CN101489286B - Broadcast signal transmitting method and apparatus in wireless communication network - Google Patents

Abstract

The present invention provides a method and device for sending broadcast signals in a transmitter of network equipment in a wireless communication network, and a method and device for processing received broadcast signals in a receiver of network equipment in a wireless communication network The method and device, wherein, by using cyclic prefixes of different lengths and/or pilot signals of different densities for broadcast signals and unicast signals, the problem of using cyclic prefixes of the same length and pilot signals of the same density for all signals in the prior art is overcome. The defects of frequency signals are eliminated, so that an optimized trade-off is achieved between spectrum utilization and communication performance.

Description

Broadcast signal transmission method and device in wireless communication network

technical field

The present invention relates to a wireless communication system, in particular to a method and device for sending broadcast signals in a transmitter, and a method and device for processing received broadcast signals in a receiver.

Background technique

Currently, multi-carrier modulation technology has been widely used in the field of wireless communication, such as Orthogonal Frequency Division Multiplexing (OFDM) and Orthogonal Frequency Division Multiple Access (OFDMA). Since the multi-carrier modulation technology has strong anti-narrowband interference and anti-multipath fading capabilities, and also has flat fading characteristics on each subcarrier, the receiver using this technology has simple equalization complexity. Similarly, the single-carrier frequency-division multiple access (SC-FDMA) system (also known as discrete Fourier transform-extended OFDM system), which is collectively referred to as OFDM technology with orthogonal frequency division multiplexing and orthogonal frequency division multiple access, is also a Advanced wireless transmission scheme. OFDM technology is widely used in high data rate wireless communication systems, such as the integration of wireless local area network (WLAN)/wireless fidelity (Wi-Fi) and wireless metropolitan area network/worldwide interoperability for microwave access (WiMAX), and has become a long-term 3G A popular candidate technology for the Evolved (LTE) air interface. Hereinafter, OFDM symbols in the OFDM system, OFDMA symbols in the OFDMA system, and SC-FDMA symbols in the SC-FDMA system are collectively referred to as OFDM/A symbols.

In an existing wireless communication system based on multi-carrier modulation, a physical transmission frame is typically the smallest transmission unit with a certain number of OFDM/A symbols, as shown in FIG. 1 . In the shown frame structure, a preamble (Preamble) composed of an OFDM/A symbol and a CP (cyclic prefix) is located at the frame head for time synchronization, and the CP attached to each OFDM/A symbol has a uniform length, and The distribution of the pilot signal (Pilot) is uniform. Among them, those marked 51 are all pilot carriers (subcarriers used to carry pilot signals), and the rest are data carriers (subcarriers used to carry data, ie, non-carrier signals).

Generally speaking, the length of the CP should be as long as possible to avoid Inter-Symbol Interference (ISI, Inter-Symbol Interference). At the same time, as a redundancy that does not include useful information, the CP should be as short as possible to achieve high-band efficiency. Generally speaking, the length of the CP is equal to the maximum delay spread of the wireless channel. In addition, the pilot carrier spacing in the frequency domain should satisfy the sampling theorem, that is, the pilot carrier spacing should be greater than the correlation bandwidth of the wireless channel, and the correlation bandwidth is generally equal to the reciprocal of the delay spread of the wireless channel. In this way, the frequency domain interpolation method can be used to estimate the adjacent channel based on the pilot signal, and the channel frequency response of the OFDM/A symbol without the pilot signal can be obtained.

Figure 2 is a schematic diagram of a simple wireless communication network, where, for unicast signals, when the base station acts as the originator, since the base stations A, B, and C transmit independently and the frequency reuse rate is low, especially when When mobile terminal D is located at the edge of the cell, its receiver will be interfered by signals from base stations B and C when it receives a signal from a specific base station such as base station A'. Since the inter-cell interference (ICI) is usually greater than the noise interference in the system, the reception of unicast signals is mainly limited by the inter-cell interference.

For the broadcast signal, the downlink broadcast signal from the core network is released to the relevant multiple base stations A, B and C through the wireless access network controller (WANC), and then these base stations send the broadcast signal out, and the mobile terminal At the receiver of D, only simple RF combining is required. It can be seen that in broadcast signal transmission, since the signals transmitted by different base stations are the same, their signal reception is mainly limited by noise rather than inter-cell interference. However, due to the different distances between the multiple base stations transmitting broadcast signals and the mobile terminal, broadcast signals from farther base stations result in greater delay spread of the broadcast wireless channel, so compared to unicast signals, broadcast signals usually require A longer cyclic prefix and a pilot signal with a smaller carrier spacing.

In fact, the frame structure in the prior art (such as shown in FIG. 1 ) does not distinguish between unicast signals and broadcast signals, that is, each OFDM/A symbol in a frame has a cyclic prefix of uniform length and a uniform lead frequency interval. In such prior art, if the length of the cyclic prefix is specially designed for the broadcast signal, the cyclic prefix will be longer than the cyclic prefix required by the unicast signal. When such a frame structure is applied to the transmission of the unicast signal, it will cause spectrum utilization On the contrary, if the length of the cyclic prefix is specially designed for unicast signals, the cyclic prefix will be shorter than the cyclic prefix required by the broadcast signal. When such a frame structure is applied to broadcast signal transmission, the length of the cyclic prefix will be less than Delay spread, so that the communication performance is significantly reduced. For example, in a WiMAX network, according to the maximum delay spread, the length of the CP can be 1/4, 1/8, 1/16 or even less than the length of an OFDM symbol. However, once the base station selects a CP length, the base station will not adjust it according to whether the signal to be transmitted is a unicast signal or a broadcast signal. Similarly, if the pilot carrier spacing is specially designed for unicast signals, the channel estimation accuracy obtained is very low for broadcast signals due to its large spacing; on the contrary, if the pilot carrier spacing is specially designed for broadcast signals Signal design, although it can also be applied to unicast signals, it undoubtedly wastes too many pilot signals.

