CN103634816A - Method for eliminating pilot pollution-based interference in multi-cell massive MIMO (Multiple Input Multiple Output) - Google Patents

Method for eliminating pilot pollution-based interference in multi-cell massive MIMO (Multiple Input Multiple Output) Download PDF

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Publication number
CN103634816A
CN103634816A CN201310530747.3A CN201310530747A CN103634816A CN 103634816 A CN103634816 A CN 103634816A CN 201310530747 A CN201310530747 A CN 201310530747A CN 103634816 A CN103634816 A CN 103634816A
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pilot pollution
sir
base station
data
formula
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Inventor
张翠芳
曾桂根
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Nanjing Post and Telecommunication University
Nanjing University of Posts and Telecommunications
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Nanjing Post and Telecommunication University
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Abstract

The invention provides a method for eliminating pilot pollution-based interference in multi-cell massive MIMO (Multiple Input Multiple Output). The method comprises the following steps: adopting an orthogonal pre-coding sequence for transmission data; multiplying all user data of an lth cell by a group of line sequences during transmission of uplink data and downlink data, wherein the sequence length of each sequence is shown in the specifications, and is relevant to the number of cells; the sequences in different cells are orthogonal to one another, and a normalization condition is met. According to the method, the orthogonal pre-coding sequence is adopted to the transmission data, so that interference coming from other cells can be eliminated fully at a receiving end. When the number of base station antennae is increased infinitely, an SIR (signal to interference ratio) is increased to infinite along with the increase of the base station antennae. The method can be applied to a massive MIMO multi-cell TDD (Time Division Duplex) system, so that the inference caused by pilot pollution in the massive MIMO multi-cell TDD system is eliminated, and the SIR increases along with the increase of the base station antennae and is not limited by the pilot pollution any more.

Description

The interference elimination method of the extensive MIMO in many communities based on pilot pollution
Technical field
The present invention relates to the interference elimination method of a kind of extensive MIMO in many communities based on pilot pollution.
Background technology
At extensive MIMO (massive MIMO) many communities TDD(time-division duplex) when pilot frequency sequence, the minizone of employing quadrature adopts identical pilot frequency sequence group in system Zhong，Dang community, there is the pilot pollution problem.The channel parameter certain user being estimated not only comprises the channel information of desired user, the interference that also exists other communities to estimate Target cell.The existence of pilot pollution, makes the signal interference ratio SIR (signal to interference ratio) of uplink and downlink transfer of data not increase and to increase along with antenna for base station number.
Solve at present the interference problem method causing due to pilot pollution and mainly contain two large classes: a class is to alleviate pilot pollution by corresponding strategies.For example, by many cell group, transmit the downlink data of certain group district pilots and other Ge Zu communities simultaneously (1).Between each group, pilot pollution disappears, but on the same group, pilot pollution still exists.(2) in one dimension Multi-cell model, the neighbor cell pilot frequency sequence transmitting time that staggers, thus avoid the pilot pollution of neighbor cell.But the silence period wasting of resources, is tending towards definite value when antenna for base station number increases SIR.(3) adopt pilot transmit power allocation strategy, by reducing interfered cell user's pilot transmit power, reduce pilot pollution.But when interfered cell becomes Target cell, its pilot pollution still can be very serious.
Another kind of is when transfer of data, to adopt precoding mode to eliminate the interference causing due to pilot pollution.For example (1) receives data estimation value formula according to the upstream or downstream of deriving, and design pre-coding matrix, can eliminate pilot pollution in theory completely.But the prerequisite of the method is, while estimating a certain community user data, need to know all community user estimated values, this is difficult to realize in actual applications.(2) adopt based on MMSE precoding mode, downlink transmission data found to an optimum pre-coding matrix, make to receive data mistake item and and the average power of the distracter of other community minimum.This kind of method is along with the increase of antenna number, number of users, and amount of calculation is along with increase, and algorithm is more complicated.(3) different districts user sends pilot tone at non-overlapping copies in the time.Dang Yige community sends pilot tone, and other communities send precoded signal.Estimation by precoded signal, estimates the characteristic of channel, thereby designs pre-coding matrix.
The problems referred to above are the problems that should pay attention to and solve in the interference cancellation process of pilot pollution in the TDD system of many communities of extensive MIMO.
