WO2008017266A1

WO2008017266A1 - A communication method in time division duplex mode and apparatus thereof

Info

Publication number: WO2008017266A1
Application number: PCT/CN2007/070377
Authority: WO
Inventors: Weijun Sun; Yongxia Lv
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-08-04
Filing date: 2007-07-30
Publication date: 2008-02-14
Also published as: CN101119154A; CN101119154B

Abstract

A communication method in TDD mode and apparatus thereof are provided. The said method, during transmitting a sub-frame, includes the steps: the upstream time slot is transmitted right after the guard period; the upstream pilot time slot is transmitted before the switch time point from upstream to downstream. The present invention can coexist with TD-SCDMA system, and change the communication coverage area.

Description

Communication method and device in time division duplex mode

This application claims priority to Chinese Patent Application No. 200610103871.1, entitled "Communication Method and Apparatus in Time Division Duplex Mode", filed on August 4, 2006, the entire contents of which are incorporated by reference. In this application.

Technical field

The present invention relates to a wireless communication method and apparatus thereof, and more particularly to a communication method and apparatus in a Time Division Duplex (TDD) mode.

Background technique

In the field of communication, the TDD communication mode is a mode for wireless transmission in a wireless channel, which is realized by periodically repeating a Time Division-Synchronous Code Division Multiple Access (TDMA) frame structure in the time domain. In TDD mode, data transmission and reception are performed in a time-sharing manner, that is, the uplink and downlink channels can be time-division multiplexed and can operate on a frequency band without an image frequency.

Referring to FIG. 1 , it is a schematic diagram of a frame structure of a TDD system proposed by the prior art in the 3rd Generation Partnership Project (3GPP, 3rd Generation Partnership Project) TR25.814 protocol. The frame structure coexists with a Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) system and uses a 10 ms radio frame structure, including two identical 5 ms subframes. In each 5 ms subframe, including 4 downlink slots 0, 4, 5, 6, 3 uplink slots 1, 2, 3, 1 downlink to uplink transition point 103, 1 uplink to downlink transition point 106, 1 downlink pilot time slot 102, 1 uplink pilot time slot 105, and a guard interval (GP, Guard Period) 104. There is a slot interval 101 between each of the upper and lower time slots. The downlink-to-uplink switching point 103 is set between the downlink transition to the uplink, that is, between the downlink slot 0 and the uplink slot 1, specifically between the downlink pilot slot 102 and the guard interval 104. . The uplink to downlink switching point 106 is disposed between the upstream time slot 3 and the downlink time slot 4.

The downlink pilot time slot 102 is followed by the downlink time slot 0, and is followed by the time slot interval 101 for transmitting downlink synchronization information. The uplink pilot time slot 105 is located between the guard interval 104 and the uplink time slot 1 for transmitting a random access sequence of the user, that is, transmitting a random access request of the user to implement the user access to the communication network. The information transmitted by the uplink pilot time slot 105 is very important, and directly affects whether the user can access the network to enjoy the service, so ensuring accurate transmission of the information is before the wireless communication network works normally. Raise. Downlink and/or upstream time slots are used to transmit other data information. The guard interval 104 following the downlink pilot time slot 102 is used to provide a guard interval for the downlink transmission to the uplink transmission transition.

In the figure, after the downlink time slot 0 is completed, it goes to the uplink after going down to the uplink switching point 103. After the uplink time slots 1 to 3 are completed, the uplink to downlink switching point 106 is turned to the downlink. The guard interval 104 is followed by the uplink pilot slot 105. The prior art utilizes the uplink pilot slot 105 and the slot 1 following it to transmit the user random access request.

In TDD wireless network transmission, the guard interval required for downlink to uplink handover is related to the range of cell coverage. The larger the cell radius requires the longer the guard interval between the downlink and the uplink handover. However, the length of the guard interval described in the prior art is fixed, and thus the cell radius that can be applied is limited. If the communication is performed according to the frame structure of the prior art in a cell with a large cell radius, the uplink and downlink signal interference may be caused, thereby affecting the subsequent uplink time slot. When carrying the important information transmission in the uplink time slot, Loss of information, resulting in communication failure.

For example, in TD-SCDMA, the guard interval is 75 μ _δ , and the theoretical maximum supported cell radius is 11.25 km.

The specific calculation formula of the maximum supportable cell radius is as follows:

7? = cxr _G /2 = 3xl0 ⁸ x75xl0" ⁶ /2 = 11.25^2 where R is the cell radius, c is the speed of light, and T _G p is the guard interval.

In the 3GPP TR25.913 protocol, the cell radius is required to support 30 km, and the application scenario of 100 km is not excluded. Obviously, the frame structure in the above prior art FIG. 1 cannot satisfy this requirement.

