CN101286812A - Method and device for transmitting and receiving pilot frequency in mixed carrier - Google Patents

Abstract

The present invention relates to the field of wireless communication, and discloses a method and device for transmitting and receiving pilots in a mixed carrier. For a subframe occupying eight symbols in the time domain in a multicast broadcast multimedia service single frequency network of a mixed carrier, the pilot frequency can be relatively accurate. for channel estimation. In the present invention, in the mixed-carrier multicast broadcast multimedia service single frequency network, for a subframe occupying eight symbols in the time domain, every two adjacent pilot subcarriers carrying pilot signals in the same symbol There is only one subcarrier carrying other signals between them, and the pilot subcarriers are configured in half of the subcarriers of two symbols. There are 3 symbols between the symbols carrying the pilot, the symbol carrying the pilot is not the first or the last symbol in the subframe, and the pilot subcarriers in the two symbols carrying the pilot are separated in the frequency domain.

Description

Method and device for transmitting and receiving pilot frequency in mixed carrier

technical field

The invention relates to the field of wireless communication, in particular to the technology of transmitting and receiving pilot frequency in multicast broadcast multimedia service single frequency network with mixed carriers.

Background technique

In recent years, the multi-carrier transmission technology represented by Orthogonal Frequency Division Multiplexing ("OFDM") has attracted widespread attention. Multi-carrier transmission decomposes a data stream into several independent sub-streams, each of which will have a much lower bit rate. Using the low-rate multi-state symbols formed at such a low bit rate to modulate the corresponding subcarriers constitutes a transmission system in which multiple low-rate symbols are sent in parallel.

As a multiplexing technique, OFDM multiplexes multiple signals on different orthogonal subcarriers. The traditional frequency division multiplexing (Frequency Division Multiplexing, referred to as "FDM") technology divides the bandwidth into several sub-channels, and uses a guard band in the middle to reduce interference, and they send data at the same time. OFDM systems require much less bandwidth than conventional FDM systems. Due to the use of interference-free orthogonal carrier technology, there is no need for guard bands between individual carriers. This results in a more efficient use of the available spectrum. In addition, OFDM technology can dynamically allocate data on sub-channels. For maximum data throughput, multicarrier modulators can intelligently allocate more data to less noisy sub-channels.

In the Long Term Evolution ("LTE") system of the 3rd Generation Partnership Project ("3GPP"), there are two frame structures applied to the mixed-carrier multicast broadcast multimedia service unit The frequency network (Multicast Broadcast Single Frequency Network, referred to as "MBSFN") is a common frame structure (as shown in Figure 1) and a candidate frame structure (as shown in Figure 2). In a common MBSFN frame with mixed carriers, each subframe includes two time slots, and each time slot has 6 OFDM symbols, that is, one MBSFN subframe has 12 OFDM symbols in total. In the MBSFN candidate frames of mixed carriers, each MBSFN subframe includes 8 OFDM symbols. It can be seen that the minimum allocated time-frequency resource blocks in the two frame structures of MBSFN are shown in Table 1:

The smallest allocated resource block Number of subcarriers number of symbols Common frame structure 12 12 Candidate frame structure 12 8

Table 1

For communication systems with high data rates, coherent demodulation is usually used to obtain ideal receiving performance. Since the realization of coherent demodulation needs to know certain channel information, it is essential to perform channel estimation at the receiving end. The task of channel estimation is to accurately identify the transmission characteristics of the channel in the time domain or frequency domain based on the received sequence that has been distorted in amplitude and phase by the influence of the channel and superimposed with white Gaussian noise. Since in the OFDM high-speed wireless communication system, data is transmitted in parallel on different orthogonal subcarriers, therefore, channel estimation needs to estimate the frequency response value of the channel on each subcarrier. The channel estimation of the OFDM system generally adopts the method of auxiliary information, that is, inserting some pilot signals known at the receiving end at the fixed position of the channel of the transmitting end, and the receiving end uses these pilot signals to perform channel estimation according to a certain algorithm.

At present, the pilot structure of the mixed-carrier MBSFN ordinary frame is shown in Figure 3, and the pilot signals known to the receiving end are inserted on some subcarriers of the third, seventh and eleventh OFDM symbols (indicated by K in the figure subcarrier sequence number, L represents the symbol sequence number).

However, the inventors of the present invention have found that since the minimum allocated resource block of the candidate frame structure is different from the minimum allocated resource block of the ordinary frame structure, the number of symbols contained in the minimum resource block allocated to the MBSFN ordinary frame is 12, while The minimum resource block allocated to the MBSFN candidate frame contains 8 symbols. Therefore, the pilot structure shown in FIG. 3 cannot be directly used for the pilot structure of the mixed-carrier MBSFN candidate frame.

