CN113114598B - Multi-cell blind interference alignment method for eliminating cross time slot interference under dynamic TDD - Google Patents

Multi-cell blind interference alignment method for eliminating cross time slot interference under dynamic TDD Download PDF

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CN113114598B
CN113114598B CN202110379690.6A CN202110379690A CN113114598B CN 113114598 B CN113114598 B CN 113114598B CN 202110379690 A CN202110379690 A CN 202110379690A CN 113114598 B CN113114598 B CN 113114598B
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CN113114598A (en
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吴亮
陈远浩
张在琛
安博
罗锐
党建
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Southeast University
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    • H04—ELECTRIC COMMUNICATION TECHNIQUE
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Abstract

The invention discloses a multi-cell blind interference alignment method for eliminating cross time slot interference under dynamic TDD, which aims to eliminate interference between base stations because of small interference between users, and in the blind interference alignment method of the invention, a sending end does not need to know channel state information, and the implementation process is mainly divided into two parts: the users of the interfered cells in the first part transmit signals together with the interference source base station; in the second part, only the interference source base station transmits signals so that the interfered base station only receives the interference signals, thereby eliminating the interference signals in the previous received signals. In order to cancel the interfering signal, the proposed scheme uses intelligent reflecting surfaces or reconfigurable antennas to control the channel pattern. The invention can eliminate interference and has higher degree of freedom.

Description

Multi-cell blind interference alignment method for eliminating cross time slot interference under dynamic TDD
Technical Field
The invention belongs to the technical field of communication, and particularly relates to a blind interference alignment scheme for solving the problem that a single cell generates cross Time slot interference to two adjacent cells in a dynamic Time Division Duplex (TDD) system.
Background
One of the key features of the fifth generation mobile communication network is ultra-dense small cell deployment, where TDD-based air interfaces are proposed for small cell signal transmission, where uplink and downlink transmission resources of each subframe can be flexibly allocated. Such TDD with flexible selection of uplink and downlink configuration is also referred to as dynamic TDD. Dynamic TDD has a high time resource utilization rate (some cells may not transmit or receive signals in the case of uniform configuration) (Hyejin Kim, Jintae Kim, Daesik Hong, "Dynamic TDD Systems for 5G and Beyond: a surface of Cross-link Interference simulation," IEEE Communications resources & Tutorials, 2020.), and each cell can more flexibly adapt to service requirements in the case of flexible configuration of uplink and downlink transmission resources by Dynamic TDD, and this also has a certain effect on reducing base station energy consumption. However, the use of dynamic TDD causes cross-slot interference, and the effect of inter-base-station interference is more serious due to the larger base station power. In order to solve the influence caused by the cross timeslot interference, researchers have proposed a method for cell cluster interference mitigation, which can avoid the cross timeslot interference in the same cluster but cannot avoid the inter-cluster interference. In addition, many researchers have proposed methods based on beamforming and interference alignment, but these methods require channel state information at the transmitting end or require more feedback, which results in less overhead.
Disclosure of Invention
The invention aims to provide a multi-cell blind interference alignment method for eliminating cross time slot interference under dynamic TDD, so as to solve the interference between base stations in the dynamic TDD, and a transmitting end is not required to have channel state information and has higher degree of freedom.
