CN100459484C - Method for information interaction between base station and user terminal - Google Patents

Abstract

This invention relates to a method for interacting information between base stations and user terminals including: a base station judges if it has received a confirmation message that data packets in a sending window are obtained by a user terminal correctly, if not, the sending window keeps unchanged, if so, it monitors by a timer the existing time length of the data packet in the window with the largest sending number in the data packets and judges if the timer is over the time, if so, it exchanges the bottom of the sending window to a first data packet after that with the largest sequence number, otherwise, the window is unchanged, finally, the station sends data packets not receiving the confirmation message.

Description

A method for information interaction between a base station and a user terminal

technical field

The invention relates to an information interaction method between a base station and a user terminal in a WCDMA network, in particular to an interaction method involving information retransmission.

Background technique

In the WCDMA system, a high-speed downlink packet access shared channel (HSDPA, highspeed downlink packet access) is introduced, and the channel uses adaptive modulation and coding to send information. The adaptive modulation and coding means that the modulation method and coding redundancy used by the channel can be dynamically adjusted according to the channel environment. When the channel condition is good, a high-order modulation method and a low-redundancy coding method are used to improve Spectrum efficiency and code resource utilization; if the channel condition is not good, low-order modulation and high-redundancy coding are used when sending information.

In order to compensate for the error of adaptive modulation and coding control, an information retransmission mechanism is introduced in the information exchange process between the system base station and the user terminal.

In the prior art, the information exchange mechanism between the base station and the user terminal is: the base station sends the data packets in the sending queue and in the sending window according to the size of the sending sequence number, and the user terminal sends a confirmation to the base station after correctly obtaining the data packets (ACK) information, the base station resends the data packets in the queue that have not received the acknowledgment information; on the user terminal (UE) side, due to the retransmission of information, the order of the data packets finally acquired by the UE has changed Therefore, the UE needs to reorder the received data packets in the cache. At the same time, the UE uses the T1 parameter set by the system to manage the data packets in the memory. The data packets are sent to the higher-level entities for processing.

It can be known from the prior art that the base station only judges whether to retransmit the data packet according to the acquired acknowledgment (ACK) information sent by the UE. And then, the defective of prior art is:

1) The base station sends data packets sequentially according to the size of the transmission sequence number (TSN, Transmission Sequence Number). Due to changes in channel conditions, data packets with a small TSN may not be correctly received by the UE initially, although the base station will process the data packets. Retransmission, however, when the packet arrives at the UE, other packets that have been reordered in the cache have been waiting for more than T1 (including packets with a large TSN) in the cache, and are sent to the UE upper layer entity for retransmission For subsequent processing, since the prior art also includes error correction processing in the upper layer entity, even if a data packet with a small TSN is successfully retransmitted, the UE side will discard the data packet and perform subsequent data packet reordering.

2) If due to changes in channel conditions, the data packets with a small TSN cannot be obtained by the UE in time, while the data packets with a large TSN are obtained by the UE and reordered in the buffer area. If the data packets with a large TSN are relatively large, So that few data packets may fill up the buffer area, causing the UE to send these data packets to the upper layer. At this time, even if the retransmission of the small TSN data packet is successful, it will be discarded by the UE, because when the existing data packet in the buffer area is sent to the upper layer of the UE for subsequent processing, the UE will only retry the subsequent data packet with a large TSN Sort.

To sum up, the existing technology causes unnecessary retransmission of some data packets on the base station side, which in turn causes waste of underlying transmission bandwidth and reduces underlying transmission efficiency.

Contents of the invention

The problem to be solved by the present invention is to provide a method for information interaction between a base station and a user terminal, which can avoid unnecessary retransmission of data packets at the base station side.

In order to solve the problems of the technologies described above, the purpose of the present invention is achieved through the following technical solutions:

1) The base station judges whether to receive the acknowledgment information that the data packet in the sending window is obtained by the user terminal, if not, then proceed to step 3), if there is, then use a timer to monitor the data packets that receive the acknowledgment information, and finally be received The duration of the data packet sent by the base station in the sending window;

2) judging whether the timer is overtime, if overtime, update the lower edge of the sending window to the first data packet after the last data packet sent by the base station; otherwise the sending window remains unchanged;

3) The base station sends the data packets for which confirmation information has not been received within the sending window.

