Background technology
MIMO (Multiple-Input Multiple-Out-put, multiple-input and multiple-output) technology, as important raising transmission quality and the physical layer multi-antenna technology of efficiency, is played an important role in communication system of new generation.For example, transmit diversity, the multiple MIMO technology such as space multiplexing technique and BF (Beam forming, beam shaping) have been applied in LTE (Long Term Evolution, Long Term Evolution) system.
In current LTE system, transmit diversity and space diversity are supported at most 4 antenna ports, and adopt public reference signal to complete the demodulation of measuring with each antenna port signal; And wave beam forming adopts DRS (Dedicated Reference Signal) demodulation user data.As illustrated in fig. 1 and 2, be respectively the mapping schematic diagram of the descending public reference signal of conventional CP in prior art LTE system (Cyclic Prefix, Cyclic Prefix) and expansion CP.LTE system descending public reference signal sends in each descending sub frame, covers whole system bandwidth on frequency domain, in time across whole descending sub frame,
As illustrated in fig. 1 and 2, in figure, R0, R1, R2, R3 represent respectively the public reference signal of antenna port 0-3.Public reference signal is mainly used in (the Physical Downlink SharedChannel to PDSCH, DSCH Downlink Shared Channel) PDCCH (Physical Downlink Control Channel, down control channel), PCFICH (Physical Control Format Indicator Channel, control format indicating channel), PHICH (Physical Hybrid ARQ Indicator Channel, mixed automatic re-transmission indicating channel), PBCH (Physical Broadcast Channel, Physical Broadcast Channel) etc. demodulation, CQI (Channel Quality Indicator, CQI) estimate, non-excipient user's channel estimating, measurement when switch community etc.Public reference signal is in full bandwidth configuration, and conventional CP reference signal expense is 14.3%, and expansion CP is 16.7%.At present, LTE-A (LongTerm Evolution-Advanced, high bandwidth Long Term Evolution) standardization effort of system carries out, and for meeting the requirement of its peak rate, the antenna Enhanced Technology such as 8X8 MIMO, multithread BF (such as double-current BF) have become critical technology.Yet complete in the plan of establishment of 4X4 antenna pilot if 8X8 antenna pilot arranges, so conventional CP reference signal expense will increase to 28.6%, expansion CP will increase to 33.4%.This will cause the expense of reference signal excessive, affects the throughput of system, causes the wasting of resources.
As shown in Figures 3 and 4, be respectively the configuration schematic diagram of the conventional CP of antenna port 5 in prior art LTE system and the URS (UE-specific Reference Signal, user equipment specific reference signal) of expansion CP, wherein R5 is DRS (Dedicated Reference Signal).In existing LTE system, URS only supports the transmission of antenna port 5.The feature of this URS is only in PDSCH channel, to transmit, and be and UE (User Equipment, subscriber equipment) PDSCH channel width is identical, only in the PDSCH of certain UE internal transmission, for the relevant function of the PDSCH demodulation of this UE, realizes and strengthens.Therefore,, if be configured according to the standard of current LTE system in LTE-A system, URS only takies antenna port 5 and has just greatly limited URS range of application and user's performance so.
Therefore, how to arrange reference signals in multi-antenna system and configuration antenna port URS become problem demanding prompt solution in LTE-A system.The plan of establishment of reference signal not only will guarantee the performance of LTE-A system, the precision of guaranteeing joint channel estimation can not reduce, can not exert an influence to the performance of system and covering, also need to reduce as much as possible the expense of being introduced by reference signal simultaneously, the throughput of raising system, raising system is to resource utilization.
Summary of the invention
Object of the present invention is intended at least solve one of above-mentioned technological deficiency, particularly solves the problem that arranges of reference signal in multi-antenna communication system.
For achieving the above object, one aspect of the present invention has proposed a kind of method to set up of reference signals in multi-antenna system, comprises the following steps:
The mapping pattern that sends downlink reference signal is determined in base station, and described mapping pattern comprises that downlink reference signal is mapped in the subcarrier group of different frequency;
Data-mapping is carried out according to described mapping pattern in described base station, and data-mapping is arrived to corresponding antenna port;
Described base station is carried out frequency hopping transmission to described downlink reference signal and is sent, and the data after mapping are sent through multiaerial system.
