CN1521968A - Generation Method and Transmission Method of New Training Symbols in Orthogonal Frequency Division Multiplexing System - Google Patents

Abstract

A method for generating new training symbols in an OFDM system, the OFDM communication system has N subcarriers, wherein the subcarriers used are L, and each transmission frame structure includes downlink subframes and In the uplink subframe, the beginning of the downlink subframe is an access preamble, and a new training symbol is generated in the base station; the training symbol is transmitted in the downlink subframe, and the transmission position of the training symbol in the downlink subframe is determined by the downlink control information; the training symbols are mapped to the known positions of the nth to mth uplink subframes from the current frame to the random access time slots. The invention can avoid the interference of the AAS terminal to the non-AAS system, because the AAS indicator is used to indicate whether the current system is an AAS system. Only when the AAS terminal captures the AAS indicator can it access the system through the AAS alarm time slot. Since the non-AAS system has no AAS indicator, the AAS terminal will never access the system through the AAS alarm time slot in the non-AAS system, thus avoiding interference.

Description

Generation Method and Transmission Method of New Training Symbols in Orthogonal Frequency Division Multiplexing System

technical field

The present invention relates to Orthogonal Frequency Division Multiplexing (OFDM) communication technology, in particular to a method for generating a new training symbol in an OFDM system and a method for transmitting the training symbol.

Background technique

In many OFDM communication systems, such as IEEE802.16a and high-performance metropolitan area network specification (Hiperman), the adaptive antenna (AAS) technology is used as an optional technology to obtain system gain. In such a system, when the base station adopts AAS technology (hereinafter referred to as AAS base station, and the corresponding system is called AAS system), the cell served by the base station can simultaneously support terminals using AAS technology (hereinafter referred to as AAS terminal) and terminals not using AAS technology. terminals (hereinafter referred to as non-AAS terminals). But when the base station does not adopt the AAS technology (hereinafter referred to as non-AAS base station, and the corresponding system is called non-AAS system), the cell served by the base station can only support non-AAS terminals. In the cell served by the non-AAS base station, when the non-AAS terminal is turned on or restarted, it will listen to the downlink (from the base station to the terminal, the same below) channel, determine the beginning of the downlink frame through a specific training sequence, and then pass the frame. At the beginning to decode the downlink broadcast information. The random access time slot of the uplink (from the terminal to the base station, the same below) subframe is known through the specific mapping relationship of some downlink broadcast information. When a non-AAS terminal wants to initially access the system, the terminal will access the system through a certain contention access mechanism in these random access time slots mapped by the broadcast information. In the cell served by the AAS base station, the process for a non-AAS terminal to access the AAS system is the same as the process for accessing the non-AAS system. For an AAS terminal, if the energy of the downlink signal received by the AAS terminal is high enough to decode the downlink broadcast information, then the process of the AAS terminal accessing the AAS system can be the same as that of a non-AAS terminal accessing the AAS system . In the cell served by the AAS base station, due to cell coverage and antenna beamforming or other reasons, sometimes there are some AAS terminals. Before these terminals access the system, the energy of the received downlink signal is not high enough to decode the downlink signal. broadcast information. But because the specific training sequence is transmitted by the base station in the form of power boost, these terminals can capture the specific training sequence to know the start of the frame. Such a terminal only knows the beginning of the frame but cannot decode the broadcast information, so it does not know the random access time slot mapped by the broadcast information. In order to allow these terminals to access the AAS system, some time slots are used in the uplink channel. The positions of these time slots are agreed in advance and are known relative to the beginning of the frame, and broadcast information is not required for mapping. We call these known time slots AAS alert time slots. When these terminals want to access the system, they send an alarm signal to the AAS base station through a certain contention access mechanism in the AAS alarm time slot to indicate that the terminal is an AAS terminal. At the same time, the AAS base station adjusts the beamforming for the terminal by measuring the transmitted signal therein, and transmits dedicated mapping information to the terminal so that the terminal can communicate with the AAS base station. In the current IEEE802.16a 256 OFDM mode and the AAS system in the high-performance metropolitan area network plan (Hiperman), define the last L OFDM symbols of each FDD uplink subframe as the AAS alarm time slot, and define each TDD uplink subframe The last L OFDM symbols of are used as AAS alert slots. Although the definition of the AAS alarm time slot is mainly aimed at those AAS terminals that cannot decode downlink broadcast information in the initial state, it can also be used for initial access to any AAS terminal. That is to say, in the initial state, any AAS terminal can directly access the system through the AAS alarm time slot without decoding the downlink broadcast information.