Contents of the invention

The main technical problem to be solved in the embodiments of the present invention is to provide a method and device for transmitting and receiving pilots in a mixed carrier, so that the subframes occupying eight symbols in the time domain in the mixed carrier multicast broadcast multimedia service single frequency network can be based on the pilot more accurate channel estimation.

In order to solve the above technical problems, the embodiment of the present invention provides a pilot transmission method in a mixed carrier, which is used in a multicast broadcast multimedia service single frequency network of a mixed carrier. When sending a subframe occupying eight symbols in the time domain, Pilot signals are sent in some subcarriers of two symbols in the subframe, and pilot signals are sent in half of the subcarriers in each symbol of the two symbols, and every two adjacent subcarriers in the same symbol The subcarriers for sending pilot signals are separated by a subcarrier carrying other signals except the pilot signal.

The embodiment of the present invention also provides a pilot receiving method in a mixed carrier, which is used in a multicast broadcast multimedia service single frequency network of a mixed carrier. When receiving a subframe occupying eight symbols in the time domain, in the subframe The pilot signal is received in each subcarrier carrying the pilot signal in the two symbols, half of the subcarriers in each of the two symbols carry the pilot signal, and every two adjacent carrying pilot signals There is a subcarrier that carries other signals except the pilot signal between the subcarriers of the pilot signal.

The embodiment of the present invention also provides a mixed-carrier mid-pilot sending device, which is used for a mixed-carrier multicast broadcast multimedia service single frequency network, including:

A mapping module, configured to map the pilot signal to a subframe occupying eight symbols in the time domain, wherein the pilot signal is mapped to some subcarriers of two symbols in the subframe, and each of the two symbols In each symbol, half of the subcarriers are mapped with pilot signals, and every two adjacent subcarriers mapped with pilot signals in the same symbol are separated by a carrier carrying other signals except the pilot signal subcarrier;

The transmitting module is used for sending the subframe output by the mapping module on the air interface.

The embodiment of the present invention also provides a mixed-carrier mid-pilot receiving device, which is used for a mixed-carrier multicast broadcast multimedia service single frequency network, including:

The receiving module is used to receive wireless signals from the air interface, and output the received results in the form of subframes occupying eight symbols in the time domain;

The pilot acquisition module is used to acquire the pilot signal from the subcarriers carrying the pilot signal in the two symbols of the subframe output by the receiving module, and half of the subcarriers are carried in each symbol of the two symbols The pilot signal, and every two adjacent subcarriers carrying the pilot signal are separated by a subcarrier carrying other signals except the pilot signal.

The main effect of the embodiments of the present invention is that the pilot frequency can be better used for channel estimation. This is because, in MBSFN, multiple adjacent cells use the same time-frequency resources to send the same content, so the multipath delay is relatively large, and the frequency-domain correlation bandwidth is the reciprocal of the multipath delay, which is relatively small, while the same symbol When the interval between the pilot subcarriers in the frequency domain is within the frequency domain correlation bandwidth, the effect of using the pilot for channel estimation will be better, and there is only one subcarrier carrying other signals between adjacent pilot subcarriers. The carrier mode can meet this requirement.

The pilot subcarriers are configured in half of the subcarriers of two symbols, and for a subframe occupying eight symbols in the time domain, the ratio of the number of pilot time-frequency blocks to the total number of time-frequency blocks is 1/8. The higher the ratio of the number of pilot time-frequency blocks to the total number of time-frequency blocks, the better the performance of coherent demodulation, and the lower the ratio of the number of pilot time-frequency blocks to the total number of time-frequency blocks, the less overhead. 1/8 is a moderate ratio, which can balance overhead and coherent demodulation performance.

Description of drawings

FIG. 1 is a schematic diagram of a common MBSFN frame structure of mixed carriers in the prior art;

FIG. 2 is a schematic structural diagram of MBSFN candidate frames of mixed carriers in the prior art;

FIG. 3 is a schematic diagram of a pilot structure of an MBSFN common frame of mixed carriers in the prior art;

FIG. 4 is a flowchart of a method for sending pilots in a mixed carrier according to a first embodiment of the present invention;

5 is a schematic diagram of sending pilot signals in some subcarriers of the second and sixth symbols in the case of no unicast control channel according to the first embodiment of the present invention;

