CN1291020A - Interference offset device of CDMA receiver - Google Patents
Interference offset device of CDMA receiver Download PDFInfo
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- CN1291020A CN1291020A CN00119919A CN00119919A CN1291020A CN 1291020 A CN1291020 A CN 1291020A CN 00119919 A CN00119919 A CN 00119919A CN 00119919 A CN00119919 A CN 00119919A CN 1291020 A CN1291020 A CN 1291020A
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Abstract
The interference canceler device is provided with one or more interference removing stages for removing interference from a received signal by generating interference replicas for individual channels by a plurality of interference replica generation units corresponding to respective channels and subtracting these interference replicas from a received signal. The device is constituted so as to demodulate by a demodulation stage the received signal from which interference is removed by the interference removing stage. Each interference replica generation unit is operated also as a data demodulation part in accordance with a traffic stage.
Description
The present invention relates generally to interference offset device, more particularly, relate on the employed receiver in a wireless base station that is used to offset a honeycomb direct sequence CDMA (DC/CDMA) mobile communication system, from an interference offset device of the interference that other channel produced.
In this honeycomb DC/CDMA mobile communication system, the multiple access that results from the asymmetry of travelling carriage disturbs becomes a principal element that reduces system transmission capacity and transmission quality.Because this reason must be removed multiple access as much as possible and disturb from the signal that is received.
Fig. 1 has schematically shown a structure of a receiver of a DC/CDMA wireless base station, and this receiver comprises a traditional interference offset device 24.
As shown in Figure 1, a CDMA ripple is received by an antenna 20, and is imported into a receiving unit 21, and in this receiving unit 21, this CDMA ripple is demodulated to a baseband signal.Then, this baseband signal is converted to a digital signal by an analog to digital (A/D) transducer 22, and this digital signal is sent to a path search circuit 23.After this, this digital signal is used as a signal that is received " r ", is input in traditional interference offset device 24.
This interference offset device 24 produces the interference replica signal of the interference in the simulation received signal " r ", removes these interference replica signals then from received signal " r ", disturbs to offset from the multiple access that asymmetry was produced of travelling carriage (user).Then, multiple access wherein disturbs removed received signal " r " to be imported into each decoder 5 (1) to 5 (n) (channel 1 to n) of user.
Fig. 2 has shown a structure of this traditional interference offset device 24 among Fig. 1, and this is the so-called Parallel Interference Cancellation device that can support 4 users.
As shown in Figure 2, that received signal " r " is imported into is parallel, each the interference offset device unit in 4 interference offset device unit (ICU) 1 (1) to 1 (4), simultaneously, be imported into Interference Cancellation part (subtracter) 3 through a decay part 2 again.This ICU1 (1) to 1 (4) produce respectively symbol reproducing signals S (1) to S (4) and by further again escape character reproducing signals S (1) produce interference replica signal d (1) to d (4) to S (4).Symbol reproducing signals S (1) is sent to receiving element 4 (1) to 4 (4) respectively to S (4).Interference replica signal d (1) is sent to Interference Cancellation part 3 to d (4).
The residual signal that is obtained " e " is imported into corresponding receiver 4 (1) to 4 (4) like this, institute's receiving symbol (multi-valued signal) R (1) that wherein represents respective channel is carried out demodulation according to symbol reproducing signals S (1) to S (4) and residual signal " e " to R (4), be sent to corresponding decoder 5 (1) to 5 (4) then, wherein deinterleave by execution, the error correction of soft-decision, perhaps similar, come the user data that transmits is decoded.
Fig. 3 has schematically shown ICU1 (1) each structure in 1 (4).
As shown in Figure 3, ICU be a 3-refer to/1 branch, received signal " r " is carried out the ICU type that RAKE mixes.This ICU comprises 12,3 cell mesh 13 in 11, one judgment parts of 10, one RAKE mixing portions of 3 cell mesh.In these 3 cell mesh 10 each has 102, one multipliers 103 of 101, one adders in a de-spread unit and a channel estimation circuit 104.In these 3 cell mesh 13 each has 131, one subtracters 132 of a multiplier and one expanding element 133 and a mixing portion 14 again.In addition, Fig. 3 has only shown in 3 cell mesh 10 in one structure and 3 cell mesh 13 only one structure.
Here, in each of 3 cell mesh 10, the 101 pairs of received signals in de-spread unit " r " carry out de-spread, and it is sent to adder 102; Adder 102 is carried out addition with the received signal " r " and the symbol reproducing signals S of de-spread, with a receiving symbol R (despread signal) who produces a character rate, and this receiving symbol R is sent to multiplier 103 and channel estimation circuit 104; Channel estimation circuit 104 comes the phase place rotation and the changes in amplitude of a transmission line are carried out channel estimating according to a frequency pilot sign of institute's receiving symbol, with a complex conjugate ξ with a channel estimation value ξ
*Send to multiplier 103; Multiplier 103 multiply by complex conjugate ξ with the symbol R that is received
*, the next phase place rotation that the removal transmission line provides from the receiving symbol R of institute and the influence of changes in amplitude.