According to embodiments of the invention, described downlink reference signal comprises public reference signal or DRS (Dedicated Reference Signal).
According to embodiments of the invention, described downlink reference signal comprises the downlink reference signal of certain customers or the part downlink reference signal of the user under described base station under the downlink reference signal of all users under described base station, described base station.
According to embodiments of the invention, described downlink reference signal comprises the downlink reference signal of the downlink reference signal of the antenna port that described base station is whole or the antenna port of described base station portion.
According to embodiments of the invention, described base station determines that the mapping pattern that sends downlink reference signal comprises:
The density of the described downlink reference signal that antenna port sends is determined in described base station, when the density of finding described downlink reference signal is during lower than predetermined threshold, selects described mapping pattern to comprise that described downlink reference signal is mapped in the subcarrier group of different frequency.
According to embodiments of the invention, described mapping pattern comprises:
Between every two time slots, between every two subframes or more than two comprising between subframe that downlink reference signal is mapped in the subcarrier group of different frequency.
According to embodiments of the invention, described mapping pattern comprises:
Between time interval T, comprising that downlink reference signal is mapped in the subcarrier group of different frequency, described time interval T is less than the correlation time of downlink wireless channel.
According to embodiments of the invention, described downlink reference signal is mapped in the subcarrier group of different frequency and comprises:
The frequency hopping frequency domain interval of the subcarrier that the subcarrier of described downlink reference signal mapping is not identical with a upper mapping is at least a subcarrier.
The present invention has proposed a kind of base station on the other hand, comprises mapping pattern determination module, data-mapping module and sending module,
Described mapping pattern determination module, for determining the mapping pattern that sends downlink reference signal, described mapping pattern comprises that downlink reference signal is mapped in the subcarrier group of different frequency;
Described data-mapping module, for carrying out data-mapping according to described mapping pattern, arrives corresponding antenna port by data-mapping;
Described sending module, sends for described downlink reference signal being carried out to frequency hopping transmission, and the data after mapping are sent through multiaerial system.
According to embodiments of the invention, also comprise selection module,
Described selection module, for the antenna port of selecting to carry out the downlink reference signal of frequency hopping transmission, the type of described downlink reference signal and transmission, wherein said downlink reference signal comprises the downlink reference signal of certain customers or the part downlink reference signal of the user under described base station under the downlink reference signal of all users under described base station, described base station, described downlink reference signal comprises public reference signal or DRS (Dedicated Reference Signal), and the antenna port of described transmission comprises antenna port that described base station is whole or the antenna port of described base station portion.
According to embodiments of the invention, described selection module is determined the density of the described downlink reference signal that antenna port sends, when the density of described downlink reference signal is during lower than predetermined threshold, described selection module selects described mapping pattern to comprise that downlink reference signal is mapped in the subcarrier group of different frequency.
According to embodiments of the invention, also comprise indicating module,
Described indicating module, for according to high-level signaling, indicates described sending module between every two time slots, sending between every two subframes or more than two existing between subframe in the subcarrier group of downlink reference signal at different frequency.
According to embodiments of the invention, described indicating module is used for according to high-level signaling, indicate described sending module when frequency hopping is transmitted described downlink reference signal, the frequency hopping frequency domain interval of the subcarrier of described downlink reference signal carrying and the subcarrier of a upper carrying is at least a subcarrier.
The present invention, by the URS of reference signal and configuration antenna port is set neatly in LTE-A system, had both guaranteed the compatibility of system, had also reduced system complexity.The plan of establishment of the reference signal proposing according to the present invention, can not only guarantee the performance of LTE-A system, the precision of guaranteeing joint channel estimation can not reduce, can not exert an influence to the performance of system and covering, also reduce as much as possible the expense of being introduced by reference signal simultaneously, the throughput of raising system, raising system is to resource utilization.
The aspect that the present invention is additional and advantage in the following description part provide, and part will become obviously from the following description, or recognize by practice of the present invention.
Embodiment
Describe embodiments of the invention below in detail, the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or has the element of identical or similar functions from start to finish.Below by the embodiment being described with reference to the drawings, be exemplary, only for explaining the present invention, and can not be interpreted as limitation of the present invention.