The AAS system defines AAS alarm time slots for initial access of AAS terminals, especially for those AAS terminals that cannot decode downlink broadcast information in the initial state. The AAS alarm time slot exists in every FDD or TDD uplink subframe. Because the AAS system needs to support non-AAS terminals and AAS terminals at the same time, when there is no AAS terminal or there are few AAS terminals in the AAS system, the AAS alarm time slot existing in each frame will become an additional overhead. At the same time, when the AAS terminal accesses the non-AAS system, and the AAS terminal cannot decode the downlink broadcast information in the initial state. The terminal does not know whether the current system is an AAS system, it will assume that the system has an AAS alarm time slot, and determine the position of the AAS alarm time slot that is assumed to exist but does not actually exist according to the position of the captured training sequence, and The presumably existing AAS alarm slot transmits an alarm signal. In fact, there are uplink signals of other non-AAS terminals (signals from the terminal to the base station) in the assumed AAS alarm time slot, so the alarm signal will become a serious interference signal.

Contents of the invention

The purpose of the present invention is to provide a new training symbol introduced into the downlink channel of the AAS system to mark the system as the AAS system. The training symbol is similar to the training sequence at the beginning of the frame but is different from the training sequence. The AAS terminal that has captured the training sequence at the beginning of the frame can capture the indicator signal.

In order to achieve the above object, a method for generating a new training symbol in an OFDM system, the OFDM communication system has N subcarriers, wherein the subcarriers used are L, and each transmission frame structure Including a downlink subframe and an uplink subframe, the beginning of the downlink subframe is an access preamble, and the method includes steps:

generating a new training symbol in the base station;

The training symbol is transmitted in a downlink subframe, and the transmission position of the training symbol in the downlink subframe is controlled by downlink control information;

The training symbols are mapped to the known positions of the nth to mth uplink subframes from the current frame to the random access time slots.

The invention can avoid the interference of the AAS terminal to the non-AAS system, because the AAS indicator is introduced into the AAS system to indicate whether the current system is the AAS system. Only when the AAS terminal captures the AAS indicator can it access the system through the AAS alarm time slot. Since the non-AAS system has no AAS indicator, the AAS terminal will never access the system through the AAS alarm time slot in the non-AAS system, thus avoiding interference. Since the AAS indicator is introduced, and the AAS indicator and the AAS alarm time slot are bundled together, there is no need to place an AAS alarm time slot in each uplink subframe, so that it is possible to reduce the additional traffic caused by the AAS alarm time slot s expenses. The AAS indicator described in the present invention and its corresponding transmission method are extremely easy to implement, especially for the current specifications of EEE802.16a and high-performance metropolitan area network specification (Hiperman), only a small modification is required.

Description of drawings

Figure 1 is a TDD frame structure combined with an AAS indicator, where the AAS indicator is transmitted in a downlink subframe through the reflection of a new DL-MAP unit, and the FCH is a frame control header.

FIG. 2 is an example of a frame structure of a Time Division Duplex (TDD) system, including downlink subframes, uplink subframes, sending and receiving intervals, and sending and receiving intervals.

FIG. 3 is an example of a frame structure of a Frequency Division Duplex (FDD) system, including downlink subframes and uplink subframes.

Figure 4 is the downlink data service, which is composed of downlink service segments.

Figure 5 is the uplink service, which is composed of uplink service segments.

Fig. 6 is a flowchart of a terminal accessing the system when there is no AAS indicator.

