CN1138370C - Interference inhibiting treatment method for forward link - Google Patents
Interference inhibiting treatment method for forward link Download PDFInfo
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- CN1138370C CN1138370C CNB001362313A CN00136231A CN1138370C CN 1138370 C CN1138370 C CN 1138370C CN B001362313 A CNB001362313 A CN B001362313A CN 00136231 A CN00136231 A CN 00136231A CN 1138370 C CN1138370 C CN 1138370C
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Abstract
The present invention relates to an interference suppression processing method for a forward link. A corresponding relation table between pilot frequency codes and spread spectrum codes is established in the present invention; according to other users' received pilot frequency codes of, a mobile station looks up the corresponding relation table to obtain users' spread spectrum codes; the mobile station obtains the characteristics of channels of all users in the same subzone /sector through channel estimation; other users' power and a threshold value are compared, and the interference suppression is only carried out to the other users and the user with the power exceeding the threshold value.
Description
The present invention relates to spread spectrum radio communications system, particularly relate to the interference inhibiting treatment method that uses in the forward link of spread spectrum radio communications system.
In the wireless frequency expansion multi-user system, because the incomplete orthogonality of spreading code is even the complete quadrature of the spreading code that is adopted also can cause the non-orthogonal of spreading code owing to the influence of multipath channel (intersymbol interference), thereby cause serious multiple access to disturb, influence the performance of system.For overcoming the influence that multiple access disturbed or weakened the multiple access interference, often adopt joint-detection, interference mitigation technology now, perhaps adopt the technology of smart antenna and other signal processing mode, improve the performance of system, but these technology are more complicated all in general, the base station end that is applied in mobile communication system still has certain degree of difficulty, uses the difficulty of above technology to well imagine for travelling carriage, can be bigger.
For example to intelligent antenna technology, because that travelling carriage takes up space is smaller, and the spatial character of the signal that travelling carriage received, and, reduce power consumption for reducing cost, general portable terminal is all unlikely used intelligent antenna technology.Only on the angle in space, the general smart antenna that adopts, the antenna element spacing is half of wavelength, adds the factors such as height of antenna element itself, and is bigger for travelling carriage, is can not be applicable in present this stage.
For joint-detection and interference mitigation technology, because most interference inhibition and joint detection algorithm all require travelling carriage must know that the channel information of other user in the sub-district, spreading code information etc. just can handle, but for general communication system, can't learn other user's information for certain user, even can allow each travelling carriage in the sub-district obtain other users' information, handle complexity and also can limit the application of this type of algorithm in travelling carriage.
But along with the development of communication system and the development of data communication service and Digital Signal Processing and chip technology, more and more obvious to the importance of travelling carriage (being forward link) transmission of high-rate data by the base station, the performance of travelling carriage must be improved.
The objective of the invention is to propose a kind of interference inhibiting treatment method of forward link, it can increase under the little situation in the complexity of travelling carriage, obviously improves the performance of travelling carriage.
The object of the present invention is achieved like this: a kind of interference inhibiting treatment method of forward link, it is characterized in that: set up the mapping table between pilot code and the spreading code, travelling carriage is consulted the spreading code that this mapping table obtains this user according to other users' that receive pilot code; And travelling carriage obtains the channel characteristics of all users in the same cell/section by channel estimating, and with other users' power and a threshold ratio, only other users and this user that power is surpassed threshold value disturbs inhibition.
Preferably, all users' pilot code obtains by the difference displacement by same basic code in the same cell/section, and described mapping table is embodied in described to the displacement of basic code and the mapping table between the spreading code.
Preferably, described mapping table also can be solidificated in the travelling carriage by the travelling carriage of base station broadcast to this cell/section.
Preferably, described threshold value is at the power setting of other users' different multipaths, when the power in other user's a footpath surpasses this threshold value, thinks that then this user's power surpasses threshold value.
Preferably, described threshold value is at the power and the setting of each multipath signal of other users, when the power of each multipath signal of other users with when surpassing this threshold value, thinks that then this user's power surpasses threshold value.
