) one in, as this MUE of supposition _jwhen being switching to PUE, its minimum and throughput that is maximum possible can be estimated as follows respectively:

$C_{P,\min }^{\left(j\right)}=\frac{B}{N_{\mathrm{PUE},k}^{\left(\mathrm{curr}\right)}+n_k+m_k}\·{\log }_2(1+{10}^{(Y_{P,0}^{\left(j\right)}-Y_M^{\left(j\right)})/10})---\left(6.1\right)$

$C_{P,\max }^{\left(j\right)}=\frac{B}{N_{\mathrm{PUE},k}^{\left(\mathrm{curr}\right)}+n_k+1}\·{\log }_2(1+{10}^{(Y_{P,0}^{\left(j\right)}-Y_M^{\left(j\right)})/10})---\left(6.2\right)$

Wherein shown in (6.1) corresponding to following scene, in this scenario, all m _kindividual MUE becomes PUE through switching.

(6.2) corresponding to following scene, in this scenario, m _kthis MUE is only had in individual MUE _jpUE is become by switching.In (6.1) and (6.2), add n _kbecause drop on the n in situation 2.1 _kindividual MUE will become the PUE served by microcell base station k, why is worth regardless of the specific RE bias of UE arranged for their.

As shown in the technical report in a lot of 3GPP standard, for the UE total number Z that any one is given, the increase of the number of the PUE caused along with RE, all UE throughput sums or come throughput (the such as Z=100 of that UE of xth % reciprocal × Z in all UE in its throughput, x%=5%, total exactly 100 UE in throughput come the throughput of that UE of 5th difference reciprocal) first can increase, after the number of the PUE then caused as RE meets or exceeds a certain particular value, the continuation of the number of the PUE caused along with RE increases, all UE throughput sums, or the throughput coming that UE of xth % reciprocal × Z in all UE in its throughput can reduce.

Therefore, when needing to carry out the switching of MUE to PUE by means of RE, wise way is, only just switches when this switching is useful to throughput performance.

For situation 2.2, only under the help of RE, MUE _jjust can be switched to microcell base station, in an embodiment of the invention, propose the following UE specific RE bias plan of establishment (it does not need any support of the RRC signaling of air interface):

For any one MUE in m the MUE belonged in the situation of dropping on 2.2 _j, only have and work as time, just can by switching this MUE _jbecome PUE.

For MUE _jif, microcell base station k (k ∈ 1 ..., and K}) be produce maximum RSRP corresponding microcell base station, by mathematical derivation, be equal to

$Y_{P,0}^{\left(j\right)}-Y_M^{\left(j\right)}>10\·{\log }_{10}({(1+{10}^{{\mathrm{SIR}}^{\left(j\right)}/10})}^{\frac{N_{\mathrm{PUE},k}^{\left(\mathrm{curr}\right)}+n_k+m_k}{N_{\mathrm{MUE}}^{\left(\mathrm{curr}\right)}-n-(m-1)}}-1)---\left(7\right)$

More specifically, for situation 2.2 (wherein ), the necessary condition that inequality (7) will be set up is the right side of inequality (7) should be a negative value.

Therefore, for situation 2.2, by comparing the switching condition shown in inequality (7) and the rule of the cell association shown in inequality (4), can be summarized as follows:

When the right side in inequality (7) is less than 0, by-the β in inequality (4) _jbe set to the value on right side in inequality (7).If inequality (4) is set up, so corresponding MUE _jwill by being switching to PUE.

When in inequality (7), right side is more than or equal to 0, thus for situation 2.2, forever be not being met, although still can by-the β in inequality (4) _jbe set to the value on right side in inequality (7), thus inequality (4) is untenable, and MUE _jremain MUE.But, due to β _jusually a nonnegative value (i.e.-β is set to _jbe less than or equal to 0), for this situation, can simply by β _jbe set to 0dB, thus for situation 2.2, inequality (4) is untenable.

Therefore, according to an embodiment of the invention, for MUE _jspecific scope expansion bias β _jbe set to ε λ _j:

Wherein

${\mathrm{\λ}}_j=-10\·{\log }_{10}({(1+{10}^{{\mathrm{SIR}}^{\left(j\right)}/10})}^{\frac{N_{\mathrm{PUE},k}^{\left(\mathrm{curr}\right)}+n_k+1}{N_{\mathrm{MUE}}^{\left(\mathrm{curr}\right)}-n}}-1)---\left(8\right)$

$\mathrm{\ϵ}=\left\{\begin{array}{c}0,{\mathrm{\λ}}_j\≤0\\ 1,{\mathrm{\λ}}_j>0\end{array}\right.---\left(9\right)$

If inequality (3) and inequality (4) can be set up, so macro cell base station will communicate with switching target microcell base station, to realize MUE _jswitching, thus this MUE _jbecome PUE.If (3) or (4) untenable, so this MUE _jremain and served by macro cell base station.

