CN104320170B - Pilot pollution suppresses beam form-endowing method in extensive mimo system - Google Patents
Pilot pollution suppresses beam form-endowing method in extensive mimo system Download PDFInfo
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- CN104320170B CN104320170B CN201410594150.XA CN201410594150A CN104320170B CN 104320170 B CN104320170 B CN 104320170B CN 201410594150 A CN201410594150 A CN 201410594150A CN 104320170 B CN104320170 B CN 104320170B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
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- Computer Networks & Wireless Communication (AREA)
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Abstract
Suppress beam form-endowing method the invention discloses pilot pollution in a kind of extensive mimo system, comprise the following steps：1) set in mimo system comprising L cell, each cell is equipped with a base station with M root antennas, all base stations in mimo system are divided into N groups, 2) k-th optimal beam forming vectors of user in i-th cell are obtained according to broad sense Rayleigh entropy, the optimal beam forming vectors of each user in each group are obtained, the transmission of data is then carried out according to the optimal beam forming vectors of each user in each group in mimo system.The present invention can improve the precision of channel estimation and spectrum efficiency performance of the extensive mimo system of multiple cell, and the expense of system is small.
Description
Technical field
The invention belongs to cooperative multipoint transmission technical field in wireless communication system, it is related in a kind of extensive mimo system
Pilot pollution suppresses beam form-endowing method.
Background technology
Theoretical research based on extensive mimo system shows, when antenna for base station number tends to infinity, base station from it is different
Channel vector between user is presented nearly orthogonal characteristic, thus the influence of intra-cell interference and noise will disappear, limitation system
The deciding factor of performance of uniting only remains pilot pollution.Now, systematic function only can be obviously improved by simple linear process.
Under such system, effectively suppress pilot pollution to reduce the performance loss brought by pilot pollution, further the big rule of lifting
The performance of mould mimo system turns into research emphasis.
The existing algorithm for suppressing pilot pollution mainly includes：Channel estimation method, precoding algorithms, pilot configuration set
Meter, pilot frequency sequence distribution etc..Wherein channel estimation method mainly includes channel estimation method and the Bayes of feature based decomposition
Channel estimation method.The two algorithms carry out substantial amounts of letter with computation complexity higher, or needs between base station
Breath interaction.Precoding algorithms mainly include the precoding algorithms based on cooperation between base stations and the precoding algorithms based on MMSE.This
Class algorithm makes up channel when known channel is estimated to there is evaluated error because of pilot pollution by designing pre-coding matrix
The inaccurate performance loss for bringing is estimated, so as to ensure systematic function.The main pilot configuration including time shift of pilot configuration design
And the pilot configuration of redundancy.The pilot configuration of time shift is to divide into some groups, the cells of difference group by by small in system
Pilot signal stagger to realize in time.Existing document is demonstrated when antenna for base station number tends to infinity, and pilot tone is dirty
Contaminate only can improve channel by from the pilot configuration with the user's generation in group using same pilot resource, therefore using time shift
The precision of estimation.And the pilot configuration of redundancy is then by increasing pilot sequence length so that the pilot frequency multiplexing factor is more than 1, with
This influence to reduce pilot pollution, this kind of method can increase pilot-frequency expense, when the performance gain brought using redundancy pilot tone is big
When the performance loss that extra pilot-frequency expense is brought, this kind of scheme just can be effective.Pilot frequency sequence allocative decision mainly include with
It is the pilot allocation scheme of object function to minimize channel estimation mean square error, and it needs to interact substantial amounts of information, or needs center
Node supports and that to maximize overall system throughput as the pilot allocation scheme of object function it is to tend to nothing in antenna for base station number
Obtained under poor big ideal scenario, do not take into account some disturbing factors under real scene.
Existing document is on pilot pollution is solved the problems, such as, or discussion is that antenna for base station number tends to infinitely great ideal
Scene, or with overhead higher, implement all more difficult.
The content of the invention
A kind of shortcoming it is an object of the invention to overcome above-mentioned prior art, there is provided pilot tone in extensive mimo system
Pollution restraint beam form-endowing method, the method can improve the precision of channel estimation and frequency spectrum of the extensive mimo system of multiple cell
Efficiency performance, and the expense of system is small.
