CN101227727A - Method and device for sending random access signal in TDD mode of LTE system - Google Patents

Abstract

The present invention provides a method and device for sending random access signals in the TDD mode of the LTE system. The method includes the following steps: obtaining the maximum allowable value Tud_max of the uplink to downlink conversion time in the TDD mode of the LTE system; judging whether Tud_max is greater than the first A predetermined value; and if Tud_max is not greater than the first predetermined value, the fourth type of structure of the RACH is set to be sent at the second predetermined value ahead of the UpPTS end position; if Tud_max is greater than the first predetermined value, then the fourth type of structure is set at the UpPTS The end position is sent ahead by a third predetermined value. The invention effectively improves the coverage of the random access channel and the working efficiency of the TDD system.

Description

Method and device for sending random access signal in TDD mode of LTE system

technical field

The present invention relates to the field of communications, in particular, to a method and device for sending random access signals in an LTE (Long Term Evolution, Long Term Evolution) system TDD (Time Division Duplex, Time Division Duplex) mode.

Background technique

Figure 1 shows the frame structure of the TDD mode of the LTE system. In this frame structure, a 10ms radio frame (wireless frame) is divided into two half frames (half frames), and each half frame is divided into 10 frames with a length of 0.5 ms time slots (numbered from 0 to 9), two time slots form a subframe with a length of 1 ms. One field contains 5 subframes (numbered from 0 to 4). For short CP (Cyclic Prefix, cyclic prefix) with a length of 5.21us and 4.69us, a time slot contains 7 symbols with a length of 66.7us, of which the length of the first symbol CP is 5.21us, and the CP length of the remaining 6 symbols It is 4.69us; for a long CP with a length of 16.67us, one time slot contains 6 symbols. In this frame structure, the configuration characteristics of the subframe are:

(1) Subframe 0 is fixed for downlink;

(2) Subframe 1 (hereinafter referred to as special subframe) contains 3 special time slots, which are DwPTS (Downlink Pilot Time Slot, downlink pilot time slot), GP (GuardPeriod, guard interval) UpPTS (Uplink Pilot Time Slot) , uplink pilot slot), where:

①DwPTS is used for downlink, and at least one symbol is used to transmit P-SCH (Primary-Synchronization Channel, primary synchronization channel). When DwPTS contains multiple symbols, P-SCH is placed on the first symbol (as shown in Figure 1 );

②GP is a guard time and does not transmit any data; and

③ UpPTS is used for uplink, and can be used to transmit RACH (Random Access Channel, random access channel), data, sounding (detection) pilot and other signals; and

(3) The first n subframes following subframe 1 are used for uplink transmission (1≤n≤3), and the last 3-n subframes are used for downlink transmission.

As shown in FIG. 2 , the RACH is composed of CP and preamble (preamble), and the lengths are Tcp and Tpre respectively. In addition, the distance between the end position of the preamble and the end position of the UpPTS is Tgt (as shown in FIG. 1 ), which ensures that the preamble will not interfere with the data of the subsequent uplink subframe. At the same time, CP is added in front of the preamble to ensure that the random access signal and its multipath of the UE (user equipment) at the cell boundary also fall within the search window of the receiver.

Fig. 3 shows a schematic diagram of the structure of the fourth type of RACH only used in the TDD mode of the LTE system. The current agreement stipulates that the fourth type of structure of RACH (format 4 is only used in the TDD mode of LTE, and format 0, 1, 2, and 3 can be used in both FDD (Frequence Division Duplex, frequency division duplex) and TDD mode. The Tcp length of middle) is 448Ts (Ts=1/30.72us), the Tpre length is 4096Ts, and the Tgt length is 288Ts. And the sending position is sent at the time when the UpPTS end position is 4832Ts ahead of the end position.

In the process of realizing the present invention, the inventor finds that because the LTE TDD mode generates the transition time from uplink to downlink by sending the uplink subframe in advance, it is assumed that the advance of the uplink subframe is Tud=max(Tud_nb, Tud_ue), where Tud_nb is the base station The conversion time experienced by the sender from uplink reception to downlink, Tud_ue is the time elapsed by the mobile phone from uplink transmission to downlink reception, if Tud is greater than Tgt (288Ts), the advanced uplink subframe will fall into the search window of RACH It will cause interference to RACH.