Summary of the invention
The object of this invention is to provide a class in the interference elimination method solution prior art of a kind of extensive MIMO in many communities based on pilot pollution and alleviate pilot pollution by corresponding strategies, the pilot pollution existing is eliminated undesirable, or the silence period wasting of resources, antenna for base station number increases the problem that SIR is tending towards definite value, and the another kind of precoding mode that adopts when transfer of data eliminates the interference causing due to pilot pollution, existence be difficult to the problems such as realization, algorithm complexity.
Technical solution of the present invention is:
The interference elimination method of the extensive MIMO in many communities based on pilot pollution, to sending the precoding sequence of quadrature for data acquisition, when transmit ascending data, downlink data, the
Figure 2013105307473100002DEST_PATH_IMAGE002
the all customer data of individual community is first multiplied by one group of row sequence
Figure 2013105307473100002DEST_PATH_IMAGE004
, this sequence wherein
Figure 2013105307473100002DEST_PATH_IMAGE004A
sequence length be
Figure 2013105307473100002DEST_PATH_IMAGE006
, this sequence length
Figure 2013105307473100002DEST_PATH_IMAGE006A
be more than or equal to community number , , the sequence of different districts
Figure 2013105307473100002DEST_PATH_IMAGE004AA
Figure 2013105307473100002DEST_PATH_IMAGE012
mutually orthogonal, meet normalizing condition
Figure 2013105307473100002DEST_PATH_IMAGE014
.
Preferably, in transmitting uplink data, the
Figure 2013105307473100002DEST_PATH_IMAGE002A
of individual community
Figure 2013105307473100002DEST_PATH_IMAGE016
individual user sends upstream data
Figure 2013105307473100002DEST_PATH_IMAGE018
, first will
Figure 2013105307473100002DEST_PATH_IMAGE020
with
Figure 2013105307473100002DEST_PATH_IMAGE004AAA
multiply each other, now
Figure 2013105307473100002DEST_PATH_IMAGE022
individual base station received signal is:
Figure 2013105307473100002DEST_PATH_IMAGE024
（12）
Wherein, for
Figure 2013105307473100002DEST_PATH_IMAGE028
independent identically distributed additive noise,
Figure 2013105307473100002DEST_PATH_IMAGE030
.
In described formula (12), estimated value be:
Figure 2013105307473100002DEST_PATH_IMAGE034
（13）
In described formula (13), according to lemma 1, can obtain
(b), in (c),
Figure 2013105307473100002DEST_PATH_IMAGE038
, according to lemma 1,
Figure 2013105307473100002DEST_PATH_IMAGE040
Figure 2013105307473100002DEST_PATH_IMAGE042
Figure 2013105307473100002DEST_PATH_IMAGE044
According to above (a), (b), (c), (d), analyze, in formula (13):
（14）
In above-mentioned formula (14), work as antenna for base station
Figure 2013105307473100002DEST_PATH_IMAGE048
time, upstream data SIR only with
Figure 2013105307473100002DEST_PATH_IMAGE050
relevant, SIR is with antenna for base station number
Figure 2013105307473100002DEST_PATH_IMAGE048A
and be increased to infinite.SIR is no longer limited to pilot pollution.
Preferably, in downlink data transmission, due to the reciprocity of TDD channel, the channel estimation value of upstream data, downlink data transmission is identical;
Figure 2013105307473100002DEST_PATH_IMAGE052
of individual community
Figure 2013105307473100002DEST_PATH_IMAGE016A
individual user's number of constellation points certificate; The
Figure 2013105307473100002DEST_PATH_IMAGE022A
of individual community
Figure 2013105307473100002DEST_PATH_IMAGE016AA
the data that individual user receives are
Figure 2013105307473100002DEST_PATH_IMAGE054
（15）
All users' additive noise meets independent system and distributes.
In described formula (15),
Figure 2013105307473100002DEST_PATH_IMAGE056
estimated value is
（16）
Sequence length in formula (16)
Figure 2013105307473100002DEST_PATH_IMAGE006AA
be more than or equal to community number
Figure 2013105307473100002DEST_PATH_IMAGE008A
,
Figure 2013105307473100002DEST_PATH_IMAGE010A
,
Figure 2013105307473100002DEST_PATH_IMAGE060
not along with antenna for base station number
Figure 2013105307473100002DEST_PATH_IMAGE062
increase and change.