6 is another schematic diagram of sending pilot signals in some subcarriers of the second and sixth symbols in the case of no unicast control channel according to the first embodiment of the present invention;

7 is a schematic diagram of sending pilot signals in some subcarriers of the third and seventh symbols in the case of no unicast control channel according to the first embodiment of the present invention;

8 is another schematic diagram of sending pilot signals in some subcarriers of the third and seventh symbols in the case of no unicast control channel according to the first embodiment of the present invention;

9 is a schematic diagram of sending pilot signals in some subcarriers of the third and seventh symbols in the case of a unicast control channel according to the first embodiment of the present invention;

10 is another schematic diagram of sending pilot signals in some subcarriers of the third and seventh symbols in the case of a unicast control channel according to the first embodiment of the present invention;

FIG. 11 is a schematic diagram assuming that pilot signals are sent in some subcarriers of the first and eighth symbols according to the first embodiment of the present invention;

12 is a schematic diagram of pilot subcarriers in two symbols carrying pilots not diverging in the frequency domain according to the first embodiment of the present invention;

FIG. 13 is a schematic diagram showing that the interval between two symbols carrying pilots is not 3 symbols according to the first embodiment of the present invention;

FIG. 14 is a schematic structural diagram of a pilot sending device in a mixed carrier according to a third embodiment of the present invention;

Fig. 15 is a schematic structural diagram of a pilot receiving device in a mixed carrier according to a fourth embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the following will further describe the implementation of the present invention in detail in conjunction with the accompanying drawings.

The first embodiment of the present invention relates to a pilot transmission method in a mixed carrier. In this embodiment, the MBSFN frame of the mixed carrier is a candidate frame, that is, each MBSFN subframe occupies 8 OFDM symbols in the time domain and 8 OFDM symbols in the frequency domain. It occupies 12 subcarriers. The specific process is shown in Figure 4.

In step 410, the sender determines whether there is a unicast control channel in the MBSFN subframe. Specifically, since MBSFN candidate frames use Time Division Duplex (TDD for short), TDD is different from Frequency Division Duplex (FDD) used by ordinary MBSFN frames, FDD must have Unicast control channel, and TDD does not necessarily have a unicast control channel. Therefore, before sending the pilot signal in the subframe of the MBSFN candidate frame, it is necessary to determine whether there is a unicast control channel in the MBSFN subframe. If there is no unicast control channel in the MBSFN subframe, go to step 420; if there is a unicast control channel in the MBSFN subframe, go to step 430.

In step 420, the transmitting end transmits the pilot signal in some subcarriers on the two symbols in the second to seventh OFDM symbols of the MBSFN subframe, and the interval between the two symbols of the transmitted pilot signal is 3 symbols. That is to say, the sending end sends the pilot signal in part of the subcarriers on the second and sixth OFDM symbols of the MBSFN subframe, or part of the third and seventh OFDM symbols on the MBSFN subframe Pilot signals are transmitted in subcarriers. The symbols carrying pilots need to be separated by 3 symbols, because if there are multiple consecutive MBSFN subframes, the symbols carrying pilots can also be evenly spaced by 3 symbols between these subframes. A uniform distribution of pilot-carrying symbols facilitates better coherent demodulation of the signal in each symbol as a whole. In addition, in MBSFN, the interval of 3 symbols can ensure that the performance of the receiving device does not decrease significantly when the speed is 350 kilometers per hour, which can meet the needs of most scenarios.

In the following, it will be described by taking the sending end sending pilot signals in some subcarriers on the second and sixth OFDM symbols of the MBSFN subframe as an example.

The sending end transmits the pilot signal in half of the subcarriers in the second and sixth symbols respectively, and every two adjacent subcarriers transmitting the pilot signal in the same symbol are spaced apart by one carrying the pilot signal subcarriers of other signals (such as data subcarriers, pilot subcarriers of other antennas, or subcarriers that do not carry any signal). In the two symbols for sending pilot signals, the subcarriers sending pilot signals in one symbol are all odd-numbered subcarriers, and the subcarriers sending pilot signals in the other symbol are all even-numbered subcarriers. That is to say, the pilot subcarriers on the second symbol and the sixth symbol are interleaved, as shown in FIG. 5 or FIG. 6 .