Like this, 3 cell mesh 10 send to mixing portion 11 with the receiving symbol R of institute; The receiving symbol R of 11 pairs of institutes of mixing portion carries out RAKE and mixes, to form a data symbol and this data symbol is sent to judgment part 12; This judgment part 12 is judged this data symbol potentially and this data symbol is sent to 3 cell mesh 13.In addition, the supposition of judgment part 12 judges it can is soft judgement (many-valued) or hard judgement (two values), in this example, the supposition that the data symbol is judged is firmly judged, comprises two values " 0 " and " 1 ".
In in 3 cell mesh 13 each, multiplier 131 multiply by channel estimation value ξ with this data symbol, brings symbol reproducing signals S disturbing and this symbol reproducing signals S is sent in subtracter 132 and the receiving element 4 (1) to 4 (4) corresponding one on transmission line with generation; Subtracter 132 deducts the symbol reproducing signals S of cell mesh 10 from the symbol reproducing signals S of multiplier 131, and the symbol reproducing signals S that a quilt deducts is sent to again expanding element 133; Again the symbol reproducing signals S that deducts of 133 pairs of quilts of expanding element expands again, to produce an interference replica signal d.Like this, 3 cell mesh 13 send to mixing portion 14 with this interference replica signal d, and mixing portion 14 is formed into a mixing interference replica signal d of Interference Cancellation part 3.
Fig. 5 has shown a frame structure of a time multiple access pilot transmission.As shown among this figure, a frequency pilot sign and an information symbol are inserted in each time slot of a transmission signals.
In addition, under one with a plurality of Interference Cancellation levels situation traditional, multistage interference offset device, a symbol reproducing signals S who is produced on the ICU of one-level (n) is sent to the ICU of one-level (n+1), and wherein adder 102 will be carried out addition from the symbol reproducing signals S of level (n) and the receiving symbol R of institute from de-spread unit 101; Subtracter 132 deducts the symbol reproducing signals S from multiplier 131.
Fig. 4 has shown in the receiving element 4 (1) to 4 (4) of traditional interference offset device 24 structure of one.Receiving element among Fig. 4 also is configured to 3 and refers to/1 branch pattern.
As shown in Figure 4, for example the receiving element in level (n) comprises 3 cell mesh 40 and a mixing portion 41.In 3 cell mesh 40 each has 4402, one multipliers 403 of 401, one adders in a de-spread unit and a channel estimation circuit 404.
In each of 3 cell mesh 40, the removed received signal of interference wherein is by Interference Cancellation part 3 outputs from one-level (n-1), and be sent to de-spread unit 401, a symbol reproducing signals S who comes from a corresponding ICU is sent to adder 402; The 402 pairs of signals that received in this de-spread unit carry out de-spread, obtain a symbol that is received; This adder 402 is carried out addition with symbol and the symbol reproducing signals S that is received, and the receiving symbol R that is produced is sent to multiplier 403 and channel estimation circuit 404; Channel estimation circuit 404 produces a channel estimation value ξ according to the frequency pilot sign of the receiving symbol R that is produced, and with its complex conjugate ξ
*Send to multiplier 403; Multiplier 403 multiply by complex conjugate ξ with the receiving symbol R of institute
*, from the receiving symbol R of institute, to remove the interference on the transmission line.
So 3 cell mesh 40 will wherein have been removed the corresponding receiving symbol R that disturbs and send to mixing portion 41, this mixing portion 41 sends to a corresponding decoder 5 with a mixed receiving symbol R.In addition, because be a multi-valued signal,, therefore, on decoder 5, it is decoded by the error correction of soft-decision decoding so the receiving symbol R of institute can be counted as a soft decision signal.
Fig. 6 has shown a structure of another the traditional interference offset device that belongs to a serial type.In addition, traditional interference offset device is configured to have a plurality of Interference Cancellation levels (Fig. 6 shown be two-stage # 1 and #2).
As shown in Figure 6, level # 1 further comprises the sub level of 3 series connection, and each has an ICU, a decay part and an Interference Cancellation part, and the structure of level # 2 is identical with the structure of level # 1.
In this example, by the corresponding ICU1 (1) of level # 1
#1To 1 (3)
#1The symbol reproducing signals S (1) that is produced
#1To S (3)
#1Sent to the ICU1 (1) of grade # 2 respectively
#2To 1 (3)
#2Can be as the ICU1 (1) receiving element 4, level # 2 of Parallel Interference Cancellation device
#2To 1 (3)
#2With the receiving symbol R of institute (1)
#2To R (3)
#2Send to decoder 4 (1) to 4 (3) respectively.In decoder 4 (1) to 4 (3), these user's data symbols are decoded.
Fig. 7 has shown ICU1 (1) among the Interference Cancellation level # 1 of counteracting serial interference device
#1To 1 (3)
#1A structure of one.Fig. 8 has shown ICU1 (1) among the Interference Cancellation level # 2 of same type interference offset device
#2To 1 (3)
#2A structure of one.
