KR101139989B1 - Method and apparatus for allocating medium access control memory of a user equipment in a high speed downlink packet access system - Google Patents

Abstract

The present invention relates to a memory allocation method of a terminal in a high speed packet data system using a complex retransmission method, the method comprising: generating a pointer to a corresponding reordering queue of a buffer when data blocks corresponding to a new queue are received from a base station; Reordering the data blocks into corresponding reordering queues of one of a plurality of logically separated reordering queues constituting the buffer in serial sequence number (TSN) order, and if there is an unreceived data block, Driving a timer for the data block to count a predetermined time, and passing all data blocks having a sequential serial number to the upper layer in the corresponding reordering queue at the time when the timer expires; When a stall avoidance operation is required, the plurality of reordering queues are used as one queue by using a pointer to a corresponding reordering queue of the buffer.

HSDPA, MAC-hs, Buffer, Memory, Size, Timer

Description

METHOD AND APPARATUS FOR ALLOCATING MEDIUM ACCESS CONTROL MEMORY OF A USER EQUIPMENT IN A HIGH SPEED DOWNLINK PACKET ACCESS SYSTEM}

1 schematically illustrates the structure of a typical HSDPA system.

2 is a diagram illustrating a MAC structure of a terminal side in a general HSDPA system;

3 is a diagram illustrating a MAC-hs buffer in a terminal in a general HSDPA system.

4 is a diagram illustrating a hierarchical structure of MAC-hs in a terminal in an HSDPA system according to an exemplary embodiment of the present invention.

5 is a diagram conceptually illustrating a memory allocation method of a MAC-hs buffer in a terminal in an HSDPA system according to an exemplary embodiment of the present invention.

6 is a diagram illustrating a memory allocation method when the required size of the MAC-hs buffer in the terminal is the largest in the HSDPA system according to an exemplary embodiment of the present invention.

The present invention relates to a memory allocation method and apparatus of a terminal in an asynchronous high speed packet data system, and more particularly, to a memory allocation method and apparatus capable of reducing a required buffer size of a terminal.

W-CDMA and CDMA 2000 related technologies are leading the standardization in 3GPP and 3GPP2, respectively, and these two organizations have been able to meet the demand for high-speed packet data service in the rapidly moving wireless environment since enacting W-CDMA and CDMA 2000 standards. To that end, we have begun developing standards to enable higher data rate packet data transmission. As a representative result of this standard development, 3GPP proposed High Speed Downlink Packet Access (HSDPA) system, and 3GPP2 proposed 1xEV-DO (EVolution Data Only) system.

In the present specification, the HSDPA system will be described as an example of an asynchronous high speed packet data system. The HSDPA system collectively refers to control channels associated with a High Speed-Downlink Shared Channel (HS-DSCH) for supporting downlink high speed packet transmission, and apparatuses, systems, and methods therefor. In the HSDPA system, a hybrid automatic retransmission request (HARQ) technique or the like is used to improve transmission efficiency. Hereinafter, a general structure and an HARQ scheme of an asynchronous high speed packet data system will be described with reference to FIG. 1.

1 is a view schematically showing the structure of a general HSDPA system.

The communication system of FIG. 1 includes a Core Network (CN) 100, a plurality of Radio Network Subsystems (RNS) 110, 120, and a User Equipment (UE) 130. It includes. The RNS (110, 120) is a radio network controller (RNC) (111, 112) for controlling the operation of a plurality of base stations (Node B) (113 ~ 116), UE 130 through a wireless network And a plurality of base stations (Node Bs) 113 to 116 for transmitting and receiving data.

In the hierarchical structure of the HSDPA system, since the HARQ function is required for the MAC (Medium Access Control) layer, the MAC-hs entity is implemented in addition to the MAC-c / sh and MAC-d entities in the MAC hierarchy of the conventional W-CDMA communication system. In addition, the HSDPA system uses a selective repeat method as a HARQ method.