Attention: if inequality (3) can be set up, so MUE _jthe n of previous definition will be become _k(n _k>=0) one in individual MUE, or become the m of previous definition _k(m _k>=0) one in individual MUE.

Particularly, if MUE _jthe n of previous definition _k(n _k>=0) one in individual MUE (if namely MUE _jdrop in situation 2.1), so no matter how RE value is arranged, this MUE _jall the PUE served by microcell base station k will be become.As front to as described in situation 2.1, to this situation, so, although λ _jbe design for the cell association of the MUE dropped in situation 2.2, but for situation 2.1, the cell association rule described in inequality (4) still can normally work; Because according to (8) and (9), ε λ _jby always non-negative, the MUE therefore dropped in situation 2.1 always can be switching to the PUE served by microcell base station k.

Except microcell base station k (k ∈ 1 ..., K}) the number of current PUE every other parameter in inequality (3) and (4) can both obtain in macro cell base station, and does not need minizone signaling.Particularly, macro cell base station by the back haul link between the macro cell base station of X2 type and microcell base station, can obtain parameter

Based on a large amount of simulation results reported in 3GPP standard, for the average DLSIR at MUE place, " well " magnitude is about or is better than 12dB, and " poor " magnitude is about or is worse than 5dB.

Next, in order to λ _jvalue have one to get information about, use SIR ^(j)=5dB, 10dB, 15dB or 20dB as an example, when during value change, to λ _jvalue carry out following Numerical evaluation.

If SIR ^(j)=5dB: when when 1/6 or 1/8, λ _j≈ 3.68dB, 5.71dB or 7.10dB;

If SIR ^(j)=10dB: when when 1/6 or 1/8, λ _j≈ 0.85dB, 3.09dB or 4.57dB;

If SIR ^(j)=15dB: when when 1/6 or 1/8, λ _j≈-1.43dB, 1.04dB or 2.63dB;

If SIR ^(j)=20dB: when 1/6, or when 1/8, λ _j≈-3.36dB ,-0.64dB or 1.08dB.

In fact, when the deployment of microcell base station is laxer, more greedy switching criterion can be used.That is, for any one MUE in m the MUE belonged in the situation of dropping on 2.2 _j, can work as time, by switching this MUE _jbecome PUE.

In this case, by mathematical derivation, can draw

${\mathrm{\λ}}_j=-10\·{\log }_{10}({(1+{10}^{{\mathrm{SIR}}^{\left(j\right)}/10})}^{\frac{N_{\mathrm{PUE},k}^{\left(\mathrm{curr}\right)}+n_k+1}{N_{\mathrm{MUE}}^{\left(\mathrm{curr}\right)}-n}}-1)---\left(10\right)$

Therefore, according to an embodiment of the invention, for this subscriber equipment specific scope expansion bias β _jbe set to ε λ _j:

Wherein

${\mathrm{\λ}}_j=-10\·{\log }_{10}({(1+{10}^{{\mathrm{SIR}}^{\left(j\right)}/10})}^{\frac{N_{\mathrm{PUE},k}^{\left(\mathrm{curr}\right)}+n_k+1}{N_{\mathrm{MUE}}^{\left(\mathrm{curr}\right)}-n}}-1)---\left(10\right)$

$\mathrm{\ϵ}=\left\{\begin{array}{c}0,{\mathrm{\λ}}_j\≤0\\ 1,{\mathrm{\λ}}_j>0\end{array}\right.---\left(9\right)$

Fig. 3 shows a block diagram subscriber equipment being switched to the device of the second cell base station from the first cell base station according to an embodiment of the invention.

As shown in Figure 3, this device 300 comprises setting unit 305, for arranging for this subscriber equipment specific scope expansion bias; Judging unit 310, for judging when subscriber equipment is from after the first cell base station is switched to the second cell base station, whether its signal interference ratio experienced is not less than first threshold, and the power of the power of the reference symbol received from the second cell base station judging that subscriber equipment measures and the reference symbol received from the first cell base station expanding for the specific scope of this subscriber equipment whether bias sum be greater than that subscriber equipment measures; And switch unit 320, for when the judged result of above-mentioned judging unit 310 is affirmatives, subscriber equipment is switched to described second cell base station from the first cell base station.