Preferably, described threshold value can be adjusted by travelling carriage or by the base station in the operating mobile station process.
Preferably, the radio receiving-transmitting unit of base station adopts array antenna.
Preferably, disturb when suppressing, can adopt parallel interference to suppress or serial interference suppresses other users that power surpassed threshold value and this user.
Preferably, travelling carriage is when comparing other users' power and described threshold value, and each other user's power all is multiplied by a weight, and this weight reflects the influence degree of these other users to this user.
The interference inhibiting treatment method of forward link of the present invention can be realized disturbing at forward link simply and suppress, and can increase under the little situation in the complexity of travelling carriage, obviously improves the performance of travelling carriage.Especially the number of users of work is more suitable when fewer in the time of system design, even when the number of users of work is many system design the time, also can reduce the amount of calculation of travelling carriage by adjusting threshold value neatly.
For making the purpose, technical solutions and advantages of the present invention clearer, by the following examples, and in conjunction with the accompanying drawings, the present invention is described in more detail.Institute it should be understood that it only is used for elaboration of the present invention explanation and unrestricted.Wherein
Fig. 1 shows the reception schematic diagram according to the travelling carriage of a preferred embodiment of the present invention.
Interference mitigation technology in the reverse link is than mature technique, because using the equipment of interference mitigation technology in reverse link mainly is the base station, itself be exactly the allocator of spreading code, therefore be easy to learn the spreading code of all users in this cell/section, and the soft hardware equipment of base station allows to carry out intensive and complicated processing, therefore disturbs and suppresses more easily to realize.Yet it is completely different that the situation in forward link is compared with reverse link, using the equipment of interference mitigation technology in the forward link mainly is travelling carriage, and travelling carriage generally can't be learnt the spreading code of all users in this cell/section, and the volume of travelling carriage is very little, generally can not carry out large-scale calculating and complicated processing, therefore the interference mitigation technology in the reverse link mechanically can not be incorporated in the forward link.
The present invention promptly is on the basis of having found above problem, the disturbance restraining method that is used for forward link of proposition.The present invention is by setting up pilot code and spreading code corresponding relation and send this corresponding relation to travelling carriage, and offers all users' of travelling carriage spreading code.The present invention and only disturb big user and this user to disturb inhibition to some by introducing threshold value, thus the workload of travelling carriage reduced.Especially in 3-G (Generation Three mobile communication system), because the TD-CDMA Time Division-Code Division Multiple Access modes that adopt more, in fact the number of users of working simultaneously in each time bursts (time slot) of sub-district is less, for example 16 or 32 users (code channel), thereby be applicable to the present invention more.
The burst structure of pilot tone can be midamble, preamble, pilot etc., in a preferred embodiment of the present invention, each user's pilot code is formed by basic code displacement a (i), figure place a (i) difference of each user's displacement, the difference W=a of the number of each user's displacement (i)-a (i-1) determines according to the feature (multipath delay) of channel.Can be to this referring to list of references [1], that is, and Bernd Steiner, Peter Jung, Optimumand Suboptimum Channel Estimation for the Uplink of CDMA Mobile RadioSystems with Joint Detection, 1994, Vol.5, No.1,39～50.
A basic code displacement a table corresponding with spreading code is set in system, and this table utilizes common signal channel or sends travelling carriage At All Other Times to by signaling or when travelling carriage inserts, also can be solidificated in the travelling carriage.
The travelling carriage received signal is done channel estimating earlier, because the shift characteristics of pilot tone, is easy to obtain each user's channel estimation value h
I.j, wherein i represents different users, j represents footpath different in the multipath (different time-delays).Be travelling carriage by channel estimating obtain in the system user's the information of influential this travelling carriage, can obtain other user's spreading code and channel characteristics.
Other user's channel estimating is obtained the power of other user's different delayed time, set a threshold value during reception, when the power of other user's different delayed time surpasses threshold value, will further handle, ignore for the component that does not surpass threshold value.This step also can be to the threshold value of the power of all time delayed signals of certain user and a judgement of setting, handles for the signal that surpasses threshold value.
