GB/T 36454-2018Information technology—Telecommunications and information exchange between systems—Medium access control and physical layer specifications for middle-high throughput wireless local area network (English PDF)

3.1 Media access control protocol data unit

A data unit exchanged between two peer MAC entities using PHY layer services.

3.2 MAC management protocol data unit

A data unit exchanged between two peer MAC entities for implementing a MAC management protocol.

3.3 MAC service data unit

Information delivered as a unit between MAC service access points.

3.4 Central access point

An entity that provides access to the site for access.

3.5 Station

A terminal device that has a MAC and PHY function interface and can communicate with the CAP.

3.6 Modulation coding scheme

A combination of a particular modulation scheme and coding rate employed on the spatial stream.

3.7 Beamforming

A technique for pre-processing transmitted data based on known channel conditions.

3.8 Spatial stream

A data stream that is spatially transmitted in parallel.

3.9 Space-time stream

A space-time encoded stream that is space-time encoded for a spatial stream.

3.10 Group acknowledgement

Batch feedback to confirm the information.

3.11 Short preamble sequence

Training sequence for automatic gain control and coarse synchronization.

3.12 Long preamble sequence

Training sequence for fine synchronization and channel estimation.

3.13 System information channel

A physical channel containing system information such as frame structure configuration.

3.14 Control channel

A physical channel containing user uplink and downlink transmission scheduling information.

3.15 Downlink sounding channel

A physical channel used to transmit a downlink sounding signal to complete downlink channel measurement.

3.16 Uplink sounding channel

A physical channel used to transmit an uplink sounding signal to complete uplink channel measurement.

3.17 Uplink scheduling request channel

A physical channel used to transmit an uplink scheduling request signal.

3.18 Uplink random access channel

A physical channel used to transmit an uplink random access signal.

3.19 Downlink transmission channel

A physical channel used to transmit user downlink service data and control information.

3.20 Uplink transmission channel

A physical channel used to transmit user uplink service data and feedback information.

3.21 Downlink guard interval

The guard interval of the downlink to uplink transition in the physical layer frame structure.

3.22 Uplink guard interval

The guard interval for uplink to downlink conversion in the physical layer frame structure.

6.1 Overview

The MAC layer is used to manage and control the allocation and sharing of physical layer transmission resources among multiple users. The functional composition is shown in Figure 2. Definition of this standard The MAC layer has the following characteristics.

--- The system adopts a centralized control architecture for multi-user scheduling;

--- The system MAC layer provides connection-oriented services that support QoS for different priority services.

6.2 Adaptation sublayer

The MAC layer is divided into an adaptation sublayer and a MAC sublayer. The adaptation sublayer uses the services provided by the MAC sublayer. Adapter sublayer completion The function is as follows.

--- Receive SDU from the upper layer;

--- classify the received upper SDUs;

--- Send the PDU of the adaptation sublayer generated by this layer to the MAC sublayer;

--- Receive the SDU of the adaptation sublayer in the peer entity.

6.3 Media Access Control Sublayer

The basic functions of the MAC sublayer are divided into a management control plane and a data plane. The management control plane includes the following functions.

a) System configuration. Manage system configuration messages and interact with the terminal to configure system configuration information.

b) Radio resource management. mainly completes the service scheduling function, completes resource allocation based on service parameters and channel conditions, and has load Balance, access control and other functions.

c) Network management. responsible for initializing and accessing the process, generating the messages required for the access process, including. access code selection, capability negotiation, and so on.

d) QoS management. manages the QoS parameters of the service and maintains the establishment, modification and deletion of each service flow.

e) Power saving management. The STA that manages no service enters the sleep state, and returns from the sleep state to the active state.

f) PHY layer control, mainly including the following sub-functions.

1) Channel management. including channel switching, management spectrum measurement and message reporting;

2) MIMO management. channel detection mechanism to determine and select MIMO working mode determination and selection;

3) Link adaptation.

---CQI measurement and feedback;

---MCS selection and feedback;

--- Power control and management. The data plane includes the following functions.

---Automatic Request Retransmission (ARQ). acknowledgement and retransmission of MPDUs or fragmented/aggregated MPDUs of the MAC layer;

---Sharding/recombination. according to the scheduling result, the upper layer business data unit is fragmented and sent to the next processing module. Reassembling and recovering multiple fragments at the receiving end;

---MPDU generation. the upper layer service unit is encapsulated into a basic MAC frame, and then sent to the next processing module;

---MPDU aggregation. According to the scheduling result, the originating end performs aggregation operation on the upper layer service data unit.

7.1 Universal Media Access Control Frame Format

7.1.1 Overview of Universal Media Access Control Frame Formats

The frame format of the MAC Protocol Data Unit (MPDU) is shown in Figure 3. Each MPDU can be divided into three parts. The first part is The fixed-length general MAC header; the second part is the payload carried by the MPDU; the third part is the verification (FCS) information.

All the fields in the MAC frame contain bits that are numbered from low to high and sent to the physical layer in descending order.

The bits within one byte are transferred to the physical layer in order from left (LSB) to right (MSB). The bits contained in the same field follow the low The number order to the high corresponds to a decimal number, for example, b9~b11=000, corresponding to 0; b9~b11=001, corresponding to 4.

7.1.2 Frame Control Field

7.1.2.1 Overview of Frame Control Fields

The frame control field contains the following fields. protocol version, frame type, subtype, stream identifier (FID), retransmission indication, and reservation. For details, see the format.

Figure 4 shows. All MAC frames contain a frame control field.

7.1.2.2 Protocol Version Field

The protocol version field is 2 bits long and is always the same length and position in all revisions of this standard. For the purposes of this standard, The version value is 0, and all other values are reserved.

7.1.2.3 Frame Type and Subtype Fields

The frame type field has a length of 1 bit and the subtype field has a length of 5 bits. These two fields collectively identify the function of the frame. Frame type Two types. management controls and data. Each frame type is subdivided into several subtypes. Table 2 defines the various types of types and subtypes that are valid. combination.

7.1.2.4 Flow Identification (FID) field

The length of the FID field is 4 bits. 0000 is used to manage the control flow, and 0001~1111 is used for the data flow.

7.1.2.5 Retransmission indication field

The retransmission indication field has a length of 1 bit. If the current frame is a retransmission frame of the previous frame, this field is set to 1; otherwise, it is set to 0.

7.1.2.6 Reserved fields

The reserved field is 3 bits and the default setting is 0.

7.1.2.7 Fragmentation