Contents of the invention

The present invention aims to provide a method and system for sending random access signals in the TDD mode of the LTE system, so as to solve the problem in the prior art that the improper setting of advanced uplink subframes interferes with RACH.

In an embodiment of the present invention, a method for sending a random access signal in the TDD mode of the LTE system is provided, comprising the following steps: obtaining the maximum allowable value Tud_max of the uplink to downlink conversion time of the TDD mode of the LTE system; judging Tud_max Whether it is greater than the first predetermined value; and if Tud_max is not greater than the first predetermined value, the fourth type of structure of RACH is set to be sent at the second predetermined value ahead of the UpPTS end position; if Tud_max is greater than the first predetermined value, then the fourth type is set The structure is sent a third predetermined value ahead of the UpPTS end position.

Preferably, the first predetermined value is 288Ts.

Preferably, the second predetermined value is 4832Ts.

Preferably, the third predetermined value is D+4832Ts, where D=Tud-288Ts.

Preferably, Tud_max=max(Tud_nb_max, Tud_ue_max), where Tud_nb_max is the maximum time that the base station allowed by the TDD mode of the LTE system from the end of the uplink reception to the start of the downlink transmission, Tud_ue_max is the mobile phone allowed by the TDD mode of the LTE system from the uplink The maximum time elapsed from the end of sending to the start of downlink receiving.

In an embodiment of the present invention, a device for sending a random access signal in the TDD mode of the LTE system is also provided, including: an acquisition module configured to acquire the maximum allowable value of the uplink-to-downlink conversion time of the TDD mode of the LTE system Tud_max; judging module, for judging whether Tud_max is greater than the first predetermined value; and setting module, for if Tud_max is not greater than the first predetermined value, then setting the fourth type structure of RACH to be sent at the second predetermined value ahead of the UpPTS end position ; If Tud_max is greater than the first predetermined value, set the fourth type of structure to be sent at the place where the UpPTS end position is ahead of the third predetermined value.

Preferably, the first predetermined value is 288Ts.

Preferably, the second predetermined value is 4832Ts.

Preferably, the third predetermined value is D+4832Ts, wherein D=Tud_max-288Ts, and Tud_max is the maximum allowable value of the transition time from uplink to downlink in the preset LTE system TDD mode.

Preferably, Tud_max=max(Tud_nb_max, Tud_ue_max), where Tud_nb_max is the maximum time that the base station allowed by the TDD mode of the LTE system from the end of the uplink reception to the start of the downlink transmission, Tud_ue_max is the mobile phone allowed by the TDD mode of the LTE system from the uplink The maximum time elapsed from the end of sending to the start of downlink receiving.

The method and system for sending random access signals in the TDD mode of the LTE system provided by the embodiments of the present invention overcome the above-mentioned problems because of the method of judging whether Tud is greater than a predetermined value under the consideration of the reserved amount of uplink and downlink time slot conversion. In the prior art, the improper setting of the advanced uplink subframe causes interference to the RACH, thereby effectively improving the coverage of the random access channel and the working efficiency of the TDD system.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention and constitute a part of the application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 shows the frame structure of LTE system TDD mode;

Figure 2 shows a schematic diagram of the RACH structure;

Fig. 3 shows a schematic diagram of the structure of the fourth type of RACH only used in the TDD mode of the LTE system;

FIG. 4 shows a flow chart of a method for sending a random access signal in a TDD mode of an LTE system according to an embodiment of the present invention;

Fig. 5 shows a block diagram of an apparatus for sending a random access signal in TDD mode of an LTE system according to an embodiment of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

In order to solve the above technical problems, the present invention provides a method for sending a random access signal in a wireless communication system. FIG. 4 shows a flowchart of a method for sending a random access signal in the TDD mode of an LTE system according to an embodiment of the present invention , including the following steps:

Step S10, obtaining the maximum allowable value Tud_max of the uplink to downlink conversion time of the TDD mode of the LTE system;

Step S20, judging whether Tud_max is greater than a first predetermined value; and

Step S30, if Tud_max is not greater than the first predetermined value, then set the fourth type of structure of RACH to be sent at the end position of UpPTS ahead of the second predetermined value; if Tud_max is greater than the first predetermined value, then set the fourth type of structure at the end position of UpPTS Sent at the third predetermined value in advance.