In described formula (16), according to lemma 1,
Figure 2013105307473100002DEST_PATH_IMAGE066
Figure 2013105307473100002DEST_PATH_IMAGE068
with antenna
Figure 2013105307473100002DEST_PATH_IMAGE062A
quantity is irrelevant;
According to above (e), (f), (g), analyze, in formula (16):
Figure 2013105307473100002DEST_PATH_IMAGE070
（17）
In formula (17), work as antenna for base station
Figure 2013105307473100002DEST_PATH_IMAGE048AA
time, the interference that downlink data transmission is caused by pilot pollution disappears, and SIR is no longer limited to pilot pollution; Due to noise item and antenna quantity is irrelevant, and SIR calculates is useful signal average power and the ratio of interference signal average power, therefore, while calculating (17) formula SIR, does not consider the impact of noise.
Described lemma 1:
Figure 2013105307473100002DEST_PATH_IMAGE072
two independent vectors are obeyed ,
Figure 2013105307473100002DEST_PATH_IMAGE076
with
Figure 2013105307473100002DEST_PATH_IMAGE078
.（6）
The invention has the beneficial effects as follows: the interference elimination method of a kind of extensive MIMO in many communities of the present invention based on pilot pollution, according to analyzing known to pilot pollution, when antenna for base station number infinitely increases, the user of same pilot sequence is mainly used in the interference of data estimation value from other communities.The present invention, to sending the precoding sequence of quadrature for data acquisition, makes can eliminate the interference from other communities completely at receiving terminal.When antenna for base station number infinitely increases, SIR is increased to infinite with antenna for base station number.SIR is no longer limited to pilot pollution.The present invention can be applied in the TDD system of many communities of extensive MIMO, solves in the TDD system of many communities of extensive MIMO, eliminates the interference that pilot pollution causes, SIR is increased with antenna for base station number, and SIR is no longer limited to pilot pollution.
Accompanying drawing explanation
Fig. 1 is in the TDD system of many communities of the extensive MIMO of embodiment
Figure DEST_PATH_IMAGE002AAA
of individual community
Figure DEST_PATH_IMAGE016AAA
individual user and
Figure DEST_PATH_IMAGE022AA
of individual community channel parameter schematic diagram between root antenna;
Fig. 2 is transmitting uplink data in the embodiment of the present invention:
Figure DEST_PATH_IMAGE082
,
Figure DEST_PATH_IMAGE084
, a=0.2, b=0.08, transmitting uplink data simulation result figure;
Fig. 3 is transmitting uplink data in the embodiment of the present invention: ,
Figure DEST_PATH_IMAGE084A
, M=100, transmitting uplink data simulation result figure;
Fig. 4 is transmitting uplink data in the embodiment of the present invention: ,
Figure DEST_PATH_IMAGE086
, a=0.2, b=0.08, transmitting uplink data simulation result figure;
Fig. 5 is downlink data transmission in the embodiment of the present invention:
Figure DEST_PATH_IMAGE082AAA
,
Figure DEST_PATH_IMAGE084AA
, a=0.8, b=0.1a, downlink data transmission simulation result figure;
Fig. 6 is downlink data transmission in the embodiment of the present invention:
Figure DEST_PATH_IMAGE082AAAA
,
Figure DEST_PATH_IMAGE084AAA
, M=300, downlink data transmission simulation result figure;
Fig. 7 is downlink data transmission in the embodiment of the present invention:
Figure DEST_PATH_IMAGE082AAAAA
, , a=0.8, b=0.1a, downlink data transmission simulation result figure.
Embodiment
Below in conjunction with accompanying drawing, describe the preferred embodiments of the present invention in detail.
The present embodiment provides the interference elimination method of a kind of extensive MIMO in many communities based on pilot pollution, to sending the precoding sequence of quadrature for data acquisition, and when transmit ascending data, downlink data, the
Figure DEST_PATH_IMAGE002AAAA
the all customer data of individual community is first multiplied by one group of row sequence
Figure DEST_PATH_IMAGE004AAAA
, this sequence wherein
Figure DEST_PATH_IMAGE004AAAAA
sequence length be
Figure DEST_PATH_IMAGE006AAA
, this sequence length
Figure DEST_PATH_IMAGE006AAAA
be more than or equal to community number
Figure DEST_PATH_IMAGE008AA
, , the sequence of different districts
Figure DEST_PATH_IMAGE004AAAAAA
Figure DEST_PATH_IMAGE012A
mutually orthogonal, meet normalizing condition
Figure DEST_PATH_IMAGE014A
.