Contents of the invention

In view of the above-mentioned problems existing in the prior art, an object of the present invention is to provide a new physical layer dynamic subframe reorganization scheme for efficient multiplexing of unicast and broadcast services, which should consider unicast signals and Broadcast signals face different delay spreads due to different multipath fading channels, and provide CPs with appropriate lengths and pilot signals with appropriate intervals for unicast and broadcast signals. In addition, high frequency band efficiency should be ensured at the same time, and the channel estimation accuracy and pilot cost should be weighed.

In order to achieve the above object, according to the first aspect of the present invention, a method for transmitting broadcast signals in a transmitter of a network device of a wireless communication network is provided, which is characterized in that it includes the following steps: b. The first sending method is different from the second sending method used for sending the signal receiving auxiliary information corresponding to the unicast signal.

According to a second aspect of the present invention, there is provided a method for processing a received broadcast signal from a broadcast source in a receiver of a network device of a wireless communication network, which includes the following steps: A. Processing received broadcast signals in a first processing manner, wherein the first processing manner is different from a second processing manner for processing received unicast signals, and corresponds to the The first transmission mode used for the signal receiving auxiliary information corresponding to the broadcast signal.

According to a third aspect of the present invention, there is provided a broadcasting device for sending a broadcast signal in a transmitter of a network device in a wireless communication network, which is characterized in that it includes: a broadcast sending device for sending Sending the signal receiving auxiliary information corresponding to the broadcast signal, wherein the first sending manner is different from the second sending manner used for sending the signal receiving auxiliary information corresponding to the unicast signal.

According to a fourth aspect of the present invention, there is provided a broadcast processing device for processing a received broadcast signal from a broadcast source in a receiver of a network device of a wireless communication network, which is characterized in that it includes: a first The processing device is configured to process the received broadcast signal in a first processing manner, wherein the first processing manner is different from the second processing manner for processing the received unicast signal.

The present invention overcomes the defects in the prior art of using cyclic prefixes of the same length and pilot signals of the same density for all signals by using cyclic prefixes of different lengths and/or pilot signals of different densities for broadcast signals and unicast signals , thus achieving an optimized trade-off between spectrum utilization and communication performance.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

FIG. 1 shows a schematic structural diagram of a physical transmission frame according to the prior art;

Fig. 2 is a schematic diagram of a wireless communication network;

FIG. 3 shows a system flowchart of a broadcast signal transmission method in a wireless communication network according to a specific embodiment of the present invention;

Fig. 4 is a schematic diagram of a transmitter for broadcast signal transmission in a wireless communication network according to a specific embodiment of the present invention;

5 is a schematic diagram of a receiver for broadcast signal transmission in a wireless communication network according to a specific embodiment of the present invention;

Fig. 6a is a schematic diagram of a frame structure according to a specific embodiment of the present invention;

Fig. 6b is a schematic diagram of a frame structure according to a specific embodiment of the present invention;

7a and 7b are schematic diagrams of pilot patterns according to specific embodiments of the present invention;

FIG. 8 is a block diagram of a broadcasting device for sending broadcast signals in a transmitter of a network device of a wireless communication network according to a specific embodiment of the present invention;

FIG. 9 is a broadcast processing apparatus for processing a received broadcast signal from a broadcast source in a receiver of a network device of a wireless communication network according to a specific embodiment of the present invention;

FIG. 10 is a schematic diagram of the performance comparison of the wireless signal SNR/BER under the present invention and the prior art.

Detailed ways

In order to facilitate the understanding of the following, the concepts appearing in it are explained as follows:

时延扩展：是一种失真类型，归因于多路径引起接收信号的展开或“拖尾效应”。当同样的信号通过不同路径到达并具有不同时延时会产生时延扩展失真。

Delay Spread: Is a type of distortion due to multipath causing spreading or "smearing" of the received signal. Delay spread distortion occurs when the same signal arrives via different paths with different delays.

Hereinafter, without loss of generality, the present invention will be described by taking an OFDM system based on OFDM technology as an example. Those skilled in the art understand that since the idea of the present invention is to use a special cyclic prefix and/or pilot density for broadcast signals, the present invention can be applied to any situation that needs to send pilots and/or pilots separately for broadcast and unicast signals. Systems using cyclic prefixes, including but not limited to OFDM-like systems.

The existing downlink frame structure in the OFDM system can also be expressed in the form shown in Table 1:

Table 1: Existing downlink frame structure in OFDM-like systems

parameters value The number of OFDM/A symbols M The number of subcarriers in one OFDM/A symbol N The number of subcarriers used in one OFDM/A symbol N _used The number of OFDM/A symbols used for broadcasting M _b The length of the cyclic prefix CP _u The number of pilot signals in one OFDM/A symbol P _b

It can be seen that no matter whether an OFDM/A symbol is used to transmit unicast signals or broadcast signals, the length of the cyclic prefix attached before the OFDM/A symbol is a constant value CP _u , and the number of pilot signals in the OFDM/A symbol Also a constant value P _b .

