CN100370876C - Downlink load estimating method in mobile communication system - Google Patents

Abstract

The present invention relates to a radio communication technology, which discloses a downlink load estimation method in a mobile communication system so that a downlink load estimation can be well charged to an actual value dynamic change effect of an interference ratio of other cells to a cell, and differences among downlink loads of different cells can be reflected exactly; thereby, a downlink load estimation error is reduced. The downlink load estimation method in a mobile communication system divides the interference ratio of the other cells to the cell into a static part and a dynamic part, wherein the static part can be obtained by experimental simulation statistical average, and the dynamic part is determined by a relative measurement value of total launched power of the other cells and the cell; downlink load factors of the cell can be obtained by calculating according to an interference ratio of other cells to the cell and the autointerference of the cell.

Description

Downlink load estimating method in the mobile communication system

Technical field

The present invention relates to wireless communication technology, particularly utilize neighboring BS information that down load is carried out estimation approach in the broadband CDMA system.

Background technology

Sharp increase along with social progress and mobile communication subscriber quantity, the frequency resource growing tension, require mobile communication system that bigger power system capacity can be provided, higher communication quality, and the data service of two-forty can be provided, to satisfy people to the requirement of multimedia communication and adapt to the personalized developing direction of communication.

3-G (Generation Three mobile communication system) is to satisfy (the InternationalTelecommunication Union of International Telecommunications Union, abbreviation " ITU ") international mobile communication (the InternationalMobile Telecommunication 2000 that proposes, be called for short " IMT-2000 ")/following public land mobile (the Future Public Land Mobile Telephone Systems of system, abbreviation " FPLMTS ") third generation mobile communication system of standard, requirement has good network compatibility, can realize the roaming between a plurality of different systems in the global range, not only will be for the mobile subscriber provide speech and low-rate data business, and multimedia service widely will be provided.

The main candidate scheme of 3-G (Generation Three mobile communication system) is code division multiple access (the Code DivisionMultiple Access of North America, be called for short " CDMA ") 2000 systems, Wideband Code Division Multiple Access (WCDMA) (the WidebandCode Division Multiple Access in Europe, be called for short " WCDMA ") system and Chinese TD SDMA (Time Division Synchronous Code Division Multiple Access, be called for short " TD-SCDMA ") system, all be to be based upon on code division multiple access (CDMA) technical foundation, CDMA extensively has been received as the important technology of 3-G (Generation Three mobile communication system).

CDMA mobile communication system has high power capacity, spectral efficient, high quality-of-service, low cost, high security, is easy to advantages such as seamless switching and grand diversity.Also having simultaneously shortcoming, cdma system is an interference limiting system but not resource limited system, and its capacity is subjected to the restriction that multiple access disturbs between the user (MultipleAccess Interference is called for short " MAI ").In the cdma communication system of reality, the multiple access that causes owing to the different user correlation between signals disturbs, along with the increase of number of users or the increase of signal power, had a strong impact on the cdma communication system communication quality, directly limited the raising of cdma system capacity, coverage and performance.

Power is common source in the cdma wireless network, the capacity of cdma system is a kind of soft capacity, is a self-interference system, and each user constitutes interference to other users, each sub-district all constitutes other sub-district disturbs, and link performance and power system capacity depend on the control result of interference power.Work such as therefore, interference analysis, power configuration and soft handover planning seem particularly important.But because the various factors mutual restriction is often pulled one hair and move the whole body.

Admission Control (Call Admission Control in the present WCDMA system, be called for short " CAC ") and load control (Load Control, abbreviation " LC ") technology is crucial RRM (Radio Resources Management, be called for short " RRM ") method, carry out by RRM core controller radio network controller (Radio Network Controller is called for short " RNC ").

Because the calling of each new access all can increase the interference level of ongoing calling and to the interference level of neighbor cell, influence quality of service in the cdma system.Therefore, in the WCDMA system, adopted call admission control method to call out the control of access, to avoid a new calling that inserts to cause the quality of service of ongoing all-calls to descend, cause the situation of one or more calling call drops to take place even.In the Admission Control process, RNC judges whether enough vacant Radio Resource is arranged in the sub-district, make and insert signal interference ratio (the Signal-To-Interference Ratio that needs are certain, be called for short " SIR ") and fast new user or the switching user of sign indicating number, the load of system can not surpass certain thresholding of predesignating.Increase new business or increase the situation of user's service rate for the user in calling out, also can carry out access and call out control.About the call admission control method of WCDMA system, see also third generation partner program (3rd Generation Partnership Project is called for short " 3GPP ") agreement TS25.215 and TS25.922 in detail.

