CN1225875C - Method of realizing data retransmission on high speed medium access control layer (MAC-HS) - Google Patents

Abstract

The invention discloses a method for realizing PDU data retransmission in a high-speed media access control layer (MAC-HS). It is to establish a retransmission PDU data queue in the MAC-HS layer, which is used to store the PDU data corresponding to the TTI data block that has not been successfully transmitted by using the hybrid automatic repeat request (HARQ) at the physical layer (PHY); The PDU data retransmission scheduling is added to the HS layer, and together with the PHY layer retransmission scheduling, the retransmission PDU data and the TTI data blocks stored in the PHY layer that have not been successfully transmitted but have not exceeded the maximum number of HARQ retransmissions are scheduled. The PDU data packet corresponding to the TTI data block whose PHY transmission fails and exceeds the maximum number of HARQ retransmissions is returned and stored in the retransmission PDU data queue of the MAC-HS layer; the MAC-HS layer prioritizes scheduling of PDUs in the retransmission PDU data queue The data is modulated and coded and sent at the PHY layer according to the new channel conditions. The time delay of data retransmission is reduced, the adaptability to channel conditions is enhanced, the reliability of retransmission is improved, and thus the data transmission speed and throughput capacity of the system are improved.

Description

Method for Realizing Data Retransmission in High-Speed Media Access Control Layer

technical field

The invention relates to a data layered retransmission technology in the field of wireless communication, in particular to a method for realizing data retransmission added in a high-speed medium access control layer (MAC-HS).

Background technique

In order to adapt to high-speed wireless data services, High Speed Downlink Packet Access (HSDPA) was proposed, including Adaptive Modulation and Coding (AMC) and Hybrid Automatic Repeat Request ( HybridAuto Retransmit Request, referred to as HARQ). Among them, the core of AMC technology is to select the appropriate modulation and coding scheme (MCS for short) according to the change of channel conditions, and use high-order modulation schemes when the channel conditions are relatively good, such as the combination of 64 amplitude and phase Modulation (64QAM), code rate 3/4, Turbo code (TURBO CODE), which can improve data transmission speed and system throughput performance. The core of the hybrid automatic repeat request (HARQ) technology is to realize the retransmission of TTI data blocks at the physical layer (PHY). The so-called TTI data blocks refer to data sent in a transmission time interval (TTI). When the receiver finds an error during decoding, it requires the sender to retransmit the erroneous data, which is faster than the high-level request for retransmission. The adoption of HARQ technology improves the accuracy of data transmission.

In high-speed data services, the communication protocol layers related to the data retransmission scheduling mechanism are the radio link control layer (RLC), the high-speed media access control layer (MAC-HS) and the physical layer (PHY). The entire structural relationship is shown in Fig. 1. Wherein, the execution of HARQ data retransmission is implemented in the physical layer, and the scheduling is implemented in the MAC-HS. The scheduling of data retransmission is implemented in the following way:

1. The protocol data unit (PDU) data divided by the radio link control layer (RLC), after being scheduled by the high-speed media access control layer (MAC-HS), is encapsulated into a TTI data block at the physical layer according to the MCS code at the time of transmission;

2. The physical layer (PHY) uses the HARQ mechanism to transmit the TTI data block. When the receiver fails to receive it correctly, the TTI data block is retransmitted, and the TTI data is discarded if the maximum number of retransmissions is exceeded;

3. The RLC layer of the receiver sends out a retransmission request for incorrectly received data, and the RLC layer of the sender resends the incorrectly received PDU data.

The analysis of the above-mentioned prior art data retransmission scheme shows the following problems:

The delay of retransmitting data is too large: the RLC layer of the sender is implemented in the radio network controller (RNC), and the MAC-HS is implemented in the base station (NodeB). The transmission delay of PDU data from RLC to MAC-HS is 100 milliseconds (ms), and the time interval (TTI) of a data transmission in HSDPA is 2ms, therefore, the time delay of the retransmission data initiated by the RLC peer entity layer is very large, which directly affects the transmission speed of the data.

The retransmission information does not change with the channel status (MCS selection): HARQ retransmission is realized at the physical layer (PHY), which is the retransmission of the TTI data block after encoding multiple PDU data, and the MCS encoding information of the data block is retransmitted The time is constant, so it cannot adapt to the situation where the channel condition changes from good to bad. In this case, even if the number of HARQ retransmissions is continuously increased, the possibility of retransmission failure is very high.