After introducing the present invention, an example of the downlink frame structure is shown in Table 2:

Table 2: Example of downlink frame structure in OFDM system after introducing the present invention

parameters value The number of OFDM/A symbols M The number of subcarriers in one OFDM/A symbol N The number of subcarriers used in one OFDM/A symbol N _used The number of OFDM/A symbols used for broadcasting M _b The length of the cyclic prefix used for broadcast signals CP _b The length of the cyclic prefix used for unicast signals CP _u The number of pilot signals in one OFDM/A symbol for broadcast signals P _b The number of pilot signals in one OFDM/A symbol for unicast signals P _u

By comparing the contents of Table 1 and Table 2, it is not difficult to find that the core idea of the present invention is to add a cyclic prefix with a first length (CP _b ) to the OFDM/A symbol used for the broadcast signal (burst, burst), And adding pilot signals with a first density (P _b in each OFDM/A symbol) to OFDM/A symbols used for broadcasting signals. According to a preferred embodiment of the present invention, CP _b >CP _u and P _b >P _u . This is generally consistent with the characteristics of unicast and broadcast signals, because the length of the cyclic prefix is generally equal to the delay spread of the wireless channel, and the broadcast signal has a greater delay spread than the unicast signal; and, the pilot The carrier spacing of the signal should generally be greater than the relevant bandwidth of the wireless channel, and the relevant bandwidth is generally equal to the reciprocal of the delay spread of the wireless channel, and the broadcast signal usually has a larger delay spread than the unicast signal, so its relevant bandwidth Smaller, the carrier spacing is smaller and the pilot signal density is larger.

FIG. 3 shows a system flowchart of a broadcast signal transmission method in a wireless communication network according to a specific embodiment of the present invention. Those skilled in the art understand that the sequence relationship between the steps shown therein is only for the convenience of expression, not Limitations on the scope of protection of the present invention. Fig. 4 and Fig. 5 are respectively schematic diagrams of a transmitter and a receiver for broadcast signal transmission in a wireless communication network according to a specific embodiment of the present invention. Wherein, in the flowchart shown in Fig. 3, for the sake of brevity, some steps that are not very closely related to the essence of the present invention are omitted, and they are put into the text part of the description for detailed description, for those skilled in the art Therefore, the above omissions will not have any influence on the implementation of the present invention.

Hereinafter, referring to FIG. 3 and in combination with FIG. 2 , FIG. 4 , and FIG. 5 , the present invention will be described in detail from a system perspective. Wherein, take base station A in FIG. 2 sending a downlink broadcast signal to mobile terminal D as an example.

In the transmitter at the base station A as shown in FIG. 4 , at the MAC (Media Access Control) layer, the scheduler assigns a special connection identifier to the broadcast signal, which is used to identify the signal as a broadcast signal. In addition, based on Table 2, the scheduler also allocates a data area including M _b OFDM/A symbols for the broadcast service signal in each frame, and the other (MM _b ) OFDM/A symbols in the frame are used for Transmit signaling and unicast service signals.

As shown in Figure 3, in step S1, mobile terminal D measures the broadcast channel between it and base station A based on the preamble or pilot, so as to obtain delay-related information such as delay extension parameters or maximum delay parameters. This process can It is implemented based on the existing technology, for example, the delay-related information is directly obtained according to the channel response obtained by preamble or pilot estimation. Those skilled in the art understand that the acquisition of the delay-related information can be done actively by the mobile terminal D, for example, periodically perform the operation of broadcast channel measurement to obtain the delay-related information, or the base station A can send the delay-related information to the mobile terminal D. Indication, the operation of performing broadcast channel measurement at mobile terminal D to obtain delay-related information is triggered by the instruction from base station A.

In step S2, the mobile terminal D reports the measured delay-related information to the base station A. So that the base station A determines the first length of the cyclic prefix corresponding to the broadcast signal and the first length of the pilot signal corresponding to the broadcast signal based on delay-related information reported by multiple broadcast signal receiving ends including the mobile terminal D. density.

According to a variation of this specific embodiment, the system determines delay-related information at the network planning stage, and does not update it in subsequent work processes. According to this variation example, the mobile terminal D does not need to measure the delay related information, thus, the step S2 can be omitted.

In step S3, the scheduler in the base station A determines the first length of the cyclic prefix used to send the broadcast signal to the mobile terminal D according to the delay-related information reported by the mobile terminal D, and the pilot signal used to send the broadcast signal to the mobile terminal D the first density of . Typically, base station A determines the first length of the cyclic prefix and the first density of pilots from a pre-stored mapping table as shown in Table 3, including cyclic prefix length, pilot density and delay related information.

Table 3: Mapping table pre-stored in base station A

The i-th predetermined condition for delay related information The first length i First Densityi ii. Scheduled Conditions for Delay Related Information The first length ii First Density ii Clause iii Pre-determined Conditions for Delay Related Information The first length iii First Density iii ... ... ... The Sth predetermined condition of delay related information The first length S The first density S

Based on Table 3, when the delay-related information reported by the mobile terminal D meets one of the conditions such as the i-th predetermined condition, the first length i and the first density i corresponding to the i-th predetermined condition are selected as the A first length of the cyclic prefix of the broadcast signal to the mobile terminal D and a first density of pilot signals for the broadcast signal to the mobile terminal D.