In transmitting uplink data, the
Figure DEST_PATH_IMAGE002AAAAA
of individual community
Figure DEST_PATH_IMAGE016AAAA
individual user sends upstream data
Figure DEST_PATH_IMAGE018A
, first will
Figure DEST_PATH_IMAGE020A
with
Figure DEST_PATH_IMAGE004AAAAAAA
multiply each other, now
Figure DEST_PATH_IMAGE022AAA
individual base station received signal is:
Figure DEST_PATH_IMAGE024A
（12）
Wherein,
Figure DEST_PATH_IMAGE026A
for
Figure DEST_PATH_IMAGE028A
independent identically distributed additive noise,
Figure DEST_PATH_IMAGE030A
.
In described formula (12), estimated value be:
（13）
In described formula (13), according to lemma 1, can obtain
Figure DEST_PATH_IMAGE036A
Lemma 1:
Figure DEST_PATH_IMAGE072A
two independent vectors are obeyed
Figure DEST_PATH_IMAGE074A
,
with
Figure DEST_PATH_IMAGE078A
.（6）
(b), in (c),
Figure DEST_PATH_IMAGE038A
, according to lemma 1,
Figure DEST_PATH_IMAGE044A
According to above (a), (b), (c), (d), analyze, in formula (13):
Figure DEST_PATH_IMAGE046A
（14）
In above-mentioned formula (14), work as antenna for base station
Figure DEST_PATH_IMAGE048AAA
time, upstream data SIR only with
Figure DEST_PATH_IMAGE050A
relevant, SIR is with antenna for base station number
Figure DEST_PATH_IMAGE048AAAA
and be increased to infinite.SIR is no longer limited to pilot pollution.
In downlink data transmission, due to the reciprocity of TDD channel, the channel estimation value of upstream data, downlink data transmission is identical;
Figure DEST_PATH_IMAGE052A
Figure DEST_PATH_IMAGE002AAAAAA
of individual community
Figure DEST_PATH_IMAGE016AAAAA
individual user's number of constellation points certificate; The
Figure DEST_PATH_IMAGE022AAAA
of individual community
Figure DEST_PATH_IMAGE016AAAAAA
the data that individual user receives are
Figure DEST_PATH_IMAGE054A
（15）
All users' additive noise meets independent system and distributes.
In described formula (15),
Figure DEST_PATH_IMAGE056A
estimated value is
Figure DEST_PATH_IMAGE058A
（16）
Sequence length in formula (16)
Figure DEST_PATH_IMAGE006AAAAA
be more than or equal to community number
Figure DEST_PATH_IMAGE008AAA
,
Figure DEST_PATH_IMAGE010AAA
, not along with antenna for base station number
Figure DEST_PATH_IMAGE062AAA
increase and change.
In described formula (16), according to lemma 1,
Figure DEST_PATH_IMAGE066A
Figure DEST_PATH_IMAGE068A
with antenna
Figure DEST_PATH_IMAGE062AAAA
quantity is irrelevant;
According to above (e), (f), (g), analyze, in formula (16):
Figure DEST_PATH_IMAGE070A
（17）
In formula (17), work as antenna for base station time, the interference that downlink data transmission is caused by pilot pollution disappears, and SIR is no longer limited to pilot pollution; Due to noise item and antenna
Figure DEST_PATH_IMAGE062AAAAA
quantity is irrelevant, and SIR calculates is useful signal average power and the ratio of interference signal average power, therefore, while calculating (17) formula SIR, does not consider the impact of noise.
Know-why
Pilot pollution is analyzed
As shown in Figure 1, suppose to have
Figure DEST_PATH_IMAGE008AAAA
individual hexagonal cell, each community has
Figure DEST_PATH_IMAGE062AAAAAA
root antenna and
Figure DEST_PATH_IMAGE016AAAAAAA
individual single antenna user.The
Figure DEST_PATH_IMAGE002AAAAAAA
of individual community
Figure DEST_PATH_IMAGE016AAAAAAAA
individual user and
Figure DEST_PATH_IMAGE022AAAAA
of individual community
Figure DEST_PATH_IMAGE080A
channel parameter between root antenna is
Figure DEST_PATH_IMAGE088
（1）
Wherein
Figure DEST_PATH_IMAGE090
the multiple Gauss of Cyclic Symmetry is rapid fading coefficient.