Contents of the invention

The purpose of the present invention is to provide a method for implementing PDU data retransmission in the high-speed media access control layer, so as to improve the retransmission performance of data in high-speed transmission.

The present invention is a method for realizing data retransmission at the high-speed media access control layer, which is applied to the data retransmission mechanism composed of the wireless link control layer, the high-speed media access control layer and the physical layer, and the method at least includes the following steps :

Establish a retransmission PDU data queue in the high-speed media access control layer;

After the retransmission times of the physical layer TTI data block reaches the HARQ maximum retransmission times, the PDU data corresponding to the TTI data block is stored in the retransmission PDU data queue of the high-speed media access control layer;

Perform retransmission scheduling on the PDU data in the retransmission PDU data queue.

The PDU data retransmission scheduling at least includes:

Determine whether there is PDU data in the retransmission PDU data queue;

If there is, the PDU data in the queue will be scheduled first, and the appropriate modulation and coding method will be selected at the physical layer according to the current channel conditions to re-encode, modulate and send;

If there is none or the PDU data in the queue is not enough to form a TTI data block, call the new PDU data from the radio link control layer, and select the appropriate modulation and coding method to encode, modulate and transmit at the physical layer according to the current channel conditions.

The PDU data retransmission scheduling further includes:

Set a PDU data retransmission scheduling counter, when scheduling retransmission of the PDU data in the PDU data queue to resend, first judge whether the PDU data retransmission scheduling count value is greater than the preset maximum retransmission times value;

If it is not greater than, the PDU data is scheduled to be resent, and the PDU data retransmission scheduling count value is increased by 1;

If it is greater than, report to the radio link control layer, and the radio link control layer initiates retransmission.

According to the above-mentioned technical solution of the present invention, when the physical layer adopts hybrid automatic repeat request (HARQ) technology for TTI data block transmission, a smaller maximum retransmission number value is selected to adapt to changes in channel conditions and improve the correctness of retransmitted data .

The present invention introduces a data retransmission mechanism composed of a radio link control layer, a high-speed media access control layer and a physical layer into a high-speed data service, and introduces a physical layer hybrid automatic repeat request (HARQ) technology and automatic modulation and coding After the technology (AMC), the implementation method of PDU data retransmission added in the high-speed media access control layer. The method of the present invention realizes the coordinated scheduling of physical layer retransmission and PDU data retransmission at the high-speed media access control layer, and can adjust the MCS coding of retransmitted PDU data in time according to channel conditions, which not only reduces the cost of data retransmission The delay improves the adaptability to channel conditions, enhances the reliability of data retransmission, improves the data transmission speed and throughput performance of the system, and further improves the overall performance of the system.

Description of drawings

FIG. 1 is a schematic diagram of a communication protocol layer related to a data retransmission scheduling mechanism;

FIG. 2 is a schematic block diagram of realizing PDU data retransmission at the high-speed media access control layer;

FIG. 3 is a schematic diagram of a scheduling flow for high-speed media access control layer physical layer retransmission and PDU data retransmission.

Detailed ways

In order to make the object, technical solution and beneficial effects of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and examples.

Firstly, refer to the structure diagram of adding data retransmission and scheduling at the MAC-HS layer shown in FIG. 2 .

The communication protocol layers related to the data retransmission scheduling mechanism are the radio link control layer (RLC), the high-speed medium access control layer (MAC-HS) and the physical layer (PHY).

The present invention adds a retransmission PDU data queue in the high-speed medium access control layer (MAC-HS), and is used for storing the PDU data corresponding to the TTI data block of the physical layer (PHY) exceeding the maximum HARQ retransmission times.

The MAC-HS implements scheduling for the PDU data stored in the queue and the TTI data that is unsuccessfully stored and transmitted at the physical layer but does not exceed the maximum number of retransmissions of the HARQ.

After the MAC-HS receives the retransmission request from the receiver, it first checks the retransmission TTI data queue in the physical layer, and when the retransmission times of the TTI data block is not greater than the maximum After the number of block retransmissions reaches the maximum number of retransmissions, the PDU data in the TTI data block is returned to the retransmission PDU data queue of the high-speed media access control layer MAC-HS.

The PDU data stored in the retransmission PDU data queue is rescheduled and sent to the physical layer for new MCS selection according to the new channel conditions, and the most suitable modulation and coding method is selected for re-encoding and modulation to form a new TTI data block for transmission.

In this way, the retransmission of PDU data at the MAC-HS layer and the scheduling of two-layer retransmission are realized.