Summary of the invention

The present invention provides a communication method in a time division duplex mode that coexists with a TD-SCDMA system and can make communication coverage variable.

The present invention also provides a communication apparatus in a time division duplex mode that coexists with a TD-SCDMA system and can make communication coverage variable.

The present invention is implemented by the following technical solutions: Providing a communication method in a time division duplex mode, the method includes the steps of: transmitting an uplink time slot immediately after the guard interval; transmitting before the uplink to downlink switching point when transmitting one subframe Uplink pilot time slot. A communication device in a time division duplex mode, comprising a subframe generation module, configured to generate an uplink time slot immediately following a guard interval, and generate an uplink pilot time slot before an uplink to a downlink handover point.

As can be seen from the above first technical solution, since the present invention adjusts the position of the uplink pilot time slot in the time division duplex subframe, it is located after the uplink time slot 1 and before the uplink to the downlink switching point, thereby "distance" the guard interval. . Thus, when the present invention is applied to a cell requiring a larger guard interval in a time division duplex subframe, since the uplink pilot slot is "away, the guard interval, the increased cell radius does not cause an uplink guide after receiving the adjustment position. The problem of frequency time slots, in turn, achieves a technical effect of making the normal communication coverage of the time division duplex mode larger in coexistence with the TD-SCDMA system.

As shown in the foregoing second technical solution, the subframe generation module of the present invention adjusts the position of the uplink pilot time slot in the time division duplex subframe, so that it is located after the uplink time slot 1 and before the uplink to the downlink switching point. Thus "away from" the guard interval. Thus, when the present invention is applied to a cell requiring a larger guard interval in a time division duplex subframe, since the uplink pilot slot is "away from" the guard interval, the increased cell radius does not cause an uplink pilot that is difficult to receive the adjusted position. The problem of time slots, in turn, achieves a technical effect of making the normal communication coverage of the time division duplex mode larger in coexistence with the TD-SCDMA system.

DRAWINGS

1 is a schematic structural diagram of a prior art time division duplex sub-frame;

2 is a flowchart of a first embodiment of a communication method in a time division duplex mode according to the present invention; FIG. 3 is a schematic diagram of a first embodiment of a time division duplex subframe structure used in the present invention;

4 is a schematic diagram of vacating the first two OFDM symbols of an OFDM in an uplink slot in FIG. 3; FIG. 5 is a schematic diagram of a second embodiment of a time division duplex subframe structure used in the present invention;

6 is a schematic diagram of a third embodiment of a time division duplex sub-frame structure used in the present invention;

Figure 7 is a block diagram showing the principle of a communication system in the time division duplex mode of the present invention. detailed description

In the TDD mode, in order to realize the coexistence with the TD-SCDMA system and enable the communication to cover a larger range of cells, adjust the position of the uplink pilot time slot in the TDD subframe, which plays a key role in realizing the transmission data in the TDD mode, so that It is "away from" the guard interval. Based on the above spirit, the present invention has been given a plurality of embodiments. The present invention will be described in detail below with reference to the embodiments and the accompanying drawings.

Referring to FIG. 2 and FIG. 3, respectively, the first embodiment of the communication method in the TDD mode of the present invention A schematic diagram of a flowchart and a subframe structure, and a prior art subframe structure (b in Fig. 3) is compared with the subframe structure of the present invention (a in Fig. 3). The method includes the following steps:

Step 201, when transmitting a subframe, first transmitting a downlink time slot 0 in the wireless subframe;

Step 202, transmitting a downlink pilot time slot 302 after the time slot interval 301;

Step 203, after the downlink to the uplink switching point 308, the downlink transmission is changed to the uplink transmission, and immediately after the guard interval 304, the uplink time slot 1 is transmitted;

This step is to transmit the uplink pilot time slot 305 and the uplink time slot 1 immediately after the guard interval 104 is transmitted, and the uplink pilot time slot 305 is not transmitted first, but is followed by the guard interval 304. After the uplink time slot 1 is transmitted. The guard interval 304 is used to provide a guard interval for downlink transmission to uplink transmission transitions.

Step 204, transmitting an uplink pilot time slot 305 after transmitting the uplink time slot 1;

In this step, the uplink pilot time slot 305 is scheduled to be transmitted after the uplink time slot 1, so that the uplink pilot time slot 305 is transmitted away from the guard interval 304 and later. The uplink pilot time slot 305 contains important user random access information. In order to satisfy the above downlink to uplink protection slot requirements, the preamble pilot frame 307 (see FIG. 4) in the uplink slot 1 may be close to the first two orthogonal frequency division multiplexing (OFDM, Orthogonal Frequency Division) of the guard interval 304. The multiplex symbol period is vacant, and as an extended downlink to uplink guard slot, an extended guard interval is formed, which is larger than the guard interval 304.

