Background technology
The cell mobile communication systems of different systems is usually by adopting different technical characterictic parameters to distinguish the signal of neighbor cell.3-G (Generation Three mobile communication system) has extensively adopted code division multiple access (CDMA) access way, and the essential characteristic of system is exactly to distinguish different users with different code words, then distinguishes the neighbor cell of common-frequency network in the TD-SCDMA system with scrambler.
The fixed correspondence of the various intersymbols of the system of TD-SCDMA shown in the table 1.Table 1:
In the table (3GPP standard), the sign indicating number that the TD-SCDMA system is used is divided into 32 groups, i.e. 32 code characters, each code character is to having: a descending pilot frequency (synchronously) sign indicating number SYNC_DL (ID is 0 to 31), 8 ascending pilot frequencies (or claiming synchronously) sign indicating number SYNC_UL (ID is 0 to 255), 4 scramblers (ID is 0 to 127) and 4 basic midamble sign indicating numbers (ID is 0 to 127).Wherein descending pilot frequency (or claiming synchronously) sign indicating number is used to distinguish different sub-districts in the cell initial search process, and ascending pilot frequency (synchronously) sign indicating number is used for the random access procedure of terminal.There is corresponding relation as shown in Table 1 in the employed descending pilot frequency intersymbol in ascending pilot frequency sign indicating number that uses in the sub-district and sub-district, corresponding 8 the ascending pilot frequency sign indicating numbers of downlink frequency pilot code.
Therefore, after the downlink frequency pilot code of determining certain sub-district, can be from table 1 select a scrambler in 4 scramblers of the scrambler group corresponding as this sub-district with this downlink frequency pilot code, and because there is one-to-one relationship in scrambler with basic midamble sign indicating number, therefore corresponding basic midamble sign indicating number has also just been determined.Basic midamble sign indicating number can produce the midamble sign indicating number that is used for channel estimating according to certain skew.
Defined 128 scrambler sequence of TD-SCDMA system in the 3GPP standard, this sequence not only can be used for finishing the frequency expansion sequence scrambling of TD-SCDMA system Uplink/Downlink, and can the neighbor cell signal from the TD-SCDMA network be identified.Therefore, 128 scrambler sequence can be used for identifying the neighbor cell signal of 128 same frequencys of TD-SCDMA network in theory.128 scramblers of TD-SCDMA system can constitute 128 * 16=2048 compound code word altogether by making up with 16 channel codes.Because TD-SCDMA system, present diversity by scrambler along with the different of scrambler with the correlation that channel code makes up between the compound code word that is constituted, therefore the interference that produces also will change with different sign indicating number allocative decisions, but under the situation of considering the channel delay diffusion fully synchronously and not, correlation between compound code word can be divided into three kinds of forms of expression on the whole, respectively with three phase relation numerical value corresponding (these three kinds of forms of expression are not enumerated one by one at this).
In the scheme of existing realization 3GPP code word planning, the flow process of planning is to carry out district code word planning according to the order of " downlink frequency pilot code → scrambler code character → scrambler ".As shown in Figure 1, promptly carry out the planning of downlink frequency pilot code earlier, (step 11) just can determine that according to table 1 (step 12) is selected scrambler (step 13) according to table 1 to the scrambler code character at last again to the allocation of downlink pilot code then.
This sign indicating number programme can guarantee the downlink frequency pilot code difference of adjacent two minizones based on downlink frequency pilot code, and the while terminal is the correct downlink frequency pilot code of search cell also.But because this yard programme is the sign indicating number distribution that is planned to the basis with downlink frequency pilot code, do not take all factors into consideration the interference problem that exists correlation (phenomenon appears overlapping in compound code word) to be brought between the compound code word that constitutes by scrambler and channel code, therefore the capacitance loss in the time of can causing the networking of TD-SCDMA system same frequency, thereby can not be applicable to the network planning of TD-SCDMA system well.