In the selective retransmission method, the base station continuously transmits a packet to the UE and receives an ACK or NACK from the UE. When the base station receives an ACK from the UE, the base station transmits a next packet to be transmitted, but retransmits the packet when the NACK is received. The selective retransmission method has the advantage of being able to retransmit other packets continuously after receiving the NACK, but has the disadvantage of requiring a large buffer in the UE because packets must be stored in order.

FIG. 2 is a diagram illustrating a MAC structure of a terminal side in a general HSDPA system, for example, 3GPP R'5 TS 25.321 MAC protocol specification.

In FIG. 2, the HS-DSCH means a downlink transport channel for packet data transmission in an HSDPA system. A MAC-hs 210 is provided to control the HS-DSCH. In the downlink, the MAC-hs 210 processes and transmits data transmitted downlink through the HS-DSCH to the MAC-d 230. In the uplink, the MAC-hs 210 receives the data transmitted from the MAC-d 230 and transmits the HS-DSCH to the lower layer.

3 is a diagram illustrating a MAC-hs buffer in a terminal in a general HSDPA system.

The MAC-hs buffer 350 is logically present between the HS-DSCH buffer 330 and the MAC-d buffer 370, and is rearranged in the HS-DSCH buffer 330 that receives the output of the HARQ buffer 310. A buffer that stores reordered data. The output of the HARQ buffer 310 is decoded by the turbo decoder 320 and transferred to the HS-DSCH buffer 350, and the output of the HS-DSCH buffer 330 is determined by the reordering unit 340. The packets are rearranged according to the packet order and transferred to the MAC-hs buffer 350. The output of the MAC-hs buffer 350 is converted to MAC-d PDUs by removing the MAC-hs header and padding bits through a disassembly 360, and then converting them to MAD-d buffers. 370 is passed.

When the general buffer allocation method is used with the parameters defined in the 3GPP R'5 MAC specification, the size of the MAC-hs buffer 350 is calculated as follows.

First, the maximum MAC-hs protocol data unit (PDU) size defined in the 3GPP R'5 MAC specification is calculated as follows, for example, when the category of the terminal is 7, 10.

Category 7

MAX MAC-hs PDU size = {14411 + (32-(14411 mod 32))} / 8

                          = 1804 bytes

Category 10

MAX MAC-hs PDU size = {27952+ (32-(27952 mod 32))} / 8

                          = 3496 bytes

The MAC-hs queue and window size defined in the 3GPP R'5 MAC specification are as follows.

MAX MAC-hs Queue ID: 8

MAX Window Size: 32

For stall avoidance, there should be one MAC-hs PDU allowed per MAC-hs queue. Therefore, the size of the entire MAC-hs buffer is as follows. The stall avoidance refers to a scheme for avoiding a stall state in which one buffer is full and no longer receive a PDU or transmit a PDU upward.

Category 7

MAX MAC-hs buffer size

= MAX MAC-hs PDU size x Number of MAC-hs queues x (MAC-hs window size + 1) = 1804 byte x 8 x (32 + 1) = 476,256 bytes

(However, the above value excludes the values of fields (eg address fields) for controlling the actual buffer.)

Category 10

MAX MAC-hs buffer size = 3496 byte x 8 x (32 + 1)

= 922,944 bytes

(However, the above value excludes the values of fields (eg address fields) for controlling the actual buffer.)

As shown in the above example, it can be seen that a memory capacity of 475,728 bytes or more in a category 7 terminal and 910,536 bytes or more is required in a category 10 terminal for a MAC-hs buffer. As such, the MAC-hs buffer requires the use of a relatively large memory considering the limited memory capacity of the terminal, which leads to an increase in the terminal price. Therefore, a memory allocation method for reducing the size of the buffer in the terminal is needed.

The present invention provides a memory allocation method and apparatus for reducing the size of a buffer required in a terminal in a high-speed packet data system.

In addition, the present invention provides a dynamic memory allocation method and apparatus that can reduce the buffer size of the terminal while satisfying the 3GPP R'5 MAC specification in a high-speed packet data system.