Figure DEST_PATH_IMAGE092
, for
Figure DEST_PATH_IMAGE096
vector.Fading coefficients independent same distribution,
Figure DEST_PATH_IMAGE098
.TDD system is within coherence time
Figure DEST_PATH_IMAGE094A
keep constant, i.e. flat fading.
Figure DEST_PATH_IMAGE100
for slow fading coefficient, mainly comprise shadow fading and path fading.Suppose
Figure DEST_PATH_IMAGE100A
predict.
Figure DEST_PATH_IMAGE102
。
In each community, adopt mutually orthogonal pilot tone, minizone adopts identical pilot frequency sequence group.Qie Ge community sends pilot tone simultaneously.Base station and user locate average power (during transmitting) and are respectively
Figure DEST_PATH_IMAGE104
with
Figure DEST_PATH_IMAGE106
Suppose that all communities send length simultaneously and are pilot tone vector.All communities
Figure DEST_PATH_IMAGE016AAAAAAAAA
individual terminal sends pilot tone simultaneously
Figure DEST_PATH_IMAGE110
(meet normalizing condition
Figure DEST_PATH_IMAGE112
), "
Figure DEST_PATH_IMAGE114
" represent conjugate transpose.Now
Figure DEST_PATH_IMAGE022AAAAAA
individual base station received signal is:
Figure DEST_PATH_IMAGE116
（2）
Wherein
Figure DEST_PATH_IMAGE118
for
Figure DEST_PATH_IMAGE120
separate additive noise.
The
Figure DEST_PATH_IMAGE022AAAAAAA
individual base station is to
Figure DEST_PATH_IMAGE016AAAAAAAAAA
individual user's estimation obtains
Figure DEST_PATH_IMAGE122
,
（3）
Wherein
Figure DEST_PATH_IMAGE126
.
From second of formula (3) end product, can find out the interference that the channel parameter estimating exists other communities to estimate Target cell, i.e. pilot pollution.
Take upstream data as example
The
Figure DEST_PATH_IMAGE002AAAAAAAA
of individual community individual user sends upstream data .Now
Figure DEST_PATH_IMAGE022AAAAAAAA
individual base station received signal is:
Figure DEST_PATH_IMAGE130
（4）
According to the channel parameter estimating, the
Figure DEST_PATH_IMAGE022AAAAAAAAA
individual base station obtain
Figure DEST_PATH_IMAGE016AAAAAAAAAAAA
individual user's data
Figure DEST_PATH_IMAGE032AA
value is
Figure DEST_PATH_IMAGE132
（5）
Lemma 1:
Figure DEST_PATH_IMAGE072AA
two independent vectors are obeyed
Figure DEST_PATH_IMAGE074AA
,
with
Figure DEST_PATH_IMAGE078AA
.（6）
Because each terminal fast fading channel is to add up independently, work as antenna for base station
Figure DEST_PATH_IMAGE048AAAAAA
time, according to lemma 1, can obtain
Figure DEST_PATH_IMAGE134
（7）
In formula (5),
Figure DEST_PATH_IMAGE136
（8）
Figure DEST_PATH_IMAGE138
（9）
Suppose that each user sends upstream data power identical, signal interference ratio
Figure DEST_PATH_IMAGE140
（10）
From formula (10), can find out, work as antenna for base station
Figure DEST_PATH_IMAGE048AAAAAAA
time, upstream data SIR only with relevant, not with antenna for base station number
Figure DEST_PATH_IMAGE048AAAAAAAA
and be increased to infinite.SIR is mainly limited to pilot pollution.Pilot pollution has become the bottleneck that restricts extensive mimo system SIR.
(3) downlink data analysis classes seemingly, can obtain same conclusions.
Figure DEST_PATH_IMAGE144
(11)
From formula (11), can find out, work as antenna for base station
Figure DEST_PATH_IMAGE048AAAAAAAAA
time, downlink data SIR only with
Figure DEST_PATH_IMAGE146
relevant, not with antenna for base station number
Figure DEST_PATH_IMAGE048AAAAAAAAAA
and be increased to infinite.
From the above analysis, due to pilot pollution, work as antenna for base station , the
Figure DEST_PATH_IMAGE016AAAAAAAAAAAAA
during individual user's uplink and downlink transfer of data, disturb mainly from other communities the
Figure DEST_PATH_IMAGE016AAAAAAAAAAAAAA
individual user.SIR is not with antenna for base station number and be increased to infinite.