To reach above-mentioned purpose, pilot pollution suppresses beam form-endowing method bag in extensive mimo system of the present invention
Include following steps：
1) set comprising L cell in mimo system, each cell is equipped with a base station with M root antennas, by MIMO systems
All base stations are divided into N groups in system, then the optimal beam forming vectors of k-th user's transmission are in i-th cell：
Wherein,It is k-th available signal power of user in i-th cell,It is
The interference that k-th downlink data of user is estimated each cell channel in all groups in i cell,
It is the interference of k-th downlink data of user to other users in this cell in i-th cell, α is weight factor,It is i-th
K-th channel estimation of user in cell,It is k-th optimal transmission beamforming vector of user, g in the i-th cellil
It is the channel matrix between base station i and base station l；
2) k-th optimal beam forming vectors of user in i-th cell are obtained according to broad sense Rayleigh entropyWherein,ΓpIt is pilot tone
Received signal to noise ratio, ΓfIt is the downlink data received signal to noise ratio of Cell Edge User, NuNumber of users in the i cells；
The optimal beam forming vectors of each user in each group are obtained, then in mimo system according to each user in each group
Optimal beam forming vectors carry out the transmission of data.
Step 1) in k-th channel estimation of user in the i-th cellWherein, yiFor base station i is received
Pilot signal, ΨkTo send pilot frequency sequence, ρkiIt is k-th ascending pilot frequency transmit power of user in i-th cell, K is every
Pilot sequence length on individual subcarrier.
The invention has the advantages that：
Pilot pollution suppresses beam form-endowing method by base station to this cell in extensive mimo system of the present invention
Subscriber channel is estimated, and obtains the optimal beam forming vectors of each user, is then carried out according to optimal beam forming vectors
The transmission of data, can not only reduce the interference to the estimation of other cell channels and ensure that the useful signal quality of reception
Under the premise of, the interference to other users in this cell is reduced as far as possible；The present invention is accurate based on letter leakage ratio is maximized relative to traditional
Coordination beamforming scheme then is obviously improved in performance, and overhead is smaller, it is possible at each cooperative base station
Distributed implementation.
Brief description of the drawings
Fig. 1 is the extensive mimo system model of multiple cell；
Fig. 2 is the channel estimation mean square error contrast of each scheme under 3 cell scenarios；
Fig. 3 is every user's average spectral efficiency (ase) contrast of each scheme under 3 cell scenarios；
Fig. 4 is the channel estimation mean square error contrast of each scheme under 7 cell scenarios；
Fig. 5 is every user's average spectral efficiency (ase) contrast of each scheme under 7 cell scenarios.
Specific embodiment
The present invention is described in further detail below in conjunction with the accompanying drawings：
With reference to Fig. 1, pilot pollution suppresses beam form-endowing method including following in extensive mimo system of the present invention
Step：
1) set comprising L cell in mimo system, each cell is equipped with a base station with M root antennas, by MIMO systems
All base stations are divided into N groups in system, then the optimal beam forming vectors of k-th user's transmission are in i-th cell：
Wherein,It is k-th available signal power of user in i-th cell,It is
The interference that k-th downlink data of user is estimated each cell channel in all groups in i cell,For
The interference of k-th downlink data of user to other users in this cell in i-th cell, α is weight factor,For i-th small
K-th channel estimation of user in area,It is k-th optimal beam forming vectors of user, g in the i-th cellilIt is base station i
With the channel matrix between the l of base station；
2) k-th optimal beam forming vectors of user in i-th cell are obtained according to broad sense Rayleigh entropyWherein,ΓpIt is pilot tone
Received signal to noise ratio, ΓfIt is the downlink data received signal to noise ratio of Cell Edge User, NuNumber of users in the i cells；
The optimal beam forming vectors of each user in each group are obtained, then in mimo system according to each user in each group
Optimal beam forming vectors carry out the transmission of data.