The method to set up that the present invention proposes a kind of reference signals in multi-antenna system, comprises the following steps:
The mapping pattern that sends downlink reference signal is determined in base station, and described mapping pattern comprises that downlink reference signal is mapped in the subcarrier group of different frequency; Data-mapping is carried out according to described mapping pattern in described base station, and data-mapping is arrived to corresponding antenna port; Described base station is carried out frequency hopping transmission to described downlink reference signal and is sent, and the data after mapping are sent through multiaerial system.
Conventionally, the mapping pattern of the reference signal of existing system is fixing, cannot rationally adjust according to channel condition the stepped-frequency interval of transmission of reference signals, the present invention is by arranging neatly the URS of reference signal and configuration antenna port, the stepped-frequency interval of reference signal is rationally set, make reference signal obtain frequency diversity gain, user terminal receives above-mentioned reference signal can obtain good channel estimating quality.
As shown in Figure 5, the method to set up flow chart for embodiment of the present invention reference signals in multi-antenna system, comprises the following steps:
Step S501, the mapping pattern of downlink reference signal is determined in base station, mapping pattern comprises that downlink reference signal is mapped in the subcarrier group of different frequency.
Based on above analysis, if be configured according to the standard of current LTE system in LTE-A system, 8X8 antenna pilot arranges complete in the plan of establishment of 4X4 antenna pilot, and so conventional CP reference signal expense will increase to 28.6%, and expansion CP will increase to 33.4%.This will cause the expense of reference signal excessive, affects the throughput of system, causes the wasting of resources, and URS only takies antenna port 5 and just greatly limited URS range of application and user's performance.
When 8 aerial transmission systems are under the good scene of channel condition, can consider to use the design of lower reference signal density.For example, according to odd even time slot or odd even subframe, carry out frequency hopping and process to obtain frequency and time diversity gain, improve the quality of channel estimating.In addition, can also can make the interference randomization between neighbor cell by adopt different frequency hop sequences in neighbor cell, avoid interference.
As embodiments of the invention, downlink reference signal is mapped in the subcarrier group of different frequency, and downlink reference signal comprises public reference signal or DRS (Dedicated Reference Signal).8 aerial transmission systems of LTE-A system of take are example, base station sends public reference signal or DRS (Dedicated Reference Signal) to user terminal, wherein terminal adopts public reference signal to complete the demodulation of measuring with each antenna port signal, adopts DRS (Dedicated Reference Signal) demodulation user wave beam figuration data.
In LTE-A system, when the public reference signal density of 0-7 antenna port is all lower, can all adopt frequency hopping design by all of the port.When part port, for example 0-3 public guide frequency density higher situation, does not carry out the configuration of frequency hopping, the port 4-7 lower to density only, or minimum port 6 and 7 carries out frequency hopping.Fine when channel condition, for example, in the situation that LOS (Line of Sight, straight line sighting distance) and rate travel are very low, even if the very low pilot frequency design of density also can be accepted, all of the port can all not wanted frequency hopping yet so.
As embodiments of the invention, when base station determines whether downlink reference signal to take frequency hopping transmission to send, the density of the downlink reference signal that can send by judgement antenna port, when the density of finding downlink reference signal is during lower than predetermined threshold, to downlink reference signal, take frequency hopping transmission to send, at this moment the definite mapping pattern in base station comprises that downlink reference signal is mapped in the subcarrier group of different frequency.Wherein the distribution mode of reference signal can be even or non-uniform Distribution.Obviously, the predetermined threshold comparing to downlink reference signal can arrange according to system requirements, for example, this predetermined threshold is the shared specific expense ratio of transmission of reference signals, 14.3% or 16.7%, when base station is found downlink reference signal lower than predetermined threshold, take this downlink reference signal to carry out frequency hopping transmission.
As embodiments of the invention, as shown in Figure 6, for the public guide frequency port to all 8 public reference signals all adopts the mapping pattern based on time slot frequency hopping, wherein, R0, R1, R2, R3, R4, R5, R6, R7 are respectively the open reference signal of open port 0-7.In the situation that pilot density is not high enough, the cycle, very little frequency hopping can improve frequency diversity, thereby reached better channel estimating.