In MBSFN, multiple adjacent cells use the same time-frequency resources to send the same content, so the multipath delay is relatively large, and the frequency-domain correlation bandwidth is the reciprocal of the multipath delay, which is relatively small, while the pilot frequency in the same symbol When the interval of the subcarriers in the frequency domain is within the relevant bandwidth of the frequency domain, the result of using the pilot for channel estimation will be better, and there is only one subcarrier that carries other signals between adjacent pilot subcarriers. This requirement can be met. Therefore, every two adjacent pilot subcarriers carrying pilot signals in the same symbol are separated by only one subcarrier carrying other signals, and the pilots can be better used for channel estimation. Moreover, through the spread of the pilot subcarriers in the frequency domain in the two symbols carrying pilot signals, the limited number of pilot subcarriers can be distributed on as many subcarriers as possible, so that the frequency can be obtained during channel estimation. The effect of domain diversity.

Of course, in practical applications, the transmitting end may also transmit pilot signals in some subcarriers on the third and seventh OFDM symbols of the MBSFN subframe. Similarly, pilot signals need to be sent in half of the subcarriers of the third and seventh symbols, and every two adjacent subcarriers sending pilot signals in the same symbol are separated by a subcarrier carrying other signals. subcarriers, and the pilot subcarriers on the third symbol and the seventh symbol are placed crosswise, as shown in FIG. 7 or FIG. 8 .

If it is determined in step 410 that there is a unicast control channel in the MBSFN subframe, go to step 430 . In step 430, the transmitting end transmits the pilot signal in some subcarriers on the two symbols in the third to seventh OFDM symbols of the MBSFN subframe, and the interval between the two symbols of the transmitted pilot signal is 3 symbols. That is to say, the sending end sends pilot signals in some subcarriers in the third and seventh OFDM symbols of the MBSFN subframe.

Specifically, the transmitting end transmits pilot signals in half of the subcarriers in the third and seventh symbols respectively, and every two adjacent subcarriers transmitting pilot signals in the same symbol are separated by a carrier Subcarriers of other signals. In the two symbols for sending pilot signals, the subcarriers sending pilot signals in one symbol are all odd-numbered subcarriers, and the subcarriers sending pilot signals in the other symbol are all even-numbered subcarriers. That is to say, the pilot subcarriers on the third symbol and the seventh symbol are interleaved, as shown in FIG. 9 or FIG. 10 .

It is not difficult to find that the difference between step 430 and step 420 is that in step 420, there is no unicast control channel in the MBSFN subframe, and the sending end can carry pilot signals from the second symbol; and in step 430, There is a unicast control channel in the MBSFN subframe, and the sending end needs to carry pilot signals starting from the third symbol. This is because the current unicast control channel may only occupy part of the subcarriers in the first symbol in the MBSFN subframe, or may occupy part of the subcarriers in the first and second symbols at the same time. Therefore, starting from the third symbol Carrying pilot signals can be applied to both situations at the same time, and the scope of application is wider.

In this embodiment, the pilot subcarriers are configured in half of the subcarriers of two symbols, and for a subframe occupying eight symbols in the time domain, the number of pilot time-frequency blocks accounts for the proportion of the total number of time-frequency blocks is 1/8. Because the higher the ratio of the number of pilot time-frequency blocks to the total number of time-frequency blocks, the better the coherent demodulation performance, and the lower the ratio of the number of pilot time-frequency blocks to the total number of time-frequency blocks, the less overhead. And 1/8 is a moderate ratio, so the performance of overhead and coherent demodulation can be taken into consideration.

Moreover, the symbol carrying the pilot is not the first or the last symbol in the subframe, which can make as many time-frequency blocks (referred to as data time-frequency blocks) carrying the data as possible can be adjacent to the time-frequency blocks carrying the pilot (referred to as the time-frequency block for short). is the pilot time-frequency block), and the coherent demodulation results of the data time-frequency block next to the pilot time-frequency block are more accurate. Conversely, if the pilot time-frequency block is placed in the first symbol and the preceding adjacent is a unicast subframe, only the data time-frequency block of the second symbol is next to the pilot time-frequency block. If the pilot time-frequency block If it is placed in the 8th symbol and there is a unicast subframe next to it, then only the data time-frequency block of the 7th symbol is next to the pilot time-frequency block, as shown in FIG. 11 .

In addition, it is worth mentioning that although in this embodiment, it is required that the symbols carrying pilots need to be separated by 3 symbols, and the pilot subcarriers on the two symbols carrying pilots need to be placed crosswise, however, In practical applications, these requirements may not be satisfied, as shown in the pilot structure of the MBSFN candidate frame shown in FIG. 12 or FIG. 13 . Although the pilot structure shown in FIG. 12 or FIG. 13 cannot fully achieve the best performance, it is still a feasible implementation manner.

The second embodiment of the present invention relates to a method for receiving a pilot in a mixed carrier, and this embodiment corresponds to the method for sending a pilot in a mixed carrier in the first embodiment.