Step 1) in k-th channel estimation of user in the i-th cellWherein, yiFor base station i is received
Pilot signal, ΨkTo send pilot frequency sequence, ρkiIt is k-th ascending pilot frequency transmit power of user in i-th cell, K is every
Pilot sequence length on individual subcarrier.
Simulated effect of the invention is as follows：
The classical pilot tone that the present invention is sent with the classical pilot tone time shift algorithm sent using high specific and using high specific
Alignment algorithm has carried out simulation comparison, and simulation parameter is shown in Table 1.The performance indications of contrast are the mean square error and use of channel estimation
The average spectral efficiency (ase) at family.The mean square error of channel estimation is calculated by following formula：
Table 1
Fig. 2 and Fig. 3 sets forth under 3 cell scenarios the channel estimation mean square error of each scheme and per user's average frequency spectrum
Efficiency with edge customer downlink data received signal to noise ratio situation of change.In this scenario, ΓfTake 0dB, 5dB, 10dB,
Corresponding weight factor α is taken as 0.5,1.5,5,6,5,1.5,0.5 respectively when 15dB, 20dB, 25dB and 30dB.From Fig. 2
As can be seen that the precision of channel estimation of pilot tone alignment scheme is unrelated with downlink transmission power, therefore not with the change of downlink data SNR
Change and change, and pilot tone time shift scheme is because it is by cell group, in 2 cell scenarios, interference during channel estimation only by with base
The downlink data interference that the base station of the different groups of the i that stands sends causes, and relevant with the transmit power of downlink data, and downlink data sends
Power is bigger, and the interference to channel estimation is also bigger.Classical time shift scheme is sweared before being sent using high specific to wave beam forming
Amount is also processed, and can eliminate looked at straight between base station and base station the interference that footpath is brought, so as to by different from base station i groups
The downlink data interference that base station sends is substantially reduced, therefore, the precision of channel estimation of pilot tone time shift scheme is much better than pilot tone alignment
Scheme.And the present invention is nearly identical with the channel estimation errors of classical pilot tone time shift scheme, this explanation is the present invention also can
Substantially eliminate due to the interference that the presence in base station direct-view footpath is caused to channel estimation.Understood in conjunction with Fig. 3, the present invention is improving letter
While road estimated accuracy, additionally it is possible to intra-cell interference has been suppressed on the premise of the useful signal quality of reception is ensured, because
The spectrum efficiency performance of this more classical pilot tone time shift scheme is obviously improved.Additionally, when downlink data transmit power is larger, leading
Spectrum efficiency performance under frequency time shift structure can reduce with the increase of transmit power, particularly with the scheme for proposing, this
Phenomenon becomes apparent., mainly due under the pilot configuration of time shift, excessive downlink data transmit power can cause channel for this
The degradation of estimated accuracy, so as to influence the overall performance of system.For the present invention, the degradation one of precision of channel estimation
Aspect can influence the quality of reception of useful signal, and on the other hand also resulting in cannot suppress well to intra-cell interference, therefore
Spectrum efficiency performance of the invention is influenceed bigger by data sending power.But by rationally setting weight factor α, we are still
Can cause that suggested plans performance is better than classical time shift scheme.
Fig. 4 and Fig. 5 sets forth under 7 cell scenarios the channel estimation mean square error of each scheme and per user's average frequency spectrum
Efficiency with edge customer downlink data received signal to noise ratio situation of change.In this scenario, ΓfTake 0dB, 5dB, 10dB,
Corresponding weight factor α is taken as 5,15,50,60,50,15,5 respectively when 15dB, 20dB, 25dB and 30dB.Comparison diagram 2 and figure
4 as can be seen that when number of cells increases in system, the error of channel estimation increases with the increase of interference source, but pilot tone
The precision of channel estimation of time shift scheme is still far better than pilot tone alignment scheme, and the present invention and classical pilot tone time shift scheme
Channel estimation errors are still nearly identical, and when interference source increases, the present invention can be also substantially eliminated due to base for this explanation
The interference that the presence of visual path of standing erectly is caused to channel estimation.
