CN106209318B - A MAC protocol data transmission method for TD-LTE - Google Patents

Abstract

The present invention provides a MAC protocol data unit for TD-LTE, including a MAC header, a MAC service data unit, and a MAC control unit. The MAC header includes a plurality of MAC subheaders, except the last one among the plurality of MAC subheaders. The remaining MAC subheaders outside the MAC subheader include six header fields R/R/E/LCID/F/L, and there is a 1-bit extension field E1 after the header field F of the MAC subheader. If the extension field E1 is set to "1" means that there is at least another group of F/E1/LI fields following it; if the extended field E1 is set to "0", it means that the following bytes are MAC service data units. The invention extends the subheader of the status PDU in the RLC AM mode to maximize resource utilization.

Description

A MAC protocol data transmission method for TD-LTE

technical field

The present invention relates to a MAC protocol data transmission method for TD-LTE.

Background technique

LTE defines a pure packet-switched network, which adopts a flat, all-IP network structure, minimizes the number of network elements, and optimizes the protocol level. The protocol structure of its air interface interface has layer one: physical layer; layer two: data link layer; layer three: network layer. For layer two, the data link layer is divided into four sublayers: MAC sublayer; RLC sublayer; PDCP sublayer; BMC sublayer [1]. For the RLC sublayer therein, it mainly completes receiving or distributing RLCSDU from the upper layer to the upper layer, and sending or receiving RLC PDUs to or from the peer RLC entity through the lower layer [1]. In order to complete the transmission of different data, the RLC entity configures three modes: Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM) [1]. The AM entity will retransmit the protocol data unit (Protocol Data Unit, PDU) that fails to transmit. This mode is mainly applied to error-sensitive, delay-tolerant non-real-time services and streaming media services that do not require high delay.

On the one hand, the MAC sublayer provides data transmission to the upper layer through logical channels, and is responsible for allocating transmission resources for each service. On the other hand, it multiplexes the scheduled data packets and transmits them to the physical layer. At present, none of the existing MAC protocols fully utilize the status PDU in the RLCAM mode, resulting in a waste of resources.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a MAC protocol data transmission method for TD-LTE, so as to solve the above problems and maximize resource utilization.

In order to achieve the above purpose, the technical scheme adopted in the present invention is: a method for transmitting MAC protocol data for TD-LTE, comprising a MAC header, a MAC service data unit, and a MAC control unit, and the MAC header includes a plurality of MAC subheaders, Among the multiple MAC subheaders, except the last MAC subheader, the rest of the MAC subheaders include six header fields R/R/E/LCID/F/L, and there is also a 1-bit extension field after the header field F of the MAC subheader. E1, if the extension field E1 is set to "1", it means that there is at least another group of F/E1/LI fields after it; if the extension field E1 is set to "0", it means that the following bytes are MAC Service Data Unit.

Further, the E1 field is followed by the LI field indicating the length.

Further, there is at least one extension field E1 of one MAC subheader.

Beneficial effects of the present invention: the present invention extends the subheader of the status PDU in the RLC AM mode to maximize resource utilization.

Description of drawings

FIG. 1 is a MAC protocol data unit for TD-LTE according to a preferred embodiment of the present invention

Figure 2 is the MAC subheader before extension

Figure 3 is the extended MAC subheader

Detailed ways

The following description serves to disclose the invention to enable those skilled in the art to practice the invention. The preferred embodiments described below are given by way of example only, and other obvious modifications will occur to those skilled in the art.

A MAC protocol data unit (PDU) as shown in FIG. 1 includes a MAC header, 0 or more MAC service data units (MAC SDUs), 0 or more MAC control units, and possibly other padding.

A MAC PDU is a byte-aligned bit string in length (ie, a multiple of 8bit), and the bit string is represented in a table format, where the most significant bit is located at the leftmost of the first row of the table, and the least significant bit is located in the last row of the table. On the far right, normally, the bit string is read line by line from left to right. The bit order of each parameter field in the MAC PDU is to place the first or most significant bit on the leftmost and the last or least significant bit on the rightmost.

MAC SDUs are contained in MAC PDUs and are byte-aligned bit strings (ie, multiples of 8 bits) in length, starting from the first bit.

The MAC header includes multiple MAC subheaders, and the other MAC subheaders except the last subheader among the multiple MAC subheaders include six header fields R/R/E/LCID/F/L. The last subheader of the MAC subheader and the fixed length MAC control element subheader contain four header fields R/R/E/LCID. The corresponding MAC PDU subheader also contains four header fields R/R/E/LCID, as shown in Figure 2.