ICU1 (1) among the Interference Cancellation level # 1
#1To 1 (3)
#1Structure and Fig. 3 in the structure of those ICU of shown Parallel Interference Cancellation device identical.On the other hand, with the output symbol reproducing signals, ICU1 (1) among the Interference Cancellation level # 1
#1To 1 (3)
#1Difference, ICU1 (1) among the Interference Cancellation level # 2
#2To 1 (3)
#2To output to the one next stage from institute's receiving symbol RAKE mixing portion 11, mixed (multi-valued signal).
But traditional interference offset device has following shortcoming.
Especially, as can be seen from Figure 2, traditional interference offset device need be provided ICU1, receiving element 4 and decoder 5, and wherein each needed number is identical with the user's who communicates at the same time number.As a result, when a base station can provide the user's of service number to increase for it, the scale of Canceller had just increased.
Further, as can be seen from Figure 6, traditional multistage types of interference Canceller need be provided ICU, and the number of ICU equals (number of level) * (user's number).As a result, the structure of multistage types of interference Canceller also has the shortcoming that its scale must increase.
In addition, in a DS-CDMA system, under the situation that its frequency band remains unchanged, transmission rate is low more, and the expansion gain is just big more, and the number of users that can hold just can be increased.On the contrary, transmission rate is high more, and the expansion gain is just more little, so the number of users that can hold has just reduced.Here, expansion gain be transmission rate (for example, 64Kbps) with the ratio of the frequency band of a CDMA ripple (for example, 64Kbps).
Because this reason, to the user, voice user for example, the image user, data information user and the similar user with various transmission rates provide in the DS-CDMA system of service, the transmission rate of supposing all users all remains on a lower speed (voice user's a state), ICU in the system, the number that receiving element and decoder must be prepared should be able to be supported this state.Under this situation, when wherein having mixed the user of several band higher transmission rates, some receiver that has been prepared has become useless, because the number of users that need be received has reduced.As a result, its hardware availability has reduced.
So, in traditional Canceller, ICU, receiving element and decoder need be prepared independently, and each the number in them need equate with the user's who is held number.As a result, the scale of interference offset device has increased, and its hardware availability has reduced, and its product expense has increased.
A general objects of the present invention provides an interference offset device in the CDMA receiver, wherein can overcome above-mentioned shortcoming.
Another and more detailed purpose of the present invention provide an interference offset device of a CDMA receiver, and its size has been dwindled, and its hardware is used effectively, has increased user's maximum number, and has good Interference Cancellation characteristic.
By an interference offset device in the cdma communication system, realized above-mentioned purpose of the present invention and other purpose, described interference offset device comprises:
At least one Interference Cancellation level, that each grade has is corresponding with channel, be used for producing the interference replica signal of described channel and be used for removing from a received signal a plurality of Interference Cancellations unit (ICU) of interference replica signal, in the demodulation part received signal that is produced is carried out demodulation;
Described ICU also carries out work as described demodulation part, responds with the professional qualification to described channel.
Realize above-mentioned purpose of the present invention and other purpose by an interference offset device in the cdma communication system, described interference offset device comprises:
At least a plurality of Interference Cancellation levels, that each grade has is corresponding with channel, be used for producing the interference replica signal of described channel and be used for removing from a received signal a plurality of Interference Cancellations unit (ICU) of interference replica signal, in the demodulation part received signal that is produced is carried out demodulation;
Described ICU also carries out work as described demodulation part, responds with the professional qualification to described channel.
By following detailed description of the present invention of reference and accompanying drawing, the feature and advantage that the present invention may be better understood, accompanying drawing has proposed to utilize an illustrative embodiments of the principle of the invention.
Fig. 1 has schematically shown the structure of a receiver of a base station of a cdma system;
Fig. 2 has schematically shown a structure of a traditional interference offset device;
Fig. 3 has schematically shown a structure of an interference offset device unit (ICU) of traditional interference offset device among Fig. 2;
Fig. 4 has schematically shown a structure of a receiving element of traditional interference offset device among Fig. 2;
Fig. 5 has shown a frame method of time division multiple access pilot transmission;
Fig. 6 has schematically shown a structure of a conventional serial interference offset device;
Fig. 7 has schematically shown a structure of the interference offset device unit (ICU) of the one-level # 1 of conventional serial interference offset device among Fig. 6;
Fig. 8 has schematically shown a structure of the interference offset device unit (ICU) of the one-level # 2 of conventional serial interference offset device among Fig. 6;
Fig. 9 has schematically shown one first execution mode according to the present invention, a structure of a Parallel Interference Cancellation device;
Figure 10 has schematically shown a structure of an interference offset device unit (ICU) in the Parallel Interference Cancellation device of first execution mode;
Figure 11 has shown a basic operation mode of the interference offset device of first execution mode, and wherein two users communicate simultaneously;
Figure 12 has shown a basic operation mode of the interference offset device of first execution mode, and wherein four users communicate simultaneously;
Figure 13 has shown another mode of operation of the interference offset device of first execution mode, wherein sorts with the power that it was received;
Figure 14 has shown another mode of operation of the interference offset device of first execution mode, wherein sorts with its transmission rate;
Figure 15 has shown another mode of operation of the interference offset device of first execution mode, wherein sorts with its communication type;
Figure 16 has shown another mode of operation of the interference offset device of first execution mode, has wherein produced a new communication request;
Figure 17 has shown another mode of operation of the interference offset device of first execution mode, has wherein produced a new communication request or similar with big received power;
Figure 18 has shown another mode of operation of the interference offset device of first execution mode, has wherein produced a new communication request or similar with less received power;
Figure 19 has schematically shown one second execution mode according to the present invention, a structure of a multistage type Parallel Interference Cancellation device; With
Figure 20 has schematically shown one the 3rd execution mode according to the present invention, a structure of a multistage type counteracting serial interference device.