On the basis of the above method, between step 2) and step 3), it also includes: calculating the sum of the lengths of the data packets sent to the same user terminal and receiving the confirmation information of the user terminal in the updated sending window, and judging the length Whether the sum is greater than the preset user terminal buffer occupancy threshold, if greater than the buffer occupancy threshold, the base station stops sending data packets in the sending window, otherwise proceed to step 3); or calculate and send to the same user in the updated sending window The terminal receives the sum of the lengths of the data packets of the confirmation information from the user terminal, and judges whether the ratio of the sum of the data packet lengths to the buffer capacity of the user terminal is greater than the buffer occupancy rate of the user terminal. If it is greater than the buffer occupancy threshold, the base station stops sending Send the data packets in the window, otherwise go to step 3).

On the basis of the above method, step 1 of the present invention) can be realized in the following manner:

11) If the acknowledgment information of the user terminal is received, it is judged whether the sending sequence number of the data packet currently receiving the acknowledgment information is not less than the sending sequence number of the data packet along the lower edge of the current sending window, if not less than, then proceed to step 12), if If it is less than, proceed to step 3);

12) determine whether the timer is monitoring the duration of the existence of the data packet in the current sending window, if so, proceed to step 2); otherwise proceed to step 13);

13) The timer starts counting, and monitors the duration of the data packet in the sending window that receives the ACK and has the largest sending sequence number in the sending window.

Further, step 11) includes the step of: judging whether the data packet receiving the current confirmation information is the lower edge of the sending window by comparing the sending sequence number of the data packet, and judging whether it is the lower edge of the sending window, if so, Then update the lower edge of the sending window to the first data packet after the data packet that has not received confirmation information; otherwise, go to step 12).

In the present invention, step 3) is to periodically send the data packets that have not received the user acknowledgment information ACK within the sending window.

It can be seen from the above technical solutions that, compared with the prior art, in the present invention, the base station side refers to the behavior of the user terminal reordering entity in the process of delivering data packets. Specifically: use the T1 parameter to predict the length of time for the data packets in the sending window to reach the user terminal cache, and at the same time, refer to the processing mechanism for data packets in the existing user terminal buffer to determine whether the data packets in the current sending window of the base station are expired for the user terminal Data, and then dynamically update the position of the base station sending window, avoiding the base station from sending data packets that have expired for the user terminal; further, on the basis of the above method, the present invention uses the length of the data packet that has received the user terminal ACK in the sending window The sum predicts the occupancy rate of the user terminal cache, and judges whether the data packets in the base station's current sending window will be discarded due to the limited user terminal buffer occupancy after being delivered, and then dynamically updates the sending window of the base station to adjust the sending speed of the base station data packets .

In summary, the present invention avoids invalid delivery of data packets at the base station side by taking the behavior of the user terminal reordering entity as a reference during the process of sending data packets, and furthermore, because the present invention saves underlying bandwidth resources and improves Low-level bandwidth utilization, so it has the advantages of improving the bottom-level transmission efficiency and reducing the high-level data packet loss rate.

Description of drawings

Fig. 1 is a flow chart of the method of the present invention;

Fig. 2 is the processing flowchart when the base station obtains the confirmation information of the user terminal in the method of the present invention;

Fig. 3 is a flow chart of the distribution behavior of the base station data packet in the method of the present invention.

Detailed ways

The core idea of the present invention is: the base station side refers to the behavior of the user terminal reordering entity in the process of sending data packets, that is, uses the T1 parameter to predict the time length for the data packets in the sending window to reach the user terminal buffer, and uses the The sum of the lengths of the data packets received from the user terminal ACK is used to predict the occupancy rate of the user terminal cache. The user terminal discards, and then dynamically adjusts the sending window of the base station to prevent the base station from sending data packets that have expired for the user terminal, or dynamically adjusts the sending speed of the base station data packet according to the occupancy rate of the current user terminal cache.

The receiving mechanism of the user terminal for the data packet in the process of information interaction with the base station is: the base station sends the data packet sequentially according to the sending sequence number of the data packet, and due to the retransmission mechanism of the data packet sent by the base station, the data arriving at the user terminal The order of the packets may have changed. After the user terminal obtains the data packets delivered by the base station, it puts them in the cache for reordering. At the same time, the timer starts to monitor the retention of the last packet in the reordering queue that arrives in the cache. Time, when the data packet exists in the cache for longer than T1, the data packet in the cache and the previously received data packet are sent to the upper layer entity for processing, and the subsequent received data packets are processed according to the sending sequence number For reordering, at this time, the prior data packets obtained through retransmission by the base station are discarded. On the other hand, when the cache occupancy rate of the user terminal exceeds the preset threshold, even if the data packets in the cache have not been sent to the upper-layer entity, the data packets acquired by the user terminal at this time are still discarded.