In an embodiment of the invention, first threshold is the target signal interference ratio of down control channel.

In another execution mode of the present invention, first threshold is the maximum in the minimum value of the target signal interference ratio of down control channel and the target signal interference ratio of downstream data channel.

In an embodiment of the invention, the second cell base station is except the first cell base station, causes that cell base station of maximum reference symbol received power at subscriber equipment place.

In an embodiment of the invention, for this subscriber equipment specific scope expansion bias β _jbe set to ε λ _j:

Wherein

${\mathrm{\λ}}_j=-10\·{\log }_{10}({(1+{10}^{{\mathrm{SIR}}^{\left(j\right)}/10})}^{\frac{N_{\mathrm{PUE},k}^{\left(\mathrm{curr}\right)}+n_k+m_k}{N_{\mathrm{MUE}}^{\left(\mathrm{curr}\right)}-n-(m-1)}}-1)$

$\mathrm{\ϵ}=\left\{\begin{array}{c}0,{\mathrm{\λ}}_j\≤0\\ 1,{\mathrm{\λ}}_j>0\end{array}\right.,$

Wherein SIR ^(j)represent subscriber equipment before handover by during the first cell base station service the descending signal interference ratio experienced;

represent the number being associated with the current user equipment of the second cell base station before handover;

represent the number being associated with the current user equipment of the first cell base station before handover;

N represents in the current user equipment being associated with the first cell base station before handover, if suppose that being switched to this situation in base station, switching target small area from the first cell base station occurs, its signal interference ratio experienced is not less than first threshold, and the power of the reference symbol received from base station, switching target small area is greater than the number of the subscriber equipment of the power of the reference symbol received from the first cell base station;

M represents in the current user equipment being associated with the first cell base station before handover, if suppose that being switched to this situation in base station, switching target small area from the first cell base station occurs, its signal interference ratio experienced is not less than first threshold, and the power of the reference symbol received from base station, switching target small area is not more than the number of the subscriber equipment of the power of the reference symbol received from the first cell base station;

N _krepresent that in a said n subscriber equipment, base station, switching target small area is the number of the subscriber equipment of the second cell base station;

M _krepresent that, in an above-mentioned m subscriber equipment, base station, switching target small area is the number of the subscriber equipment of the second cell base station.

In an embodiment of the invention, for this subscriber equipment specific scope expansion bias β _jbe set to ε λ _j:

Wherein

${\mathrm{\λ}}_j=-10\·{\log }_{10}({(1+{10}^{{\mathrm{SIR}}^{\left(j\right)}/10})}^{\frac{N_{\mathrm{PUE},k}^{\left(\mathrm{curr}\right)}+n_k+1}{N_{\mathrm{MUE}}^{\left(\mathrm{curr}\right)}-n}}-1)$

$\mathrm{\ϵ}=\left\{\begin{array}{c}0,{\mathrm{\λ}}_j\≤0\\ 1,{\mathrm{\λ}}_j>0\end{array}\right.$

Wherein base station, switching target small area is except the first cell base station, causes that cell base station of maximum reference symbol received power at subscriber equipment place.

It should be noted that to make the present invention be easier to understand, description above eliminates to be known for a person skilled in the art and may to be required some ins and outs more specifically for realization of the present invention.

Those skilled in the art it is also understood that and the invention is not restricted to step described above, and the present invention also comprises the combination, sequential transformations etc. carried out step described above.Final scope of the present invention is defined by the appended claims.

Therefore; selecting and describing execution mode is to explain principle of the present invention and practical application thereof better; and those of ordinary skill in the art are understood, under the prerequisite not departing from essence of the present invention, all modifications and change all fall within protection scope of the present invention defined by the claims.

In addition, those skilled in the art will appreciate that the step of above-described various method can be realized by the computer of programming.Here, some execution mode is intended to overlay program storage device, and it is machine or computer-readable, and coding has machine to perform or computer executable instructions program, and wherein said instruction performs the some or all of steps of said method.This program storage device can be such as magnetic recording medium such as Disk and tape, hard disk drive or optical readable digital data storage medium.Execution mode is also intended to cover the computer being programmed for the described step performing said method.