Reference diagram describes below preferred implementation of the present invention.
At first, with reference to figure 9, provided a description about an interference offset device of the present invention's one first execution mode.
Fig. 9 interference offset device shown, first execution mode can be applied in the employed receiver in base station of the shown CDMA mobile communication system of Fig. 1, and is configured to and can provides service, its structure traditional interference offset device identical parallel type shown with Fig. 2 to 4 users.
As shown in Figure 9, interference offset device comprises parallel I CU1 (1) and 1 (2), decay part 2, Interference Cancellation part 3, receiving element 4 (1) and 4 (2), 5 (1) to 5 (4) and two switching circuits 6 (1) and 6 (2) of decoder.
Received signal " r " is sent to ICU1 (1) concurrently, and 1 (2) and decay part 2.Received signal " r " from decay part 2 is imported into Interference Cancellation part 3.Identical as those ICU in traditional Canceller, ICU1 (1) and 1 (2) produces interference replica signal d (1) and d (2) and symbol reproducing signals S (1) and S (2) respectively.
Interference replica signal d (1), d (2) is imported into Interference Cancellation part 3, and Interference Cancellation part 3 is with interference replica signal d (1), and d (2) gets rid of from received signal " r ", has wherein removed a received signal " e " of disturbing to produce.Then, this received signal " e " is imported into corresponding receiving element 4 (1) and 4 (2).
Different with the traditional interference offset device that comprises 4 (1) to 4 (4) and 4 decoders 5 (1) to 5 (4) of 4 receiving elements, the interference offset device of first execution mode comprises two receiving elements 4 (1) and 4 (2) and 4 decoders 5 (1) to 5 (4), can support 4 users.
Here, construct ICU1 (1) and 1 (2) like this, be sent to receiving element 4 (1) and 4 (2) so that symbol reproducing signals S (1) that is produced and S (2) pass through switching circuit 6 (1) and 6 (2), and by multiply by the complex conjugate ξ of channel estimation value ξ
*From the interference of wherein having offset transmission line, the receiving symbol R of institute (1) and R (2), passed through switching circuit 6 (1) and 6 (2) to send to decoder 5 (2) and 5 (4).
In addition, because comprise multi-valued signal, receiving symbol R of institute (1) and R (2) can be considered to soft decision signal and modulating data.So wherein receiving symbol R of institute (1) and R (2) pass through switching circuit 6 (1) and 6 (2) structures from ICU1 (1) and 1 (2) proposition can make ICU1 (1) and 1 (2) be used as the data demodulates part.
In the switching circuit 6 (1) and 6 (2) each has two on off states " a " and " b ".In state " a ", their admissible mark reproducing signals S (1) and S (2) can transmit between ICU1 and receiving element 4, and in state " b ", allow receiving symbol R of institute (1) and R (2) between ICU1 and decoder 5 (1) and 5 (2), to transmit.
Figure 10 has shown the structure of the ICU1 of interference offset device among Fig. 9, and it is identical with traditional ICU1 among Fig. 3 basically, and wherein the RAKE that carries out institute's receiving symbol by 3 structures that refer to/1 branch mixes.
Different with traditional ICU1, in the ICU1 of this execution mode, mix if 11 pairs of RAKE mixing portions carry out RAKE from receiving symbol 10 outputs of corresponding units part, will a receiving symbol R, and it is sent to judgment part 12 and decoder 5 (not demonstration).
Like this, in the interference offset device of this execution mode, after carrying out the RAKE mixing, ICU1 sends to decoder 5 (2) and 5 (4) with the symbol (multi-valued signal) that is received through switching circuit 6 (1) and 6 (2).When switching circuit 6 (1) and 6 (2) is in state " a ", ICU1 (1) and 1 (2) Interference Cancellation level as traditional interference offset device.On the other hand, when switching circuit 6 (1) and 6 (2) was in state " b ", ICU1 (1) and 1 (2) was as Interference Cancellation level and receiving element.Even under this situation, because ICU1 (1) and 1 (2) can produce the interference replica signal and they are got rid of (that is, as the Interference Cancellation level) from the signal that is received, interference offset device of the present invention can provide the Interference Cancellation service for certain customers.