Based on the above core idea and the receiving mechanism of the user terminal data packet, a complete implementation mode of the present invention is introduced.

Fig. 1 is a schematic diagram of the processing flow of the embodiment of the present invention; With reference to this figure, it can be seen that:

Step 11: The base station obtains the confirmation information that the user terminal obtains the data packet, and according to the data packet corresponding to the confirmation information, dynamically adjusts the position of the transmission window of the data packet transmission queue of the base station, and monitors the duration of the data packet in the transmission window to predict the user Terminal cache timer duration;

Step 12: judging whether the timer timing reaches T1, and if so, adjusting the position of the sending window of the base station data packet sending queue;

Step 13: judging whether the buffer occupancy rate of the user terminal exceeds a preset threshold value, if not, proceed to step 14, otherwise the base station suspends sending data packets;

Step 14: The base station sends the data packets for which the user terminal acknowledgment message (ACK) has not been received in the sending window.

Referring to FIG. 2 , the processing flow of the base station obtaining the confirmation information of the user terminal described in step 11 in the present invention is described, that is, the method for the base station to update the transmission window.

Step 21: After obtaining the data packet sent by the base station, the user terminal feeds back an acknowledgment information (ACK) about the data packet, and the base station obtains the acknowledgment information;

Step 22: Determine the size of the transmission sequence number (ACK_TSN) of the data packet corresponding to the ACK and the transmission sequence number (LowerEdge_TSN) of the data packet at the lower edge of the base station data packet transmission window (TxWindow_LowerEdge) to determine the data packet obtained by the user terminal Whether it is in the sending window, if the ACK_TSN is less than LowerEdge_TSN, it means that the data packet is no longer in the sending window, in this case, do not prompt the base station to adjust the sending window, that is, proceed to step 23; if the ACK_TSN is not less than LowerEdge_TSN, then proceed to step 24;

As known to those skilled in the art, the sending sequence numbers of the data packets are used to identify the order in which the data packets are sent by the base station, and generally, the sending sequence numbers identified by the data packets sent later are greater than those of the data packets sent earlier The identified transmission sequence number, in this embodiment, only uses the use of the transmission sequence number in the prior art to illustrate the implementation method of the present invention, but does not limit the identification method of the data packet transmission sequence number, such as: according to the transmission of the data packet sequence, the sending sequence number gradually decreases, etc.;

As known to those skilled in the art, the sending window determines the range of data packets to be sent by the base station at a certain moment, that is, at a certain moment, only data packets within the sending window are allowed to be sent; If it is correctly acquired by the user terminal, the sending window will be updated to the new data packet to be sent in the data packet queue, and the base station will send the data packets sequentially according to the data packet sending sequence number;

Step 23: do not make any changes to the sending window, proceed to step 28;

Step 24: Determine whether ACK_TSN is equal to LowerEdge_TSN, if equal, that is, the data packet of the ACK_TSN is the lower edge of the sending window, then proceed to step 25, otherwise proceed to step 26;

Step 25: For the situation that the data packet of ACK_TSN described in step 24 is the lower edge of the sending window, adjust the position of the sending window, specifically starting from the data packet of the above ACK_TSN, search along the direction of TSN increase, and place the first Not receiving the data packet of the ACK of the user terminal as the lower edge (TxWindow_LowerEdge) of the new sending window; proceed to step 26;

Step 26: judge whether the timer on the base station side is timing the data packets in the current sending window, if not, then including that the timer is not opened to timing any data packets, or the timer is currently timing the data packets outside the sending window (the data The TSN of packet is less than these two situations of timing along the data packet TSN) of sending window, at this moment, carry out step 27, otherwise carry out step 28;

Step 27: re-start the timer, and among the data packets received from the user terminal ACK in the sending window, time the data packet with the largest sending sequence number (TSN), and proceed to step 28;

Step 28: Calculate the sum of the lengths of the received ACKs in a data packet sending queue in the current sending window.