The method of the present invention provides a method of allocating a memory of a terminal in a high speed packet data system using a complex retransmission method, the method comprising: generating a pointer to a corresponding reordering queue of a buffer when data blocks corresponding to a new queue are received from a base station; Reordering the received data blocks into corresponding reordering queues of one of a plurality of logically separated reordering queues constituting the buffer in the order of Transmission Sequence Number (TSN), and if there are unreceived data blocks, Driving a timer on the unreceived data block, counting a predetermined time, and delivering all data blocks having a sequential serial number to a higher layer in a corresponding reordering queue at the time when the timer expires; When a stall avoidance operation is required, the plurality of reordering queues are used as one queue by using a pointer to a corresponding reordering queue of the buffer.

In addition, the apparatus of the present invention is a HARQ block for determining whether a data block received from a radio channel is normally received as a result of HS-DSCH reception in a memory allocation apparatus of a terminal in a high speed packet data system using a complex retransmission scheme. And a reordering queue distribution block for transferring the data block delivered to the HARQ block to a corresponding reordering buffer when the data block is normally received, and a plurality of reordering queues for reordering the transferred data blocks in a predetermined serial number order. When an operation for stall avoidance is required, the reordering block may be configured to perform the reordering operation by using the plurality of logically separated reordering queues as one queue.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

4 is a diagram illustrating a hierarchical structure of MAC-hs in a terminal in an HSDPA system according to an exemplary embodiment of the present invention.

In FIG. 4, if no error occurs for the data block received from the radio channel, that is, the MAC-hs PDU as a result of the HS-DSCH reception, the HARQ block 401 generates and transmits an ACK to the base station and transmits the data block. When the occurrence of an error is detected, the NACK requesting retransmission is generated for the data block in which the error occurs. If no error is detected, the re-ordering queue distribution block 430 receives the data block from the HARQ block 401 and reorders the buffer of the corresponding queue ID, that is, the MAC-hs buffer 350. Store in

In FIG. 4, the reordering blocks 450 ₁ to 450 _n rearrange the received data blocks in a transmission sequence number (TSN) order. In the terminal, there is one reordering block for each Queue ID. Accordingly, when there are n queues, n reorder blocks 450 ₁ to 450 _n are provided as shown in FIG. 4. The reordered data blocks, that is, the MAC-hs PDUs are converted into MAC-d PDUs by removing the MAC-hs header and padding bits through corresponding n decomposition blocks 470 ₁ to 470 _n . Then, it is transmitted to the MAC-d layer. The n reorder blocks 450 ₁ to 450 _n and the n decomposition blocks 470 ₁ to 470 _n are divided into uplinks and downlinks. In FIG. 4, the MAC control block (MAC-control) controls the overall operation of the layer of the MAC-hs of the present invention.

In the present invention, the plurality of reordering blocks 450 ₁ to 450 _n are provided to correspond to n queues so as to perform a general reordering operation and logically separate when an operation for stall avoidance is required. The reordering operation is performed using n queues as one queue.

The memory allocation of the MAC-hs buffer is controlled according to the memory allocation method of the present invention described with reference to FIGS. 5 and 6.

5 is a diagram conceptually illustrating a memory allocation method of a MAC-hs buffer in a terminal in an HSDPA system according to an exemplary embodiment of the present invention, which is performed by the reordering blocks 450 ₁ to 450 _{n of} FIG. The operation is shown.

First, Table 1 briefly summarizes terms used in the description of the present invention.

5 illustrates a dynamic memory (buffer) allocation scheme when only MAC-hs PDUs for one queue, that is, MAC-hs queue 0, exist.

If no data block with TSN 1 as the serial number was received while data blocks for queue 0 were received, the NET of queue 0 is set to "1". Since it is assumed that the terminal receives all data blocks in order without receiving the data block having TSN 1 retransmitted from the base station, the memory allocation method according to the present invention separately assigns a memory address field to each data block. Save the memory address of the next block of data to be stored.