Specifically, if there is no unicast control channel in the MBSFN subframe, the pilot signal is received in the following manner:

The receiving end receives the pilot signal in each subcarrier carrying the pilot signal on two symbols in the second to seventh OFDM symbols of the MBSFN subframe, and the interval between these two symbols is 3 symbols. In the following, description will be made by taking the second and sixth symbols as an example in which the symbols carrying the pilot signal in the MBSFN subframe are used.

Since in the second and sixth symbols, half of the sub-carriers carry pilot signals, and every two adjacent sub-carriers carrying pilot signals in the same symbol are separated by one carrier except for the pilot signal subcarriers of other signals (such as data subcarriers, pilot subcarriers of other antennas, or subcarriers that do not carry any signal). Among the two symbols carrying pilot signals, the subcarriers carrying pilot signals in one symbol are all odd-numbered subcarriers, and the subcarriers carrying pilot signals in the other symbol are all even-numbered subcarriers. That is, the second symbol is interleaved with the pilot subcarriers on the sixth symbol. Therefore, the receiving end can receive pilot signals in the corresponding subcarriers in the second and sixth symbols through these known rules.

If there is a unicast control channel in the MBSFN subframe, the receiving end receives the pilot signal in the following manner:

The receiving end receives the pilot signal in each subcarrier carrying the pilot signal on two symbols in the third to seventh OFDM symbols of the MBSFN subframe, and the interval between these two symbols is 3 symbols. That is to say, the receiving end receives pilot signals in some subcarriers in the third and seventh OFDM symbols of the MBSFN subframe. Since in the third and seventh symbols, half of the sub-carriers carry pilot signals, and every two adjacent sub-carriers carrying pilot signals in the same symbol are separated by one carrier except the pilot signal subcarriers of other signals (such as data subcarriers, pilot subcarriers of other antennas, or subcarriers that do not carry any signal). Among the two symbols carrying pilot signals, the subcarriers carrying pilot signals in one symbol are all odd-numbered subcarriers, and the subcarriers carrying pilot signals in the other symbol are all even-numbered subcarriers. That is, the third symbol is interleaved with the pilot subcarriers on the seventh symbol. Therefore, the receiving end can receive pilot signals in the corresponding subcarriers in the third and seventh symbols according to these known rules.

The third embodiment of the present invention relates to a pilot transmission device in a mixed carrier. In this embodiment, the MBSFN frame of the mixed carrier is a candidate frame, that is, each MBSFN subframe occupies 8 OFDM symbols in the time domain. It occupies 12 subcarriers in the frequency domain.

The device for sending pilots in the mixed carrier is shown in Figure 14, including: a mapping module, configured to map the pilot signal to a subframe occupying eight symbols in the time domain, wherein the pilot signal is mapped to the subframe Among the partial subcarriers of the two symbols, in each of the two symbols, half of the subcarriers are mapped with pilot signals, and every two adjacent subcarriers in the same symbol are mapped with pilot signals The subcarriers are separated by a subcarrier carrying signals other than the pilot signal (such as data subcarriers, pilot subcarriers of other antennas, or subcarriers that do not carry any signal); The air interface sends the subframes output by the mapping module.

Specifically, the symbols and/or subcarriers mapped with pilot signals also meet one of the following characteristics or any combination thereof: the interval between two symbols mapped with pilot signals is 3 symbols; The two symbols are two of the second to seventh symbols in the subframe; among the two symbols mapped with pilot signals, the subcarriers mapped with pilot signals in one symbol are subcarriers with odd numbers, The subcarriers mapped with the pilot signal in the other symbol are all even-numbered subcarriers, that is, the pilot subcarriers on the two symbols are placed alternately so that the limited number of pilot subcarriers are distributed in as many places as possible. , so that the effect of frequency domain diversity can be obtained during channel estimation.

Since the MBSFN candidate frame adopts TDD, and TDD does not necessarily have a unicast control channel. In the case of a unicast control channel, the unicast control channel may only occupy part of the subcarriers in the first symbol in the MBSFN subframe, or may occupy part of the subcarriers in the first and second symbols at the same time. Therefore, Before sending the pilot signal in the subframe of the MBSFN candidate frame, it needs to judge whether there is a unicast control channel in the MBSFN subframe. In the absence of a unicast control channel, the two symbols mapped with the pilot signal are the second and sixth symbols, or the third and seventh symbols in the subframe; In the case of , the two symbols mapped with the pilot signal are the third and seventh symbols in the subframe, that is, the pilot signal is carried from the third symbol to adapt to various unicast control channel distribution.