The method and system for sending random access signals in the TDD mode of the LTE system provided by the embodiments of the present invention use the method of judging whether Tud_max is greater than a predetermined value, so it overcomes the improper setting of the advanced uplink subframe in the above-mentioned prior art. The problem of interference is generated, and then the effect of anti-interference on the RACH is achieved.

Preferably, the method for sending random access signals in the TDD mode of the LTE system provided by the embodiments of the present invention includes: the first predetermined value is 288Ts; the second predetermined value is 4832Ts; the third predetermined value is D+4832Ts, where D= Tud_max-288Ts.

Preferably, Tud_max=max(Tud_nb_max, Tud_ue_max), where Tud_nb_max is the maximum time that the base station allowed by the TDD mode of the LTE system from the end of the uplink reception to the start of the downlink transmission, Tud_ue_max is the mobile phone allowed by the TDD mode of the LTE system from the uplink The maximum time elapsed from the end of sending to the start of downlink receiving. The value range of Tud_max may be 215Ts-2560Ts.

FIG. 5 shows a block diagram of an apparatus for sending a random access signal in TDD mode of an LTE system according to an embodiment of the present invention, including:

The obtaining module is used to obtain the maximum allowable value Tud_max of the uplink to downlink conversion time of the LTE system TDD mode;

A judging module, configured to judge whether Tud_max is greater than a first predetermined value; and

Setting module, for if Tud_max is not greater than the first predetermined value, then set the fourth type of structure of RACH to send at the position where the UpPTS end position is ahead of the second predetermined value; if Tud_max is greater than the first predetermined value, then set the fourth type of structure Sent when the UpPTS end position is advanced by a third predetermined value.

The method and system for sending random access signals in the TDD mode of the LTE system provided by the embodiments of the present invention use the method of judging whether Tud_max is greater than a predetermined value, so it overcomes the improper setting of the advanced uplink subframe in the above-mentioned prior art. The problem of interference is generated, and then the effect of anti-interference on the RACH is achieved.

Preferably, the device for sending random access signals in the TDD mode of the LTE system provided by the embodiments of the present invention includes: the first predetermined value is 288Ts; the second predetermined value is 4832Ts; the third predetermined value is D+4832Ts, where D= Tud_max-288Ts, Tud_max is the maximum allowable value of the transition time from uplink to downlink in the preset LTE system TDD mode.

Preferably, Tud_max=max(Tud_nb_max, Tud_ue_max), where Tud_nb_max is the maximum time that the base station allowed by the TDD mode of the LTE system from the end of the uplink reception to the start of the downlink transmission, Tud_ue_max is the mobile phone allowed by the TDD mode of the LTE system from the uplink The maximum time elapsed from the end of sending to the start of downlink receiving. The value range of Tud_max may be 215Ts-2560Ts.

The following examples are given for specific application scenarios of Tud_max, so as to enhance the understanding of the present invention.

Embodiment one

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=250Ts, then the fourth type of structure of the RACH channel is sent at a position 4832Ts ahead of the end of UpPTS.

Embodiment two

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=350Ts, then the fourth structure of the RACH channel is sent at a position ahead of the end of UpPTS by 4832Ts+(350-288)Ts=4894Ts.

Embodiment three

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=338Ts, then the fourth type of structure of the RACH channel is sent at a position ahead of the end position of UpPTS by 4832Ts+(338-288)Ts=4882Ts.

Embodiment four

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=308Ts, then the fourth type of structure of the RACH channel is sent at a position ahead of the end of UpPTS by 4832Ts+(308-288)Ts=4852Ts.

Embodiment five

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=369Ts, then the fourth type of structure of the RACH channel is sent at a position ahead of the end of UpPTS by 4832Ts+(369-288)Ts=4913Ts.

Embodiment six

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=400Ts, then the fourth type of structure of the RACH channel is sent at a position ahead of the end of UpPTS by 4832Ts+(400-288)Ts=4944Ts.

Embodiment seven

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=431Ts, then the fourth type of structure of the RACH channel is sent at a position ahead of the end of UpPTS by 4832Ts+(431-288)Ts=4975Ts.

Embodiment Eight

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=461Ts, then the fourth type of structure of the RACH channel is sent at a position ahead of the end of UpPTS by 4832Ts+(461-288)Ts=5005Ts.

Embodiment nine

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=492Ts, then the fourth type of structure of the RACH channel is sent at a position ahead of the end of UpPTS by 4832Ts+(492-288)Ts=5036Ts.

