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Narrow band power line communication over low-voltage mains -- Part 31: Narrow band orthogonal frequency division multiplexing power line -- Communication physical layer specification
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Basic data | Standard ID | GB/T 31983.31-2017 (GB/T31983.31-2017) | | Description (Translated English) | Narrow band power line communication over low-voltage mains -- Part 31: Narrow band orthogonal frequency division multiplexing power line -- Communication physical layer specification | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | N22 | | Classification of International Standard | 17.220.20 | | Word Count Estimation | 35,388 | | Date of Issue | 2017-05-12 | | Date of Implementation | 2017-12-01 | | Quoted Standard | GB/T 31983.11-2015 | | Issuing agency(ies) | General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China | | Summary | This standard specifies the low-voltage narrowband power line communication (PLC) physical layer protocol specification based on orthogonal frequency division multiplexing (OFDM) technology, including physical layer protocol data unit format (PPDU), channel coding, interleaving, OFDM modulation, physical layer signal Frame generation and continuous transmission mode and power frequency synchronization zero time slot transmission mode. This standard applies to the 3 kHz ~ 500 kHz band through indoor or outdoor low voltage AC distribution line or DC transmission line for data transmission and communication. On the basis of the standard physical layer protocol specification, a complete PLC system composed of multiple communication nodes established on the low voltage distribution network also includes a data link layer (DLL, a medium access control sublayer MAC and a logical link Control sublayer LL | GB/T 31983.31-2017: Narrow band power line communication over low-voltage mains -- Part 31: Narrow band orthogonal frequency division multiplexing power line -- Communication physical layer specification
---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Narrow band power line communication over low-voltage mains - Part 31.Narrow band orthogonal frequency division multiplexing power line - Communication physical layer specification
ICS 17.220.20
N22
National Standards of People's Republic of China
Low-voltage narrowband power line communications. Part 31.Physical layer specification for narrowband orthogonal frequency division multiplexing power line communications
2017-05-12 released
2017-12-01 implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Issued by China National Standardization Administration
Table of contents
Foreword Ⅰ
Introduction Ⅱ
1 Scope 1
2 Normative references 1
3 Terms and definitions, symbols, abbreviations 1
4 Network model 4
4.1 PLC domain 4
4.2 Reference model 4
5 Physical layer coding and modulation 5
5.1 Overview 5
5.2 Physical layer block diagram 6
5.3 Data preprocessing 6
5.4 Physical layer frame format 7
5.5 Subcarrier 9
5.6 Channel coding 10
5.7 OFDM modulation 13
6 Physical layer signal transmission mode 20
6.1 Overview 20
6.2 Continuous transmission mode 20
6.3 Power frequency synchronization zero-crossing time slot transmission mode 20
7 Physical layer services 20
7.1 Overview 20
7.2 Data Services 20
7.3 Physical layer management services 23
7.4 Physical layer constants and attributes 24
8 Electrical index requirements 25
Appendix A (normative appendix) CRC-5 and CRC-16 structure 26
Appendix B (Normative Appendix) Frequency Scheme 27
Appendix C (Normative Appendix) Structure of Bit Scrambling 28
Appendix D (Normative Appendix) Structure of Convolutional Encoder 29
Appendix E (normative appendix) Pseudo random sequence PNb(k) generator structure diagram 30
Reference 31
Foreword
GB/T 31983 "Low-Voltage Narrowband Power Line Communication" is divided into the following parts.
---Part 11.3kHz~500kHz frequency band division, output level and electromagnetic disturbance limit;
---Part 21.3kHz~500kHz frequency band communication equipment and system immunity requirements;
---Part 31.Narrowband Orthogonal Frequency Division Multiplexing Power Line Communication Physical Layer Specification;
---Part 32.Narrowband Orthogonal Frequency Division Multiplexing Power Line Communication Data Link Layer Specification.
This part is part 31 of GB/T 31983.
This section was drafted in accordance with the rules given in GB/T 1.1-2009.
Please note that certain contents of this document may involve patents. The issuing agency of this document is not responsible for identifying these patents.
This part was proposed by China Machinery Industry Federation.
This part is under the jurisdiction of the National Electrical Instrumentation Standardization Technical Committee (SAC/TC104).