In MBSFN, multiple adjacent cells use the same time-frequency resources to send the same content, so the multipath delay is relatively large, and the frequency-domain correlation bandwidth is the reciprocal of the multipath delay, which is relatively small. When the interval of the subcarriers in the frequency domain is within the relevant bandwidth of the frequency domain, the result of using the pilot for channel estimation will be better, and there is only one subcarrier that carries other signals between adjacent pilot subcarriers. This requirement can be met. Therefore, every two adjacent pilot subcarriers carrying pilot signals in the same symbol are separated by only one subcarrier carrying other signals, and the pilots can be better used for channel estimation.

Moreover, since in this embodiment, the pilot subcarriers are configured in half of the subcarriers of two symbols, for a subframe occupying eight symbols in the time domain, the number of pilot time-frequency blocks occupies 100% of the time-frequency blocks. The total number ratio is 1/8. Because the higher the ratio of the number of pilot time-frequency blocks to the total number of time-frequency blocks, the better the coherent demodulation performance, and the lower the ratio of the number of pilot time-frequency blocks to the total number of time-frequency blocks, the less overhead. And 1/8 is a moderate ratio, so the performance of overhead and coherent demodulation can be taken into consideration.

It should be noted that each module in this embodiment is a logic module, and in practical applications, there may be various physical implementation manners.

The fourth embodiment of the present invention relates to a pilot receiving device in a mixed carrier. In this embodiment, the MBSFN frame of the mixed carrier is a candidate frame, that is, each MBSFN subframe occupies 8 OFDM symbols in the time domain and 8 OFDM symbols in the frequency domain. It occupies 12 subcarriers. The pilot receiving device in the mixed carrier in this embodiment is configured to receive the pilot signal sent by the pilot sending device in the mixed carrier in the third embodiment.

The pilot receiving device in the mixed carrier is shown in Figure 15, including: a receiving module, which is used to receive wireless signals from the air interface, and output the received results in the form of subframes occupying eight symbols in the time domain; and pilot acquisition A module for obtaining pilot signals from the subcarriers carrying pilot signals in the two symbols of the subframe output by the receiving module, half of the subcarriers carrying pilots in each of the two symbols signal, and every two adjacent subcarriers carrying pilot signals are separated by a subcarrier carrying signals other than the pilot signal (such as data subcarriers, pilot subcarriers of other antennas, or not carrying subcarriers of any signal).

Specifically, the symbols and/or subcarriers carrying the pilot signals also meet one of the following characteristics or any combination thereof: the interval between two symbols carrying the pilot signals is 3 symbols; the two symbols carrying the pilot signals are Two of the second to seventh symbols in the subframe; among the two symbols carrying the pilot signal, the subcarriers carrying the pilot signal in one symbol are subcarriers with odd numbers, and the other symbol carries the pilot signal The subcarriers of the frequency signal are all even-numbered subcarriers, that is to say, the pilot subcarriers on the two symbols are placed alternately.

In addition, in the case that there is no unicast control channel in the subframe, the two symbols carrying the pilot signal are the second and sixth symbols, or the third and seventh symbols in the subframe; In the case of a unicast control channel in a frame, the two symbols carrying pilot signals are the third and seventh symbols in the subframe.

It should be noted that each module in this embodiment is a logic module, and in practical applications, there may be various physical implementation manners.

To sum up, in the embodiment of the present invention, every two adjacent pilot subcarriers carrying pilot signals in the same symbol are separated by only one subcarrier carrying other signals, which can make better use of the pilot subcarriers. frequency channel estimation. This is because, in MBSFN, multiple adjacent cells use the same time-frequency resources to send the same content, so the multipath delay is relatively large, and the frequency-domain correlation bandwidth is the reciprocal of the multipath delay, which is relatively small, while the same symbol When the interval between the pilot subcarriers in the frequency domain is within the frequency domain correlation bandwidth, the effect of using the pilot for channel estimation will be better, and there is only one subcarrier carrying other signals between adjacent pilot subcarriers. The carrier mode can meet this requirement.

The pilot subcarriers are configured in half of the subcarriers of two symbols, and for a subframe occupying eight symbols in the time domain, the ratio of the number of pilot time-frequency blocks to the total number of time-frequency blocks is 1/8. The higher the ratio of the number of pilot time-frequency blocks to the total number of time-frequency blocks, the better the performance of coherent demodulation, and the lower the ratio of the number of pilot time-frequency blocks to the total number of time-frequency blocks, the less overhead. 1/8 is a moderate ratio, which can balance overhead and coherent demodulation performance.