Do the interference inhibition for other subscriber signal that surpasses threshold value and this subscriber signal, suppress as parallel interference, serial interference suppresses or the like.Suppressing its step as parallel interference can be for being mainly:
Parallel interference suppresses all users are carried out same operation.(1), with the output of each matched filter the signal of valuation first as each user; (2), again with valuation signal first through judgement, amplitude Estimation and again spread spectrum reconstruct received signal; (3), to certain user k, from total received signal, deduct the interference signal of all interference users, just obtained the valuation new to this subscriber signal; (4), then it is sent into second level matched filter, obtain the new estimated value of each user profile bit through judgement.
Repeating step (2) then, (3), (4) meet the requirements up to the error rate, or all handle in all footpaths of all users.Can be with meeting the requirements of the error rate by the variance (eye pattern) that receives subscriber signal being estimated or other method obtains.
Will be about choosing of power threshold according to the implementation complexity of travelling carriage, the performance of performance requirement and real system is chosen.Choosing the influence of the performance of system and complexity of threshold value is bigger, threshold value choosing more little, and the complexity of realization is big more, and performance is good more.
Choosing of threshold value can also so be set, and surpasses certain threshold value and chooses several wherein maximum multipath components.Can guarantee to disturb total operand of inhibition like this within certain scope.
System is if use array antenna at transmitting terminal, this moment in the ordinary course of things, other number of users that certain user is produced the multiple access interference will significantly reduce, have only this moment the multipath component of minority time-delay of the power of a few users to surpass threshold value generally speaking, in this case, the complexity to travelling carriage is easier to be controlled within the acceptable scope.
In another preferred embodiment of the present invention, for the system module of base station end TD-SCDMA system with reference to CWTS (China Wireless Telecommunication Standar tissue), or the TDD scheme of the high code check option of 3GPP.Specific practice can be: system adopts the TDD mode and adopts the structure of time slot of burst (burst); Comprise the pilot configuration in the list of references [1] in the burst structure; Each user is distributed the different pilot code in shift position; Obtain each user's spreading code according to the position of user's pilot code displacement; All users send through array antenna through behind the spread spectrum, and wherein each user sends through different wave beam formings.
In travelling carriage side, all users' signal receives at certain specific travelling carriage after the overshoot channel.Owing to send the wave beam forming of signal through array antenna, not all user's power is all the same.Be divided into the reception structure and the process of A, B, C, D, five steps specific descriptions of E travelling carriage below, and please refer to accompanying drawing 1:
After receiving through antenna, A, signal obtain baseband signal R after process radio frequency processing and other processing.
B, do channel estimating according to pilot tone to the received signal.Channel estimation methods is to utilize pilot code to estimate, for example can adopt computing formula to be
h=
Me, wherein
M=(
G ★ T G)
-1 G ★ T, matrix _ be the Toeplitz matrix, its element determined by each user's pilot code, the concrete grammar of relevant channel estimating and parameter is given can be referring to list of references [1].The method of specific implementation can be taked the technology of fast fourier transform, reduces amount of calculation etc. to simplify.So once just obtained the channel characteristics of all users with respect to certain specific travelling carriage.
Each user's channel characteristics (channel impulse response), i represents i user, j represents that relative time delay is a j chip.
C, according to channel estimating the multipath component of other user's signal is carried out power and estimates, power estimate directly to win the confidence estimate amplitude square, can by
Obtain, to P (i, j) setting threshold, have only P (i, j)＞multipath component of Pm just further handles.Threshold value must be provided by the setting by the amount of calculation that can provide of travelling carriage, in the TD-SCDMA system, because the base station end has used array antenna, needs other user's of processing multipath component greatly to reduce.
D, according to the 3rd the step obtain other user's multipath component and this user's multipath component, further handle.The position that pilot tone was shifted of the multipath component of handling according to each needs obtains the pairing spreading code of user of required processing.