So the number of ICU1 that interference offset device of the present invention had and employed receiving element 4 wherein is identical with half of number of users.
Below, the various modes of operation of the interference offset device of first execution mode are described.
At first, with reference to Figure 11 and 12 a basic operation mode is described.In this basic operation mode, all users are served liberally, and do not have the received power to them, transmission rate, and communication type perhaps similarly sorts.
Figure 11 has only shown the situation that several users (in this example, only two users) communicates at the same time.Switching circuit 6 (1) and 6 (2) is switched to the state of being in " a ", so that the interference offset device of this execution mode is as traditional interference offset device.Under this situation, ICU1 (1), receiving element 4 (1) and decoder 5 (1) are assigned to a user A service are provided, and ICU1 (2), receiving element 4 (2) and decoder 5 (3) are assigned to a user B service are provided.In addition, decoder 5 (2) and 5 (4) is not used.
Figure 12 has shown the situation that many users (in this example, 4 users) communicate at the same time.Switching circuit 6 (1) and 6 (2) is switched to the state of being in " b ", provide service so that receiving element 4 (1) and 4 (2) is assigned to user A and B, and ICU1 (1) and 1 (2) is assigned to user C and D.Like this, by use with the user A that is assigned with to the corresponding extended code of D, received signal carried out de-spread or expand again at corresponding circuit.
As a result, on ICU1 (1), the mediation of separating of carrying out the interference replica signal d (1) of user C produces, and on the other hand, on ICU1 (2), the mediation of separating of carrying out the interference replica signal d (2) of user D produces.Interference replica signal d (1) that is produced and d (2) are sent to the Interference Cancellation part 3 of removing these interference replica signals d (1) and d (2) from received signal " r ".Like this, concerning user C and D, from received signal " r ", remove these interference.Further, passed through switching circuit 6 (1) and 6 (2) as the receiving symbol R of institute (1) of the demodulating data of user C and D and R (2) and sent to the decoder 5 (2) and 5 (4) that the corresponding data symbol is decoded.
On the other hand, receiving element 4 (1) and 4 (2) uses the received signal " e " of the interference of wherein having removed user C and D, carry out demodulation with receiving symbol R of institute (1) and R (2), then they are sent to corresponding decoder 5 (1) and 5 (3) user A and B.
Below, with reference to Figure 13, describe that the power that the user received is responded, and change another mode of operation that circuit distributes.The interference offset device of this execution mode is configured to 4 user A, B, and C and D provide service, and are A＞B＞C＞D according to the ordering of institute's received power.
In this mode of operation, in ICU1 (1) and 1 (2), received signal " r " is handled, so that produce the interference replica signal, and, from received signal " r ", removed these users' interference by from received signal " r ", removing the interference replica signal.
Generally, the received power of a signal is strong more, and this signal is just big more to the interference that received signal applies, so a more weak relatively signal of its received power just may disturbed institute flood.Institute's received power often is subjected to the influence of a link between a base station and the travelling carriage, the result, just produced a far-near problem, wherein far user's (its received power is more weak user relatively) reception is easy to be disturbed by very near user (its received power is stronger user relatively).
So,, then, just can from received signal, remove its interference if the relative stronger user of its received power is assigned to ICU1 (1) and 1 (2).Further, if the removed received signal of interference wherein is used to the signal from the more weak relatively user of its received power is carried out demodulation, then, can receive the more weak signal of this intensity with high reliability.
That is, ICU1 (1) and 1 (2) is assigned to its received power relative stronger user A and B, and receiving element 4 (1) and 4 (2) is assigned to its received power relative more weak user C and D.Thus, in receiving element 4 (1) and 4 (2), the received signal " e " of wherein having offset the interference d (1) of user A and B and d (2) is used to the signal of demodulation user C and D.Like this, just solved far-near problem.
Like this, by in relative level than the front, relative stronger user handles to its received power, can more effectively carry out Interference Cancellation.Under this situation, in order to measure received power, need prepare a circuit matched with wave filter independently, perhaps use the path search circuit.
Below, be described with reference to Figure 14 that transmission rate to subscriber signal responds and executive circuit distributes, another mode of operation.In this mode of operation, user A, B, the ordering of the transmission rate of the signal of C and D is A＞B＞C＞D.
Generally, the transmission rate of a signal is high more, and its expansion gain is just more little, and it is strong more that the power of its signal just becomes.So, with the example class of Figure 13 seemingly, by in the level than the front relatively, the subscriber signal that its transmission rate is higher is relatively handled, can more effectively carry out Interference Cancellation.Under this situation, ICU1 (1) and 1 (2) is assigned to its transmission rate relative higher user A and B, and receiving element 4 (1) and 4 (2) is assigned to its transmission rate relatively low user C and D.In addition, the transmission rate of user A to D also known in this base station, so, can carry out its ordering easily.