When the maximum window size of the HSDPA system is 32, data blocks 51 with TSN 2 to data blocks 53 with TSN 33 are stored in Queue 0, and each data block is stored in a random memory space. Connected as a pointer. When a data block having TSN 34 is received, the data block having TSN 2 is delivered to disassembly blocks 470 ₁ to 470 _n due to the limitation of the window size, and TSN 34 is stored in the queue.

In this case, the reordering blocks 450 ₁ to 450 _n of FIG. 4 actually receive the data blocks having TSN 34, and then transfer the data blocks having TSN 2 to the decomposition blocks 470 ₁ to 470 _n . Further buffer (memory) space is needed to store a data block (not shown) with 34, i.e., to control stall avoidance.

To this end, the memory allocation method of the present invention uses eight reordering queues as one queue when a spool avoidance operation is required, and since the data blocks of each queue are connected by pointers, the memory allocation method is empty without using additional memory space. Stall avoidance is controlled by using the memory space as a memory space for storing data blocks of Queue 0.

In the embodiment of FIG. 5, only one queue, Queue 0, is substantially present, and stall avoidance is controlled using the remaining empty memory space. Here, the fields and parameters for general reordering operations of the reordering blocks 450 ₁ to 450 _n (for example, fields to store the queue ID and parameters to store information on the window size are omitted for convenience of description). Shall be.

6 is a diagram illustrating a memory allocation method when the required size of the MAC-hs buffer in the terminal is the largest in the HSDPA system according to an embodiment of the present invention.

In the dynamic memory allocation method of the present invention, when data blocks corresponding to a new queue come in, a pointer to the queue is created to create the corresponding queue. Suppose that data blocks for all reordering queues from Queue 0 to Queue 7 come in sequentially through the reorder queue distribution block 410 of FIG. If Inter TTI is 1 and all data blocks are assumed to have the same priority, the received data blocks are rearranged from Queue 0. In other words, the network assumes that data blocks with Queue IDs from Queue 0 to Queue 7 are sent sequentially. Therefore, data blocks received by the UE are sequentially stacked from Queue 0 to Queue 7. Assuming that inter TTI, which represents an interval of arrival time between data blocks, is 1 (2 ms), the time interval for each data block is accumulated in a buffer is 2 ms.

If a data block with TSN 1 corresponding to Queue 0 is not received, the NET of Queue 0 is set to "1" and the T1 timer is started. If the next data block corresponding to Queue 1 has TSN 1, and this data block is also not received, the NET corresponding to Queue 1 is set to "1", and the T1 timer corresponding to Queue 1 starts. Assuming that all the queues are queued from Queue 0 to 8, as shown in FIG. It is assumed that all data blocks of all subsequent queues are received correctly.

The MAX T1 value, which is the maximum value of the T1 timer defined in the 3GPP R'5 MAC specification, is, for example, 400 ms. After all, if the MAX T1 value is set to 400 ms, the data blocks stacked on Queue 0 at the moment when the T1 value for Queue 0 expires, that is, when the T1 timer for Queue 0 reaches 400 ms, are stored in the data block with TSN 2 (61). 26 data blocks are stacked up to the data block 63 having TSN 27. At the moment when the T1 timer for Queue 0 expires, all data blocks with sequential TSNs in Queue 0 are passed to decomposition blocks 470 ₁ to 470 _n .

Eventually, the data block with TSN 27 entering Queue 0, which is received at the next TTI, will be filled using the space freed in Queue 0, and once Queue 1's T1 timer completes, all PDUs with sequential TSNs in Queue 1 will be filled. Transfer to decomposition block 470 ₁ ~ 470 _n . These processes are all performed from Queue 0 to Queue 7. In this case, a memory capacity of a size in which one data block is to be stored is required to control stall avoidance.

That is, in the present invention, since all queues logically separate reordering queues as one queue during a stall avoidance operation, a memory having a size of one data block is stored to control stall avoidance. (Buffer) space is sufficient (assuming the system can handle all data blocks in a queue within a minimum TTI)

When applying the present invention as described above, the maximum buffer size of MAC-hs is as follows when the category 7, 10 of the terminal as an example.