Figure 7 is AAS indicator structure 1, where Tg represents the length of the cyclic prefix, Tb represents the length of one OFDM data symbol, and the sign of AI is opposite to the sign of A.

Figure 8 is AAS indicator structure II, where Tg represents the length of the cyclic prefix, Tb represents the length of one OFDM data symbol, and the sign of AI is opposite to that of A. The sign of BI is the opposite of that of B.

FIG. 9 is a flowchart of an AAS terminal accessing an AAS system through an AAS indicator.

Detailed ways

In many OFDM systems, such as IEEE802.16a and high-performance metropolitan area network specification (Hiperman), both time division duplex (TDD) and frequency division duplex (FDD) communication methods are included. Compared with these two methods, there are two different transmission frame structures. Examples of these two frame structures are shown in Figure 2 and Figure 3 respectively. In these two frame structures, each frame includes a downlink subframe and uplink subframes, where the TDD also includes a sending and receiving gap and a sending and receiving gap. The beginning of the downlink subframe is a long access preamble, which is a specific training sequence and is used to determine the beginning of each frame. Following the long access preamble is frame control header information, which is some control information used to describe the current frame length, service type, and current channel quality. At the same time, the frame control header also includes downlink mapping information (DL-MAP) and uplink mapping information (UL-MAP), where DL-MAP maps the data service segmentation of the current downlink subframe, including location, used users, etc.; UL-MAP maps the data service segmentation of the current uplink subframe or the next uplink subframe, including location, used users, etc. At the same time, UL-MAP also maps the information of random access slots and bandwidth request slots. Figure 4 and Figure 5 are examples of downlink data services and uplink services respectively. For the AAS system, certain known positions of the uplink subframe are defined in advance as a known business segment, called the AAS alarm time slot, corresponding to the 802.16 256 OFDM (P802.16a/D7-2003.1) system mode And HipermanOFDM mode (BRAN031d89-2002.12 BRAN031d88-2002.12), the AAS alarm time slot is the last L OFDM symbols of the current uplink subframe.

The DL-MAP unit and the UL-MAP unit map different service segments in the downlink subframe and uplink subframe respectively. The format of the DL-MAP is shown in Table 1, where the start time indicates the starting position of the segment relative to the beginning of the frame, and different downlink segment use codes (DIUC) indicate different downlink service segments. Also, a similar format exists for UL-MAP.

For a non-AAS terminal, when the terminal wants to access the current system, it must first decode the frame control header to obtain the position of the random access slot mapped by UL-MAP, and then perform initial random access in the random access slot. Access process. For an AAS terminal, if the terminal can decode the frame control header and wants to perform an initial random access in a random access slot, the procedure is the same as for a non-AAS terminal. Otherwise, the terminal will directly perform initial random access through the AAS alert slot. The access flow diagram is shown in Figure 6.

The present invention introduces a new downlink service segment to the AAS system, which is called the AAS indicator. We assign a new downlink segment usage code to the AAS pointer, and the DL-MAP containing the downlink segment usage code indicates the location of the AAS pointer. FIG. 1 is an illustration of an AAS pointer in a frame structure of a TDD system.

The AAS indicator is a previously known access preamble, which can have two structures:

The first structure is shown in Figure 7. The indicator includes two parts. The first part is composed of a cyclic prefix and an OFDM symbol. The OFDM is composed of four subparts, wherein the first and third subparts are the same, and the second Identical to the fourth subsection and the inverse sign of the first and third subsections, the second section consists of a cyclic prefix and an OFDM symbol consisting of two identical repeating sections.

The second structure is shown in Figure 8, the indicator includes two parts, the first part is composed of a cyclic prefix and an OFDM symbol, the OFDM is composed of four sub-parts, wherein the first and third sub-sub-parts are the same, the first The second and fourth subparts are the same and are opposite signs of the first and third subparts, the second part is composed of a cyclic prefix and an OFDM symbol consisting of two repeating parts with opposite signs.

Corresponding to the 802.16 256 OFDM system mode and the Hiperman OFDM mode, the length of the A part and the AI part in the AAS indicator structure 1 and structure 2 is 64, and the length of the B and BI is 128.