The interference problem that causes at correlation between the compound code word that scrambler and channel code constituted, in the sign indicating number planing method of another kind based on basic scrambler group, proposed 128 scramblers of TD-SCDMA are divided into 12 basic scrambler groups, and be the planning that cell scrambling is carried out on the basis with these basic scrambler groups, as shown in Figure 2.The flow process of planning be according to " basic scrambler set of dispense (step 21) → downlink frequency pilot code is distributed (step 22) → determine scrambler (step 23) " in sequence.In this programme, the basic scrambler group that obtains according to its group technology has following feature: overlap phenomenon with occurring compound code word between the scrambler in the basic scrambler group, and the phenomenon that compound code word overlaps can not appear between the scrambler of different basic scrambler groups, thereby when carrying out sign indicating number planning, will stipulate to select in same basic scrambler group the scrambler of neighbor cell, the scrambler of neighbor cell can only be selected in different basic scrambler groups.
Carry out sign indicating number planning by basic scrambler group, though can solve the strong jamming problem of being brought because of compound code word coincidence, but because basic scrambler group has only 12 groups altogether, so when a scrambler has been determined in a sub-district in a single day, then its neighbor cell just can only be selected in remaining 11 basic scrambler groups, the adjacent number of cells that require to be investigated this moment must be lower than 11, just can finish the planning of basic scrambler group.Limited basic scrambler code character will make the size of multiplexing cluster reduce, thereby cause the utilance of scrambler to descend greatly, and promptly this scheme is to reduce strongly disturbing probability of happening by sacrificing certain scrambler utilance.
In sum, the TD-SCDMA system presents diversity by scrambler with correlation between compound code word that channel code is constituted along with the different of scrambler, and therefore the interference that produces also will change with different sign indicating number allocative decisions; Traditional cdma system network plan method based on the scrambler allocative decision owing to the correlation that does not take into full account between compound code word changes the interference effect that brings, thereby can not be applicable to the network planning of TD-SCDMA system well; This traditional scheme is carried out improved cell scrambling programme based on basic scrambler group, though the correlation that can solve between compound code word changes the interference effect problem of being brought, the utilance of scrambler is low excessively.
Summary of the invention
The objective of the invention is to design a kind of method that realizes optimizing code planning CDMA system, reduce because compound code word overlaps the interference that the brought influence to power system capacity as far as possible, improve the whole antijamming capability of network, guaranteeing the sign indicating number planning of the system that finishes under the less prerequisite of co-channel interference.
The technical scheme that realizes the object of the invention is: a kind of method that realizes optimizing code planning CDMA system is characterized in that comprising:
A. at first carry out scrambling code planning, be included as scrambler Cell searching to be allocated and can use scrambler and when satisfying the search end condition, finish search, output scrambling code planning result;
B. determine scrambler group and planning downlink frequency pilot code according to the fixed correspondence of scrambler and scrambler group, descending pilot frequency intersymbol by the scrambling code planning result then.
In the described steps A, for scrambler Cell searching to be allocated can be used scrambler, be with whole scramblers as candidate scramble code, therefrom be available scrambler of scrambler cell selecting to be allocated, this available scrambler satisfies scrambler with the neighbor cell of this sub-district to be allocated and is not in condition in the same scrambler group.
In the described steps A, can use scrambler for scrambler Cell searching to be allocated, be to set up the scrambler resource pond with priority level in advance; During search, preferentially from other scrambler resource pond of limit priority, select available scrambler, and in other scrambler resource pond of high priority during no available scrambler, select available scrambler from other scrambler resource pond of low priority, this available scrambler satisfies scrambler with the neighbor cell of this sub-district to be allocated and is not in condition in the same scrambler group.
The described scrambler resource pond of setting up in advance with priority level, be that will to meet the identical correlation form of expression be that the identical scrambler of phase relation numerical value is placed in the scrambler resource pond of same priority level, the priority level in the scrambler resource pond that phase relation numerical value is big more is low more, and the priority level in the scrambler resource pond that phase relation numerical value is more little is high more.
The sign indicating number planning that optimization method of the present invention adopts is " scrambler → scrambler group → downlink frequency pilot code " in proper order, after scrambling code planning is finished, just the scrambler group can be determined according to the intrinsic relation between scrambler and scrambler group, and just downlink frequency pilot code can be obtained according to the intrinsic relation of scrambler group and descending pilot frequency intersymbol.When carrying out scrambling code planning, the present invention is that scrambler Cell searching to be allocated can be used scrambler and in search procedure, optimize the scrambler search procedure by creating other scrambler resource pond of different priorities by a kind of searching method.