Below, be described with reference to Figure 15 to the user's communications type (voice, image, data communication and similarly) respond and executive circuit distributes, another mode of operation.In this mode of operation, user A and B carry out voice communication, and user C and D carry out data communication.
Brought processing delay at ICU1 (1) and 1 (2) the mediation generation of separating performed, the interference replica signal.This processing delay is decided by to a great extent that during demodulating process transmission line performed on channel estimation circuit is estimated.For example, in order to improve the accuracy that transmission line is estimated, a plurality of frequency pilot sign pieces are averaged, but this has produced the increase of processing delay.Here, because need real-time speech communicating or similar, a signal has long processing delay and just can not be accepted.On the other hand, data communication can be tolerated processing delay to a certain extent.So, by in relative level, the signal of the voice channel that can not tolerate long processing delay is handled than the front, can eliminate this delay issue.In other words, ICU1 (1) and 1 (2) is assigned to the user A and the B that can not tolerate that long process postpones, and receiving element 4 (1) and 4 (2) is assigned to the user C and the D that can tolerate long delay.
Below, with reference to Figure 16, describe when other user communicates, on the interference offset device of first execution mode, channel allocation is given another mode of operation of a user who produces a new request.
Figure 16 has shown at a state that produces before newly asking.In this embodiment, user's number is 4.The number of users that communicates simultaneously therein is under this situation of 2 (user A and B), and user A is assigned to ICU1 (1), accept unit 4 (1) and decoder 5 (1), and user B is assigned to ICU1 (2), accepts unit 4 (2) and decoder 5 (3).ICU1 (1) and 1 (2) is as traditional ICU.
At this constantly, suppose that user C has produced a new communication request.If compare with B with user A, user C has a stronger power and the high transmission rate accepted, if perhaps user C is the voice communication user that can not tolerate processing delay, then, is assigned with a demodulation part as user C than the ICU in the earlier stages.
Especially, as shown in Figure 17, concerning user C, the ICU of prime, for example, ICU1 (2) is assigned with as the demodulation part, and switching circuit 6 (2) is set to be in state " b ", and at decoder 5 (4) data of user C is decoded.Till now, ICU1 (2) has been assigned to user B, now, only accepts unit 4 (2) and is assigned to user B as its demodulation part.
In this structure, even because user C has stronger received power and high transmission rate, its interference ratio is bigger, but among user A and the B each and has been carried out demodulation to received signal with having removed interference per family from received signal.As a result, improved the reliability of interference offset device of the present invention.
On the contrary, if compare with B with user A, produce new communication request user C received power a little less than, and its transmission rate is lower, if perhaps user C is the data information user that can tolerate processing delay, just be assigned to user C as the demodulation part than a receiving element in the later stages then.
In more detail, as shown in Figure 18, concerning user C, receiving element in the later stages, for example, receiving element 4 (2) is assigned with as the demodulation part, switching circuit 6 (2) is set to be in state " b ", and at decoder 5 (3) data of user C is decoded.Till now, receiving element 4 (2) has been assigned to user B, and now, only ICU1 (2) is assigned to user B as its demodulation part, and in decoder 5 (4) its data is carried out demodulation.
As previously described, user A, B and C have been assigned with corresponding optimum allocation level, come institute's received power and its transmission rate are responded, and perhaps its communication type are responded, and carry out demodulation.As a result, can realize the optimum efficiency of Interference Cancellation.
Below, be described with reference to Figure 19 an interference offset device of the present invention's one second execution mode.The interference offset device of this execution mode is configured to comprise a multistage type of two Interference Cancellation levels, and supports 6 users.
As shown in Figure 19, #1 and #2 identify two Interference Cancellation levels respectively.Further, interference offset device is provided with and 6 corresponding 6 decoders 5 (1) to 5 (6) of user.
Interference Cancellation level # 1 mainly comprises two ICU1 (1)
#1With 1 (2)
#1, a decay part 2
#1, an Interference Cancellation part 3
#1And two switching circuits 6 (1)
#1With 6 (2)
#1
These two ICU1 (1)
#1With 1 (2)
#1Produce symbol reproducing signals S (1)
#1And S (2)
#1, and through switching circuit 6 (1)
#1With 6 (2)
#1They are sent to next stage #2.Further, from two ICU1 (1)
#1With 1 (2)
#1Output, receiving symbol R (1)
#1And R (2)
#1Through switching circuit 6 (1)
#1With 6 (2)
#1Be imported into decoder 5 (3) and 5 (6).