Consider the uncertain factor in the mobile communication, such as the adjacent area to the interference variations of this sub-district, environment to the influence of wireless channel etc., RNC can also adopt load control to carry out RRM more reliably.Different with Admission Control is, load control is a continuous process, and Admission Control is event driven process.Load control guarantees that the load of system maintains some predesignate below horizontal.It need carry out continuous supervision to system load.Such as, load control is carried out continuous measurement to system load, when system load overloads, then require to take certain measure to reduce the load of system, the system that makes is unlikely to collapse, such as the speed that reduces the certain user, postpone those data of emission to the insensitive business of time delay, perhaps directly allow other conversation loss of low priority.

Admission Control and load control all needs system load is measured or estimated, whether surpass the thresholding of certain regulation and judge whether to insert the user with the load of determining current system, whether perhaps definite system load overloads and judges whether starting load control.In cdma system, because the load of up-downgoing is asymmetric, therefore measurement and the estimation to system load also is that up-downgoing separates.As seen the accuracy of up-downgoing load estimation has directly influenced the performance of Admission Control and load control, and RRM even whole C DMA systematic function are had very large influence.

Document (H.Holma and A.Toskala, " WCDMA for UMTS, " John Wiley ﹠amp; SonsInc., two kinds of downlink load estimating methods have been provided 2000).

First method is based on the method for the total transmitting power of base station down, recently determines descending load by the percentage of descending total transmitting power and descending maximum transmission power, thereby calculates the down load factor.Its computing formula is as follows:

${\mathrm{\η}}_{\mathrm{DL}}=\frac{P_{\mathrm{total}}}{P_{\max }}---\left(1\right)$

Wherein, η _DLBe the down load factor, P _TotalBe descending total transmitting power, P _MaxBe descending maximum transmission power.

This method is come approximate reflection cell downlink load by measuring descending total transmission power level at the place, base station.And in actual applications, because differences such as the coverage of different sub-districts and wireless environment cause the power-carrying of different districts that bigger difference is arranged.This makes the descending total transmitting power measure cell base station can not accurately reflect the size that cell system disturbs, the down load that obtains thus well indication mechanism whether near power-carrying.And in fact, when system during near power-carrying, concuss can take place, it is very unstable that performance becomes, and causes a large number of users call drop easily, can not reach the effect of load control.

For the drawback of this method is described, Fig. 1 has provided the experiment simulation result to descending total transmitting power of different districts and down load factor relation.Adopt four different sub-districts of radius of society to carry out emulation, corresponding different radius of society has different greatest path loss (Max path loss), is respectively 130dB, 140dB, 145dB and 150dB.As seen, for different sub-districts, the descending total transmitting power and the down load factor concern that difference is very big.Such as, the maximum transmission power of supposing the base station is 20W, it then is the sub-district of 150dB for greatest path loss, when load is 45% left and right sides, base station transmitting power has just reached 20W, and be the sub-district of 135dB for greatest path loss, even cell load is 90%, maximum transmission power does not also reach 10W.As can be seen, under same descending total transmitting power, the air interface interference of the cell system that the air interface interference of the cell system that radius of society is smaller is bigger than radius of society is big.This shows that descending total transmitting power can not accurately reflect system interference information, and is also closely related with factors such as radius of societies.Therefore estimate that with first method the down load that obtains can not satisfy the demand of accurate wireless resource management.

Second method is to suppose that earlier other cell base stations and this cell base station are constant to the ratio (the F factor) that the user disturbs, then by adding up of unique user load factor obtained the load factor that this community user brings, count the load factor that bring other sub-districts according to the F factor again, obtain the load factor of system at last, this method is called F factor method.

Further specify the theoretical foundation and the performing step of F factor method below.The following power control of considering cdma system makes each user's received power arrive certain target signal interference ratio in its portable terminal everywhere convergent, then has for k user among the m of sub-district:

(E wherein _b/ N _o) _kIt is the target signal interference ratio of k customer service.In addition, user's processing gain can be calculated by spreading rate and service rate, user's incoming level is then obtained this user's the down transmitting power and the path loss calculation of respective wireless link by the base station, total reception is disturbed then and can be made up of this area interference and other area interference two parts, therefore formula (2) can further be written as

${\left(\frac{E_b}{N_o}\right)}_k=\frac{W}{R_k}\·\frac{p_k/L_{k,m}}{(1-\mathrm{\α})I_{\mathrm{ik}}+I_{\mathrm{ok}}+N}---\left(3\right)$

Here, W is a spreading rate, R _kBe k user's service rate, W/R _kBe user's processing gain; p _kBe the down transmitting power of k user's correspondence, L _{K, m}Be the path loss between the antenna for base station of k user and this sub-district (sub-district m), p _k/ L _{K, m}Be user's incoming level; I _IkBe this area interference of k user, I _OkBe other area interference, N is that the end at mobile phone place is hot-tempered, and α is the average orthogonalization factor in sub-district, and this three part is added up can obtain total reception interference.