The combination of data retransmission and physical layer retransmission added by MAC-HS can select a smaller maximum number of retransmissions of HARQ, and the data retransmission of MAC-HS can increase the adaptability to the channel. The MCS information in the HARQ retransmission remains unchanged, and the success rate of the HARQ retransmission is very low when the channel condition becomes worse or the AMC selects the wrong MCS code. MAC-HS data retransmission re-modulates and encodes the PDU data that fails to be retransmitted to adapt to channel changes, and the probability of successful transmission is much greater.

And the PDU data contained in the TTI data of HARQ retransmission failure must be the PDU data with a smaller sequence number required by the receiver's RLC recombination. It is necessary to retransmit these data as soon as possible at the MAC-HS layer. This method can achieve these The priority scheduling of data packets reduces the time delay for these PDU data to be retransmitted from RLC.

Refer to Figure 3 for the scheduling process of MAC-HS physical layer retransmission and PDU data retransmission. First check whether the retransmission PDU data queue is empty, judge whether there is PDU data that has not been successfully transmitted, and then schedule and retransmit these PDU data packets first. Link control layer RLC, the retransmission is initiated by the RLC layer. If not, the PDU data will be re-encoded into a new TTI data block and sent at the physical layer PHY according to the new MCS. If there is no unsuccessful PDU data transmission or the PDU data is not enough to reassemble a TTI data block, call new PDU data from the radio link layer RLC. If the transmission of the TTI data block is unsuccessful, it will be scheduled to be resent. If the number of transmissions exceeds the maximum number of HARQ retransmissions N1, the transmission will fail, and the PDU data will be returned and stored in the retransmission PDU data queue of the high-speed media access control layer MAC-HS layer. PDU retransmission scheduling.

The present invention provides a method for implementing retransmission of PDU data at the MAC-HS layer, which can combine changes in channel conditions and HARQ mechanisms, and has the following advantages:

1. Realize retransmission of PDU data at the MAC-HS layer, reduce the discarding of PDU data, thereby reducing the retransmission of PDU data at the RLC layer, reducing the delay of PDU data retransmission, and improving system throughput performance.

2. Realize PDU data retransmission at the MAC-HS layer, remodulate and code the unsuccessfully transmitted PDU data to adapt to changes in channel conditions (MCS selection), and improve the correctness of retransmitted data.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of the claims.

Claims (4)

1, a kind of in high speed medium access control layer (MAC-HS) realization data retransmission method, in the data re-transmission mechanism that is applied to form, it is characterized in that this method may further comprise the steps at least by wireless chain control layer, high speed medium access control layer (MAC-HS) and physical layer:

In high speed medium access control layer (MAC-HS), set up the formation of retransmission protocol data unit data;

When the number of retransmissions of the transmission time interval data block of physical layer reach mix automatic repeat requests maximum retransmission after, with the pairing protocol Data Unit deposit data of this transmission time interval data block in the retransmission protocol data unit data formation of described high speed medium access control layer (MAC-HS);

The protocol Data Unit data that retransmit in the protocol Data Unit data queue are carried out retransfer scheduling.

2, according to claim 1 in high speed medium access control layer (MAC-HS) realization data retransmission method, it is characterized in that described retransfer scheduling comprises at least:

Judge in the formation of described retransmission protocol data unit data and whether have the protocol Data Unit data;

If any the protocol Data Unit data in this formation of priority scheduling then, select suitable modulation and the modulation of coded system recompile to send according to current channel conditions in physical layer;

When forming a transmission time interval data block as the protocol Data Unit data in nothing or this formation are not enough, then call new protocol Data Unit data, select suitable modulation and coded system coded modulation to send according to current channel conditions in physical layer from wireless chain control layer.

3, realize data retransmission method according to the described of claim 2 at high speed medium access control layer (MAC-HS), it is characterized in that described retransfer scheduling further comprises:

One protocol Data Unit data retransmission scheduling counter is set, when the protocol Data Unit data in the formation of scheduling retransmission protocol data unit data resend, judge that at first whether this protocol Data Unit data retransmission scheduling count value is greater than predefined maximum retransmission value;

As be not more than and then dispatch these protocol Data Unit data and resend, protocol Data Unit data retransmission scheduling count value adds 1 simultaneously;

As greater than then reporting wireless chain control layer, initiate to retransmit by wireless chain control layer.

4, according to claim 1 in high speed medium access control layer (MAC-HS) realization data retransmission method, it is characterized in that:

Select the less automatic repeat requests maximum retransmission of mixing value,, improve the correctness of data retransmission with the variation of adaptive channel situation.