The planning of TD-SCDMA system cell code word is carried out in sign indicating number planning according to " scrambler → scrambler group → downlink frequency pilot code " in proper order, and can not exist owing to the group technology of scrambler or scrambling code etc. change influences yard problem of planing method applicability; Simultaneously,, then can reduce the harmful effect of co-channel interference, improve the whole antijamming capability of network the TD-SCDMA power system capacity by creating the process that the scrambler search is optimized in other scrambler resource pond of different priorities.
The invention has the beneficial effects as follows: can reduce because compound code word overlaps the interference that brought to Effect on Performance such as power system capacities as far as possible, improve the whole antijamming capability of network, in the sign indicating number planning that guarantees to finish under the less prerequisite of co-channel interference the TD-SCDMA system.
In a word, the present invention is the sign indicating number planing method of a kind of TD-SCDMA of being highly suitable for system.
Embodiment
The present invention proposes the sign indicating number planing method of distributing based on scrambler of a kind of TD-SCDMA of being suitable for system.This method with scrambling code planning, be assigned as the basis, carrying out sign indicating number when planning, carry out cell code planning according to the order of " scrambler → scrambler group → downlink frequency pilot code ".Promptly at first utilize the optimization searching algorithm, be that target is carried out scrambling code planning with sign indicating number allocative decision coefficient of total correlation minimum, determine the scrambler group according to the distribution relation of scrambler in the scrambler group then, carry out the distribution of downlink frequency pilot code at last again according to the relation of scrambler group and downlink frequency pilot code.
Referring to Fig. 3, the sign indicating number programme flow chart that the TD-SCDMA system distributes based on scrambler.By the correlation difference between TD-SCDMA system different composite code word is analyzed, with coefficient correlation influence degree between scrambler is described, utilize the coefficient of total correlation of scrambler allocative decision to weigh the annoyance level of yard allocative decision to whole system, and under the target of coefficient of total correlation minimum, according to the planning order of " scrambler → scrambler group → downlink frequency pilot code ", realize the sign indicating number programme of TD-SCDMA network.
Step 31 is based on the scrambling code planning of scrambler correlation.In the sign indicating number programme flow process that the TD-SCDMA system distributes based on scrambler, be the first step based on the scrambling code planning of scrambler correlation, also be a very crucial step, because its can directly influence the distribution of the definite and downlink frequency pilot code of scrambler group.Carrying out scrambling code planning (step 312) before, need calculate and preserve the coefficient correlation (step 311) between all scramblers earlier, and then be that target is carried out scrambling code planning with the sign indicating number allocative decision coefficient of total correlation (total disturb) minimum.When calculating the sign indicating number allocative decision coefficient of total correlation, access the coefficient correlation between the related scrambler of yard allocative decision the coefficient correlation between all scramblers of preserving, and calculate the coefficient of total correlation.The coefficient correlation of calculating and preserving between all scramblers only need be carried out once.
Step 32 is determined the scrambler group.After the scrambler allocative decision is determined, just determined the scrambler group according to scrambler place code character in the table 1.
Step 33, the planning downlink frequency pilot code.According to the relation of scrambler place code character in the table 1 and descending pilot frequency intersymbol, corresponding downstream pilot code allocative decision has also just been determined (promptly in fact do not need to carry out specially definite work of scrambler group and downlink frequency pilot code, only need just can obtain according to checking result).
In the sign indicating number programme flow process that the TD-SCDMA system that the inventive method proposes distributes based on scrambler, because scrambler distribute to be based on the correlation analysis between scrambler, even the application that also can not influence yard planing method itself has taken place to change for the group technology of scrambler group even the scrambler in the code character, therefore has very strong adaptability.Simultaneously, because scrambler, downlink frequency pilot code and scrambler interblock exist corresponding relation as shown in table 1, so after the scrambler allocative decision is determined, relation according to scrambler place code character and descending pilot frequency intersymbol, corresponding downstream pilot code allocative decision has also just been determined, and do not need to carry out specially the distribution of scrambler group and downlink frequency pilot code, in guaranteed performance, also greatly reduce the complexity of yard planning.
Stress in the step 31 scrambling planning method (step 312) below in conjunction with Fig. 4 based on intersymbol dependence.