Make that F is the interference ratio of other sub-district to this sub-district, i.e. F=I _Ok/ I _Ik, establish P again _mBe total transmitting power of the base station of sub-district m, then area interference is I _Ik=P _m/ L _{K, m}So formula (3) further is written as,

${\left(\frac{E_b}{N_o}\right)}_k=\frac{W}{R_k}\·\frac{p_k/L_{k,m}}{(1-\mathrm{\α}+F)I_{\mathrm{ik}}+N}=\frac{W}{R_k}\·\frac{p_k/L_{k,m}}{(1-\mathrm{\α}+F)\·p_m/L_{k,m}+N}---\left(4\right)$

Can write out p according to formula (4) _kExpression formula as follows,

$p_k=\frac{{\mathrm{\γ}}_k}{J_k}\·[(1-\mathrm{\α}+F)\·P_m+N\·L_{k,m}]$

γ wherein _k=(E _b/ N _o) _k, J _k=W/R _kSo total transmitting power of the m base station, sub-district that can be represented by the corresponding down transmitting powers of all users among the m of sub-district is as follows,

$P_m=\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·p_k=\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}\·[(1-\mathrm{\α}+F)\·P_m+N\·L_{k,m}]---\left(5\right)$

Wherein, v _kBe user's activity factor, K (m) represents the set that all users that insert sub-district m form.Total transmitting power that the arrangement following formula can be tried to achieve m base station, sub-district is,

$P_m=\frac{\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}\·L_{k,m}\·N}{1-\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}\·(1-\mathrm{\α}+F)}---\left(6\right)$

Cell downlink load factor η _DLBy formula $P_m=\frac{P_N}{1-{\mathrm{\η}}_{\mathrm{DL}}}$ Be defined as: ${\mathrm{\η}}_{\mathrm{DL}}=1-\frac{P_N}{P_m},$ P wherein _NBe that the supposition orthogonalization factor is α=1, and when not having other area interference, descending total transmitting power of sub-district m, promptly

$P_N=\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}\·L_{k,m}\·N---\left(7\right)$

By formula (6) (7), the cell downlink load factor can be expressed as,

${\mathrm{\η}}_{\mathrm{DL}}=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\frac{v_k\·{\mathrm{\γ}}_k}{J_k}\·[(1-\mathrm{\α})+F]---\left(8\right)$

The F factor be other sub-district of statistical average to this area interference ratio, it can determine by emulation, thereby generally is to estimate under all sub-districts evenly distribute the much the same situation of the descending interference of each sub-district the supposition user to obtain.And in fact, the dynamic change of F value and concrete wireless channel environment, cell layout and other sub-district and this cell load is relevant, but in the present load estimating method, all use the interference ratio of a statistical average to estimate, this just inevitably brings because the error that the loading condition dynamic change is produced between the different districts.

As seen, F factor method is according to characteristic and other sub-district of business the assembly average of the disturbing effect of this sub-district to be come the computational load factor.But in the real system, because other sub-district is not constant to the interference ratio of this sub-district, be different at first for different districts, low at this cell load and under the situation that the peripheral cell load is high, other sub-district is to this area interference ratio height, otherwise other sub-district is low to this area interference ratio; Secondly inscribing when the difference for same sub-district also is dynamic change, and the number of users of each sub-district and load all are dynamic changes, so other sub-district also inevitably will change to this area interference ratio.As seen, the F factorization method can not be considered the dynamic effect of other sub-districts to this area interference ratio, in actual applications, must cause bigger down load evaluated error.

In actual applications, there is following problem in such scheme: the method estimated accuracy based on descending total transmitting power is low, can not reflect the power system capacity Limiting Level well; F factor method estimates that accuracy is subjected to that other sub-districts are to the dynamic effects of this area interference ratio in the practical application, and therefore the evaluated error of resulting down load is all very big, can not satisfy requirement of actual application well.

Cause the main cause of this situation to be, directly represent system interference information with descending total transmitting power based on the method for descending total transmitting power, and the difference of different districts is very big in the practical application, descending total transmitting power can't the indication mechanism interference level; F factor method adopts other constant sub-districts the assembly average of this area interference ratio to be estimated this compares the actual value of this area interference ratio with other sub-districts of dynamic change and has error.

Summary of the invention

In view of this, main purpose of the present invention is to provide downlink load estimating method in a kind of mobile communication system, make down load estimate to count the effect of other sub-districts well to the actual value dynamic change of this area interference ratio, accurately reflect the difference between the different districts down load, thereby reduce the down load evaluated error.