E, do to disturb according to the user of each required processing and multipath component thereof and suppress to handle.The processing method that adopts serial interference to suppress in this example.Suppose that receiving baseband signal is R, each user's of (1) demodulation (despreading) most powerful path obtains each user symbol data S (i, 0), and (2) carry out the preceding signal R (i, 0) of spread spectrum reconstruct despreading by S (i, 0) then.(3) remove the signal R=R-h of reconstruct at the signal that receives
(i, 0)R (i, 0).(4) to each with the strong footpath of the number of households involved carry out despreading obtain S ' (i, k).S (i, k)=S (i, k-1)+(i k) repeats 2,3,4 steps and meets the requirements to the demodulating data error rate of this travelling carriage S ' then, or all handle in all footpaths of all users.Wherein meeting the requirements of the error rate can be by estimating the variance (eye pattern) that receives subscriber signal or other method obtains.
Above embodiment is only unrestricted in order to explanation the present invention, although the present invention is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that, can carry out various modifications or be equal to replacement embodiments of the invention according to principle of the present invention and spirit, and not breaking away from the spirit and scope of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.
Claims (9)
1, a kind of interference inhibiting treatment method of forward link is characterized in that: set up the mapping table between pilot code and the spreading code, travelling carriage is consulted the spreading code that this mapping table obtains this user according to other users' that receive pilot code; And travelling carriage obtains the channel characteristics of all users in the same cell/section by channel estimating, with other users' power and a threshold ratio, only other users and this user that power is surpassed threshold value disturbs inhibition, and described threshold value is determined according to the hardware condition and the design requirement of travelling carriage.
2, the interference inhibiting treatment method of forward link as claimed in claim 1, it is characterized in that: all users' pilot code obtains by the difference displacement by same basic code in the same cell/section, and described mapping table is embodied in described to the displacement of basic code and the mapping table between the spreading code.
3, the interference inhibiting treatment method of forward link as claimed in claim 1 is characterized in that: described mapping table also can be solidificated in the travelling carriage by the travelling carriage of base station broadcast to this cell/section.
4, the interference inhibiting treatment method of forward link as claimed in claim 1, it is characterized in that: described threshold value is at the power setting of other users' different multipaths, when the power in other user's a footpath surpasses this threshold value, think that then this user's power surpasses threshold value.
5, the interference inhibiting treatment method of forward link as claimed in claim 1, it is characterized in that: described threshold value is provided with at the power sum of each multipath signal of other users, when the power sum of each multipath signal of other users surpasses this threshold value, think that then this user's power surpasses threshold value.
6, the interference inhibiting treatment method of forward link as claimed in claim 1 is characterized in that: described threshold value can be adjusted by travelling carriage or by the base station in the operating mobile station process.
7, the interference inhibiting treatment method of forward link as claimed in claim 1 is characterized in that: the radio receiving-transmitting unit of base station adopts array antenna.
8, the interference inhibiting treatment method of forward link as claimed in claim 1 is characterized in that: disturb when suppressing other users that power surpassed threshold value and this user, can adopt parallel interference to suppress or serial interference suppresses.
9, the interference inhibiting treatment method of forward link as claimed in claim 1, it is characterized in that: travelling carriage is when comparing other users' power and described threshold value, each other user's power all is multiplied by a weight, and this weight reflects the influence degree of these other users to this user.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB001362313A CN1138370C (en) | 2000-12-14 | 2000-12-14 | Interference inhibiting treatment method for forward link |
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| CNB001362313A CN1138370C (en) | 2000-12-14 | 2000-12-14 | Interference inhibiting treatment method for forward link |
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| CN1357989A CN1357989A (en) | 2002-07-10 |
| CN1138370C true CN1138370C (en) | 2004-02-11 |
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| CN102638423A (en) * | 2011-02-11 | 2012-08-15 | 中兴通讯股份有限公司 | Interference and noise elimination method and device |
| CN102338878B (en) * | 2011-07-19 | 2013-11-06 | 电子科技大学 | Novel multi-path inhibition BOC (Binary Offset Carrier) code tracking method and code tracking ring |
| CN116896419B (en) * | 2023-09-11 | 2023-11-14 | 荣耀终端有限公司 | Performance test method, system, terminal and storage medium |
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