From pilot pollution above, analyzed, work as antenna for base station
Figure DEST_PATH_IMAGE048AAAAAAAAAAAAA
, the during individual user's uplink and downlink transfer of data, disturb the user who mainly uses same pilot sequence from other communities.The interference causing in order to eliminate pilot pollution, when up, the downlink data of transmission, the
Figure DEST_PATH_IMAGE002AAAAAAAAA
the all customer data of individual community is first multiplied by one group of row sequence
Figure DEST_PATH_IMAGE004AAAAAAAA
(establishing sequence length is ) (sequence length and community number
Figure DEST_PATH_IMAGE008AAAAA
relevant), the sequence of different districts
Figure DEST_PATH_IMAGE004AAAAAAAAA
Figure DEST_PATH_IMAGE012AA
mutually orthogonally (meet normalizing condition
Figure DEST_PATH_IMAGE014AA
).
1, transmitting uplink data
The
Figure DEST_PATH_IMAGE002AAAAAAAAAA
of individual community
Figure DEST_PATH_IMAGE016AAAAAAAAAAAAAAAA
individual user sends upstream data
Figure DEST_PATH_IMAGE032AAA
.First will
Figure DEST_PATH_IMAGE032AAAA
with
Figure DEST_PATH_IMAGE004AAAAAAAAAA
multiply each other.Now
Figure DEST_PATH_IMAGE022AAAAAAAAAA
individual base station received signal is:
Figure DEST_PATH_IMAGE024AA
（12）
Wherein for
Figure DEST_PATH_IMAGE028AA
independent identically distributed additive noise,
Figure DEST_PATH_IMAGE030AA
.
Figure DEST_PATH_IMAGE032AAAAA
estimated value be:
Figure DEST_PATH_IMAGE034AA
（13）
According to lemma 1, can obtain
Figure DEST_PATH_IMAGE036AA
(b) (c),
Figure DEST_PATH_IMAGE038AA
. according to lemma 1,
Figure DEST_PATH_IMAGE040AA
Figure DEST_PATH_IMAGE042AA
Figure DEST_PATH_IMAGE044AA
According to above analysis,
Figure DEST_PATH_IMAGE046AA
（14）
From formula (14), can find out, work as antenna for base station
Figure DEST_PATH_IMAGE048AAAAAAAAAAAAAA
time, upstream data SIR only with
Figure DEST_PATH_IMAGE050AA
relevant, SIR is with antenna for base station number
Figure DEST_PATH_IMAGE048AAAAAAAAAAAAAAA
and be increased to infinite.SIR is no longer limited to pilot pollution.
2, downlink data analysis
Due to the reciprocity of TDD channel, the channel estimation value of uplink and downlink transfer of data is identical.
Figure DEST_PATH_IMAGE052AA
Figure DEST_PATH_IMAGE002AAAAAAAAAAA
of individual community
Figure DEST_PATH_IMAGE016AAAAAAAAAAAAAAAAA
individual user's number of constellation points certificate.The
Figure DEST_PATH_IMAGE022AAAAAAAAAAA
of individual community the data that individual user receives are
Figure DEST_PATH_IMAGE054AA
（15）
All users' additive noise meets independent system and distributes.
Its estimated value is
Figure DEST_PATH_IMAGE058AA
（16）
In formula (16) sequence length is by community number it is relevant,
Figure DEST_PATH_IMAGE060AA
not along with antenna for base station number
Figure DEST_PATH_IMAGE062AAAAAAA
increase and change.According to lemma 1,
Figure DEST_PATH_IMAGE064AA
Figure DEST_PATH_IMAGE068AA
with antenna
Figure DEST_PATH_IMAGE062AAAAAAAA
quantity is irrelevant.
Figure DEST_PATH_IMAGE070AA
（17）
From formula (17), can find out, work as antenna for base station
Figure DEST_PATH_IMAGE048AAAAAAAAAAAAAAAA
time, the interference that downlink data transmission is caused by pilot pollution disappears, and SIR is no longer limited to pilot pollution.Due to noise item and antenna
Figure DEST_PATH_IMAGE062AAAAAAAAA
quantity is irrelevant, and SIR calculates is useful signal average power and the ratio of interference signal average power, while therefore calculating (17) formula SIR, does not consider the impact of noise.