Category 7

MAX MAC-hs buffer size

= (MAX MAC-hs PDU size + 32bit (NEXT pointer)) x (MAC-hs window size of Queue 0 + MAC-hs window size of Queue 1 + ... + MAC-hs window size of Queue 7 + 1)

= 1808 byte x (26 + 7 x 25 + 1) = 365,216 bytes

The unit value is a value excluding a value of an address field for controlling an actual buffer other than an address field additionally required in the present invention.

The additionally required address field will be described in more detail. When the re-ordering queue distribution block 430 receives a data block from the HARQ block 410, the re-ordering queue distribution block 430 may store the data block in the queue and be received next. Prepend the data block with a NEXT pointer field that records the location of the buffer where the data block with the same queue ID will be stored. In this way, when the data block is transmitted from the decomposition blocks 470 ₁ to 470 _n to the upper layer, information on the starting position of each queue received through the MAC control, that is, the first data block of each queue Only the location information can be used to transfer all remaining data blocks of the queue. To this end, an additional address field is required in the present invention.

Category 10

MAX MAC-hs buffer size

= (MAX MAC-hs PDU size + 32bit (NEXT porter)) x (MAC-hs window size of Queue 0 + MAC-hs window size of Queue 1 + ... + MAC-hs window size of Queue 7 + 1 )

= 3500 byte x (26 + 7 x 25 + 1) = 707,000 bytes

The unit value is a value excluding a value of an address field for controlling an actual buffer other than an address field additionally required in the present invention.

Table 2 below shows the size of the MAC-hs buffer when the dynamic memory allocation scheme proposed in the present invention and the general memory allocation scheme are used.

As shown in Table 1, the dynamic memory allocation scheme presented in the present invention can reduce the MAC-hs buffer size to about 108 Kbytes in the terminal satisfying category 7, and 210 Kbytes in the terminal satisfying the category 10.

As described above, according to the present invention, the size of a buffer required in a terminal can be reduced in a high-speed packet data system.

In addition, according to the present invention, the buffer size of the terminal can be reduced while satisfying the 3GPP R'5 MAC specification.

Claims (6)

A memory allocation method of a terminal in a high speed packet data system using a complex retransmission method, When the data blocks corresponding to the new queue are received from the base station, generating a pointer to the corresponding reordering queue of the buffer; Reordering the received data blocks into corresponding reordering queues of one of a plurality of logically separated reordering queues constituting the buffer in a Transmission Sequence Number (TSN) order; Counting a predetermined time by driving a timer for the unreceived data block when the unreceived data block exists; Passing all data blocks having a sequential serial number in a corresponding reordering queue to a higher layer at the time when the timer expires; When a stall avoidance operation is required, the plurality of reordering queues are used as a queue by using a pointer to a corresponding reordering queue of the buffer. The method of claim 1, And the memory is a MAC-hs buffer provided in a terminal of the HSDPA system. delete A memory allocation apparatus of a terminal in a high speed packet data system using a complex retransmission method, A HARQ block for determining whether a data block received from a radio channel is normally received as a result of the HS-DSCH reception; A reorder queue distribution block for transferring the data block delivered to the HARQ block to a corresponding reordering buffer when the data block is normally received; And a plurality of reordering queues for reordering the transferred data blocks in a predetermined serial number order, and reordering the plurality of reordering queues using logically separated reordering queues as one queue when an operation for stall avoidance is required. And a reordering block for performing an operation. The method of claim 4, wherein And the memory is a MAC-hs buffer provided in the terminal of the HSDPA system. The method of claim 4, wherein If there is a data block that has not been received, the reordering block operates a timer for the corresponding data block to count a predetermined time, and at the moment when the timer expires, all the data blocks having a sequential serial number in the reordering queue are upper layer. Device for media access control memory allocation of the terminal, characterized in that for transmitting to.

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