As embodiments of the invention, as shown in Figure 7, for the 4-7 public guide frequency port to 4 public reference signals adopts the mapping pattern based on subframe frequency hopping, wherein, R0, R1, R2, R3 are respectively the reference signal of port 0-3, and 4,5,6,7 are respectively the reference signal of port 4-7.In Fig. 7, public port 0-3 is not adopted to any frequency hopping configuration, the every subframe of port 4-7 is carried out to frequency hopping transmission, frequency pattern is as shown in Figure 7.With respect to the embodiment shown in Fig. 6, the hop period in the present embodiment has increased one times, and hop period is larger.If in the time span of a PRB, constant when channel meets (Time Invariant) characteristic, namely be greater than the time span of a PRB correlation time (Coherence Time), frequency hopping so as shown in Figure 7 still can obtain frequency diversity gain, terminal is received and can obtain good channel estimating quality.Obviously, as long as comprising between time interval T that downlink reference signal is mapped in the subcarrier group of different frequency, described time interval T is less than the correlation time of downlink wireless channel, described downlink reference signal will obtain frequency diversity gain, terminal is received and can obtain good channel estimating quality.
In addition, downlink reference signal is adopted to the transmission plan based on frequency hopping, comprise the downlink reference signal of all users under this base station is adopted to the transmission plan based on frequency hopping; Comprise the downlink reference signal of certain customers under this base station is adopted to the transmission plan based on frequency hopping, according to system requirements or system configuration, select corresponding user's downlink reference signal to transmit based on frequency hopping; Also comprise the part downlink reference signal of the user under this base station is transmitted based on frequency hopping, only public reference signal, described user's DRS (Dedicated Reference Signal) or described user's part DRS (Dedicated Reference Signal) is transmitted based on frequency hopping.
In addition, in specific embodiment, downlink reference signal is adopted to the transmission plan based on frequency hopping, can realize by the downlink transfer of the whole antenna port in base station, or the downlink transfer of the antenna port by base station portion realizes.
Downlink reference signal is being carried out in frequency hopping transmission, and the frequency hopping frequency domain interval of the subcarrier that the subcarrier of described downlink reference signal mapping is not identical with a upper mapping is at least a subcarrier.Obviously, frequency hopping frequency domain interval can arrange according to system requirements.
Conventionally, reference signal is carried transmission by one or more subcarrier groups, and in technical scheme of the present invention, when upper once transmission of reference signals, one or more several subcarriers of subcarrier group overall offset of carrying reference signal, realize frequency hopping transmission.As embodiments of the invention, as shown in Figure 8, for to the mapping pattern of user terminal embodiment, wherein R0, R1, R2, R3 represent respectively the public reference signal of 4 public ports, and 4,5,6,7 represent respectively the DRS (Dedicated Reference Signal) of 4 private ports.As shown in Figure 8, public reference signal R0, R1 Hopping time are spaced apart 4 RE to frequency pattern, and the Hopping time of public reference signal R2, R3 and DRS (Dedicated Reference Signal) 4-7 is spaced apart 7 RE; Public reference signal R0, R1, R2,2 RE of R3 frequency hopping frequency domain interval, 2 RE of DRS (Dedicated Reference Signal) 4 frequency hopping frequency domain interval, 3 RE of DRS (Dedicated Reference Signal) 5-7 frequency hopping frequency domain interval.
Downlink reference signal is being carried out in frequency hopping transmission, can, between every two time slots, between every two subframes or more than two between subframe, downlink reference signal is being carried out to frequency hopping transmission, to the Hopping time interval of downlink reference signal, can arrange according to system requirements.
As embodiments of the invention, as shown in Figure 9, for to the mapping pattern of user terminal embodiment, wherein R0, R1, R2, R3 represent respectively the public reference signal of 4 public ports, and 4,5,6,7 represent respectively the DRS (Dedicated Reference Signal) of 4 private ports.In the present embodiment, with respect to the embodiment of Fig. 8,4 private ports have reduced the density of pilot tone in a subframe, and DRS (Dedicated Reference Signal) carries out frequency hopping transmission between subframe.
Step S502, data-mapping is carried out according to mapping pattern in base station, and data-mapping is arrived to corresponding antenna port.