The above-mentioned a kind of realization mechanism to data packet timing is: T1IsStarting is set as the Boolean variable of whether marking timer is opened, and T1IsStarting value is Yes or No; T1_TSN instruction is set to cause the sending serial number (TSN) of the data packet of timer timing, That is, the TSN of the data packet currently timed by the timer; TimeT1Starting records the start time of the timer; TimePresent is the current time. According to the above parameters of the T1 time timer, those skilled in the art can realize the application of the timer in the present invention. Taking step 26 as an example, the application method of the above parameters is: judge the Boolean value of T1IsStarting, if it is No, then proceed to step 27; if it is Yes, then further judge whether T1_TSN is less than the sending sequence number (LowerEdge_TSN ), if so, proceed to step 27, otherwise proceed to step 28. Referring to this example, it is not difficult for those skilled in the art to use the above parameters to implement other steps in this embodiment, and the present invention does not exclude other methods for implementing timer applications.

From step 26 to step 27, it can be seen that if ACK_TSN is greater than or equal to LowerEdge_TSN, that is, when the data packet currently acquired by the user terminal is in the transmission window of the base station, the base station monitors the TSN among all data packets received from the user terminal ACK in the transmission window. The length of the largest packet in the send window. For the data packets in the sending window, the base station will resend the data packets that have not received the ACK from the user terminal, and the data packets that have been acquired by the user terminal have been reordered in the cache of the user terminal, and the timer will reorder the acquired data Time the data packet with the largest TSN in the packet queue, and monitor whether its buffering time exceeds T1. Therefore, the timing of the data packet with the largest TSN in the ACK received by the base station within the sending window will be closest to the timer in the user terminal buffer Timing, and then the base station can judge the behavior of the user terminal according to the timing of the sending window data packet, so as to adjust the behavior of sending the data packet of the base station.

Referring to FIG. 3 , corresponding to steps 12 , 13 , and 14 , the adjustment of the above-mentioned data packet distribution behavior is described. If the base station sends data packets periodically, the processing flow on the base station side when the sending cycle is reached is:

Step 31: Determine whether the value of the timer exceeds the duration T1, if so, proceed to step 32; otherwise, proceed to step 35;

Step 32: Starting from the data packet counted by the timer, search along the direction of TSN increase (that is, start searching from T1_TSN), and update the first data packet that has not received the user terminal ACK to the lower edge of the sending window (TxWindow_LowerEdge) , go to step 33;

Step 33: Determine whether there is a data packet received from the user terminal ACK in the updated sending window, if so, proceed to step 34, otherwise proceed to step 310, that is, turn off the timer and proceed to step 35;

Step 34: re-start the timer, and among the data packets received from the user terminal ACK in the sending window, time the data packet with the largest sending sequence number (TSN), and proceed to step 35;

Step 35: Calculate the sum of the lengths of the data packets that have received ACK in the current sending window in a data packet sending queue;

Step 36: For the data packet transmission queue sent to the same user terminal, add the sum of the data packet lengths to obtain the sum of the data packet lengths of the user terminal;

Step 37: Obtain the ratio of the sum of the user terminal data packet lengths to the size of the user terminal cache, that is, predict the occupancy rate of the user terminal cache, and judge whether it exceeds the preset user terminal cache occupancy rate threshold, and if it exceeds the threshold, proceed to step 38, Otherwise proceed to step 39;

Step 38: The base station data packet is not sent in the current sending cycle;

Step 39: the base station sends the data packets that have not received the user terminal acknowledgment message (ACK) in the sending window.

In the above embodiment, the MAC-hsReordering Buffer Size for RLC-UM parameter in the 3GPP protocol can be applied to the judgment of the buffer occupancy rate of the base station. This parameter is used for the management of the user terminal side buffer. The above prediction of the cache occupancy rate of the user terminal can be realized, but the present invention does not exclude other implementation manners that can achieve the same purpose.

An alternative to step 37 is: judging whether the sum of the lengths is greater than a preset user terminal buffer occupancy threshold, and if so, proceed to step 38 ; otherwise, proceed to step 39 .

In the 3GPP R5 version of the high-speed downlink packet access shared channel (HSDPA), the channel adopts a method of providing high-order modulation and less redundant channel coding to improve spectral efficiency. The modulation method of the HSDPA channel is QPSK or 16QAM, the channel coding is Trubo coding, and the maximum coding redundancy is 1/3; the modulation method and coding redundancy of this channel can be dynamically adjusted according to the channel environment, and high-order modulation and Low-redundancy channel coding provides a high upper-layer rate, and the opposite is true when the channel condition is poor. The HSDPA channel adopts a transmission time interval (TTI) of 2 milliseconds, that is, the sending period of the base station data packet is 2 milliseconds. Since the TTI is small, it can better track the change of the channel condition of each user, and then capture the channel condition in time. time for sending data.