Step 41, the adjacent sub-district of determining the sub-district of scrambler to be allocated and needing to investigate.
Step 42 determines that from the sub-district of above-mentioned scrambler to be allocated needs distribute the sub-district of scrambler.
Step 43 can be used scrambler for this Cell searching to be allocated, promptly carries out the search of scrambling code planning.This search has two kinds of schemes selective:
Scheme one, because sign indicating number planning has no special requirements to real-time, can therefrom select an available scrambling code with all scramblers all as the candidate scrambler, searching method is simple, but search time is longer, to the requirement of searching algorithm than higher;
Scheme two, checking and to improve search efficiency by the method for setting up other scrambler resource pond of different priorities in advance for before distributing to the scrambler of this sub-district to be allocated.The scrambler combination that is about to meet the identical correlation form of expression (correlation between compound code word has three kinds of forms of expression and corresponding three phase relation numerical value) is placed in the same scrambler resource pond, the scrambler combination of the different correlation forms of expression is placed in the different scrambler resource ponds, therefore can set up the scrambler resource pond of three kinds of priority levels, and these scrambler resource ponds are provided with different stage according to the phase relation numerical value under the different correlation forms of expression, phase relation numerical value is more little, and scrambler resource pond priority is high more.Specifically when search, then carry out according to the priority in scrambler resource pond, promptly at first search for other scrambler resource pond of limit priority, have only when not having available scrambling code in the scrambler resource pond of highest level, just select time other scrambler resource pond of high priority to carry out the scrambler search, the rest may be inferred, until searching available scrambling code.Owing to dwindled the hunting zone, thereby search procedure shortened greatly.
Step 44 checks whether this scrambler is available, availablely then continues execution in step 45, searches for scrambler again otherwise return step 43.
Check scrambler whether available be to judge to distribute to the scrambler of this sub-district and whether the scrambler of its all adjacent sub-districts is in same scrambler group (with reference to table 1).When the scrambler of the scrambler of the sub-district of distributing scrambler and its all adjacent sub-districts of only satisfying the demand is not in same scrambler group, could guarantee need to distribute the scrambler of sub-district adjacent, sub-district of scrambler inequality and downlink frequency pilot code is inequality with it, this moment, this scrambler just can be assigned with use, otherwise need redistribute.
Step 45, according to the sub-district of the definite needs distribution scrambler of step 41, judge whether the sub-district of current distribution scrambler is last scrambler to be allocated sub-district, be then to continue execution in step 46, otherwise return step 42, from scrambler to be allocated sub-district, select another sub-district to be allocated.
Step 46, calculate search end condition (condition of convergence in other words), when the end condition of search is the coefficient of total correlation of scrambler allocative decision when reaching threshold value, then the scrambler allocative decision coefficient of total correlation is calculated in the adjacent sub-district of investigating according to the sub-district of determining in the step 41 to be allocated and needs thereof.Calculating the scrambler allocative decision coefficient of total correlation is to calculate total interference volume of scrambler allocative decision, can design accordingly at different sub-district spatial separation (the far and near relation of distance) situation, and following two kinds of different numerical procedures can be arranged:
1) only the coefficient correlation between the scrambler that neighbor cell distributed is carried out read group total;
2) in conjunction with the spatial separation situation of sub-district, the coefficient correlation between the scrambler that these sub-districts are distributed is carried out read group total.
When calculating the scrambler allocative decision coefficient of total correlation, be between all scramblers that abovementioned steps 311 is calculated and preserved, the coefficient correlation, to access coefficient correlation between the related scrambler of scrambler allocative decision, again they carried out the calculating of the coefficient of total correlation.
Step 47, judging whether to satisfy can be with the search end condition of scrambler for Cell searching to be allocated, is execution in step 48 then, carries out otherwise return step 42.The search end condition is the search end condition that can set, the variable quantity that reaches as the coefficient of total correlation that reaches set point, scrambler allocative decision when searching times between the coefficient correlation of the coefficient correlation of threshold value (this threshold value is that target is set with coefficient of total correlation minimum) or this scrambler allocative decision and last scrambler allocative decision reaches threshold value (this threshold value is that target is set with the variable quantity minimum) etc., and process will stop search.
Step 48, the output scrambler distributes (planning) result.