In order to achieve the purpose, the invention adopts the technical scheme that:
a multi-cell blind interference alignment method for eliminating cross time slot interference under dynamic TDD is disclosed, wherein the cell comprises a second cell, and a first cell and a third cell adjacent to the second cell, the second cell interferes with the first cell and the third cell, the first cell comprises a first base station, the second cell comprises a second base station, and the third cell comprises a third base station;
the method comprises the following steps:
the whole blind interference alignment process is divided into 7 parts, and the number of antennas at the transmitting end of the ith cell is set as MiThe number of receiving end antennas is Ni，i∈[1,2,3]；
The user of the first cell, the second base station and the user of the third cell respectively send n1、n2、n3Independent signals, the transmitted ith independent signal is respectively represented as xi、yi、zi(ii) a The independent signals sent by the users of the first cell and the third cell need to be sent repeatedly r1And r3Secondly;
in the first part, the users of the first cell transmit n in total1An independent signal, aOne signal needs to be repeatedly transmitted r1Then, the next signal is sent; r for users in a first cell transmitting the same signal1In each time slot, the first base station uses the mode 1 to the mode r in the corresponding time slot1Receiving a signal;
in the second part, the user in the first cell does not send a signal, at this time, the first base station only receives an interference signal from the second base station, and for each signal sent by the second base station, the receiving mode of the user in the first cell is consistent with the receiving mode in the corresponding time slot of the first part, so that the first base station can subtract the interference signal received in the second part from the signal received in the first part so as to recover the desired signal;
in the third part, the second base station transmits n in total2A separate signal, each signal being transmitted only once, such that r is transmitted continuously22 rounds of, wherein r2Is M2/N2Rounded up values, expressed as
Figure BDA0003012502250000021
M2Divided by N2The remainder of (D) is denoted as rem (M)2,N2) If rem (M)2,N2) Other than 0, the reception pattern of the corresponding time slot for the user of the second cell goes from 1 up to (r)2-2)N2Wherein the same signal and the signal jointly demodulated therewith differ from each other in reception pattern; if rem (M)2,N2) 0, the reception pattern of the time slot corresponding to the user of the second cell is from 1 to r2-2；
In the fourth section, if rem (M)2,N2) Not 0, the second base station will n2The signals are grouped according to a corner mark, then the signals are transmitted according to the groups, the signals are divided into n2/N2Groups of N in each2Each signal in the same group having a corner mark interval of r1k1Wherein k is1Is an integer represented by r1、r3And N2Determined together by the formula
Figure RE-GDA0003079436180000021
The first group of signals is
Figure RE-GDA0003079436180000022
The second group of signals is
Figure RE-GDA0003079436180000023
Up to the n-th2/N2Group signal
Figure RE-GDA0003079436180000024
One time slot for transmitting a set of signals, and a continuous rem (M) transmission2,N2) Wheel, up to r1n1A time slot; the users of the second cell use the same reception mode in each time slot in the same round, the reception modes used in different rounds are different, and the reception mode is selected from (r)2-2)N2+1 to (r)2-2)N2+rem(M2,N2) If rem (M)2,N2) To 0, the second base station will n2The signals are sent in sequence, and the user using mode r of the second cell2-1 receiving;
in the fifth part, the second base station will n2The signals are transmitted again, if rem (M)2,N2) Other than 0, then the reception mode used by the user of the second cell is from (r)2-2)N2+rem(M2,N2) +1 to (r)2-2)N2+rem(M2,N2)+N2In which jointly demodulated N2The receiving modes corresponding to the signals are different from each other; if rem (M)2,N2) 0, then the reception modes of the users in the second cell are all r2；
In the sixth part, the users of the third cell transmit n in total3A separate signal, similar to the first part, is transmitted r by the user of the third cell3Next, the next signal is transmitted, and the users in the third cell transmit the same signal r3In each time slot, the third base station uses the mode 1 to the mode r in the corresponding time slot3Receiving a signal;
in the seventh part, the user of the third cell does not send a signal, and the third base station only receives the interference channel from the second base station at this time; for each signal transmitted by the second base station, the receiving mode of the user in the third cell is consistent with the receiving mode in the time slot corresponding to the sixth part, so that the third base station can subtract the interference signal received in the seventh part from the signal received in the sixth part so as to recover the desired signal;
the degree of freedom obtained by adopting the steps is as follows:
Figure BDA0003012502250000031
the modes are obtained through an intelligent reflecting surface or a reconfigurable antenna, and one mode corresponds to one independent channel.
Has the advantages that: compared with the prior art, the invention has the following advantages:
1. the transmitting end of the blind interference alignment method does not need channel state information;
2. the blind interference alignment method provided by the invention can obtain higher degree of freedom.