In step S502, utilize the definite mapping pattern of step S501, data-mapping is carried out in base station, and data-mapping is arrived to corresponding antenna port.Wherein, base station can adopt the transmission plan based on frequency hopping to the downlink reference signal of all users under this base station, and downlink reference signal is mapped to corresponding antenna port.Base station also can adopt the transmission plan based on frequency hopping to the downlink reference signal of certain customers under this base station, according to system requirements or system configuration, selects corresponding user's downlink reference signal to be mapped to corresponding antenna port.In addition, base station can also be transmitted based on frequency hopping the part downlink reference signal of the user under this base station, only public reference signal, described user's DRS (Dedicated Reference Signal) or described user's part DRS (Dedicated Reference Signal) is mapped to corresponding antenna port.
In addition, in specific embodiment, downlink reference signal is adopted to the transmission plan based on frequency hopping, can carry out data-mapping by the whole antenna port in base station, or carry out data-mapping by the antenna port of base station portion.
Step S503, base station sends the data after mapping through multiaerial system.
In said method, by the reference signal of reference signal and configuration antenna port is set neatly, both guaranteed the compatibility of system, also reduced system complexity.According to the plan of establishment of above-mentioned reference signal, can not only guarantee the performance of LTE-A system, the precision of guaranteeing joint channel estimation can not reduce, can not exert an influence to the performance of system and covering, also reduce as much as possible the expense of being introduced by reference signal simultaneously, the throughput of raising system, raising system is to resource utilization.
The invention allows for a kind of base station, as shown in figure 10, is the structural representation of embodiment of the present invention base station.This base station comprises mapping pattern determination module 100, data-mapping module 200 and sending module 300.
Wherein, mapping pattern determination module 100 is for determining the mapping pattern that sends downlink reference signal, and mapping pattern comprises that downlink reference signal is mapped in the subcarrier group of different frequency; Data-mapping module 200, for carrying out data-mapping according to mapping pattern, arrives corresponding antenna port by data-mapping; Sending module 300 sends for downlink reference signal being carried out to frequency hopping transmission, and the data after mapping are sent through multiaerial system.
As embodiments of the invention, above-mentioned base station equipment also comprises selects module 400.Select module 400 for selecting to carry out the antenna port of the downlink reference signal of frequency hopping transmission, the type of downlink reference signal and transmission, wherein downlink reference signal comprises the downlink reference signal of certain customers or the part downlink reference signal of the user under base station under the downlink reference signal, base station of all users under base station, downlink reference signal comprises public reference signal or DRS (Dedicated Reference Signal), and the antenna port of transmission comprises antenna port that base station is whole or the antenna port of base station portion.
As embodiments of the invention, select module 400 to determine the density of the downlink reference signal that antenna port sends, when the density of finding downlink reference signal is during lower than predetermined threshold, the mapping pattern of selecting module 400 to select comprises that downlink reference signal is mapped in the subcarrier group of different frequency.Wherein the distribution mode of reference signal can be even or non-uniform Distribution.Obviously, the predetermined threshold comparing to downlink reference signal can arrange according to system requirements, for example, this predetermined threshold is the shared specific expense ratio of transmission of reference signals, 14.3% or 16.7%, when base station is found downlink reference signal lower than predetermined threshold, to take this downlink reference signal to carry out frequency hopping transmission, the mapping pattern of at this moment selecting module 400 to select comprises that downlink reference signal is mapped in the subcarrier group of different frequency.
As embodiments of the invention, above-mentioned base station equipment also comprises indicating module 500.Indicating module 500 is for according to high-level signaling, and indication sending module 300 is between every two time slots, sending between every two subframes or more than two existing between subframe in the subcarrier group of downlink reference signal at different frequency.
As embodiments of the invention, indicating module 500 is also for according to high-level signaling, indication sending module 300 is when at frequency hopping transmission downlink reference signal, and the frequency hopping frequency domain interval of the subcarrier of downlink reference signal carrying and the subcarrier of a upper carrying is at least a subcarrier.
Above-mentioned base station equipment disclosed by the invention, by the URS of reference signal and configuration antenna port is set neatly, both guaranteed the compatibility of system, also reduced system complexity, the precision of guaranteeing user terminal joint channel estimation can not reduce, and can not exert an influence to the performance of system and covering, also reduces as much as possible the expense of being introduced by reference signal simultaneously, the throughput of raising system, raising system is to resource utilization.
Although illustrated and described embodiments of the invention, for the ordinary skill in the art, be appreciated that without departing from the principles and spirit of the present invention and can carry out multiple variation, modification, replacement and modification to these embodiment, scope of the present invention is by claims and be equal to and limit.