According to a specific embodiment of the present invention, the mapping table shown in Table 3 may not be pre-stored at base station A. Instead, the scheduler in base station A performs calculations according to a specific algorithm, thereby generating an appropriate first length and A first density. For example, the maximum delay spread among multiple user channel delay spread measurements is selected as the first length, or a cyclic prefix longer than the maximum time extension of the wireless channel is used for the broadcast signal, for example, the maximum delay The length of is multiplied by a coefficient (for example, 1.2) to be the first length. This belongs to the common knowledge of those skilled in the art and will not be repeated here.

According to another specific embodiment of the present invention, the scheduler in the base station A does not rely on the delay-related information fed back by the mobile terminal D to determine the first length and the first density, but uses the preset first length and For the first density, during downlink transmission, the preset first length and first density usually do not change.

In step S4, the base station A sends the determined first length and first density and the information indicating the starting position of the broadcast area to the mobile terminal D via the downlink signaling channel. Wherein, in order to reduce the overhead of the signaling channel, different first lengths and first densities can be given different identifiers, and the corresponding relationship between the identifiers and the corresponding first lengths and first densities is pre-stored at the mobile terminal D, by Therefore, the base station A only needs to transmit the identifier on the downlink signaling channel, and then the mobile terminal D searches the pre-stored correspondence based on the identifier sent by the base station A, and can accurately know the first identifier. length and first density, so that it is used for processing the received broadcast signal.

The above steps are mainly aimed at the MAC layer operations performed in the transmitter. Based on the instructions of the MAC layer scheduler, the working principle of the physical layer transmission model shown in the lower part of Figure 4 will be described in the following steps:

In step S5, the base station A judges whether the signal (burst) to be sent is a broadcast signal, specifically, the judgment may be made according to the CID assigned to the broadcast signal by the scheduler before. In fact, the broadcast and unicast signals in the downlink signal to be sent at base station A may be interspersed with each other. Therefore, after step S5, the signal to be sent is sorted into the broadcast signal as shown in the leftmost part of the lower part of Figure 4 and unicast signals.

In subsequent step S6, at the physical layer, base station A performs channel coding, interleaving and modulation on the unicast signal and the broadcast signal respectively according to corresponding coding and modulation schemes. After the subsequent subcarrier mapping and IFFT transformation, according to the determined first length of the MAC layer, base station A adds a cyclic prefix with the first length to the OFDM/A symbol used for broadcasting, and for the OFDM/A symbol used for unicast An OFDM/A symbol may be appended with a cyclic prefix having a second length based on the prior art, wherein the first length is different from and preferably greater than the second length.

In the final framing process, according to the first length of the CP used for broadcasting and the pilot pattern indicating that the pilot signal used for broadcasting signals has a first density, base station A reassembles OFDM in the broadcasting area according to a predefined frame structure symbol structure. In the generated downlink frame, pilots inserted in OFDM/A symbols used for broadcasting have a first density, and CPs with a first length are attached.

Those skilled in the art understand that, based on the core idea of the present invention, the present invention is applicable to various frame structures that have been applied or may be applied in the future. The following takes a simple frame structure as an example, in which it is assumed that a 2 ms long All sub-channels in the frame are used to transmit broadcast signals, as shown in Figures 6a and 6b. Wherein, the structure shown in FIG. 6a includes 8 OFDM/A symbols, while the structure shown in FIG. 6b includes 7 OFDM/A symbols. Not shown in the figure, pilot signals with a density of the first density have been added to each of the OFDM/A symbols shown, and each of the CPs shown has a first length. The difference between the two structures shown in Figures 5a and 5b is that the latter occupies fewer OFDM/A symbols, but each OFDM/A symbol is assigned a longer CP.

The comparison of pilot signal density in the OFDM/A symbols used for broadcasting between the present invention and the prior art will be discussed below. Those skilled in the art understand that there are mature pilot placement schemes in the prior art. For example, an OFDM/A symbol called a pilot symbol can be inserted every few OFDM/A symbols (usually a frame), and all sub-channels within the pilot symbol will be used for channel estimation. For another example, several pilot signals may also be inserted into each OFDM/A symbol, so as to use part of the sub-channels in each OFDM/A symbol to perform channel estimation. The former is called block pilot insertion, which assumes that the channel satisfies the condition of slow fading; the latter is called comb pilot insertion, which can meet the condition of constantly changing channels. Further, the structure of the pilot signal can be divided into the pilot structure of the square distribution, the pilot signal is distributed at equal intervals in both the time domain and the frequency domain; the block pilot structure refers to the periodic distribution in the direction of the time axis. The pilot signal is permanently inserted, the cycle must satisfy the sampling theorem, and the pilot signal occupies all the subcarriers on the frequency axis; and the comb-shaped pilot structure refers to inserting the pilot signal at equal intervals on the frequency axis, in the time The on-axis pilot signal is in continuous comb shape. The present invention can determine the pilot signal according to the above method, but the difference from the prior art is that the present invention uses a pilot signal with a higher density than the unicast signal for the broadcast signal, which can be specifically embodied as the insertion of pilot symbols or pilot signals More frequent.