Interference Cancellation level # 2 mainly comprises two ICU1 (1)
#2With 1 (2)
#2, a decay part 2
#2, an Interference Cancellation part 3
#2And two switching circuits 6 (1)
#2With 6 (2)
#2
These two ICU1 (1)
#2With 1 (2)
#2Produce symbol reproducing signals S (1)
#2And S (2)
#2, and through switching circuit 6 (1)
#2With 6 (2)
#2They are sent to receiving element 4 (1) and 4 (2).Further, from two ICU1 (1)
#2With 1 (2)
#2Output, receiving symbol R (1)
#2And R (2)
#2Through switching circuit 6 (1)
#2With 6 (2)
#2Be imported into decoder 5 (2) and 5 (5).
In addition, receiving symbol R (1) and the R (2) from receiving element 4 (1) and 4 (2) outputs is input to decoder 5 (1) and 5 (4) respectively.
In this structure, supposing has two users, and wherein each is with producing a communication request per family.So switching circuit 6 is configured to state " a ", ICU and the receiving element of level # 1 and #2 are assigned to this two users respectively thus.Then, decoder 5 (1) and 5 (4) uses has wherein removed the received signal of disturbing, and two user's data are decoded.If user's number has increased, then, by suitable switching switch circuit 6 with further by correctly these users being assigned to ICU and the receiving element 4 of grade # 1 and #2, with as its demodulation part, just can its data of demodulation.
Especially, preferably, the power and transmission rate that it received is responded, perhaps its communication type is responded, fancy grade is assigned to handle the demodulation of relative users.In other words, as previously described, preferably the ICU in the earlier stages is assigned to the relatively strong and higher user of its transmission rate of its received power, perhaps distribute to the user who belongs to the communication type that to tolerate processing delay, and the ICU in the later stages is assigned to the more weak relatively and lower user of its transmission rate of its received power, perhaps distributes to the user who belongs to the communication type that can tolerate processing delay
Such structure can be with 1/3rd of the number of the decreased number of ICU1 and receiving element 4 these ICU1 and receiving element 4 in traditional interference offset device.In addition, if the user's who communicates simultaneously number equates with 2 or is more that all ICU1 and receiving element 4 are all constructed.As a result, can effectively utilize hardware.
Below, be described with reference to Figure 19 an interference offset device of the present invention 1 the 3rd execution mode.The interference offset device of this execution mode is configured to one and comprises two Interference Cancellation levels and support 4 users' a multistage type counteracting serial interference device.
As shown in Figure 20, #1 and #2 show two Interference Cancellation levels respectively.Further, interference offset device is provided with and 4 corresponding 4 decoders 5 (1) to 5 (4) of user.
Interference Cancellation level # 1 comprises two series-connected stages, and wherein each level has an ICU1 (1)
#1Perhaps 1 (2)
#1, a decay part and an Interference Cancellation part.Similarly, Interference Cancellation level # 2 comprises two series-connected stages, and wherein each level has an ICU1 (1)
#2Perhaps 1 (2)
#2, a decay part and an Interference Cancellation part.
ICU1 (1) from level # 2
#2With 1 (2)
#2Output, receiving symbol R (1)
#2And R (2)
#2Be input to decoder 5 (1) and 5 (3) respectively, wherein the data symbol of relative users is decoded.
The ICU1 (1) of its structure level # 1 identical with ICU structure among Figure 10, the counteracting serial interference device
#1With 1 (2)
#1Produce symbol reproducing signals S (1)
#1And S (2)
#1, and process switching circuit 6 (1) and 6 (2) sends to the ICU1 (1) of grade # 2 with them
#2With 1 (2)
#2On the other hand, from ICU1 (1)
#1With 1 (2)
#1Output, receiving symbol R (1)
#1And R (2)
#1Be imported into decoder 5 (2) and 5 (4) through switching circuit 6 (1) and 6 (2).In addition, because the ICU1 (1) of the level # 2 of counteracting serial interference device
#2With 1 (2)
#2Structure identical with the structure of ICU among Fig. 8, just the descriptions thereof are omitted.
In this structure, by suitable switching switch circuit 6 (1) and 6 (2), the ICU of level # 1 and #2 can be assigned to these users as its demodulation part, and can make conventional dry disturb Canceller can to provide the user's of service maximum number to double.
Top description is provided, so that any technical staff in this field can make and use the present invention, and the proposition optimal mode that the present inventor expected is carried out the present invention.
The present invention be based on July 2nd, 1999 filing, Japanese priority application number No.11-188934, its whole contents is used as reference here.
Should be understood that when enforcement is of the present invention, can do various substituting embodiments of the present invention as described herein.For example, disclosed interference offset device great majority belong to the parallel type of hard decision in the execution mode described above, during description, do not say that the present invention also can be used for the interference offset device of a soft-decision serial type.It should be noted that following claims have defined scope of the present invention, and the equivalence of the structure in the scope of these claims and method and they is comprised also.
Claims (12)
1. an interference offset device in cdma communication system, described interference offset device comprises:
At least one Interference Cancellation level, have and the corresponding a plurality of Interference Cancellations of channel unit (ICU), be used to produce the interference replica signal of described channel, and be used for removing described interference replica signal from a received signal, in the demodulation part received signal that is produced is carried out demodulation, wherein
Respond the professional qualification of described channel, described ICU is also as described demodulation part.