For achieving the above object, the invention provides downlink load estimating method in a kind of mobile communication system, comprise following steps,

A sets or adjusts the static parameter factor of this sub-district;

B is according to the relative measurement value of descending total transmitting power of descending total transmitting power of this sub-district and other sub-districts, and the described static parameter factor of this sub-district, calculates other sub-districts to this area interference ratio;

C to this area interference ratio, calculates the down load factor of this sub-district according to described other sub-districts;

Wherein, the described static parameter factor is used for indicating described other sub-districts that this area interference is compared along with allocation of radio resources changes static constant part, represents the relativeness of other sub-district path losses and this sub-district path loss; The relative measurement value of descending total transmitting power of described this sub-district and descending total transmitting power of other sub-districts is used for indicating described other sub-districts that this area interference is compared along with allocation of radio resources changes and the part of dynamic change.

Wherein, described downlink load estimating method is applied in the access control or load control of the base station in the WCDMA mobile communication system.

Described steps A comprises following substep,

According to the actual conditions of cell system, to the described static parameter factor simulation calculation that experimentizes;

According to the statistics that described experiment simulation calculates, set or adjust the described static parameter factor.

The static parameter factor of this sub-district described in the described steps A obtains by the statistical average to all users' of this sub-district the described static parameter factor, wherein k user's of this sub-district described static parameter because of $C_{k,m}=\frac{\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}\·\frac{L_{k,m}}{L_{k,n}}}{\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}}$ K user's the described static parameter factor, P _nBe described descending total transmitting power of described other sub-districts n, P _mBe respectively described descending total transmitting power of this sub-district, L _{K, n}Be the wireless link path loss of the base station of described other sub-districts, L to k user of described this sub-district _{K, m}Be the wireless link path loss to k user of described this sub-district of the base station of this sub-district, M be the set of this sub-district and all described other sub-districts compositions,

Expression is to all described other sub-district summations.

Step B comprises following substep,

B1 measures the absolute measured value of descending total transmitting power of the absolute measured value of descending total transmitting power of described this sub-district and described other sub-districts;

B2 is obtained the relative measurement value of descending total transmitting power of descending total transmitting power of described this sub-district and other sub-districts by the ratio of the absolute measured value sum of descending total transmitting power of the absolute measured value of descending total transmitting power of described this sub-district and all described other sub-districts;

B3 obtains described other sub-districts to this area interference ratio by the relative measurement static parameter factor with described this sub-district on duty of descending total transmitting power of descending total transmitting power of described this sub-district and other sub-districts.

Described step B1 comprises following substep,

This sub-district is measured the absolute measured value of descending total transmitting power of described this sub-district in real time;

This sub-district is broadcast to all described other sub-districts with the absolute measured value of descending total transmitting power of described this sub-district;

This sub-district receives the absolute measured value of descending total transmitting power of all described other sub-districts.

Other sub-districts calculate according to following formula this area interference beguine described in the described step B,

$F_m=C\·\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}$

Wherein, F _mFor other sub-districts of described this sub-district to this area interference ratio, C is the static parameter factor of described this sub-district, P _nBe described descending total transmitting power of described other sub-districts n, P _mBe respectively described descending total transmitting power of this sub-district m, M is the set that this sub-district and all described other sub-districts are formed,

Expression is to all described other sub-district summations, F _mBe the interference ratio of other sub-districts to this sub-district.

This cell downlink load factor calculates according to following formula described in the described step C,

${\mathrm{\η}}_{\mathrm{DL},m}=(1-\mathrm{\α})\·\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}+F_m\·\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}$

Wherein, η _{DL, m}Be the down load factor of described this sub-district, α is the average orthogonalization factor of this sub-district, v _kBe k the user's in this sub-district activity factor, γ _kBe the target signal interference ratio of this k customer service in sub-district, J _kBe user's processing gain of k the user in this sub-district, K (m) represents the set that all users of this sub-district form, F be other sub-districts of described this sub-district to this area interference ratio,

Expression is to all user's summations of this sub-district.

Described other sub-districts only comprise the adjacent cell in the limit of consideration.

By relatively finding, technical scheme difference with the prior art of the present invention is, is static part and dynamic part with other sub-districts to the score of this area interference, wherein static part is obtained by experiment simulation statistical average, dynamic part is determined by the relative measurement value of total transmitting power of other sub-districts and this sub-district, according to the down load factor of other sub-districts, calculate this cell downlink load factor again to this area interference ratio and this sub-district self interference.