Embodiment analysis of simulation result
In emulation, consider the worst situation: each community adopts identical orthogonal pilot frequency sequence.
Figure DEST_PATH_IMAGE150
,
Figure DEST_PATH_IMAGE152
, pilot sequence length
Figure DEST_PATH_IMAGE154
.If
Figure DEST_PATH_IMAGE156
,
Figure DEST_PATH_IMAGE158
.If
Figure DEST_PATH_IMAGE160
,
Figure DEST_PATH_IMAGE162
.For other
Figure DEST_PATH_IMAGE164
with
Figure DEST_PATH_IMAGE002AAAAAAAAAAAA
,
Figure DEST_PATH_IMAGE166
.The useful signal average power of SIR representative of consumer and the ratio of interference signal average power, i.e. signal interference ratio.
Transmitting uplink data:
Figure DEST_PATH_IMAGE082AAAAAA
,
Figure DEST_PATH_IMAGE084AAAA
, a=0.2, b=0.08, transmitting uplink data simulation result, as shown in Figure 2.Transmitting uplink data:
Figure DEST_PATH_IMAGE082AAAAAAA
,
Figure DEST_PATH_IMAGE084AAAAA
, M=100, transmitting uplink data simulation result, as shown in Figure 3.Transmitting uplink data:
Figure DEST_PATH_IMAGE082AAAAAAAA
,
Figure DEST_PATH_IMAGE086AA
, a=0.2, b=0.08, transmitting uplink data simulation result, as shown in Figure 4.
Simulation result when Fig. 2, Fig. 3, Fig. 4 are transmitting uplink data.From Fig. 2, Fig. 4, find out, SIR of the present invention is significantly improved, and increases rapidly along with the increase of M.As seen from Figure 3, when M=100, when the slow fading factor changes, SIR of the present invention is along with the increase of M is obviously better than additive method.
Downlink data transmission:
Figure DEST_PATH_IMAGE082AAAAAAAAA
,
Figure DEST_PATH_IMAGE084AAAAAA
, a=0.8, b=0.1a, downlink data transmission simulation result, as shown in Figure 5.Downlink data transmission:
Figure DEST_PATH_IMAGE082AAAAAAAAAA
,
Figure DEST_PATH_IMAGE084AAAAAAA
, M=300, downlink data transmission simulation result, as shown in Figure 6.Downlink data transmission:
Figure DEST_PATH_IMAGE082AAAAAAAAAAA
,
Figure DEST_PATH_IMAGE086AAA
, a=0.8, b=0.1a, downlink data transmission simulation result, as shown in Figure 7.
Simulation result when Fig. 5, Fig. 6, Fig. 7 are downlink data transmission.From Fig. 5, Fig. 7, find out, SIR of the present invention improves rapidly along with the increase of M.As seen from Figure 6, when M=300, when the slow fading factor changes, SIR of the present invention is along with the increase of M is obviously better than additive method.
From above-mentioned simulation result, can find out, the present invention has effectively eliminated the interference being caused by pilot pollution, the SIR of transfer of data be improved significantly.This has certain actual application value in the TDD system of many communities of extensive MIMO.

Claims (8)

  1. The interference elimination method of the extensive MIMO in 1.Yi Zhongduo community based on pilot pollution, is characterized in that: to sending the precoding sequence of quadrature for data acquisition, and when transmit ascending data, downlink data, the
    Figure 2013105307473100001DEST_PATH_IMAGE002
    the all customer data of individual community is first multiplied by one group of row sequence
    Figure 2013105307473100001DEST_PATH_IMAGE004
    , this sequence wherein
    Figure DEST_PATH_IMAGE004A
    sequence length be
    Figure 2013105307473100001DEST_PATH_IMAGE006
    , this sequence length
    Figure DEST_PATH_IMAGE006A
    be more than or equal to community number ,
    Figure 2013105307473100001DEST_PATH_IMAGE010
    , the sequence of different districts
    Figure DEST_PATH_IMAGE004AA
    Figure DEST_PATH_IMAGE012
    mutually orthogonal, meet normalizing condition
    Figure DEST_PATH_IMAGE014
    .