Embodiment ten

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=523Ts, then the fourth type of structure of the RACH channel is sent at a position ahead of the end of UpPTS by 4832Ts+(523-288)Ts=5067Ts.

Embodiment Eleven

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=553Ts, then the fourth type of structure of the RACH channel is sent at a position ahead of the end of UpPTS by 4832Ts+(553-288)Ts=5097Ts.

Embodiment 12

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=584Ts, then the fourth type of structure of the RACH channel is sent at a position ahead of the end of UpPTS by 4832Ts+(584-288)Ts=5128Ts.

Embodiment Thirteen

Assuming that the maximum allowable value of the transition time from uplink to downlink in LTE TDD mode is Tud_max=615Ts, then the fourth type of structure of the RACH channel is sent at a position ahead of the end position of UpPTS by 4832Ts+(615-288)Ts=5159Ts.

It can be seen from the above solutions that the present invention solves the method of sending RACH in UpPTS when the uplink and downlink subframe switching time configuration is reserved in the TDD system. On the basis of considering the realization of the hardware system, the coverage of the random access channel is effectively improved, the work efficiency of the TDD system is improved, and a high random access success rate can also be guaranteed in a multipath environment.

Obviously, those skilled in the art should understand that each module or each step of the above-mentioned present invention can be realized by a general-purpose computing device, and they can be concentrated on a single computing device, or distributed in a network formed by multiple computing devices Optionally, they can be implemented with program codes executable by a computing device, so that they can be stored in a storage device and executed by a computing device, or they can be made into individual integrated circuit modules, or they can be integrated into Multiple modules or steps are fabricated into a single integrated circuit module to realize. As such, the present invention is not limited to any specific combination of hardware and software.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. a method for sending random access signal in LTE system TDD mode, is characterized in that, comprises the following steps: Obtain the maximum allowable value Tud_max of the uplink to downlink conversion time of the TDD mode of the LTE system; judging whether Tud_max is greater than a first predetermined value; and If Tud_max is not greater than the first predetermined value, set the fourth type of structure of RACH to be sent at the second predetermined value ahead of the UpPTS end position; if Tud_max is greater than the first predetermined value, then set the fourth type of structure at The UpPTS end position is sent a third predetermined value ahead. 2. The sending method according to claim 1, wherein the first predetermined value is 288Ts. 3. The sending method according to claim 2, wherein the second predetermined value is 4832Ts. 4. The sending method according to claim 3, wherein the third predetermined value is D+4832Ts, where D=Tud_max-288Ts. 5. The sending method according to any one of claims 1 to 4, characterized in that, Tud_max=max(Tud_nb_max, Tud_ue_max), wherein Tud_nb_max is the base station allowed by the TDD mode of the LTE system from the end of uplink reception to the downlink transmission The maximum time elapsed from the beginning, Tud_ue_max is the maximum time elapsed from the end of uplink transmission to the start of downlink reception allowed by the user equipment in the TDD mode of the LTE system. 6. A sending device for a random access signal in an LTE system TDD mode, characterized in that it comprises: An acquisition module, configured to acquire the maximum allowable value Tud_max of the uplink to downlink conversion time of the LTE system TDD mode; A judging module, configured to judge whether Tud_max is greater than a first predetermined value; and Setting module, for if Tud_max is not greater than the first predetermined value, then set the fourth type of structure of RACH to send at the position where the UpPTS end position is ahead of the second predetermined value; if Tud_max is greater than the first predetermined value, then set the A fourth type of structure is sent at the position where the UpPTS end position is advanced by a third predetermined value. 7. The sending device according to claim 6, wherein the first predetermined value is 288Ts. 8. The sending device according to claim 7, wherein the second predetermined value is 4832Ts. 9. The transmitting device according to claim 8, wherein the third predetermined value is D+4832Ts, wherein D=Tud_max-288Ts, and Tud_max is the preset ratio from uplink to downlink of the TDD mode of the LTE system The maximum allowable value of the conversion time. 10. The sending device according to any one of claims 6 to 9, characterized in that Tud_max=max(Tud_nb_max, Tud_ue_max), wherein Tud_nb_max is the base station allowed by the TDD mode of the LTE system from uplink reception to downlink transmission The maximum time elapsed from the beginning, Tud_ue_max is the maximum time elapsed from the end of uplink transmission to the start of downlink reception allowed by the user equipment in the TDD mode of the LTE system.

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