Drafting organizations of this section. State Grid Heilongjiang Electric Power Co., Ltd., Shenzhen Lihe Microelectronics Co., Ltd., Harbin Electrical Instrument
Research Institute, China Electric Power Research Institute, Qingdao Dingxin Communication Co., Ltd., Juquan Optoelectronics Technology (Shanghai) Co., Ltd., State Grid
Qingshi Electric Power Company Electric Power Research Institute, Heilongjiang Electric Power Co., Ltd. Measurement Center, Shenzhen Aerospace Teruijie Electronics Co., Ltd., China
Grid Jiangsu Electric Power Research Institute, Yunnan Power Grid Co., Ltd. Electric Power Research Institute, State Grid Jiangxi Electric Power Research Institute
Institute, Yantai Oriental Weston Electric Co., Ltd., Jiangsu Linyang Energy Co., Ltd., Holley Technology Co., Ltd.
The main drafters of this section. Liu Kun, Wang Xuan, Chen Bo, Ge Dehui, Liu Xuan, Meng Yu, Zhang Xuming, Li Wanhong, Zhao Feng, Guan Wenju, Yang Xiaoyuan,
Sun Hongliang, Cao Min, Wang Tianyu, Zhao Zhenyu, Ji Feng, Liu Jian, Wang Wenguo, Lu Hanxi, Zeng Shitu, Chen Wenxin, Jiang Bin.
Introduction
With the rapid development of smart grid and power Internet of Things, there is an urgent need to improve network and communication technology according to new demands. The grid itself
It is a huge network connecting various electrical equipment and terminals, using power lines for data transmission and realizing various electrical equipment and terminals
The network connection has the advantage of not requiring rewiring. Developed countries and the International Organization for Standardization use power lines as the medium for communication technologies and standards
With the advancement of industrialization, standards such as ITU.g.9901/2/3/4 and IEEE1901.2 have been introduced successively. In this context, this standard system is formulated in accordance with China's national conditions.
This physical layer protocol specification supports 3kHz~500kHz power line communication dedicated frequency band, suitable for data equipment passing indoor or outdoor
Low-voltage AC distribution lines or DC transmission lines for data transmission and communication. This physical layer protocol specification is based on Orthogonal Frequency Division Multiplexing (OFDM)
Technology, and allows specific application systems to define specific center frequency and bandwidth.
On the basis of this physical layer protocol specification, the data link layer protocol can be defined. This physical layer protocol specification is not limited to any specific
Narrowband power line communication application layer protocol, which is suitable for various low-voltage narrowband power line communication application systems, including (but not limited to) smart
Energy meter centralized meter reading (AMR), AMI/AMM, smart home control, street lamp control, building intelligence, electric vehicle charging control, etc.
Low-voltage narrowband power line communication
1 Scope
This part of GB/T 31983 specifies the physics of low-voltage narrow-band power line communication (PLC) based on orthogonal frequency division multiplexing (OFDM) technology
Layer protocol specifications, including physical layer protocol data unit format (PPDU), channel coding, interleaving, OFDM modulation, physical layer signal frame generation
And continuous transmission mode and power frequency synchronization zero-crossing time slot transmission mode, etc.
This part is applicable to data transmission in the frequency range of 3kHz~500kHz through indoor or outdoor low-voltage AC power distribution lines or DC transmission lines
And communication. On the basis of this part of the physical layer protocol specifications, a complete set of multiple communication nodes established on the low-voltage distribution network
The entire PLC system also includes a data link layer (DLL, which is composed of a medium access control sublayer MAC and a logical link control sublayer LLC) to
And the application layer related to the specific application situation. Typical low-voltage narrow-band power line communication application scenarios include centralized meter reading of smart energy meters
(AMR), AMI/AMM, home smart control, street light control, smart building, four-meter collection and smart grid (SmartGrid) other
Applications, such as. electric vehicle charging control, etc.
This section also applies to medium-voltage power line communications, and long-distance power line communications in cities and rural areas.
2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article
Pieces. For undated references, the latest version (including all amendments) applies to this document.
GB/T 31983.11-2015 Low-voltage narrowband power line communication Part 11.3kHz~500kHz frequency band division, output level
And electromagnetic disturbance limit
3 Terms and definitions, symbols, abbreviations
3.1 Terms and definitions
The following terms and definitions apply to this document.
3.1.1
Power line communication
The information data is modulated to a suitable carrier frequency, and the power line is used as a physical medium for transmission to realize communication between data terminals.