There are 3 symbols at intervals between the symbols carrying the pilot, and if there are multiple consecutive MBSFN subframes, the symbols carrying the pilot may also be evenly spaced at 3 symbols among these subframes. A uniform distribution of pilot-carrying symbols facilitates better coherent demodulation of the signal in each symbol as a whole. In addition, in MBSFN, the interval of 3 symbols can ensure that the performance of the receiving device does not decrease significantly when the speed is 350 kilometers per hour, which can meet the needs of most scenarios.

The symbol carrying the pilot is not the first or last symbol in the subframe, which allows as many data time-frequency blocks as possible to be adjacent to the pilot time-frequency block, and the data time-frequency blocks adjacent to the pilot time-frequency block are in the coherent solution. The timing result is more accurate. Conversely, if the pilot time-frequency block is placed in the first symbol and the preceding adjacent is a unicast subframe, only the data time-frequency block of the second symbol is next to the pilot time-frequency block. If the pilot time-frequency block If it is placed in the 8th symbol and there is a unicast subframe next to it, then only the data time-frequency block of the 7th symbol is next to the pilot time-frequency block.

The pilot subcarriers in the two pilot-carrying symbols are separated in the frequency domain, that is, the pilot subcarriers in one symbol are all odd-numbered subcarriers, while the pilot subcarriers in the other symbol are all even-numbered subcarriers Carrier, the limited number of pilot subcarriers can be distributed on as many subcarriers as possible, so that the effect of frequency domain diversity can be obtained during channel estimation.

In the case that there is a unicast control channel in the MBSFN subframe, the third and seventh symbols in the MBSFN subframe are used to carry the pilot, which can adapt to various distribution situations of the unicast control channel. Because the current unicast control channel may only occupy part of the subcarriers in the first symbol in the MBSFN subframe, or it may occupy part of the subcarriers in the first and second symbols at the same time, and the pilot frequency is carried from the third symbol to this. Either situation can apply.

Although the present invention has been illustrated and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the present invention. The spirit and scope of the invention.

Claims (19)

1. pilot sending method in the mixed carrier, the professional single frequency network of multicast broadcast multimedia that is used for mixed carrier, it is characterized in that, when being sent in time domain and accounting for the subframe of eight symbols, pilot signal transmitted in the parton carrier wave of two symbols in this subframe, in each symbol of these two symbols, each pilot signal transmitted in the subcarrier of half, and the subcarrier of other signals of a carrying except that this pilot signal at interval between the subcarrier of per two adjacent pilot signal transmitteds in the prosign.

2. pilot sending method in the mixed carrier according to claim 1 is characterized in that, 3 symbols in interval between described two symbols of pilot signal transmitted.

3. pilot sending method in the mixed carrier according to claim 1 is characterized in that, described two symbols of pilot signal transmitted are two in second to the 7th symbol in the described subframe.

4. pilot sending method in the mixed carrier according to claim 1, it is characterized in that, in described two symbols of pilot signal transmitted, the subcarrier of pilot signal transmitted is the subcarrier of odd indexed in symbol, and the subcarrier of pilot signal transmitted is the subcarrier of even number sequence number in another symbol.

5. according to pilot sending method in each described mixed carrier in the claim 1 to 4, it is characterized in that described subframe is the subframe in the candidate frame structure of long evolving system.

6. pilot sending method in the mixed carrier according to claim 5, it is characterized in that not having in described subframe under the situation of clean culture control channel, described two symbols of pilot signal transmitted are second and the 6th symbols in this subframe, perhaps, the 3rd and the 7th symbol.

7. pilot sending method in the mixed carrier according to claim 5 is characterized in that, has in described subframe under the situation of clean culture control channel, and described two symbols of pilot signal transmitted are the 3rd and the 7th symbols in this subframe.

8. pilot reception method in the mixed carrier, the professional single frequency network of multicast broadcast multimedia that is used for mixed carrier, it is characterized in that, when being received in time domain and accounting for the subframe of eight symbols, in two symbols of this subframe, receive pilot signal in each subcarrier of carrying pilot signal, the subcarrier carrying pilot signal that half is respectively arranged in each symbol of these two symbols, and the subcarrier of other signals of a carrying except that this pilot signal at interval between the subcarrier of per two adjacent carrying pilot signals.