Difference on this technical scheme, brought comparatively significantly beneficial effect, promptly owing to considered static part and the dynamic part comprehensive effect of other sub-districts to the interference ratio of this sub-district, the actual motion-change effect of Kao Lving well, improve the down load factor greatly and estimated accuracy, dynamic part is determined by the relative measurement value of total transmitting power of other sub-districts and this sub-district simultaneously, therefore the static shift error of having avoided absolute measured value to bring has effectively further improved the estimation accuracy of the down load factor.

Description of drawings

Fig. 1 is the descending total transmitting power of different districts and the experiment simulation result schematic diagram of down load factor relation;

Fig. 2 is that neighbor cell according to an embodiment of the invention produces the physical mechanism schematic diagram that disturbs to this sub-district;

Fig. 3 is a downlink load estimating method flow chart according to an embodiment of the invention.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, the present invention is described in further detail below in conjunction with accompanying drawing.

The present invention is according to the relative size information of total transmitting power measured value of total transmitting power measured value of adjacent other sub-districts and this sub-district, dynamically determine the interference ratio of other sub-districts to this sub-district, thereby considered the motion-change effect in the practical application, and the relative measurement value information that is adopted can effectively avoid the influence that static shift brought in the absolute measured value, and therefore the estimated down load precision that obtains is greatly improved.Here define the C factor and be described according to the relative measurement value information other sub-districts of dynamically determining to the interference ratio of this sub-district, and the downlink load estimating method that is adopted is called C factor method.

C factor method is utilized total transmitting power measured value of adjacent other sub-districts, calculate of the influence of other sub-district to this cell load factor, make to the situation of the different and same cell load real-time change of different districts load, all can correctly react the actual value of other sub-districts of dynamic change this area interference ratio.

Other sub-districts of expression of the present invention obtain through strict theoretical the C factor of this area interference effect, and are verified well in actual applications, have obtained actual effect.Provide the derivation of the C factor according to an embodiment of the invention below in detail.

As previously mentioned, descending power control makes each user's received power arrive certain signal interference ratio in the portable terminal everywhere convergent in the CMDA system.

Suppose that descending power control makes each user's received power arrive certain signal interference ratio in the mobile phone everywhere convergent.Have for k user among the m of sub-district:

${\mathrm{\γ}}_k=J_k\frac{p_k/L_{k,m}}{(1-\mathrm{\α})I_{\mathrm{ik}}+I_{\mathrm{ok}}+N}---\left(9\right)$

γ wherein _k=(E _b/ N _o) _kIt is the target signal interference ratio of k customer service; J _kIt is user's processing gain of k user; I _IkBe this area interference of k user, I _OkBe other area interference, N makes an uproar at the end at portable terminal place, and α is the average orthogonalization factor in sub-district; p _kBe the down transmitting power of k user's correspondence, L _{K, m}Be the path loss between the antenna for base station of k user and this sub-district (sub-district m).

Consider this area interference I _IkCan be by the total transmitting power P of this cell downlink _mAnd path loss L between user base station _{K, m}Determine that other area interference can be disturbed to add up to the user and obtain by every other sub-district, and a certain sub-district (sub-district n, n ∈ M, n ≠ m, the set that M forms for all base stations) can be by the total transmitting power P of this cell downlink to user's interference _nAnd its base station is to the path loss L between the user _{K, n}Determine.So following formula can further be written as,

${\mathrm{\γ}}_k=J_k\frac{p_k/L_{k,m}}{(1-\mathrm{\α})\·P_m/L_{k,m}+\underset{n\∈M,n\≠m}{\mathrm{\Σ}}{P}_n/L_{k,n}+N}---\left(10\right)$

L wherein _{K, n}Be the path loss between the antenna for base station of k user and other sub-districts (sub-district n); P _nBe descending total transmitting power of sub-district n, the set that M forms for all base stations.

In the following formula, this area interference and other area interference all are accurately to derive from the physical mechanism of cell communication to obtain, thereby guarantee that C factor method of the present invention can accurately estimate the contribution of other sub-districts to this cell downlink load factor.Fig. 2 is that neighbor cell according to an embodiment of the invention produces the physical mechanism schematic diagram that disturbs to this sub-district.Wherein, k user among the m of sub-district is subjected to the interference of this cell base station and n base station, sub-district, and this cell base station is L to the path loss of user's Radio Link 201 _{K, m}, n base station, sub-district is L to the path loss of user's Radio Link 202 _{K, n}

Notice that formula (10) place different with F factor method is, adopt accurate expression to represent other area interference, and other constant sub-districts of hypothesis of no use represented to this area interference ratio here.This has guaranteed that theoretical foundation of the present invention is enough accurate.