In an OFDM system, known training symbols are obtained by performing fast inverse Fourier transform (IFFT) on a known sequence in the frequency domain, and we call this kind of sequence a frequency domain training sequence.

Let the frequency-domain training sequence be {p _i |i=-N/2,...,N/2-1} where N is the length of IFFT, and i corresponds to the label of the OFDM modulated subcarrier (subcarrier), then, the known training symbol

$<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; N</span>}}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;ik</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \}</span>$

In the 256 OFDM mode, there are a total of 256 subcarriers, numbered from -128 to 127, and only 200 of them are used, numbered from -100 to -1 and 1 to 100.

In order to generate the first part of the AAS indicator structure 1 and structure 2 signals, the following frequency domain training sequence is used

{p1 _i |i=-100:100}={0, 0, +1+j, 0, 0, 0, +1+j, 0, 0, 0, +1+j, 0, 0, 0, +1-j, 0, 0, 0, -1+j, 0, 0, 0, +1+j, 0, 0, 0, +1+j, 0, 0, 0, +1+j, 0 ,0,0,+1-j,0,0,0,-1+j,0,0,0,+1+j,0,0,0,+1+j,0,0,0,+ 1+j, 0, 0, 0, +1-j, 0, 0, 0, -1+j, 0, 0, 0, +1-j, 0, 0, 0, +1-j, 0, 0, 0, +1-j, 0, 0, 0, -1-j, 0, 0, 0, +1+j, 0, 0, 0, -1+j, 0, 0, 0, -1 +j, 0, 0, 0, -1+j, 0, 0, 0, +1+j, 0, 0, 0, -1-j, 0, 0, 0, +1+j, 0, 0 , 0, -1-j, 0, 0, 0, +1-j, 0, 0, 0, +1+j, 0, 0, 0, -1-j, 0, 0, 0, -1+ j, 0, 0, 0, +1-j, 0, 0, 0, +1+j, 0, 0, 0, -1+j, 0, 0, 0, +1-j, 0, 0, 0, -1-j, 0, 0, 0, +1+j, 0, 0, 0, -1+j, 0, 0, 0, -1-j, 0, 0, 0, +1+j ,0,0,0,+1-j,0,0,0,-1-j,0,0,0,+1-j,0,0,0,+1+j,0,0,0 , -1-j, 0, 0, 0, -1+j, 0, 0, 0, -1+j, 0, 0, 0, -1-j, 0, 0, 0, +1-j, 0,0,0,-1+j,0,0}*W

Only the values of i from -100 to 100 are given here, and those not given are zero, where W is a fixed value.

In order to generate the signal of the second part of AAS pointer structure one, the following frequency domain training sequence is used

{p2 _i |i=-100:100}={1,0,-1,0,-1,0,-1,0,1,0,1,0,1,0,1,0,-1 ,0,1,0,-1,0,-1,0,-1,0,1,0,-1,0,1,0,1,0,1,0,1,0,-1, 0,1,0,1,0,1,0,-1,0,1,0,-1,0,1,0,1,0,-1,0,-1,0,1,0, -1,0,1,0,-1,0,1,0,1,0,-1,0,1,0,1,0,-1,0,-1,0,-1,0, 1,0,-1,0,-1,0,-1,0,-1,0,-1,0,1,0,1,0,0,0,1,0,-1,0, -1,0,1,0,-1,0,1,0,1,0,1,0,1,0,-1,0,1,0,1,0,1,0,1,0 ,-1,0,1,0,-1,0,-1,0,-1,0,-1,0,1,0,1,0,-1,0,1,0,-1, 0, -1, 0, -1, 0, -1, 0, -1, 0, -1, 0, -1, 0, -1, 0, 1, 0, 1, 0, 1, 0, - 1,0,-1,0,-1,0,1,0,1,0,-1,0,-1,0,-1,0,1,0,-1,0,-1,0 ,1,0,-1,0,-1,0,-1}*W

Only the values of i from -100 to 100 are given here, and those not given are zero, where W is a fixed value.