Drawings
Fig. 1 is a schematic diagram of a cell to which the method of the present invention is directed;
FIG. 2 shows an example of the case where N is1＝N2＝N3Degree of freedom obtained when 2;
FIG. 3 shows an example of the case where N is1＝4N2＝2N3Degree of freedom obtained when 4;
FIG. 4 shows an example of M1＝5N1＝2M2＝7N2＝2M3＝3N3Bit error rate simulation result under 2 condition;
FIG. 5 shows an example of M1＝5N1＝4M2＝8N2＝2M3＝7N3The bit error rate simulation result in the case of 4.
Detailed Description
The present invention will be further described with reference to the accompanying drawings.
As shown in fig. 1, the cells involved in the multi-cell blind interference alignment method for eliminating cross timeslot interference under dynamic TDD of the present invention include a second cell, and a first cell and a third cell adjacent to the second cell, where the second cell interferes with the first cell and the third cell, the first cell includes a first base station, the second cell includes a second base station, and the third cell includes a third base station;
as shown in table 1, the whole blind interference alignment process is divided into 7 parts, and the number of antennas at the transmitting end of the ith cell is set as MiThe number of receiving end antennas is Ni，i∈[1,2,3]；
In the invention, a user of a first cell, a second base station and a user of a third cell respectively send n1、n2、n3Independent signals, the transmitted ith independent signal is respectively represented as xi、yi、zi(ii) a The independent signals sent by the users of the first cell and the third cell need to be sent repeatedly r1And r3Secondly; wherein the content of the first and second substances,
Figure BDA0003012502250000041
variable n2Is n21And n23Can be expressed as n2＝〔n21,n23Where n is21＝r1N2，n23＝r3N2， n21Representing the number of independent signals that the second cell should send when the second cell only interferes with the first cell (two cells in total), n23Representing the number of independent signals that the second cell should send when the second cell only interferes with the third cell (two cells in total), n2Is the number of independent signals that the second cell should send in the scenario of the proposed scheme of the invention (three cells total), since the invention is a 3-cell scenario, n2Is derived from n of two cells21And n23Further deducing that in the present invention n21And n23Is to calculate n2. Variable n1＝k1(M2-N2) Wherein k is1＝n2/n21；n3＝k3(M2-N2)，k3＝n2/n23。
Table 1 blind interference alignment scheme
Figure BDA0003012502250000042
Figure BDA0003012502250000051
In the first part, the users of the first cell transmit n in total1A separate signal, one signal requiring repeated transmission r1Then, the next signal is sent; r for users in a first cell transmitting the same signal1In each time slot, the first base station uses the mode 1 to the mode r in the corresponding time slot1Receiving a signal;
in the second part, the user in the first cell does not send a signal, at this time, the first base station only receives an interference signal from the second base station, and for each signal sent by the second base station, the receiving mode of the user in the first cell is consistent with the receiving mode in the corresponding time slot of the first part, so that the first base station can subtract the interference signal received in the second part from the signal received in the first part so as to recover the desired signal; the modes are obtained through an intelligent reflecting surface or a reconfigurable antenna, and one mode corresponds to an independent channel;
in the third part, the second base station transmits n in total2A separate signal, each signal being transmitted only once, such that r is transmitted continuously22 rounds of, wherein r2Is M2/N2Rounded up values, expressed as
Figure BDA0003012502250000052
M2Divided by N2The remainder of (D) is represented as rem (M)2,N2) If rem (M)2,N2) Other than 0, then the use of the second cellThe receiving mode of the corresponding time slot of the user is from 1 to (r)2-2)N2Wherein the same signal and the signal jointly demodulated therewith differ from each other in reception pattern; if rem (M)2,N2) 0, the reception pattern of the time slot corresponding to the user of the second cell is from 1 to r2-2；
In the fourth section, if rem (M)2,N2) Not 0, the second base station will n2The signals are grouped according to the indices and then transmitted in groups, the signals being divided into n2/N2Groups of N in each2Each signal in the same group having a corner mark interval of r1k1Wherein k is1Is an integer represented by r1、r3And N2Co-determination of k1＝n2/n21，n21＝r1N2，n23＝r3N2， n2＝〔n21，n23Is integrated to obtain the formula
Figure BDA0003012502250000061
The first group of signals is