Can be got by formula (10), k the pairing cell base station down transmitting power of user be,

$p_k=\frac{{\mathrm{\γ}}_k}{J_k}\·[(1-\mathrm{\α})\·P_m+\underset{n\∈M,n\≠m}{\mathrm{\Σ}}{P}_n\·\frac{L_{k,m}}{L_{k,n}}+N\·L_{k,m}]---\left(11\right)$

Consider the summation of the base station of sub-district m, promptly obtain descending total transmitting power P of sub-district m all users' down transmitting power in this sub-district _m, can be written as,

$P_m=\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·p_k=\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}\·[(1-\mathrm{\α})\·P_m+\underset{n\∈M,n\≠m}{\mathrm{\Σ}}{P}_n\·\frac{L_{k,m}}{L_{k,n}}+N\·L_{k,m}]---\left(12\right)$

V wherein _kBe user's activity factor, K (m) represents the set that all users that insert sub-district m form.So have,

$P_m=\frac{\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}\·L_{k,m}\·N}{1-\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}\·[(1-\mathrm{\α})+\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}\·\frac{L_{k,m}}{L_{k,n}}]}---\left(13\right)$

According to definition $P_m=\frac{P_N}{1-{\mathrm{\η}}_{\mathrm{DL}}},$ Can write out the down load factor η of sub-district m _{DL, m}For,

${\mathrm{\η}}_{\mathrm{DL},m}=\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}\·[(1-\mathrm{\α})+\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}\·\frac{L_{k,m}}{L_{k,n}}]---\left(14\right)$

In one embodiment of the invention, consider in the real system, the relative position of cell base station and wireless link environment basic fixed thereof, therefore in the regular hour, other cell base stations in the formula (14) satisfy the standard of static parameter substantially to the path loss of this user's Radio Link, therefore this static parameter is separated, and characterize other sub-district path losses and this sub-district path loss relativeness with parameter factors C, be that the transmitting power measured value of available other sub-districts calculates other required area interference on this basis.Parameter factors C is defined as follows,

$C_{k,m}=\frac{\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}\·\frac{L_{k,m}}{L_{k,n}}}{\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}}---\left(15\right)$

As seen, to be cell base station by the relative physical location of sub-district basically determined to user's path loss parameter factors C, reflected the static characteristic of cell system.In a preferred embodiment of the present invention, this parameter factors can be obtained by experimentize according to the real cell physical location simulation result and statistical average.

With reference to F factor method, define the ratio F of other sub-districts to this area interference _{K, m}, and further be expressed as follows with parameter factors C,

$F_{k,m}=\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}\·\frac{L_{k,m}}{L_{k,n}}=C_{k,m}\·\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}---\left(16\right)$

As can be seen, by two parts gained that multiplies each other, wherein parameter factors C reflection static parameter characteristic is called the static part parameter to this area interference ratio in other sub-districts; Another part reflection dynamic parameter characteristic is called the dynamic part parameter.In fact, dynamic part is the ratio sum of total transmitting power of total transmitting power of other sub-districts and this sub-district, as previously mentioned, and in real system, because community user skewness, variant, the same community user traffic load of geographical environment such as change in time at dynamic factor, to cause total transmitting power dynamic change of sub-district, therefore the dynamic part parameter is the amount of a dynamic change, these are different to be that parameter factors C is only determined by the relative physical location in sub-district with the static part parameter, does not move with the user in time basically and changes.

Contrast F factor method as seen, have only when the service distribution of all users in system even, and it is the same to insert the number of users of different districts, and when causing the total transmitting power of each cell downlink the same, above-mentioned dynamic part parameter just equals a constant.In the ordinary course of things, professional distribution in system is not necessarily uniform, descending total transmitting power of each sub-district is also different, and this dynamic part parameter can not represent with a constant, but one along with sub-district difference, asynchronism(-nization) and different running parameters.Obviously F factor method can not reflect this dynamic effect, and the ratio of C factor rule by different total transmitting power sums of other cell downlink and the total transmitting power of this cell downlink can dynamically reflect this situation.

It is as follows to rewrite the down load factor by formula (15) (16),

${\mathrm{\η}}_{\mathrm{DL},m}=\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}\·\left[(1-\mathrm{\α}){+F}_{k,m}\right]=\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}\·[(1-\mathrm{\α})+C_{k,m}\·\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}]---\left(17\right)$

In one embodiment of the invention, with assembly average C replaced C _{K, m}, then have,

${\mathrm{\η}}_{\mathrm{DL},m}=\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}\·(1-\mathrm{\α})+C\·\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}\·\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}---\left(18\right)$

As can be seen from the above equation, the cell load factor can be divided into two parts, and a part is the load factor that this area interference causes, and another part is the load factor that other sub-district causes this area interference; Other sub-district to this cell load not only on physical significance but also can be divided into two parts and multiply each other, i.e. static part parameter and dynamic part parameter.The only basic and wireless environment of static part, the sub-district distributes relevant with the statistical property of user distribution, is the constant of a static state substantially, is reflected among the parameter factors C; The dynamic part parameter is relevant with the total transmitting power ratio of this cell downlink with this Zone and the total transmitting power of other cell downlink, and the dynamic change of this each cell radio resource of part reflection is a dynamic subitem.