The order of the MAC subheaders is consistent with the order of the corresponding MAC SDUs, MAC control elements and padding.

The MAC control element is placed at the front of all MAC SDUs, and the padding is placed at the end of the MAC PDU.

Each UE can transmit at most one MAC PDU per TB block. A maximum of one MCH MAC PDU can be transmitted per TTI.

The MAC subheader is variable in size and consists of the following fields:

LCID: logical channel ID field, which identifies the logical channel corresponding to each MAC SDU, the type or padding of the MAC control unit, and each MAC SDU, MAC control unit or padding in the MAC PDU corresponds to an LCID field. LCID field length is 5 bits;

L: Length field, indicating the number of bytes corresponding to the MAC SDU or variable-length MAC control unit. Except for the last subheader and the subheader corresponding to the fixed-length MAC control element, there is an L field in the subheader of the MAC PDU. The size of the L field is indicated by the F field;

F: Format field, indicating the length of the length field. Except for the last subheader and the subheader corresponding to the fixed-length MAC control unit, each MAC PDU subheader contains an F field, and the length of the F field is 1 bit. If the length of the MAC SDU or variable length MAC control unit is less than 128 bytes, the F field shall be set to 0, otherwise it shall be set to 1;

E: Extended field, the extended field is a flag bit, indicating whether there are other fields in the MAC header. If the E field is set to "1", it means that there is at least one other group of R/R/E/LCID fields following it. If the E field is set to "0", it means that the following bytes are MAC SDU or MAC control unit or padding.

R: reserved bit, set to "0".

Both the MAC header and the MAC subheader are byte aligned.

Normally, when the MAC entity encapsulates the MAC layer SDU into a PDU, if the length of an SDU is too large to be completely encapsulated into a PDU, it will be encapsulated in segments, and the remaining segments of the SDU will wait for the next transmission; Small, there are remaining resources after encapsulating one SDU, continue to encapsulate the next SDU in the PDU, that is, concatenate with other SDUs, each SDU has a MAC subheader corresponding to it, and the E field in the MAC subheader The indication is followed by SDUs, so that each encapsulated PDU will fully utilize the indicated resources.

In the implementation mechanism of the RLC AM transmission mode, the transmission status needs to be confirmed, and there are a large number of status PDUs. Since each TTI can transmit at most one MCH MAC PDU, when the transmission PDU is a status PDU, due to the short status packet, a TB block cannot be filled, and there is a waste of resources. When the transmission PDU is a status PDU, the algorithm judges whether there are data units remaining in the current transmission, and if so, the status PDU is used for data transmission. The original MAC subheader is shown in Figure 2. The MAC subheader is now extended, as shown in Figure 3. Add a 1-bit extension field E1 after the format field F. If the E1 field is set to "1", it means that there is at least another group of F/E1/LI fields after it; if the E field is set to "0", it means that The following bytes are MAC SDU, the E1 field is followed by the LI field indicating the length, and a MAC subheader can have multiple E1 fields.

The foregoing has shown and described the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions describe only the principles of the present invention. Without departing from the spirit and scope of the present invention, there are various Variations and improvements are intended to fall within the scope of the claimed invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims (2)

1. a MAC protocol data transmission method for TD-LTE, is characterized in that, when MAC entity encapsulates MAC layer SDU into PDU, if an SDU length is less, after encapsulating an SDU, there are remaining resources, then continue in The next SDU is encapsulated in the PDU encapsulated by the SDU. Each SDU has a MAC subheader corresponding to it. The E field in the MAC subheader indicates that there are SDUs to follow. In the RLC AM transmission mode, when the transmission PDU is a status PDU When there is a data unit remaining in this transmission, it is judged whether there is any remaining data unit in the current transmission, and if so, the data transmission is performed by using the status PDU; wherein, the status PDU includes a MAC header, a MAC service data unit, and a MAC control unit, and the MAC header includes multiple MAC subheaders, except for the last MAC subheader in the MAC subheader, the rest of the MAC subheaders include six header fields R/R/E/LCID/F/L, and there is also a 1 bit after the header field F of the MAC subheader The extension field E1, the E1 field is followed by the LI field indicating the length, if the extension field E1 is set to "1", it means that there is at least another group of F/E1/LI fields after it; if the extension field E1 is set to " 0", indicating that the following bytes are MAC service data units. 2 . The method for transmitting MAC protocol data for TD-LTE according to claim 1 , wherein the extension field E1 of one MAC subheader is at least one. 3 .