Figure BDA0003012502250000062
The second group of signals is
Figure BDA0003012502250000063
Up to the n-th2/N2Group signal
Figure BDA0003012502250000064
One time slot for transmitting a set of signals, and a continuous rem (M) transmission2,N2) Wheel, up to r1n1A time slot; the users of the second cell use the same reception mode in each time slot in the same round, the reception modes used in different rounds are different, and the reception mode is selected from (r)2-2)N2+1 to (r)2-2)N2+rem(M2,N2) If rem (M)2,N2) To 0, the second base station will n2The signals are sent in sequence once, in the second cellUser usage pattern r2-1 receiving;
in the fifth part, the second base station will n2The signals are transmitted again, if rem (M)2,N2) Other than 0, then the reception mode used by the user of the second cell is from (r)2-2)N2+rem(M2,N2) +1 to (r)2-2)N2+rem(M2,N2)+N2In which jointly demodulated N2The receiving modes corresponding to the signals are different from each other; if rem (M)2,N2) 0, then the reception modes of the users in the second cell are all r2；
In the sixth part, the users of the third cell transmit n in total3A separate signal, similar to the first part, is transmitted r by the user of the third cell3Next, the next signal is transmitted, and the users in the third cell transmit the same signal r3In each time slot, the third base station uses the mode 1 to the mode r in the corresponding time slot3Receiving a signal;
in the seventh part, the user of the third cell does not send a signal, and the third base station only receives the interference channel from the second base station at this time; for each signal transmitted by the second base station, the receiving mode of the user in the third cell is consistent with the receiving mode in the time slot corresponding to the sixth part, so that the third base station can subtract the interference signal received in the seventh part from the signal received in the sixth part so as to recover the desired signal;
the degree of freedom obtained by adopting the steps is as follows:
Figure BDA0003012502250000071
the present invention will be further described with reference to the following examples.
Example 1
M1＝5 N1＝2 M2＝7 N2＝2 M3＝3 N3Case 2
Table 2 example 1 (M)1＝5 N1＝2 M2＝7 N2＝2 M3＝3 N3＝2)
Figure BDA0003012502250000072
Figure BDA0003012502250000081
Table 2 shows M1＝5 N1＝2 M2＝7 N2＝2 M3＝3 N3The transmission and reception procedure of each cell in case 2.
The whole process has a total of 42 slots, as shown in the table, where the users of the first cell transmit a total of 10 independent 5 × 1 signals, denoted as xi(i ═ 1,2,3,4,5,6,7,8,9,10), a total of 12 independent 7 × 1 signals, denoted y, were transmitted by the second base stationi(i ═ 1,2,3,4,5,6,7,8,9,10,11,12), a total of 15 independent 3 × 1 signals, denoted z, were transmitted by the users of the third celli(i is 1,2,3,4,5,6,7,8,9,10,11,12,13,14, 15). As can be seen from table 2, in the first 30 time slots, three cells are transmitting signals, and in the last 12 time slots, only base station 2 transmits signals, and at this time, the first base station and the third base station only receive the interference signals of the second base station, so that these interference signals can be subtracted from the signals received in the first 30 time slots, which is equivalent to a non-interference receiving process. Since the signal transmitted by the user of the first cell is x of 5 x 1iAnd the first base station has two antennas, so the users of the first cell need to transmit x 3 timesiCan the first base station recover xi. The signal transmitted by the user of the third cell is z of 3 x 1iAnd the third base station has two antennas, so that the user of the third cell needs to transmit z 2 timesiCan the third base station recover zi. Due to rem (M)2,N2) To 1, the second base station needs to send every yiTransmitted 4 times, each twice in the first 24 slots and with one another in the following 6 slotsyiThe joint is transmitted once and then once in the last 12 slots. When the users of the second cell receive the same signal and the jointly transmitted signal transmitted by the second base station at different time slots, the used receiving modes are different from each other, so as to obtain an independent equation set. The first base station and the third base station receive the same y in different time slotsiThe same reception mode will be used in order to cancel the interference. The brief procedure for each cell to recover the signal is as follows:
the signals obtained by the first base station in the 1 st, 2 nd, 3 rd, 31 th, 32 th, 33 th time slots are recorded as
Figure BDA0003012502250000091
Wherein Hij(m) denotes a channel matrix in mode m from the jth cell transmitting end to the ith cell receiving end, vi(t) (i ═ 1,2,3) is a complex gaussian noise vector.