In one embodiment of the invention, each sub-district is measured dynamically and monitored and obtain calculating the total transmitting power in the required sub-district of the down load factor.Corresponding to each sub-district, total transmitting power measured value of all sub-districts that can be provided by other sub-districts calculates the dynamic part parameter.Thereby calculate down load factor estimated value according to formula (18).

C parameter factors method of the present invention can be utilized the actual measured value of other sub-district in real time, estimates this cell downlink load factor, thereby has avoided F factor method directly to suppose the drawback of other cell load factor by this cell load factor.In addition, adopt total transmitting power of other cell downlink and the total transmitting power ratio in this sub-district as estimated parameter, the influence that the absolute error of avoiding is brought.Because in real system, because the base station is relatively responsive to environmental factors such as temperature, there is the error of a static shift in the total transmission power level that causes measuring, makes total transmitting power absolute measured value of sub-district have error.And the base station of considering a certain zone all is in same temperature province, therefore variations in temperature is basic identical to the static shift that total transmitting power measurement brings, this makes the relative measurement value of the total transmitting power in sub-district can keep stable, thus the influence of avoiding environmental factor such as temperature to bring.

In a preferred embodiment of the present invention, consider that other cell base stations are to user's the path loss and the relation of actual range exponentially time decay under the actual conditions, therefore for distance sub-district far away, the huge decay that is caused by path loss makes this sub-district can ignore user's interference.Based on these actual conditions, when calculating the total transmitting power ratio of other sub-districts to this sub-district, gather with the adjacent cell that M (m) is illustrated in the limit of consideration sub-district that a consideration is contiguous with this sub-district, and then formula (18) is written as,

${\mathrm{\η}}_{\mathrm{DL},m}=\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}\·(1-\mathrm{\α})+C\·\underset{n\∈M\left(m\right),n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}\·\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}---\left(19\right)$

In a preferred embodiment of the present invention, the statistics by to the experiment simulation of sub-district actual conditions is provided with statistical parameter factor C value, and the value to parameter factors C adjusts accordingly when cell environment or setting change.

In a preferred embodiment of the present invention, all sub-districts are all measured the total transmitting power of self in real time, and self total transmitting power measured value is broadcast to other cell systems, realize that each sub-district all can obtain total transmitting power measured value of all sub-districts in real time, estimates this cell downlink load factor by C factor method thus.

According to aforementioned C factor method derivation, Fig. 3 shows down load factor method of estimation flow chart according to an embodiment of the invention.

Then enter step 301, obtain the parameter factors C value on the statistical significance of this sub-district by simulation calculation or experiment measuring, computing formula is as (15).Carry out emulation such as simulation softwares such as can adopting MATLAB, perhaps carry out field survey, obtain the parameter factors C value of statistical average the real cell signal intelligence.

Then enter step 302, in the communication process, each sub-district is measured the total transmission power level of self in real time.Because the present invention adopts the relative measurement value, so this measurement allows the static shift error.

Then enter step 303, calculate the interference ratio of other sub-districts to this sub-district according to the parameter factors C that obtains in total transmission power level of total transmission power level of this sub-district that measures in the step 302 and other sub-districts and the step 301, computing formula is suc as formula (16).

Then enter step 304, calculate the down load factor of this area interference, be i.e. a preceding part in the formula (19).

Then enter step 305, according to the interference ratio of other sub-districts that calculate in the step 303 to this sub-district, and the down load factor of this area interference of obtaining of step 304, can calculate the down load factor of other area interference, it is a back part in the formula (19), obtain the down load factor of this sub-district thus, computing formula is suc as formula (19).

Though by reference some preferred embodiment of the present invention, the present invention is illustrated and describes, but those of ordinary skill in the art should be understood that, can do various changes to it in the form and details, and the spirit and scope of the present invention that do not depart from appended claims and limited.