Claims (2)
1. pilot pollution suppresses beam form-endowing method in a kind of extensive mimo system, it is characterised in that comprise the following steps：
1) set comprising L cell in mimo system, each cell is equipped with a base station with M root antennas, by mimo system
All base stations are divided into N groups, then the optimal beam forming vectors of k-th user's transmission are in i-th cell：
Wherein,It is k-th available signal power of user in i-th cell,It is i-th
The interference that k-th downlink data of user is estimated each cell channel in all groups in cell,It is i-th
The interference of k-th downlink data of user to other users in this cell in individual cell, α is weight factor,It is the i-th cell
The channel estimation of interior k-th user,It is k-th optimal transmission beamforming vector of user, g in the i-th cellilIt is base
The channel matrix stood between i and base station l；
2) k-th optimal beam forming vectors of user in i-th cell are obtained according to broad sense Rayleigh entropyWherein,ΓpIt is pilot tone
Received signal to noise ratio, ΓfIt is the downlink data received signal to noise ratio of Cell Edge User, NuNumber of users in the i cells；
The optimal beam forming vectors of each user in each group, then mimo system according in each group each user it is optimal
Beamforming vector carries out the transmission of data.
2. pilot pollution suppresses beam form-endowing method in extensive mimo system according to claim 1, it is characterised in that
Step 1) in k-th channel estimation of user in the i-th cellWherein, yiFor the pilot tone letter that base station i is received
Number, ΨkTo send pilot frequency sequence, ρkiIt is k-th ascending pilot frequency transmit power of user in i-th cell, K is each subcarrier
On pilot sequence length.
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105703812B (en) * | 2016-01-27 | 2018-07-17 | 西安交通大学 | Downlink precoding and base station power control method in a kind of extensive mimo system of pilot tone time shift |
| CN105978836B (en) * | 2016-05-06 | 2019-04-02 | 华东交通大学 | Multi-district pilots abatement of pollution method under extensive mimo system |
| CN109004962B (en) * | 2017-06-06 | 2021-04-02 | 上海交通大学 | Stratospheric large-scale MIMO user side beam forming method |
| CN113567936B (en) * | 2021-07-29 | 2023-11-17 | 哈尔滨工业大学 | Single-channel multilink beam forming echo detection method based on m sequence |
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| CN103209496A (en) * | 2013-04-19 | 2013-07-17 | 华北电力大学（保定） | User scheduling method based on beam selection in multi-base-station cooperative system |
| CN103298124A (en) * | 2013-06-14 | 2013-09-11 | 东南大学 | Spatial-orthogonality-based large-scale MIMO (multiple input multiple output) system pilot frequency distribution method |
| CN103634816A (en) * | 2013-11-01 | 2014-03-12 | 南京邮电大学 | Method for eliminating pilot pollution-based interference in multi-cell massive MIMO (Multiple Input Multiple Output) |
| WO2014039849A1 (en) * | 2012-09-06 | 2014-03-13 | Qualcomm Incorporated | D2d relays as an underlay in lte uplink |
| EP2512193B1 (en) * | 2008-01-30 | 2014-03-19 | Qualcomm Incorporated | Method and apparatus for mitigating pilot pollution in a wireless network |
| CN103701577A (en) * | 2013-12-11 | 2014-04-02 | 北京邮电大学 | Pilot frequency distribution method for inhibiting pilot frequency pollution in cloud wireless access network |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2512193B1 (en) * | 2008-01-30 | 2014-03-19 | Qualcomm Incorporated | Method and apparatus for mitigating pilot pollution in a wireless network |
| WO2014039849A1 (en) * | 2012-09-06 | 2014-03-13 | Qualcomm Incorporated | D2d relays as an underlay in lte uplink |
| CN103209496A (en) * | 2013-04-19 | 2013-07-17 | 华北电力大学（保定） | User scheduling method based on beam selection in multi-base-station cooperative system |
| CN103298124A (en) * | 2013-06-14 | 2013-09-11 | 东南大学 | Spatial-orthogonality-based large-scale MIMO (multiple input multiple output) system pilot frequency distribution method |
| CN103634816A (en) * | 2013-11-01 | 2014-03-12 | 南京邮电大学 | Method for eliminating pilot pollution-based interference in multi-cell massive MIMO (Multiple Input Multiple Output) |
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