Step 205, transmitting uplink time slots 2 and 3;

Step 206, transmitting downlink time slots 4 to 6 after the uplink to downlink switching point 306;

By looping through the above steps, wireless data communication in TDD mode can be realized.

It can be seen from the dotted line in FIG. 3 that the subframe structure a transmitted by the present invention is compared with the subframe structure b of the existing TD-SCDMA system, and can ensure the same uplink and downlink transmission time, thereby realizing coexistence with the TD-SCDMA system. .

A specific example is given below to illustrate the method in more detail:

For example, to satisfy a wireless cell with a cell radius of 30 km, the present invention can use the subframe structure shown in a of FIG. 3, that is, the uplink pilot time slot 305 is placed after the uplink transmission time slot 1. In order to meet the requirement of a cell radius of 30 km, the downlink to uplink guard interval required by the system is: T _GP = 2W / c = 200|L Referring to FIG. 4, in order to satisfy the above-mentioned downlink to uplink protection slot requirement, the two OFDM symbol periods in which the preamble pilot frame 307 in the uplink slot 1 is close to the guard interval 304 are vacant. And as an extended downlink to uplink protection slot, an extended guard interval is formed.

The preamble pilot frame 307 is composed of 8 OFDM symbols, numbered 0 to 7, and is used for transmitting: F-CPICH (Forward Common Pilot Channel), F-pBCH0 (Forward Primary Broadcast Channel) 0, forward primary broadcast channel 0), F-pBCH1 (forward primary broadcast channel 1), F-ACQCH (forward acquisition channel), and F-OSICH (Forward Other Sector Interference) Channel, forward to other shoulder zone interference channel).

Table 1 below reveals the case where the channel specified in the IEEE 802.20 protocol draft published on January 6, 2006 occupies OFDM symbols.

Table 1 Distribution of channels in preamble pilot frames in 802.20 protocol

"" in Table 1 indicates that the channel occupies part or all of the time-frequency resources in the OFDM symbol, and the unfilled indicates that it is not occupied. For example, the 0th and 1st OFDM symbols contain subcarriers occupied by the F-CPICH, and the 2nd to 7th OFDM symbols do not include the subcarriers occupied by the F-CPICH.

The foregoing two OFDM symbol time periods preceding the preamble pilot frame 307 in the uplink time slot 1 are vacant. That is, the 0th and 1st OFDM symbols are vacant. The 0th and 1st OFDM symbols do not contain subcarriers occupied by F-CPICH, F-pBCHO, and F-pBCH1. Therefore, the preamble pilot frame 307 in the upstream slot 1 is modified as shown in the following table:

Table 2 Distribution of channels in preamble pilot frames in the present invention

According to the parameters of TR25.814, if a short cyclic prefix (CP, Cyclic Prefix) is used, an OFDM (Orthogonal Frequency Division Multiplexing) length is 71.36 μ _δ . If vacant 2 OFDM symbols are considered and the guard slots in the subframe are considered, the downlink to uplink guard time that can be provided at this time is:

71.36μ?χ2 + 75μ? = 217.72μ? > 200μ?

The above subframe structure can flexibly meet the requirements of implementing TDD communication in a cell with an arbitrary cell radius below 30 km. Since the subframe structure of the present invention is the same as the uplink and downlink transmission time of the TDS-CDMA system, the subframe provided by the embodiment of the present invention can coexist with the TDS-CDMA system.

As can be seen from the above, the present invention adjusts the position of the uplink pilot time slot in the TDD subframe so that it is located after the uplink time slot 1 and before the uplink to the downlink switching point, thereby "away from" the guard interval. In this way, when the present invention is applied to a cell requiring a larger guard interval in a TDD subframe, since the uplink pilot slot is far away from the "guard interval, the increased cell radius does not cause difficulty in receiving the uplink pilot slot after the adjustment position. The problem, in turn, achieves a technical effect of making the normal communication coverage of the TDD mode larger in coexistence with the TD-SCDMA system. The OFDM symbol in the uplink time slot 1 is vacant, which provides a flexible and effective technical means for actually increasing the guard interval. Adjusting the number of vacant OFDM symbols is not limited to vacating two OFDM symbols, which is equivalent to adjusting the length of the guard interval, thereby implementing TDD communication within different cell radii as required. The formula for calculating the number of vacant OFDM symbols/length T is: At least the value obtained by subtracting 75 microseconds from the cell diameter and the speed of light, ie:

r≥2R/c _ 75^

In other embodiments of the present invention, the uplink pilot time slot may be transmitted after the uplink time slot 1 and before the uplink to downlink switching point. For example, referring to FIG. 5 and FIG. 6, respectively, transmitting the uplink pilot time slots 505, 605 after the second and third uplink time slots (upper time slots 2, 3) respectively, a technical effect similar to that of the first embodiment described above can be obtained.