2. this interference offset device as claimed in claim 1, wherein said at least one Interference Cancellation level is configured to so that its described ICU walks abreast.
3. this interference offset device as claimed in claim 1, wherein said at least one Interference Cancellation level is configured to so that its described ICU is serial.
4. this interference offset device as claimed in claim 1, under wherein described therein at least one Interference Cancellation level situation that to be the channel number that communicates simultaneously in a plurality of and described channel lack than a predetermined number, described a plurality of Interference Cancellation levels are as the interference offset device of a multistage type.
5. this interference offset device as claimed in claim 1, wherein:
Under the situation that the channel number that communicates simultaneously in the described therein channel is Duoed than a predetermined number, described ICU is as described demodulation part, to increase the user's that can hold number; With
Under the situation that the channel number that communicates simultaneously in the described therein channel lacks than described predetermined number, described ICU as interference replica signal generation unit to be used for Interference Cancellation.
6. this interference offset device as claimed in claim 1, wherein measure the received power of described channel, and according to described received power order from big to small, with described channel allocation ICU than earlier stages in the level so that described than the described ICU in the earlier stages as the demodulation part.
7. this interference offset device as claimed in claim 1, wherein according to described channel transmission rate order from high to low, with described channel allocation ICU than earlier stages in the level so that described than the described ICU in the earlier stages as the demodulation part.
8. this interference offset device as claimed in claim 1, a channel that wherein is used for tolerating the communication of the delay longer than the scheduled time is assigned to the ICU than earlier stages so that described than the described ICU in the earlier stages as the demodulation part.
9. this interference offset device as claimed in claim 1 wherein when producing a new channel communication request, is measured the received power of described channel,
The described received power of described channel than the big situation of a predetermined value under, will be assigned to than the ICU of earlier stages described channel and
The described received power of described channel than the little situation of a predetermined value under, will be assigned to described channel than the ICU or the receiving element of later stages.
10. this interference offset device as claimed in claim 1, wherein when producing a new channel communication request,
A transmission rate of described channel than the high situation of a predetermined value under, will be assigned to than the ICU of earlier stages described channel and
The described transmission rate of described channel than the low situation of a predetermined value under, will be assigned to described channel than the ICU or the receiving element of later stages.
11. this interference offset device as claimed in claim 1, wherein when producing a new channel communication request,
Can not tolerate at described channel under the situation of the delay longer than the scheduled time, will be assigned to than the ICU of earlier stages described channel and
Can tolerate at described channel under the situation of described delay, will be assigned to described channel than the ICU or the receiving element of later stages.
12. this interference offset device as claimed in claim 1 further comprises:
A plurality of decoders are used for the data symbol of described channel is decoded, and the number of described decoder equates with user's maximum number; With
The switch path, by it, the receiving symbol that described ICU produced of described each grade is used as demodulating data from wherein output, and is sent to described decoder;
When an ICU of a channel was used as described demodulation part, the demodulating data of described channel was sent to described decoder through described switch path from described ICU.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11188934A JP2001024554A (en) | 1999-07-02 | 1999-07-02 | Interference canceler device for cdma receiver |
| JP188934/1999 | 1999-07-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1291020A true CN1291020A (en) | 2001-04-11 |
Family
ID=16232465
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN00119919A Pending CN1291020A (en) | 1999-07-02 | 2000-06-30 | Interference offset device of CDMA receiver |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP2001024554A (en) |
| CN (1) | CN1291020A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102201835A (en) * | 2011-05-16 | 2011-09-28 | 中兴通讯股份有限公司 | Interference cancellation multi-path selection method, device, and interference cancellation system |
| CN102611648A (en) * | 2011-01-20 | 2012-07-25 | 中兴通讯股份有限公司 | Successive interference cancellation system and method |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7389099B2 (en) * | 2005-04-22 | 2008-06-17 | Telefonaktiebolaget L M Ericsson (Publ) | Method and apparatus for canceling interference from high power, high data rate signals |
| US8676124B2 (en) * | 2007-09-28 | 2014-03-18 | Qualcomm Incorporated | Scheduling based on effective target load with interference cancellation in a wireless communication system |
-
1999
- 1999-07-02 JP JP11188934A patent/JP2001024554A/en not_active Withdrawn
-
2000
- 2000-06-30 CN CN00119919A patent/CN1291020A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102611648A (en) * | 2011-01-20 | 2012-07-25 | 中兴通讯股份有限公司 | Successive interference cancellation system and method |
| CN102611648B (en) * | 2011-01-20 | 2015-04-01 | 中兴通讯股份有限公司 | Successive interference cancellation system and method |
| CN102201835A (en) * | 2011-05-16 | 2011-09-28 | 中兴通讯股份有限公司 | Interference cancellation multi-path selection method, device, and interference cancellation system |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2001024554A (en) | 2001-01-26 |
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