Then eliminating interference by subtraction to obtain
Figure BDA0003012502250000092
If zero-forcing detection is used, x can be set1Is recorded as
Figure BDA0003012502250000093
Wherein
Figure BDA0003012502250000094
A pseudo-inverse matrix is represented. x is the number ofiThe recovery process of (i ═ 2,3,4,5,6,7,8) is similar. Due to reception of x9,x10Then the second base station is in the process of joint transmission, x9And x10Is slightly different, and finally gets about x9Has the equation set as
Figure BDA0003012502250000095
X can still be recovered using zero-forcing detection or other linear detection methods9，x10And similarly.
The user of the second cell needs to change y1And y7Recovered together. Similarly, the signals received by the users in the second cell in the 1 st, 7 th, 13 th, 19 th, 25 th, 31 th and 37 th time slots are marked as
Figure BDA0003012502250000101
Where O is a 2 x 7 zero matrix. Here y can still be recovered using simple zero-forcing detection1And y7Their estimated values are noted
Figure BDA0003012502250000102
yiThe recovery process of (i ═ 2,3,4,5,6,8,9,10,11,12) is similar.
For the third base station, the procedure for recovering the signal is similar to that of the first base station, e.g. z1Is recorded as
Figure BDA0003012502250000103
ziThe estimated value of (i ═ 2,3,4,5,6,7,8,9,10,11,12) is similar. z is a radical of13Is recorded as
Figure BDA0003012502250000104
z14And z15Similar to that.
In the above case, the proposed blind interference alignment method has the freedom of
Figure BDA0003012502250000105
The mean degree of freedom in Time Division Multiple Access (TDMA) is
Figure BDA0003012502250000111
Fig. 3 shows the bit error rate simulation results of the proposed blind interference alignment scheme and TDMA in this case. In the simulation, the channel is assumed to be a Rayleigh channel with zero mean, unit variance and independent Gaussian complex random variables. Signal-to-noise ratio is SNR (SNR) ═ P/sigma2Where P is the user power, σ2Is the noise power. And sets the base station power to 100 times that of the user. During simulation, the transmission rate of each cell under the two schemes is approximately the same by adjusting the modulation mode so as to compare the error rate conditions.
Example 2
M1＝5 N1＝4 M2＝8 N2＝2 M3＝7 N3Case of 4
Table 3 example 2 (M)1＝5 N1＝4 M2＝8 N2＝2 M3＝7 N3＝4)
Figure BDA0003012502250000112
Figure BDA0003012502250000121
Table 3 shows M1＝5 N1＝4 M2＝8 N2＝2 M3＝7 N3The transmission and reception procedure of each cell in case 4.