As shown in Figures 7a and 7b, according to this example, the present invention reuses the pilot pattern in the prior art, and allocates sparse pilots for unicast services based on the prior art, and allocates denser pilots for broadcast services based on the present invention. the pilot frequency.

Next, referring to steps S7 and S8 shown in FIG. 3 and combining with the receiver shown in FIG. 5 , the operation of the mobile terminal D after receiving the signal sent by the base station A in step S6 is performed.

Corresponding to the framing operation at base station A, after receiving a physical transmission frame from base station A, the receiver at mobile terminal D first deframes it, which requires mobile terminal D to know the frame structure. Specifically, the base station A may send the indication information indicating the frame structure to the mobile terminal D together with the first length and the first density in the previous step S4. Optionally, the system may pre-store the indication information indicating the frame structure at the mobile terminal D, and during the validity period of the frame structure, the base station A always uses the frame structure to perform framing operations, thereby ensuring that the mobile terminal D can Deframe it correctly. When the frame structure becomes invalid, the system updates the pre-stored frame structure at the mobile terminal D.

After the deframing, the received transmission frame is decomposed into a unicast signal and a broadcast signal. However, an OFDM/A symbol for unicast is preceded by a CP of the second length, and an OFDM/A symbol for broadcast is preceded by a CP of the first length. Since the first length is different from the second length, the receiver needs to know which signals are unicast signals and which signals are broadcast signals, so that according to the first length previously known in step S4 and the preset or agreed with base station A The second length of is used to accurately remove the CP for the deframed signal.

Then, in step S7, the mobile terminal D judges whether the deframed OFDM/A symbol with one CP is a broadcast signal. Specifically, the determination can still be made through the special CID assigned to the broadcast signal by the scheduler of the MAC layer of the base station A.

If the judgment result obtained in step S7 is negative, that is, the OFDM/A symbol is used for a unicast signal, then the mobile terminal D will remove the CP for it according to the second length corresponding to the unicast signal, thereby obtaining The OFDM/A symbol used for unicast of the CP is obtained, and then undergoes FFT transformation. According to the pilot pattern, the channel estimation of the unicast channel is performed based on the pilot signal with the second density, and the result of the channel estimation is used for unicast Signal equalization processing, after that, demodulate and decode the signal according to the preset unicast signal demodulation and decoding methods until the original unicast data is obtained, wherein the demodulation and decoding methods are the same as those of base station A Corresponding to the modulation and coding methods at the location, this process belongs to the common knowledge of those skilled in the art, and will not be described in detail here.

If the judgment result obtained in step S7 is affirmative, that is, the OFDM/A symbol is used for broadcasting signals, the mobile terminal D will remove the CP of the OFDM/A symbol according to the first length obtained in step S4. Thus, OFDM/A symbols for broadcasting with CP removed are obtained. Thereafter, after FFT transformation, the broadcast channel is estimated based on the pilot signal with the first density according to the pilot pattern shown in Fig. 7b, and the channel estimation result is used for equalization processing of the broadcast signal. Thereafter, based on the preset demodulation and decoding schemes corresponding to the modulation and coding schemes at base station A, the equalized broadcast signal is processed to obtain original broadcast data.

As mentioned above, if the base station A uses the fixed first length and the first density to send the broadcast signal, the first length and the first density should be pre-stored in the mobile terminal D accordingly.

According to a variation of the present invention, base station A adds a cyclic prefix with a first length to OFDM/A symbols used for broadcast signals, and the first length is different from OFDM/A symbols used for unicast signals The additional cyclic prefix has a second length, however, base station A uses the same pilot signal density for OFDM/A symbols for broadcast signals as for OFDM/A symbols for unicast signals.

According to yet another variation of the present invention, wherein base station A uses pilot signals with a first density for OFDM/A symbols used for broadcast signals, and the first density is different from OFDM/A symbols used for unicast signals. The second density of pilot signals used by A symbols, however, the cyclic prefix appended by base station A for OFDM/A symbols for broadcast signals is the same as the cyclic prefix for OFDM/A symbols for unicast signals The prefixes have the same length. According to the actual situation, the system can switch between the schemes described in the above examples under human control or automatic control.

Fig. 8 is a block diagram of a broadcasting device used in a transmitter of a network device of a wireless communication network for sending broadcast signals according to a specific embodiment of the present invention. The broadcasting device 10 shown is typically configured in each of the base stations shown in FIG. 2 , and the base station A is taken as an example for illustration below. The broadcast device 10 shown includes a first judging device 100 and a broadcast sending device 101, and the broadcast sending device 101 specifically includes a broadcast pilot sending device 1010, a broadcast pilot density determining device 1011, a broadcast prefix sending device 1012, and a broadcast prefix length determining device 1010. device 1013.

The broadcasting device 10 will be described below with reference to FIG. 8 in combination with FIGS. 2 and 4 . First, the delay-related information reported by the mobile terminal D is received by a receiving device not shown in FIG. 8 , and the received delay-related information will be provided to the broadcast pilot density determination device 1011 and the broadcast prefix length determination device 1013, The broadcast pilot density determining means 1011 and the broadcast prefix length determining means 1013 determine the length of the cyclic prefix used for sending broadcast signals to the mobile terminal D according to the delay-related information reported by the mobile terminal D, and send the mobile terminal D The density of the pilot signal used to transmit the broadcast signal. Typically, the broadcast pilot density determining means 1011 and the broadcast prefix length determining means 1013 determine the cyclic prefix length from a pre-stored mapping table including cyclic prefix length, pilot density and delay related information as shown in Table 3 above and pilot density. According to a specific embodiment of the present invention, the process of determining the pilot density is realized by determining a pilot pattern, wherein the pilot pattern includes a pilot pattern used for broadcast signal pilots and a pilot pattern used for Pilot pattern of the pilot of the unicast signal.