9. pilot reception method in the mixed carrier according to claim 8 is characterized in that, the described symbol and/or the subcarrier of carrying pilot signal also satisfy one of following feature or its combination in any:

3 symbols in interval between described two symbols of carrying pilot signal;

Described two symbols of carrying pilot signal are two in second to the 7th symbol in the described subframe;

In described two symbols of carrying pilot signal, the subcarrier of carrying pilot signal is the subcarrier of odd indexed in symbol, and the subcarrier of carrying pilot signal is the subcarrier of even number sequence number in another symbol.

10. pilot reception method according to Claim 8 or in the 9 described mixed carriers is characterized in that, described subframe is the subframe in the candidate frame structure of long evolving system.

11. pilot reception method in the mixed carrier according to claim 10, it is characterized in that not having in described subframe under the situation of clean culture control channel, described two symbols of carrying pilot signal are second and the 6th symbols in this subframe, perhaps, the 3rd and the 7th symbol;

Have in described subframe under the situation of clean culture control channel, described two symbols of carrying pilot signal are the 3rd and the 7th symbols in this subframe.

12. pilot tone transmitting apparatus in the mixed carrier is used for the professional single frequency network of multicast broadcast multimedia of mixed carrier, it is characterized in that, comprises:

Mapping block, be used for pilot signal is mapped to the subframe that accounts for eight symbols in time domain, wherein, pilot signal is mapped in the parton carrier wave of two symbols in this subframe, in each symbol of these two symbols, respectively have in the subcarrier of half to be mapped with pilot signal, and the subcarrier of other signals of a carrying except that this pilot signal at interval between per two adjacent subcarriers that are mapped with pilot signal in the prosign;

Transmitter module, being used for aloft, interface sends the subframe that described mapping block is exported.

13. the pilot tone transmitting apparatus is characterized in that in the mixed carrier according to claim 12, described mapping block is mapped to pilot signal symbol and/or the subcarrier that satisfies one of following feature or its combination in any:

Be mapped with between described two symbols of pilot signal 3 symbols at interval;

Described two symbols that are mapped with pilot signal are two in second to the 7th symbol in the described subframe;

In being mapped with described two symbols of pilot signal, the subcarrier that is mapped with pilot signal in symbol is the subcarrier of odd indexed, and the subcarrier that is mapped with pilot signal in another symbol is the subcarrier of even number sequence number.

14., it is characterized in that described subframe is the subframe in the candidate frame structure of long evolving system according to pilot tone transmitting apparatus in claim 12 or the 13 described mixed carriers.

15. pilot tone transmitting apparatus in the mixed carrier according to claim 14, it is characterized in that not having in described subframe under the situation of clean culture control channel, described two symbols that are mapped with pilot signal are second and the 6th symbols in this subframe, perhaps, the 3rd and the 7th symbol;

Have in described subframe under the situation of clean culture control channel, described two symbols that are mapped with pilot signal are the 3rd and the 7th symbols in this subframe.

16. pilot reception equipment in the mixed carrier is used for the professional single frequency network of multicast broadcast multimedia of mixed carrier, it is characterized in that, comprises:

Receiver module is used for receiving wireless signal from air interface, and the result who receives is exported by the subframe form that accounts for eight symbols in time domain;

The pilot tone acquisition module, be used for from each subcarrier of two symbols carrying pilot signals of the subframe of described receiver module output, obtaining pilot signal, the subcarrier carrying pilot signal that half is respectively arranged in each symbol of these two symbols, and the subcarrier of other signals of a carrying except that this pilot signal at interval between the subcarrier of per two adjacent carrying pilot signals.

17. pilot reception equipment is characterized in that in the mixed carrier according to claim 16, described pilot tone acquisition module obtains pilot signal from the symbol that satisfies one of following feature or its combination in any and/or subcarrier:

3 symbols in interval between described two symbols of carrying pilot signal;

Described two symbols of carrying pilot signal are two in second to the 7th symbol in the described subframe;

In described two symbols of carrying pilot signal, the subcarrier of carrying pilot signal is the subcarrier of odd indexed in symbol, and the subcarrier of carrying pilot signal is the subcarrier of even number sequence number in another symbol.

18., it is characterized in that described subframe is the subframe in the candidate frame structure of long evolving system according to pilot reception equipment in claim 16 or the 17 described mixed carriers.

19. pilot reception equipment in the mixed carrier according to claim 18, it is characterized in that not having in described subframe under the situation of clean culture control channel, described two symbols of carrying pilot signal are second and the 6th symbols in this subframe, perhaps, the 3rd and the 7th symbol;

Have in described subframe under the situation of clean culture control channel, described two symbols of carrying pilot signal are the 3rd and the 7th symbols in this subframe.

Images