By the described scrambling code planning searching method of Fig. 4 flow process, even adopted different scrambler group technologies even adopted different scrambling codes, but cross correlation between scrambler carries out because this scrambling code planning is based on, and do not exist because the cross correlation between scrambler has taken place to change and the problem of influence sign indicating number planing method applicability.
In order to understand the sign indicating number planing method based on scrambler of the present invention better, below in conjunction with the existing scrambling code situation of TD-SCDMA system, the implementation process that the scrambler search is carried out in the scrambler resource pond that has priority level at the calculating and the utilization of scrambler coefficient correlation is described in detail the inventive method.
Calculate about coefficient correlation between the scrambler of Fig. 3 step 311.
For any two scrambler A and B, because scrambler and 16 channel codes constitute 16 compound code words, for convenience of explanation, 16 compound code words for scrambler A is constituted are numbered respectively: A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, Aa, Ab, Ac, Ad, Ae, Af; 16 compound code words for scrambler B is constituted are numbered respectively: B0, B1, B2, B3, B4, B5, B6, B7, B8, B9, Ba, Bb, Bc, Bd, Be, Bf.16 compound code words that scrambler A is constituted (A0, A1 ..., Af) with 16 compound code words that constituted by scrambler B (B0, B1 ..., Bf) calculate correlation respectively in twos, will obtain (16 * 16) individual cross correlation value.
In above-mentioned (16 * 16) individual cross correlation value, the cross correlation mould value (taking absolute value) that finds a maximum is as cross-correlation coefficient, consider intuitive and convenient storage, cross-correlation coefficient is carried out normalized, the value after the processing is as the coefficient correlation between scrambler A and the scrambler B.
Wherein, because the length of the compound key that existing scrambler and channel code are constituted is the binary sequence of 16 chips (chip), therefore the peaked absolute value of cross-correlation coefficient is 16 (cross correlation mould values) between compound key, and normalized is that the cross correlation numerical value that will calculate is divided by 16.Because cross correlation mould value has only 16,8,4 and 0 four kind of situation between scrambler, therefore have corresponding relation between three kinds of forms of expression of correlation between the phase relation numerical value after the normalization and compound code word, be respectively 1 (16/16), 0.5 (8/16) and 0.25 (4/16) three kind of situation.
The following describes the process of utilizing the scrambler resource pond to carry out the scrambler search in Fig. 4 step 43.
As previously mentioned, when utilizing scrambling code planning searching method flow process shown in Figure 4 to carry out scrambling code planning,, need in advance the scrambler combination with different their cross correlations to be provided with different priority levels in order to improve search efficiency.When specific implementation, can be undertaken by setting up the scrambler resource pond.For example 128 scramblers are divided into 12 bunches shown in table 2 scrambler resource pond, bunch number be respectively A, B..., L, correlation between any two scramblers in every bunch meets the correlation form of expression one (phase relation numerical value is 1), and the correlation between any scrambler between bunch meets the correlation form of expression two (phase relation numerical value is 0.5) or the form of expression three (phase relation numerical value is 0.25).
Table 2
A |
1 5 26 27 29 30 34 40 42 43 49 53 55 57 85 90 |
B |
2 6 8 11 16 21 41 47 48 50 62 65 76 83 119 127 |
C |
3 4 7 12 13 18 23 24 35 36 37 39 46 51 66 87 |
D |
9 10 14 15 19 20 25 28 33 38 45 68 71 105 117 118 |
E |
17 22 31 32 44 60 79 86 93 95 100 106 108 110 125 126 |
F |
52 59 10 31 28 |
G |
54 81 92 10 11 21 |
H |
56 61 72 84 88 113 116 |
I |
58 78 82 89 97 98 102 |
J |
63 69 70 77 109 123 |
K |
64 67 73 80 94 96 107 111 114 124 |
L |
74 75 91 99 104 112 115 120 122 |
After 128 scramblers having been carried out sub-clustering numbering as shown in table 2, just can set up other scrambler resource pond of different priorities according to correlations different between scrambler, wherein the scrambler resource pond of limit priority is as shown in table 3, the scrambler resource pond of inferior high priority is as shown in table 4, and the scrambler resource pond of lowest priority is as shown in table 5.In the table, first hurdle is listed 12 bunches numbers, other bunch number that corresponding relation is arranged for above-mentioned bunch number with each listed on second hurdle, a kind of corresponding relation of one line display, when certain row scrambler bunch number any given scrambler is distributed to certain sub-district in selecting first hurdle, will distribute to its neighbor cell by any scrambler bunch number any given scrambler in this row second hurdle.