Claims (14)

1. a subscriber equipment is switched to a method for the second cell base station from the first cell base station, comprises step:

Arrange for this subscriber equipment specific scope expansion bias;

Judge that supposition is when described subscriber equipment is from after described first cell base station is switched to described second cell base station, whether its signal interference ratio experienced is not less than first threshold, and the power of the power of the reference symbol received from described second cell base station judging that described subscriber equipment measures and the reference symbol received from described first cell base station expanding for the specific scope of this subscriber equipment whether bias sum be greater than that described subscriber equipment measures; And

When the result of above-mentioned judgement is affirmative, described subscriber equipment is switched to described second cell base station from described first cell base station;

Wherein, described for this subscriber equipment specific scope expansion bias for described subscriber equipment is arranged respectively, and described relevant to the descending signal interference ratio experienced during described first cell base station to described user device association for this subscriber equipment specific scope expansion bias.

2. method according to claim 1, wherein said first threshold is the target signal interference ratio of down control channel.

3. method according to claim 1, wherein said first threshold is the maximum in the minimum value of the target signal interference ratio of down control channel and the target signal interference ratio of downstream data channel.

4. method according to claim 1, wherein said second cell base station is except described first cell base station, causes that cell base station of maximum reference symbol received power at described subscriber equipment place.

5. method according to claim 1, wherein for this subscriber equipment specific scope expansion bias β _jbe set to ε λ _j:

Wherein

${\mathrm{\λ}}_j=-10\·{\log }_{10}({(1+{10}^{{\mathrm{SIR}}^{\left(j\right)}/10})}^{\frac{N_{\mathrm{PUE}.k}^{\left(\mathrm{curr}\right)}+n_k+m_k}{N_{\mathrm{MUE}}^{\left(\mathrm{curr}\right)}-n-(m-1)}}-1)$

$\mathrm{\ϵ}=\left\{\begin{array}{c}0,{\mathrm{\λ}}_j\≤0\\ 1,{\mathrm{\λ}}_j>0\end{array}\right.,$

Wherein SIR ^(j)represent that described user device association is to the descending signal interference ratio experienced during described first cell base station;

represent the number being associated with the current user equipment of described second cell base station before handover;

represent the number being associated with the current user equipment of described first cell base station before handover;

N represents in the current user equipment being associated with described first cell base station before handover, if suppose that being switched to this situation in base station, switching target small area from described first cell base station occurs, its signal interference ratio experienced is not less than first threshold, and the power of the reference symbol received from base station, switching target small area is greater than the number of the subscriber equipment of the power of the reference symbol received from described first cell base station;

M represents in the current user equipment being associated with described first cell base station before handover, if suppose that being switched to this situation in base station, switching target small area from described first cell base station occurs, its signal interference ratio experienced is not less than first threshold, and the power of the reference symbol received from base station, switching target small area is not more than the number of the subscriber equipment of the power of the reference symbol received from described first cell base station;

N _krepresent that in a said n subscriber equipment, base station, switching target small area is the number of the subscriber equipment of described second cell base station;

M _krepresent in an above-mentioned m subscriber equipment, base station, switching target small area is the number of the subscriber equipment of described second cell base station.

6. method according to claim 1, wherein for this subscriber equipment specific scope expansion bias β _jbe set to ε λ _j:

Wherein

${\mathrm{\λ}}_j=-10\·{\log }_{10}({(1+{10}^{{\mathrm{SIR}}^{\left(j\right)}/10})}^{\frac{N_{\mathrm{PUE}.k}^{\left(\mathrm{curr}\right)}+n_k+1}{N_{\mathrm{MUE}}^{\left(\mathrm{curr}\right)}-n}}-1)$

$\mathrm{\ϵ}=\left\{\begin{array}{c}0,{\mathrm{\λ}}_j\≤0\\ 1,{\mathrm{\λ}}_j>0\end{array}\right.,$

Wherein SIR ^(j)represent that described user device association is to the descending signal interference ratio experienced during described first cell base station;

represent the number being associated with the current user equipment of described second cell base station before handover;

represent the number being associated with the current user equipment of described first cell base station before handover;

N represents in the current user equipment being associated with described first cell base station before handover, if suppose that being switched to this situation in base station, switching target small area from described first cell base station occurs, its signal interference ratio experienced is not less than first threshold, and the power of the reference symbol received from base station, switching target small area is greater than the number of the subscriber equipment of the power of the reference symbol received from described first cell base station;

N _krepresent that in a said n subscriber equipment, base station, switching target small area is the number of the subscriber equipment of described second cell base station.

7. the method according to claim 5 or 6, base station, wherein said switching target small area is except described first cell base station, causes that cell base station of maximum reference symbol received power at described subscriber equipment place.