In order to generate the signal of the second part of AAS indicator structure 2, the following frequency domain training sequence {p3 _i |i=-100:100}={0 -1 0 1 0 1 0 1 0 1 0 1 0 1 is used 0 -10 -1 0 1 0 -1 0 1 0 -1 0 1 0 1 0 1 0 -1 0 -10 1 0 -1 0 1 0 -1 0 -1 0 1 0 1 0 1 0 1 0 -10 -1 0 -1 0 1 0 1 0 1 0 1 0 -1 0 1 0 1 0 1 0-1 0 1 0 1 0 1 0 1 0 -1 0 -1 0 -1 0 -1 0 -1 0- 1 0 1 0 1 0 1 0 -1 0 -1 0 1 0 1 0 1 0 1 0 -1 0 -1 0 1 0 -1 0 1 0 1 0 1 0 1 0 -1 0 -1 01 0 1 0 -1 0 -1 0 1 0 -1 0 1 0 1 0 1 0 1 01 0 1 0 1 0 -1 0 1 0 -1 0 1 0 -1 0 -1 0 -1 0-1 0 -1 0 1 0 -1 0 -1 0 -1 0 -1 0 1 0 -1 0 1 01 0 -1 0}*W

Only the values of i from -100 to 100 are given here, and those not given are zero, where W is a fixed value.

According to the above-mentioned frequency domain training sequence, the sequence is BPSK modulated on the subcarrier of the corresponding subchannel. When it is realized, the average power can be adjusted appropriately according to the condition of the air channel or the power transmission requirement, that is, the value of W can be adjusted. The purpose of power boost or power voltage drop can be achieved. After IFFT, the corresponding AAS indicator is obtained.

The AAS indicator can be placed at any position behind the FCH in the downlink subframe, but a new DL-MAP unit is required to map its position. Corresponding to the 802.16 256 OFDM system mode and the HipermanOFDM mode, the present invention introduces a new DL-MAP unit as shown in Table 2. The unit's DUIC value is 15, while the extended DIUC value is one of 3 to 15. This ensures that other terminals communicating with the BS know the location of the AAS indicator by decoding the information, thereby skipping the service segment.

The present invention introduces an AAS indicator to indicate that the current system is an AAS system. In an AAS system combined with an AAS indicator, when an AAS terminal wants to initially access the system through an AAS alarm time slot, it must first capture the AAS indicator. Only in this way can we know that the current system is an AAS system and there is an AAS alarm time slot.

The AAS indicator not only indicates whether the current system is an AAS system, but also indicates whether there is an AAS alarm time slot in the current frame. When the AAS base station schedules resources, it must ensure that the AAS indicators are bundled together, that is, when there is an AAS indicator in the current downlink subframe, then there must be an AAS alarm time slot in the current uplink subframe, corresponding to 802.16 256 OFDM In system mode and Hiperman OFDM mode, the AAS alarm time slot is the last L OFDM symbols of the current uplink subframe. Otherwise, there is no AAS alarm time slot in the current uplink subframe.

In the AAS system combined with the AAS pointer, when the AAS terminal is turned on or restarted, it first needs to determine the start position of the frame through the access preamble at the beginning of the frame. If the terminal wants to access the system through the AAS alarm time slot, it searches the downlink subframe to see if there is an AAS indicator. After finding the AAS indicator, the terminal determines the position of the AAS alarm time slot defined in advance through the beginning of the current frame, and then performs initial access to the system in the AAS alarm time slot. The flow diagram is shown in Figure 9.

Based on the different methods of resource scheduling by AAS base stations, another common AAS indicator and AAS alarm time slot bundling scheme is that the AAS indicator of the current downlink subframe indicates that the nth (n greater than or equal to 0 ) from the uplink subframe to the mth (m greater than or equal to n) uplink subframe has an AAS alarm time slot. Corresponding to the 802.16 256 OFDM system mode and Hiperman OFDM mode, if there is an AAS indicator in the current downlink subframe, then from the nth (n greater than or equal to 0) uplink subframe counted from the current frame to the mth (m greater than or equal to n) The last L OFDM symbols of the uplink subframe are AAS alert time slots.