Table 3:
A |
F J K L |
B |
C H K L |
C |
B G H I |
D |
E G H I |
E |
D F I J |
F |
A E J L |
G |
C D H I |
H |
B C D G |
I |
C D E G |
J |
A E F K |
K |
A B J L |
L |
A B F K |
In the resource pool shown in the table 3, some scramblers and meet the form of expression three in first hurdle (scrambler bunch number) with the correlation between any scrambler in any one scrambler in delegation second hurdle bunch (scrambler bunch number), pairing scrambler phase relation numerical value is 0.25.
Table 4:
A |
B C D E G H I |
B |
A D E F G I J |
C |
A D E F J K L |
D |
A B C F J K L |
E |
A B C G H K L |
F |
B C D G H I K |
G |
A B E F J K L |
H |
A E F I J K L |
I |
A B F H J K L |
J |
B C D G H I L |
K |
C D E F G H I |
L |
C D E G H I J |
In the resource pool shown in the table 4, some scramblers and meet the form of expression two in first hurdle (scrambler bunch number) with the correlation between any scrambler in delegation's any one scrambler of second hurdle bunch (scrambler bunch number), pairing scrambler phase relation numerical value is 0.5.
Table 5:
A |
A’ |
B |
B’ |
C |
C’ |
D |
D’ |
E |
E’ |
F |
F’ |
G |
G’ |
H |
H’ |
I |
I’ |
J |
J’ |
K |
K’ |
L |
L’ |
In the resource pool shown in the table 5, some scramblers and meet the form of expression one in first hurdle (scrambler bunch number) with the correlation between any scrambler in delegation's any one scrambler of second hurdle bunch (scrambler bunch number), pairing scrambler phase relation numerical value is 1.Need to prove that because the scrambler that meets the form of expression one only can occur in 12 scramblers bunch, therefore, first hurdle and second hurdle only may be identical scramblers bunch in the table 5, the form with mirror image embodies here, and promptly A ' and A represent is same scrambler bunch.
When utilizing above-mentioned scrambler resource pond is that scrambler when search carried out in sub-district to be allocated, can adopt following method to carry out: if the scrambler that certain sub-district is distributed is X, and then preferentially selection during meeting the scrambler resource pond (table 3) of the form of expression three of its adjacent sub-district to be allocated.From the table 3 first hurdle (A, B, ..., L) search in scrambler X place bunch, when finding this scrambler place bunch, as A bunch, then in this resource pool, be in scrambler bunch F with delegation with scrambler X place bunch A, J, K, among the L, select earlier any scrambler bunch as F, again any scrambler Y of selection from scrambler bunch F, if not satisfying, the scrambler Y that chooses do not distribute requirement, promptly not available scrambler, continue in this scrambler resource pond, to select, comprise and still in scrambler bunch F, select or select in bunch as J at another scrambler, by that analogy, this available scrambler Y satisfies with scrambler X and is not in condition in the same scrambler group (with reference to table 1); When not had the scrambler that meets the demands in this resource pool, scrambler resource pond (table 4) the identical method of middle employing that then enters the lower form of expression of priority two is selected, and the rest may be inferred, distributes until the scrambler of finishing all sub-districts.
Sign indicating number planing method of distributing of the present invention based on scrambler, the sign indicating number planning under can be used for existing scrambler grouping of TD-SCDMA system and scrambling code situation, also applicable to scrambler grouping or scrambling code when the TD-SCDMA system situation about changing having taken place, even has been applicable to the sign indicating number planning of other code division multiple access system.Situation about changing has taken place in grouping for scrambler, only needs simply to adjust in the process of carrying out the scrambler search; And situation about changing has taken place for scrambling code, then only need the calculating of cross-correlation coefficient between scrambler and the structure in scrambler resource pond are simply adjusted.In a word, the situation of its use can not take place to influence because scrambler grouping or scrambling code have taken place to change in the inventive method, has adaptability more widely.