The present invention can also use a long cyclic prefix according to the parameter of TR25.814, and then an orthogonal frequency division multiplexing length is 83.34 μ _δ. If two OFDM symbols are considered to be vacant, and the guard slot in the subframe is considered, then The downlink to uplink protection time that can be provided is:

83.34μ?χ2 + 75μ? = 241.68μ? > 200μs

It can meet the communication requirements of cells within a radius of more than 30 km.

Referring to FIG. 7, the present invention further provides a communication device 700 in a TDD mode, where the device 700 includes a subframe generation module 710, a transmitting module 720, and an antenna 730, and the subframe generation module 710 includes an uplink slot vacant module 711. . The subframe generation module 710 is configured to generate an uplink slot immediately after the guard interval, and generate an uplink pilot slot before the uplink to the downlink handover point.

Referring to Figures 3, 5, 6, the subframe generation module 710 can generate an uplink pilot time slot after the first, second or third uplink time slots.

The uplink slot vacancy module 711 is configured to generate a vacant uplink slot immediately before the uplink pilot slot and immediately after the guard interval. In a specific implementation, the uplink slot vacancy module 711 vacates the preceding OFDM symbol period in the first uplink slot.

The subframe generation module 710 generates the subframe of the above structure and transmits it to the transmitting module 720, and transmits it through the antenna 730, and uses the subframe to perform wireless communication in the TDD mode on the network side and the user.

As can be seen from the above, the subframe modulating module 710 of the present invention adjusts the position of the uplink pilot time slot in the TDD subframe so that it is located after the uplink time slot 1 and before the uplink to the downlink switching point, thereby "distance" protection. interval. Thus, when the present invention is applied to a cell requiring a larger guard interval in a TDD subframe, Since the uplink pilot time slot is "far away, the guard interval, the increased cell radius does not cause the problem of difficulty in receiving the uplink pilot time slot after adjusting the position, thereby realizing the normal communication of the TDD mode in coexistence with the TD-SCDMA system. Greater technical coverage.

The OFDM symbol in the uplink time slot 1 is vacant by the uplink time slot vacant module 711, which provides a flexible and effective technical means for actually increasing the guard interval. Adjusting the number of vacant OFDM symbols is not limited to vacating two OFDM symbols, which is equal to adjusting the length of the guard interval, thereby implementing TDD communication within different cell radii.

The foregoing detailed description of the communication method and apparatus in the TDD mode provided by the present invention is only for helping to understand the method of the present invention and its core idea; meanwhile, for those skilled in the art, according to the present invention The present invention is not limited by the scope of the present invention.

Claims

Rights request

A communication method in a time division duplex mode, characterized in that the method includes the following steps when transmitting one subframe:

Transmitting an uplink time slot immediately following the guard interval;

The uplink pilot time slot is transmitted before the uplink to downlink switching point.

The communication method in the time division duplex mode according to claim 1, wherein the step of transmitting the uplink pilot time slot before the uplink to downlink switching point is specifically: in the first, second or The uplink pilot time slot is transmitted after three uplink time slots.

The communication method in the time division duplex mode according to claim 1 or 2, wherein the uplink time slot includes a vacant time period.

The communication method in the time division duplex mode according to claim 3, wherein the vacant time period is located in a time division period of the orthogonal frequency division multiplexing symbol near the guard interval in the first uplink time slot.

The communication method in the time division duplex mode according to claim 4, wherein the length of the vacant portion of the uplink slot is greater than or equal to a difference between a downlink-to-uplink guard interval required by the system and the guard interval.

The communication method in the time division duplex mode according to claim 5, wherein the downlink to uplink guard interval required by the system is a quotient of a cell diameter and an optical speed, and the guard interval is 75 microseconds.

7. A communication device in a time division duplex mode, comprising: a subframe generation module, configured to generate an uplink time slot immediately after a guard interval, and generate an uplink pilot time slot before an uplink to a downlink handover point .

The communication device in the time division duplex mode according to claim 7, wherein the subframe generation module specifically generates an uplink pilot time slot after the first, second or third uplink time slot.

The communication device in the time division duplex mode according to claim 7 or 8, wherein the subframe generation module further includes an uplink time slot vacant module, which is used before the uplink pilot time slot. A vacant upstream time slot is generated following the guard interval.

The communication device in the time division duplex mode according to claim 7 or 8, wherein the generating the vacant uplink time slot specifically refers to: Orthogonal frequency of the first uplink time slot close to the guard interval The sub-multiplex symbol period is vacant.