The determined first length is provided to the broadcast prefix sending device 1012 , and the determined first density is provided to the broadcast pilot sending device 1010 .

The first judging means 100 judges whether it is a broadcast signal according to the CID of the signal (burst), and if the signal to be sent is a broadcast signal, then the broadcast pilot sending means 1010 and the broadcast prefix sending means 1012 are used for the broadcast signal Pilot signals having a first density and a cyclic prefix having a first length are transmitted. If the signal to be sent is a unicast signal, the solution in the prior art may be followed to send the pilot signal with the first density and the cyclic prefix with the first length.

Fig. 9 is a broadcast processing apparatus for processing a received broadcast signal from a broadcast source in a receiver of a network device of a wireless communication network according to a specific embodiment of the present invention. The broadcast processing device 20 shown is typically configured in the mobile terminal D shown in FIG. 2 , and the communication between the mobile terminal D and the base station A will be described below as an example. The shown broadcast processing device 20 includes a first processing device 200, a delay estimating device 201, a delay reporting device 202, and a second judging device 203. Specifically, the first processing device 200 includes: a broadcast channel estimating device 2000, an auxiliary processing device 2001 and broadcast prefix removal device 2002.

The broadcast processing apparatus 20 will be described below with reference to FIG. 9 in conjunction with FIG. 2 and FIG. 5 . First, the delay estimating means 201 estimates the time delay generated by the broadcast signal from the base station A, so as to generate delay related information. The generated delay related information is provided to the delay reporting means 202 .

Thereafter, the delay reporting means 202 reports the generated delay related information to base station A, so that base station A can determine the pilot density (first density) and CP length (first length) for broadcasting signals accordingly.

When the downlink frame from base station A arrives, corresponding to the framing operation at base station A, after receiving a physical transmission frame from base station A, a deframing device not shown in Figure 9 (similar function The deframing module shown in FIG. 5) performs a deframing operation on it, which requires the mobile terminal D to know the frame structure used at the base station A. The frame structure may be previously notified by the base station A to the mobile terminal D, or pre-stored at the mobile terminal D according to an agreement. Optionally, the system may pre-store the indication information indicating the frame structure at the mobile terminal D, and during the validity period of the frame structure, the base station A always uses the frame structure to perform framing operations, thereby ensuring that the mobile terminal D can Deframe it correctly. When the frame structure becomes invalid, the system updates the pre-stored frame structure at the mobile terminal D.

After the deframing, the received transmission frame is decomposed into a unicast signal and a broadcast signal. However, an OFDM/A symbol for unicast is preceded by a CP of the second length, and an OFDM/A symbol for broadcast is preceded by a CP of the first length. Since the first length is different from the second length, the receiver needs to know which signals are unicast signals and which signals are broadcast signals, so that according to the previously known first length and the second length preset or agreed with base station A To accurately remove the CP for the deframed signal.

Therefore, the second judging means 203 judges whether each OFDM/A symbol added with a CP obtained by deframing is a broadcast signal. Specifically, the determination can still be made through the special CID assigned to the broadcast signal by the scheduler of the MAC layer of the base station A.

If the judgment result obtained by the second judging means 203 is negative, that is, the OFDM/A symbol is used for a unicast signal, then the judgment result is notified to a unicast prefix removal device not shown in the figure, and the unicast prefix is removed by the unicast signal The broadcast prefix removal device removes the CP according to the second length corresponding to the unicast signal, thereby obtaining the OFDM/A symbol for unicast with the CP removed, and then through FFT transformation, by the unicast channel estimation device (not shown in FIG. 9 ) according to the pilot pattern, the channel estimation of the unicast channel is performed based on the pilot signal with the second density, and the result of the channel estimation is used at a device for auxiliary processing of the unicast signal. Unicast signal equalization processing, after that, the device demodulates and decodes the signal according to the preset unicast signal demodulation and decoding methods until the original unicast data is obtained, wherein the demodulation, The decoding method corresponds to the modulation and coding method at the base station A, and the device for auxiliary processing of the unicast signal can be performed by the auxiliary processing device 2001 shown in FIG. Shown is a device dedicated to auxiliary processing of unicast signals.

If the judgment result obtained in the second judgment means 203 is affirmative, that is, the OFDM/A symbol is used for a broadcast signal, then the judgment result is notified to the broadcast prefix removal means 2002, and then the broadcast prefix removal means 2002 to remove the CP for the OFDM/A symbol based on the learned first length. Thus, OFDM/A symbols for broadcasting with CP removed are obtained. Afterwards, after FFT transformation, the broadcast channel estimation apparatus 2000 estimates the broadcast channel based on the pilot signal with the first density according to the pilot pattern shown in FIG. Equalization processing for broadcast signals. Thereafter, the auxiliary processing device 2001 processes the equalized broadcast signal based on the preset demodulation and decoding methods corresponding to the modulation and coding methods at base station A, so as to obtain original broadcast data.