In the AAS system combined with the AAS pointer, when the AAS terminal is turned on or restarted, it first needs to determine the start position of the frame through the access preamble at the beginning of the frame. If the terminal wants to access the system through the AAS alert time slot, it searches the downlink subframe to see if there is an AAS indicator. When the AAS indicator is found, the terminal determines the pre-defined The location of the AAS alert slot, and then the initial access to the system is performed during the AAS alert slot.

[Table 1] DL-MAP unit format

syntax

length

note

DL-MAP format content () {

Downstream Fragmentation Usage Code (DIUC)

4 bits

if(DIUC==15)

Extended DIUC

variable length

Report_IE()_or AAS_DL_IE()_or STC_IE() or AAS_INDICATOR_IE()

otherwise

Starting time

12 bits

}

[Table 2] AAS Messenger Mapping Unit Format

syntax

length

note

AAS Messenger Unit() {

DIUC

4 bits

DIUC=15

Extended DIUC

4 bits

AAS indicator = A (A is greater than or equal to 3

and A is less than or equal to 15)

Starting time

12 bits

reserve}

4 bits

Claims (20)

1. the production method of new training symbol in the ofdm system, described orthogonal FDM communication system has N subcarrier, use therein subcarrier is L, every transmission frame-form comprises descending sub frame and sub-frame of uplink, the beginning of descending sub frame is an access lead, and described method comprises step:

In the base station, produce a kind of new training symbol;

Described training symbol transmits in descending sub frame, and described training symbol is controlled by Downlink Control Information at the transmission location of descending sub frame;

Described training symbol maps from present frame backward the n of number be random access time slot to the known location of m sub-frame of uplink.

2. by the described method of claim 1, it is characterized in that comprising step:

When subscriber access system, the access lead that at first will catch descending sub frame is determined the beginning of frame;

And then whether the searching downlink subframe exist described training symbol, if exist, this user just can be at the random access time slot connecting system of this training symbol maps so;

If there is no, whether access lead and this frame descending sub frame of search of catching next frame so exist described training symbol, find till the random access time slot by this training symbol maps always.

3. by the described method of claim 1, it is characterized in that a described carrier number N=256 subcarrier, label is-128 to 127.

4. by the described method of claim 1, it is characterized in that described training symbol comprises two parts, every part is made up of an OFDM symbol and Cyclic Prefix thereof.

5, by the described method of claim 4, it is characterized in that described OFDM symbol is by inserting frequency domain training sequence on the subcarrier that uses, carrying out inverse-Fourier transform and generate

6. by the described method of claim 4, it is characterized in that described training symbol divides two parts, first is made of a Cyclic Prefix and an OFDM symbol, this OFDM is made of four subdivisions, wherein first is identical with the 3rd subdivision, second is identical with the 4th subdivision and be the contrary sign of the first and the 3rd subdivision, and second portion is to be made of a Cyclic Prefix and an OFDM symbol, and this OFDM is made of two identical repeating parts.

7. by the described method of claim 5, it is characterized in that label for [100 ..., 100] subcarrier on insert frequency domain training sequence { p1 accordingly _i| i=-100: 100} carries out the OFDM symbol and the first of its Cyclic Prefix as this indicating device that inverse-Fourier transform obtains

{ p1 wherein _i| i=-100: 100} is as follows:

{0，0，+1+j，0，0，0，+1+j，0，0，0，+1+j，0，0，0，+1-j，0，0，0，-1+j，0，0，0，+1+j，0，0，0，+1+j，0，0，0，+1+j，0，0，0，+1-j，0，0，0，-1+j，0，0，0，+1+j，0，0，0，+1+j，0，0，0，+1+j，0，0，0，+1-j，0，0，0，-1+j，0，0，0，+1-j，0，0，0，+1-j，0，0，0，+1-j，0，0，0，-1-j，0，0，0，+1+j，0，0，0，-1+j，0，0，0，-1+j，0，0，0，-1+j，0，0，0，+1+j，0，0，0，-1-j，0，0，0，+1+j，0，0，0，-1-j，0，0，0，+1-j，0，0，0，+1+j，0，0，0，-1-j，0，0，0，-1+j，0，0，0，+1-j，0，0，0，+1+j，0，0，0，-1+j，0，0，0，+1-j，0，0，0，-1-j，0，0，0，+1+j，0，0，0，-1+j，0，0，0，-1-j，0，0，0，+1+j，0，0，0，+1-j，0，0，0，-1-j，0，0，0，+1-j，0，0，0，+1+j，0，0，0，-1-j，0，0，0，-1+j，0，0，0，-1+j，0，0，0，-1-j，0，0，0，+1-j，0，0，0，-1+j，0，0}*W

W is a fixed numeric values,

At label be [100 ..., 100] subcarrier on insert frequency domain training sequence { p2 accordingly _i| i=-100: 100} carries out the OFDM symbol and the second portion of its Cyclic Prefix as this indicating device that inverse-Fourier transform obtains

{ p2 wherein _i| i=-100: 100} is as follows:

{1，0，-1，0，-1，0，-1，0，1，0，1，0，1，0，1，0，-1，0，1，0，-1，0，-1，0，-1，0，1，0，-1，0，1，0，1，0，1，0，1，0，-1，0，1，0，1，0，1，0，-1，0，1，0，-1，0，1，0，1，0，-1，0，-1，0，1，0，-1，0，1，0，-1，0，1，0，1，0，-1，0，1，0，1，0，-1，0，-1，0，-1，0，1，0，-1，0，-1，0，-1，0，-1，0，-1，0，1，0，1，0，0，0，1，0，-1，0，-1，0，1，0，-1，0，1，0，1，0，1，0，1，0，-1，0，1，0，1，0，1，0，1，0，-1，0，1，0，-1，0，-1，0，-1，0，-1，0，1，0，1，0，-1，0，1，0，-1，0，-1，0，-1，0，-1，0，-1，0，-1，0，-1，0，-1，0，1，0，1，0，1，0，-1，0，-1，0，-1，0，1，0，1，0，-1，0，-1，0，-1，0，1，0，-1，0，-1，0，1，0，-1，0，-1，0，-1}*W

W is a fixed numeric values.

8. by the described method of claim 4, it is characterized in that training symbol divides two parts, first is made of a Cyclic Prefix and an OFDM symbol, this OFDM is made of four subdivisions, wherein first is identical with the 3rd subdivision, second is identical with the 4th subdivision and be the contrary sign of the first and the 3rd subdivision, and second portion is to be made of a Cyclic Prefix and an OFDM symbol, and this OFDM is made of two opposite repeating parts.

9: by the described method of claim 5, it is characterized in that label for [100 ..., 100] subcarrier on insert frequency domain training sequence { p1 accordingly _i| i=-100: 100} carries out the OFDM symbol and the first of its Cyclic Prefix as this indicating device that inverse-Fourier transform obtains

{ p1 wherein _i| i=-100: 100} is as follows:

{0，0，+1+j，0，0，0，+1+j，0，0，0，+1+j，0，0，0，+1-j，0，0，0，-1+j，0，0，0，+1+j，0，0，0，+1+j，0，0，0，+1+j，0，0，0，+1-j，0，0，0，-1+j，0，0，0，+1+j，0，0，0，+1+j，0，0，0，+1+j，0，0，0，+1-j，0，0，0，-1+j，0，0，0，+1-j，0，0，0，+1-j，0，0，0，+1-j，0，0，0，-1-j，0，0，0，+1+j，0，0，0，-1+j，0，0，0，-1+j，0，0，0，-1+j，0，0，0，+1+j，0，0，0，-1-j，0，0，0，+1+j，0，0，0，-1-j，0，0，0，+1-j，0，0，0，+1+j，0，0，0，-1-j，0，0，0，-1+j，0，0，0，+1-j，0，0，0，+1+j，0，0，0，-1+j，0，0，0，+1-j，0，0，0，-1-j，0，0，0，+1+j，0，0，0，-1+j，0，0，0，-1-j，0，0，0，+1+j，0，0，0，+1-j，0，0，0，-1-j，0，0，0，+1-j，0，0，0，+1+j，0，0，0，-1-j，0，0，0，-1+j，0，0，0，-1+j，0，0，0，-1-j，0，0，0，+1-j，0，0，0，-1+j，0，0}*W