  2. 2. the interference elimination method of the extensive MIMO in many communities as claimed in claim 1 based on pilot pollution, is characterized in that:
    In transmitting uplink data, the
    Figure DEST_PATH_IMAGE002A
    of individual community
    Figure DEST_PATH_IMAGE016
    individual user sends upstream data
    Figure DEST_PATH_IMAGE018
    , first will with
    Figure DEST_PATH_IMAGE004AAA
    multiply each other, now
    Figure DEST_PATH_IMAGE022
    individual base station received signal is:
    （12）
    Wherein, for
    Figure DEST_PATH_IMAGE028
    independent identically distributed additive noise,
    Figure DEST_PATH_IMAGE030
    .
  3. 3. the interference elimination method of the extensive MIMO in many communities as claimed in claim 2 based on pilot pollution, is characterized in that: in described formula (12),
    Figure DEST_PATH_IMAGE032
    estimated value be:
    Figure DEST_PATH_IMAGE034
    （13）。
  4. 4. the interference elimination method of the extensive MIMO in many communities as claimed in claim 3 based on pilot pollution, is characterized in that: in described formula (13), according to lemma 1, can obtain
    Figure DEST_PATH_IMAGE036
    (b), in (c),
    Figure DEST_PATH_IMAGE038
    , according to lemma 1,
    Figure DEST_PATH_IMAGE040
    Figure DEST_PATH_IMAGE042
    According to above (a), (b), (c), (d), analyze, in formula (13):
    Figure DEST_PATH_IMAGE046
    （14）
    In above-mentioned formula (14), work as antenna for base station
    Figure DEST_PATH_IMAGE048
    time, upstream data SIR only with
    Figure DEST_PATH_IMAGE050
    relevant, SIR is with antenna for base station number
    Figure DEST_PATH_IMAGE048A
    and be increased to infinite; SIR is no longer limited to pilot pollution.
  5. 5. the interference elimination method of the extensive MIMO in many communities as claimed in claim 1 based on pilot pollution, is characterized in that:
    In downlink data transmission, due to the reciprocity of TDD channel, the channel estimation value of upstream data, downlink data transmission is identical;
    Figure DEST_PATH_IMAGE052
    of individual community
    Figure DEST_PATH_IMAGE016A
    individual user's number of constellation points certificate; The
    Figure DEST_PATH_IMAGE022A
    of individual community
    Figure DEST_PATH_IMAGE016AA
    the data that individual user receives are
    （15）
    All users' additive noise meets independent system and distributes.
  6. 6. the interference elimination method of the extensive MIMO in many communities as claimed in claim 5 based on pilot pollution, is characterized in that: in described formula (15),
    Figure DEST_PATH_IMAGE056
    estimated value is
    Figure DEST_PATH_IMAGE058
    （16）
    Sequence length in formula (16)
    Figure DEST_PATH_IMAGE006AA
    be more than or equal to community number
    Figure DEST_PATH_IMAGE008A
    ,
    Figure DEST_PATH_IMAGE010A
    ,,
    Figure DEST_PATH_IMAGE060
    not along with antenna for base station number
    Figure DEST_PATH_IMAGE062
    increase and change.
  7. 7. the interference elimination method of the extensive MIMO in many communities as claimed in claim 6 based on pilot pollution, is characterized in that: in described formula (16), and according to lemma 1,
    Figure DEST_PATH_IMAGE064
    Figure DEST_PATH_IMAGE066
    Figure DEST_PATH_IMAGE068
    with antenna
    Figure DEST_PATH_IMAGE062A
    quantity is irrelevant;
    According to above (e), (f), (g), analyze, in formula (16):
    Figure DEST_PATH_IMAGE070
    （17）
    In formula (17), work as antenna for base station
    Figure DEST_PATH_IMAGE048AA
    time, the interference that downlink data transmission is caused by pilot pollution disappears, and SIR is no longer limited to pilot pollution; Due to noise item and antenna
    Figure DEST_PATH_IMAGE062AA
    quantity is irrelevant, and SIR calculates is useful signal average power and the ratio of interference signal average power, therefore, while calculating (17) formula SIR, does not consider the impact of noise.
  8. 8. the interference elimination method of the extensive MIMO in Duo community based on pilot pollution as described in claim 4-7 any one, is characterized in that: described lemma 1:
    Figure DEST_PATH_IMAGE072
    two independent vectors are obeyed
    Figure DEST_PATH_IMAGE074
    ,
    Figure DEST_PATH_IMAGE076
    with
    Figure DEST_PATH_IMAGE078
    (6).
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