8. a subscriber equipment is switched to a device for the second cell base station from the first cell base station, comprises:

Setting unit, for arranging for this subscriber equipment specific scope expansion bias;

Judging unit, for judging that supposition is when described subscriber equipment is from after described first cell base station is switched to described second cell base station, whether its signal interference ratio experienced is not less than first threshold, and the power of the power of the reference symbol received from described second cell base station judging that described subscriber equipment measures and the reference symbol received from described first cell base station expanding for the specific scope of this subscriber equipment whether bias sum be greater than that described subscriber equipment measures; And

Switch unit, for when the judged result of above-mentioned judging unit is affirmative, is switched to described second cell base station by described subscriber equipment from described first cell base station;

Wherein, described for this subscriber equipment specific scope expansion bias for described subscriber equipment is arranged respectively, and described relevant to the descending signal interference ratio experienced during described first cell base station to described user device association for this subscriber equipment specific scope expansion bias.

9. device according to claim 8, wherein said first threshold is the target signal interference ratio of down control channel.

10. device according to claim 8, wherein said first threshold is the maximum in the minimum value of the target signal interference ratio of down control channel and the target signal interference ratio of downstream data channel.

11. devices according to claim 8, wherein said second cell base station is except described first cell base station, causes that cell base station of maximum reference symbol received power at described subscriber equipment place.

12. devices according to claim 8, wherein for this subscriber equipment specific scope expansion bias β _jbe set to ε λ _j:

Wherein

${\mathrm{\λ}}_j=-10\·{\log }_{10}({(1+{10}^{{\mathrm{SIR}}^{\left(j\right)}/10})}^{\frac{N_{\mathrm{PUE}.k}^{\left(\mathrm{curr}\right)}+n_k+m_k}{N_{\mathrm{MUE}}^{\left(\mathrm{curr}\right)}-n-(m-1)}}-1)$

$\mathrm{\ϵ}=\left\{\begin{array}{c}0,{\mathrm{\λ}}_j\≤0\\ 1,{\mathrm{\λ}}_j>0\end{array}\right.,$

Wherein SIR ^(j)represent that described user device association is to the descending signal interference ratio experienced during described first cell base station;

represent the number being associated with the current user equipment of described second cell base station before handover;

represent the number being associated with the current user equipment of described first cell base station before handover;

N represents in the current user equipment being associated with described first cell base station before handover, if suppose that being switched to this situation in base station, switching target small area from described first cell base station occurs, its signal interference ratio experienced is not less than first threshold, and the power of the reference symbol received from base station, switching target small area is greater than the number of the subscriber equipment of the power of the reference symbol received from described first cell base station;

M represents in the current user equipment being associated with described first cell base station before handover, if suppose that being switched to this situation in base station, switching target small area from described first cell base station occurs, its signal interference ratio experienced is not less than first threshold, and the power of the reference symbol received from base station, switching target small area is not more than the number of the subscriber equipment of the power of the reference symbol received from described first cell base station;

N _krepresent that in a said n subscriber equipment, base station, switching target small area is the number of the subscriber equipment of described second cell base station;

M _krepresent in an above-mentioned m subscriber equipment, base station, switching target small area is the number of the subscriber equipment of described second cell base station.

13. devices according to claim 8, wherein for this subscriber equipment specific scope expansion bias β _jbe set to ε λ _j:

Wherein

${\mathrm{\λ}}_j=-10\·{\log }_{10}({(1+{10}^{{\mathrm{SIR}}^{\left(j\right)}/10})}^{\frac{N_{\mathrm{PUE}.k}^{\left(\mathrm{curr}\right)}+n_k+1}{N_{\mathrm{MUE}}^{\left(\mathrm{curr}\right)}-n}}-1)$

$\mathrm{\ϵ}=\left\{\begin{array}{c}0,{\mathrm{\λ}}_j\≤0\\ 1,{\mathrm{\λ}}_j>0\end{array}\right.$

Wherein SIR ^(j)represent that described user device association is to the descending signal interference ratio experienced during described first cell base station;

represent the number being associated with the current user equipment of described second cell base station before handover;

represent the number being associated with the current user equipment of described first cell base station before handover;

N represents in the current user equipment being associated with described first cell base station before handover, if suppose that being switched to this situation in base station, switching target small area from described first cell base station occurs, its signal interference ratio experienced is not less than first threshold, and the power of the reference symbol received from base station, switching target small area is greater than the number of the subscriber equipment of the power of the reference symbol received from described first cell base station;

N _krepresent that in a said n subscriber equipment, base station, switching target small area is the number of the subscriber equipment of described second cell base station.

14. devices according to claim 12 or 13, base station, wherein said switching target small area is except described first cell base station, causes that cell base station of maximum reference symbol received power at described subscriber equipment place.