W is a fixed numeric values,

This device will be at label [100 ..., 100] subcarrier on insert frequency domain training sequence { p3 accordingly _i| i=-100: 100} carries out the OFDM symbol and the second portion of its Cyclic Prefix as this indicating device that inverse-Fourier transform obtains

{ p3 wherein _i|i＝-100∶100}：{0-1 0 1 0 1 0 1 0 1 0 1 0 1 0-10-1 0 1 0-1 0 1 0-1 0 1 0 1 0 10-1 0-1 0 1 0-1 0 1 0-1 0-1 0 10 1 0 1 0 1 0-1 0-1 0-1 0 1 0 10 1 0 1 0-1 0 1 0 1 0 1 0-1 0 10 1 0 1 0 1 0-1 0-1 0-1 0-1 0-10-1 0 1 0 1 0 1 0-1 0-1 0 1 0 10 1 0 1 0-1 0-1 0 1 0-1 0 1 0 10 1 0 1 0-1 0-1 0 1 0 1 0-1 0-10 1 0-1 0 1 0 1 0 1 0 1 0 1 0 10 1 0-1 0 1 0-1 0 1 0-1 0-1 0-10-1 0-1 0 1 0-1 0-1 0-1 0-1 0 10-1 0 1 0 1 0-1 0}*W。

W is a fixed numeric values.

10. the transmission method of new training symbol in the ofdm system, described orthogonal FDM communication system has N subcarrier, and use therein subcarrier is L, and every transmission frame-form comprises descending sub frame and sub-frame of uplink, and described method comprises step:

Training symbol transmits at descending sub frame, and the position of described training symbol in descending sub frame controlled by the frame control head in the descending sub frame.

11., it is characterized in that in frame control head that described training symbol is as shown in table 1 in the control information of descending sub frame transmission by the described method of claim 10, it is 15 that code value is used in descending segmentation wherein, has used expansion DIUC to come this training symbol of mark simultaneously.

12., it is characterized in that in frame control head that training symbol is as shown in table 2 in the control information of descending sub frame transmission by the described method of claim 11, the value of expansion DIUC is from 3 to 15.

13., it is characterized in that in frame control head that training symbol is as shown in table 2 in the control information of descending sub frame transmission by the described method of claim 12, the value of expansion DIUC is 3.

14., it is characterized in that the adaptive antenna system alarm slot transmission of described training symbol binding sub-frame of uplink by the described method of claim 10.

15., it is characterized in that described training symbol indication adaptive antenna system alarm time slot occurs to the known location of m sub-frame of uplink at the n that counts from present frame backward by the described method of claim 14.

16. by the described method of claim 15, it is characterized in that described training symbol indication from present frame backward the n of number be adaptive antenna system alarm time slot to last L OFDM symbol of m sub-frame of uplink.

17. by the described method of claim 16, it is characterized in that the indication of adaptive antenna system indicating device from present frame backward the n of number be adaptive antenna system alarm time slot to last 5 OFDM symbols of m sub-frame of uplink.

18., it is characterized in that described training symbol indication adaptive antenna system alarm time slot occurs in the known location of current sub-frame of uplink by the described method of claim 14.

19., it is characterized in that described training symbol indication adaptive antenna system alarm time slot is a last L OFDM symbol of current sub-frame of uplink by the described method of claim 18.

20., it is characterized in that described training symbol indication adaptive antenna system alarm time slot is last 5 OFDM symbols of current sub-frame of uplink by the described method of claim 19.

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