According to a specific embodiment of the present invention, some public system parameters of the 2ms broadcast area are defined as shown in Table 4:

Table 4: Common system parameters for 2ms broadcast zone

parameter value Sampling frequency f _S =1/T 10MHz Valid symbol part duration T _U 1024xT (102.4 microseconds) Total number of active subcarriers N _ST 896 the duration of a frame 2 milliseconds

According to this specific embodiment, Table 5 and Table 6 show two special parameters defined for the broadcast area respectively:

Table 5: Special parameters of the 2ms broadcast area

parameter value Length CP _b of the cyclic prefix used for the broadcast signal 56xT (5.6 microseconds) Symbol interval T _S 1080xT (1.08 microseconds) The total number of effective subcarriers N _used 897 Preamble signal T _p 290xT (29.0 microseconds) Total number of OFDM symbols in the broadcast region 9 the duration of a frame 2 milliseconds

Table 5: Special parameters of the 2ms broadcast area

parameter value Cyclic prefix duration CP _b 190xT (19 microseconds) Symbol interval T _S 1214xT (121.4 microseconds) Preamble signal T _p 288xT (28.8 microseconds)

Total number of OFDM symbols per frame 8 the duration of a frame 2 milliseconds

FIG. 10 is a schematic diagram of the performance comparison of the wireless signal SNR/BER under the present invention and the prior art. Specifically, the prior art and the resource allocation scheme according to the present invention are simulated and compared through the COST207 channel, and Table 6 shows the node time delay line (TDL) parameters of the COST207 channel:

path number Latency [nanoseconds] Average power [dB] Doppler spectrum Small big 123456 02004006008001000 0600012000180002400030000 0-6-12-18-24-30 Jakes (U-shaped spectrum) JakesJakesJakesJakesJakes

Among them, for a relatively fair comparison, the code rate of the channel coding in the present invention is increased in the simulation process to compensate for the data rate reduction caused by reducing the number of OFDM/A symbols, and the pilot signal is increased so that the two frame structures have the same data rate. Accordingly, Fig. 10 shows the simulation results. As expected, if the broadcast area is transmitted through the wireless channel with a small time delay spread, then the structure of the present invention can obtain performance similar to the frame structure of the prior art; wireless channel transmission (which is a case in the broadcast area), the frame structure of the prior art will cause significant performance degradation due to ISI due to the lack of sufficient cyclic prefix length, and the channel estimation accuracy due to the sparse pilot signal density , which makes it no longer possible to reliably transmit broadcast data, in which case the frame structure of the present invention achieves a significant performance improvement due to reduced ISI and increased channel estimation accuracy.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various variations or modifications within the scope of the appended claims.

Claims (13)

1. a method that in the transmitter of the network equipment of cordless communication network, is used to send broadcast singal is characterized in that, may further comprise the steps:

A. signal letter sorting to be sent is broadcast singal and unicast signal;

B. send with the corresponding signal of broadcast singal with first send mode and receive supplementary, wherein, said first send mode is different from transmission and receives the second used send mode of supplementary with the corresponding signal of unicast signal, and wherein, this step comprises:

-b1. confirms one first density; Comprise according to the delay relevant information of being reported by one or more broadcast reception ends of said broadcast singal and confirm said first density; Wherein, said delay relevant information is corresponding with the time delay that present networks equipment is produced when the respective broadcast receiving terminal sends broadcast singal;

-determined first density is sent to receiving terminal;

-b2. sends and the corresponding pilot signal of said broadcast singal with determined said first density, and wherein, said first density is different from and is used to send second density used with the corresponding pilot signal of unicast signal.

2. method according to claim 1 is characterized in that, said cordless communication network adopts multi-carrier modulation, and said signal receives supplementary and comprises Cyclic Prefix, and said step b comprises:

Ii. send and the corresponding Cyclic Prefix with first length of broadcast singal, wherein, said first length is different from second length that is had with the corresponding Cyclic Prefix of unicast signal.

3. method according to claim 2 is characterized in that, among the said step b, before said step I i, also comprises:

I. confirm said first length;

Said step I i also comprises:

-send and the corresponding Cyclic Prefix of broadcast singal with determined said first length, wherein, said first length is different from second length that is had with the corresponding Cyclic Prefix of unicast signal.

4. method according to claim 3 is characterized in that, said step I also comprises:

-according to the delay relevant information of being reported by one or more broadcast reception ends of said broadcast singal; Confirm said first length; Wherein, said delay relevant information is corresponding with the time delay that present networks equipment is produced when the respective broadcast receiving terminal sends broadcast singal.

5. one kind is used for method that the broadcast singal from broadcast source that receives is handled in the receiver of the network equipment of cordless communication network, it is characterized in that, may further comprise the steps:

-reception is from first density of broadcast source;

-transmission frame that receives is decomposed into unicast signal and broadcast singal;

A. with first processing mode broadcast singal that receives is handled; Wherein, Said first processing mode is different from handles the second used processing mode to the unicast signal that receives; And said first processing mode is sent with the corresponding signal of said broadcast singal corresponding to said broadcast source place and is received the first used send mode of supplementary, and wherein said signal receives supplementary and comprises pilot signal, and this step comprises

-according to have first density come the broadcast channel of said broadcast source and present networks equipment room is estimated with the corresponding pilot signal of said broadcast singal, with acquisition broadcast channel estimated result;

-utilize said broadcast channel estimated result to come the said broadcast singal that receives is handled;

Wherein, said first density is different from second density that is had with the corresponding pilot signal of unicast signal that is used for the unicast tunnel of said broadcast source and present networks equipment room is estimated;

This method also comprises the steps:

I. estimate the time delay that broadcast singal produced of said broadcast source, generate the delay relevant information;

The said delay relevant information that II. will generate reports to said broadcast source;

This first density is to be confirmed to get according to said delay relevant information by said broadcast source.