Claims (9)

1. downlink load estimating method in the mobile communication system is characterized in that, comprises following steps,

A sets or adjusts the static parameter factor of this sub-district;

B is according to the relative measurement value of descending total transmitting power of descending total transmitting power of this sub-district and other sub-districts, and the described static parameter factor of this sub-district, calculates other sub-districts to this area interference ratio;

C to this area interference ratio, calculates the down load factor of this sub-district according to described other sub-districts;

Wherein, the described static parameter factor is used for indicating described other sub-districts that this area interference is compared along with allocation of radio resources changes static constant part, represents the relativeness of other sub-district path losses and this sub-district path loss; Described relative measurement value is used for indicating described other sub-districts that this area interference is compared along with allocation of radio resources changes and the part of dynamic change.

2. downlink load estimating method in the mobile communication system according to claim 1 is characterized in that, described method is applied in the access control or load control of the base station in the WCDMA mobile communication system.

3. downlink load estimating method in the mobile communication system according to claim 1 is characterized in that described steps A comprises following substep,

According to the actual conditions of cell system, to the described static parameter factor simulation calculation that experimentizes;

According to the statistics that described experiment simulation calculates, set or adjust the described static parameter factor.

4. according to downlink load estimating method in the described mobile communication system of claim 1, it is characterized in that, the static parameter factor of this sub-district described in the described steps A obtains by the statistical average to all users' of this sub-district the described static parameter factor, wherein k user's of this sub-district the described static parameter factor is calculated by following formula

$C_{k,m}=\frac{\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}\·\frac{L_{k,m}}{L_{k,n}}}{\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}}$

Wherein, C _{K, m}Be k the user's of described this sub-district m the described static parameter factor, P _nBe described descending total transmitting power of described other sub-districts n, P _mBe respectively described descending total transmitting power of this sub-district, L _{K, n}Be the wireless link path loss of the base station of described other sub-districts, L to k user of described this sub-district _{K, m}Be the wireless link path loss to k user of described this sub-district of the base station of this sub-district, M be the set of this sub-district and all described other sub-districts compositions,

Expression is to all described other sub-district summations.

5. according to downlink load estimating method in the described mobile communication system of claim 1, it is characterized in that step B comprises following substep,

B1 measures the absolute measured value of descending total transmitting power of the absolute measured value of descending total transmitting power of described this sub-district and described other sub-districts;

B2 is obtained the relative measurement value of descending total transmitting power of descending total transmitting power of described this sub-district and other sub-districts by the ratio of the absolute measured value sum of descending total transmitting power of the absolute measured value of descending total transmitting power of described this sub-district and all described other sub-districts;

B3 obtains described other sub-districts to this area interference ratio by the relative measurement static parameter factor with described this sub-district on duty of descending total transmitting power of descending total transmitting power of described this sub-district and other sub-districts.

6. according to downlink load estimating method in the described mobile communication system of claim 5, it is characterized in that described step B1 comprises following substep,

This sub-district is measured the absolute measured value of descending total transmitting power of described this sub-district in real time;

This sub-district is broadcast to all described other sub-districts with the absolute measured value of descending total transmitting power of described this sub-district;

This sub-district receives the absolute measured value of descending total transmitting power of all described other sub-districts.

7. according to downlink load estimating method in the described mobile communication system of claim 5, it is characterized in that other sub-districts calculate according to following formula this area interference beguine described in the described step B,

$F_m=C\·\underset{n\∈M,n\≠m}{\mathrm{\Σ}}\frac{P_n}{P_m}$

Wherein, F _mFor other sub-districts of described this sub-district to this area interference ratio, C is the static parameter factor of described this sub-district, P _nBe described descending total transmitting power of described other sub-districts n, P _mBe respectively described descending total transmitting power of this sub-district m, M is the set that this sub-district and all described other sub-districts are formed, Expression is to all described other sub-district summations.

8. according to downlink load estimating method in the described mobile communication system of claim 7, it is characterized in that this cell downlink load factor calculates according to following formula described in the described step C,

${\mathrm{\η}}_{\mathrm{DL},m}=(1-\mathrm{\α})\·\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}+F_m\·\underset{k\∈K\left(m\right)}{\mathrm{\Σ}}{v}_k\·\frac{{\mathrm{\γ}}_k}{J_k}$

Wherein, η _{DL, m}Be the down load factor of described this sub-district, α is the average orthogonalization factor of this sub-district, v _kBe k the user's in this sub-district activity factor, γ _kBe the target signal interference ratio of this k customer service in sub-district, J _kBe user's processing gain of k the user in this sub-district, K (m) represents the set that all users of this sub-district form, F be other sub-districts of described this sub-district to this area interference ratio,

Expression is to all user's summations of this sub-district, F _mBe the interference ratio of other sub-districts to this sub-district.

9. according to downlink load estimating method in each described mobile communication system in the claim 1 to 8, it is characterized in that described other sub-districts only comprise the adjacent cell in the limit of consideration.

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