In order to make up for the error of adaptive modulation and coding control of HSDPA, HARQ protocol is introduced in the bottom layer for retransmission; in order to make full use of the information of each retransmission, incremental redundant decoding is adopted. The present invention is more suitable for the control of sending data packets of the channel. The above content constitutes a complete embodiment of the present invention.

The method for information interaction between the base station and the user terminal provided by the present invention has been described above in detail. In this paper, specific examples are used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only used to help understand the present invention. method and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and application scope. Invention Limitations.

Claims (7)

1. A method for information interaction between a base station and a user terminal, characterized in that: 1) The base station judges whether to receive the acknowledgment information that the data packet in the sending window is obtained by the user terminal, if not, then proceed to step 3), if there is, then use a timer to monitor the data packets that receive the acknowledgment information, and finally be received The duration of the data packet sent by the base station in the sending window; 2) Determine whether the timer is overtime, if overtime, update the lower edge of the sending window to the first data packet that has not received confirmation information after the last data packet sent by the base station; otherwise the sending window remains unchanged ; 3) The base station sends the data packets for which confirmation information has not been received within the sending window. 2. The method for information interaction between a base station and a user terminal according to claim 1, characterized in that: Step 2) includes step 4) between step 3): calculate the sum of the lengths of the data packets sent to the same user terminal and receiving the confirmation information of the user terminal in the updated sending window; determine whether the sum of the lengths is greater than the preset The user terminal cache occupancy threshold set, if greater than then proceed to step 5), otherwise proceed to step 3); 5) The base station stops delivering data packets within the sending window. 3. The method for information interaction between a base station and a user terminal according to claim 1, characterized in that: Step 2) includes step 4) between step 3): calculate the sum of the lengths of the data packets sent to the same user terminal and receiving the confirmation information of the user terminal in the updated sending window; judge the sum of the lengths of the data packets and Whether the ratio of the user terminal buffer capacity is greater than the preset user terminal buffer occupancy rate threshold, if greater then proceed to step 5), otherwise proceed to step 3); 5) The base station stops delivering data packets within the sending window. 4. The method for information interaction between a base station and a user terminal according to claim 1, wherein step 1) is specifically: 11) If the confirmation information of the user terminal is received, then it is judged whether the transmission sequence number of the data packet receiving the confirmation information is not less than the transmission sequence number of the data packet along the lower edge of the current transmission window, if not less than, then proceed to step 12), If it is less than, no change is made to the sending window, proceed to step 3); 12) determine whether the timer is monitoring the duration of the existence of the data packet in the current sending window, if so, proceed to step 2); otherwise proceed to step 13); 13) The timer starts counting, monitors the duration of the data packet with the largest sending sequence number in the sending window for receiving confirmation information in the sending window, and proceeds to step 2). 5. The method for information interaction between a base station and a user terminal according to claim 1, wherein step 1) is specifically: 11) If the confirmation information of the user terminal is received, it is judged whether the sending sequence number of the data packet currently receiving the confirmation information is not less than the sending sequence number of the data packet along the lower edge of the current sending window, if not less than, then proceed to step 14), Otherwise, the sending window does not make any changes, and proceeds to step 3); Step 14): judge whether the data packet of the current receipt confirmation information is the lower edge of the sending window, if so, proceed to step 15); otherwise proceed to step 12); 15) updating the lower edge of the sending window to the first data packet that has not received confirmation information after the data packet that currently receives confirmation information, and proceeds to step 12); 12) determine whether the timer is monitoring the duration of the existence of the data packet in the current sending window, if so, proceed to step 2); otherwise proceed to step 13); 13) The timer starts counting, monitors the duration of the data packet with the largest sending sequence number in the sending window for receiving confirmation information in the sending window, and proceeds to step 2). 6. The method for information interaction between a base station and a user terminal according to claim 5, characterized in that: In step 14), it is judged whether the data packet currently receiving confirmation information is the lower edge of the sending window by comparing the sending sequence numbers of the data packets. 7. The method for information interaction between a base station and a user terminal according to claim 1, characterized in that: Step 3) is to periodically send the data packets that have not received the confirmation information of the user terminal within the sending window.

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