6. method according to claim 5 is characterized in that, said cordless communication network is based on multi-carrier modulation, and said signal receives supplementary and also comprises Cyclic Prefix, and said steps A also comprises:

-remove Cyclic Prefix for said broadcast singal with first length, remove the broadcast singal of Cyclic Prefix with generation;

Wherein, said first length is different from second length that Cyclic Prefix had from the unicast signal of this broadcast source.

7. a broadcaster that in the transmitter of the network equipment of cordless communication network, is used to send broadcast singal is characterized in that, comprising:

First judgment means is used to judge whether signal to be sent is broadcast singal;

Broadcast transmitting device; Be used for sending and the corresponding signal reception of broadcast singal supplementary with first send mode; Wherein, Said first send mode is different from and is used to send and the second used send mode of the corresponding signal reception supplementary of unicast signal, and this broadcast transmitting device comprises:

Broadcast pilot density is confirmed device; Be used for the delay relevant information that basis is reported by one or more broadcast reception ends of said broadcast singal; Confirm one first density; Wherein, said delay relevant information is corresponding with the time delay that a plurality of network equipments that comprise present networks equipment are produced when the respective broadcast receiving terminal sends broadcast singal;

The broadcast pilot dispensing device sends and the corresponding pilot signal of broadcast singal with said first density of confirming, wherein, said first density is different from and is used to send second density used with the corresponding pilot signal of unicast signal;

This broadcaster sends to receiving terminal with said first density.

8. broadcaster according to claim 7 is characterized in that, said cordless communication network adopts multi-carrier modulation, and said signal receives supplementary and comprises Cyclic Prefix, and said broadcast transmitting device comprises:

Broadcasting prefix dispensing device is used to send and the corresponding Cyclic Prefix with first length of broadcast singal, and wherein, said first length is different from second length that is had with the corresponding Cyclic Prefix of unicast signal.

9. broadcaster according to claim 8 is characterized in that, said broadcast transmitting device also comprises:

The broadcasting prefix length is confirmed device, is used for confirming said first length;

Said broadcasting prefix dispensing device also is used for, and sends and the corresponding Cyclic Prefix with determined said first length of broadcast singal, and wherein, said first length is different from second length that is had with the corresponding Cyclic Prefix of unicast signal.

10. according to Claim 8 or 9 described broadcasters, it is characterized in that said broadcasting prefix dispensing device also is used for:

-according to the delay relevant information of being reported by one or more broadcast reception ends of said broadcast singal; Confirm said first length; Wherein, said delay relevant information is corresponding with the time delay that a plurality of network equipments that comprise present networks equipment are produced when the respective broadcast receiving terminal sends broadcast singal.

11. one kind is used for broadcast processing apparatus that the broadcast singal from broadcast source that receives is handled in the receiver of the network equipment of cordless communication network, it is characterized in that, said broadcast processing apparatus receives first density from broadcast source, and comprises:

Separate the frame device, be used for the transmission frame that receives is decomposed into unicast signal and broadcast singal;

Second judgment means is used to judge whether the signal that receives is broadcast singal;

First processing unit is used for first processing mode broadcast singal that receives being handled, and wherein, said first processing mode is different from second processing mode that the unicast signal that receives is handled, and said first processing unit comprises:

The broadcast channel estimation unit is used for when received signal is broadcast singal, comes the broadcast channel of said broadcast source and present networks equipment room is estimated according to the broadcast pilot with first density, to obtain the broadcast channel estimated result;

Auxiliary Processing Unit is used to utilize said broadcast channel estimated result to come the said broadcast singal that receives is handled;

Wherein, said first density is different from and is used for second density that unicast pilot signal had that the unicast tunnel of said broadcast source and present networks equipment room is estimated;

This broadcast processing apparatus also comprises:

Postpone estimation unit, be used to estimate the time delay that broadcast singal produced from a plurality of other network equipments, generate the delay relevant information, wherein, said a plurality of other network equipments comprise said broadcast source;

The delay report device is used for the said delay relevant information that generates is reported to said each other network equipment;

This first density is to be confirmed to get according to said delay relevant information by said broadcast source.

12. broadcast processing apparatus according to claim 11 is characterized in that, said cordless communication network is based on multi-carrier modulation, and said first processing unit also comprises:

Broadcasting prefix removal device is used for when received said signal is broadcast singal, for said broadcast singal is removed the Cyclic Prefix with first length, to generate the broadcast singal of removing Cyclic Prefix;

Wherein, said first length is different from second length that Cyclic Prefix had from the unicast signal of this broadcast source.

13. network equipment in cordless communication network; It is characterized in that, comprise according to each saidly is used for sending the broadcaster of broadcast singal and/or according to each described broadcast processing apparatus that the broadcast singal from broadcast source that receives is handled of claim 11 to 12 in the claim 7 to 10.

Images