The whole process has a total of 16 slots, as shown in the table, where the users of the first cell transmit a total of 6 independent 5 × 1 signals, denoted as xi(i ═ 1,2,3,4,5,6), the secondThe base station transmits a total of 4 independent 8 × 1 signals, denoted by yi(i 1,2,3), the users in the third cell have transmitted a total of 6 independent 7 × 1 signals, denoted as zi(i ═ 1,2,3,4, 5). As can be seen from table 3, in the first 12 time slots, three cells are transmitting signals, and only the second base station transmits signals in the last 4 time slots, and the first base station and the third base station only receive the interference signals of the second base station, so that these interference signals can be subtracted from the signals received in the first 12 time slots, which is equivalent to a non-interference receiving process. Since the signal transmitted by the user of the first cell is x of 5 x 1iAnd the first base station has 4 antennas, so the users of the first cell need to transmit x 2 timesiCan the first base station recover xi. The signal transmitted by the user of the third cell is z of 7 x 1iAnd the third base station has 4 antennas, so the users of the third cell also need to transmit z 2 timesiCan the base station 3 recover zi. Due to rem (M)2,N2) 0, in which case joint transmission is not required. The second base station needs to send every yiTransmitted 4 times, 3 times each in the first 12 slots and once in the last 4 slots. And when the users of the second cell receive the same signal sent by the second base station in different time slots, the used receiving modes are different from each other, so that unrelated equation sets can be obtained. The first base station and the third base station receive the same y in different time slotsiThe same reception mode will be used in order to cancel the interference. The brief procedure for each cell to recover the signal is as follows:
signals obtained by the base station 1 at time slots 1,2, 13,14 are denoted as
Figure BDA0003012502250000122
Wherein Hij(m) denotes a channel matrix in mode m from the jth cell transmitting end to the ith cell receiving end, vi(t) (i ═ 1,2,3) is a complex gaussian noise vector.
Then eliminating interference by subtraction to obtain
Figure BDA0003012502250000131
If zero-forcing detection is used, x can be set1Is recorded as
Figure BDA0003012502250000132
Wherein
Figure BDA0003012502250000133
A pseudo-inverse matrix is represented. x is the number ofiThe recovery process of (i ═ 2,3,4,5,6) is similar.
Similarly, the signals received by the users in the 1 st, 5 th, 9 th and 13 th time slots of the second cell are recorded as
Figure BDA0003012502250000134
Here y can still be recovered using simple zero-forcing detection1Its estimated value is recorded as
Figure BDA0003012502250000135
yiThe recovery process of (i ═ 2,3,4) is similar.
For the third base station, the procedure for recovering the signal is similar to that of the first base station, e.g. z1Is recorded as
Figure BDA0003012502250000136
ziThe estimated value of (i ═ 2,3,4,5,6) is similar to this.
In the above case, the proposed blind interference alignment method has the freedom of
Figure BDA0003012502250000137
The average degree of freedom in TDMA is
Figure BDA0003012502250000141
Fig. 4 shows the bit error rate simulation results of the proposed blind interference alignment scheme and TDMA in this case. In the simulation, the channel is assumed to be a Rayleigh channel with zero mean, unit variance and independent Gaussian complex random variables. Signal-to-noise ratio is SNR (SNR) ═ P/sigma2Where P is the user power, σ2Is the noise power. The base station power is set to be 100 times that of the user. During simulation, the transmission rate of each cell under the two schemes is approximately the same by adjusting the modulation mode so as to compare the error rate conditions.
The present invention does not require channel state information at the transmitting end in practice, and it can be found in the above example that the present invention has a higher degree of freedom compared to TDMA.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.

Claims (2)

1. A multi-cell blind interference alignment method for eliminating cross time slot interference under dynamic TDD is characterized in that: the cells comprise a second cell, a first cell and a third cell which are adjacent to the second cell, the second cell interferes with the first cell and the third cell, the first cell comprises a first base station, the second cell comprises a second base station, and the third cell comprises a third base station;
the method comprises the following steps:
the whole blind interference alignment process is divided into 7 parts, and the number of antennas at the transmitting end of the ith cell is set as MiThe number of receiving end antennas is Ni，i∈[1,2,3]；
Users of a first cellThe users of the second base station and the third cell respectively send n1、n2、n3Independent signals, the transmitted ith independent signal is respectively represented as xi、yi、zi(ii) a The independent signals sent by the users of the first cell and the third cell need to be sent repeatedly r1And r3Secondly;
in the first part, the users of the first cell transmit n in total1A separate signal, one signal requiring repeated transmission r1Then, the next signal is sent; r for users in a first cell transmitting the same signal1In each time slot, the first base station uses the mode 1 to the mode r in the corresponding time slot1Receiving a signal;
in the second part, the user in the first cell does not send a signal, at this time, the first base station only receives an interference signal from the second base station, and for each signal sent by the second base station, the receiving mode of the user in the first cell is consistent with the receiving mode in the corresponding time slot of the first part, so that the first base station can subtract the interference signal received in the second part from the signal received in the first part so as to recover the desired signal;
in the third part, the second base station transmits n in total2A separate signal, each signal being transmitted only once, such that r is transmitted continuously22 rounds of, wherein r2Is M2/N2Rounded up values, expressed as
Figure FDA0003012502240000011
M2Divided by N2The remainder of (D) is represented as rem (M)2,N2) If rem (M)2,N2) Other than 0, the reception pattern of the corresponding time slot for the user of the second cell goes from 1 up to (r)2-2)N2Wherein the same signal and the signal jointly demodulated therewith differ from each other in reception pattern; if rem (M)2,N2) 0, the reception pattern of the time slot corresponding to the user of the second cell is from 1 to r2-2；
In the fourth section, if rem (M)2,N2) Not 0, the second base station will n2The signals are grouped according to a corner mark, then the signals are transmitted according to the groups, the signals are divided into n2/N2Groups of N in each2Each signal in the same group having a corner mark interval of r1k1Wherein k is1Is an integer represented by r1、r3And N2A joint determination, which is calculated as
Figure FDA0003012502240000021
The first group of signals is
Figure FDA0003012502240000022
The second group of signals is
Figure FDA0003012502240000023
Up to the n-th2/N2Group signal
Figure FDA0003012502240000024
One time slot transmits a group of signals, and rem (M) is continuously transmitted2,N2) Wheel until r1n1A time slot; the users of the second cell use the same reception mode in each time slot in the same round, the reception modes used in different rounds are different, and the reception mode is selected from (r)2-2)N2+1 to (r)2-2)N2+rem(M2,N2) If rem (M)2,N2) To 0, the second base station will n2The signals are sent in sequence, and the user using mode r of the second cell2-1 receiving;
in the fifth part, the second base station will n2The signals are transmitted again, if rem (M)2,N2) Other than 0, then the reception mode used by the user of the second cell is from (r)2-2)N2+rem(M2,N2) +1 to (r)2-2)N2+rem(M2,N2)+N2In which jointly demodulated N2The receiving modes corresponding to the signals are different from each other; if rem (M)2,N2) 0, then the reception modes of the users in the second cell are all r2；
In the sixth part, the users of the third cell transmit n in total3A separate signal, similar to the first part, is transmitted r by the user of the third cell3Next, the next signal is transmitted, and the users in the third cell transmit the same signal r3In each time slot, the third base station uses the mode 1 to the mode r in the corresponding time slot3Receiving a signal;
in the seventh part, the user of the third cell does not send a signal, and the third base station only receives the interference channel from the second base station at this time; for each signal transmitted by the second base station, the receiving mode of the user in the third cell is consistent with the receiving mode in the time slot corresponding to the sixth part, so that the third base station can subtract the interference signal received in the seventh part from the signal received in the sixth part so as to recover the desired signal;
the degree of freedom obtained by adopting the steps is as follows:
Figure FDA0003012502240000025
2. the method according to claim 1, wherein the method for aligning the blind interference of multiple cells with cross slot interference cancellation under dynamic TDD is characterized in that: the modes are obtained through an intelligent reflecting surface or a reconfigurable antenna, and one mode corresponds to one independent channel.
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