Letter or control.
3.1.2
Power line carrier communication
That is power line communication.
3.1.3
Narrowband power line communication
Power line communication with carrier frequency in 3kHz~500kHz frequency band.
3.1.4
Low voltage power line communication
Power line communication using low-voltage distribution lines as the medium.
3.1.5
PLC low-level protocol
The PLC low-level protocol includes the physical layer and the data link layer (consisting of the medium access control sublayer and the logical link control sublayer).
3.1.6
PLC application
The specific power line communication application system based on the PLC low-level protocol has certain business functions and application-level protocols.
3.2 Symbols
The following symbols and codes apply to this document.
b ---The width of the bit group loaded on the subcarrier.
DL --- The length factor of the payload carrying data.
G ---The number of subcarrier groups.
4 Network model
4.1 PLC domain
The PLC domain refers to a power line communication category established on the low-voltage distribution network. It has the following characteristics.
a) A PLC domain contains a domain management node (DM) and multiple terminal equipment nodes (TN). DM is responsible for managing the
Terminal equipment nodes, including network management and routing management. Each node has a medium access control (MAC) ground
The address should be unique in a domain.
b) There may be multiple PLC domains on the same low-voltage distribution network, and each domain has a domain ID (DID).
Within the power grid, the domain identifier should be unique. The division of these domains is logical rather than physical, and adjacent domains may partially overlap.
Therefore, nodes belonging to a certain domain may "hear" nodes in another domain at the physical layer. To eliminate or reduce this inter-domain string
For the impact of interference on PLC communication, certain measures should be taken, including wave isolation, domain identification, and time domain or frequency domain multiplexing channels
Access mechanism, etc.
c) The PLC domain can be an "incomplete connection" domain, that is, due to channel noise, interference and signal attenuation between two nodes in the domain.
Can not realize the physical layer point-to-point communication. Therefore, the communication between nodes in the domain may need to be relayed by other nodes.
4.2 Reference model
4.2.1 Overview
The PLC domain protocol reference model and its corresponding relationship with the OSI reference model are shown in Figure 1.It includes the physical layer (PHY), media access
Ask the control sublayer (MAC), logical link control sublayer (LLC), application support layer (APS) and application layer (APP). PHY layer, MAC sub
The composition of the layer and LLC sub-layer does not depend on the low-level protocol of the specific application. It provides services for the application layer through the APS layer and the application interface (AI).
In the actual system, the application layer corresponds to a specific application situation and application layer protocol, such as. AMR, home energy management
(HEM) and so on.
Figure 1 PLC reference model
4.2.2 Main functions and services of each layer
The APS layer provides adaptation functions for the application layer protocol data to be transmitted through the DLL layer. Application interface (AI) consists of specific application scenarios
The definition generally includes physical or logical interfaces and interactive protocols. The application layer submits data to be sent through AI, and receives data through AI.
APS uses data link layer services for data transmission and reception.
The LLC sublayer and the MAC sublayer constitute the data link layer DLL. DLL provides an end-to-end data link for the application layer. LLC sublayer
Responsible for the establishment, management and control of network routing, including node relay and forwarding control. The MAC sublayer is responsible for the access control of the power line shared medium
Controls, including carrier sense and collision avoidance (CSMA/CA) algorithms, to avoid sending conflicts.
The physical layer is responsible for channel coding and OFDM modulation of MAC sublayer data, generating physical layer signal frames, and coupling signals to
Transmission on the power line. In the receiving direction, the physical layer will demodulate and decode the signal frame received from the power line to restore the data link
Layer data and submit it to the MAC sublayer.
The medium-independent physical layer interface (PMI) is a physical layer service interface independent of the specific physical medium. PMI is a functional interface,
Service primitive definition, including PHY layer data and management services.
The physical layer is connected to the physical medium through the medium-dependent interface (MDI). MDI is related to the specific physical medium. MDI includes signal
Electrical index requirements, as well as the coupling and connection specifications of signals and physical media.
In addition, the physical layer, MAC sublayer, LLC sublayer, and APS layer pass the management primitives PHY-MGMT, MAC-MGMT,
LLC-MGMT and APS-MGMT provide management services.
4.2.3 Physical layer services
The physical layer provides data services and management services that do not depend on specific physical media through PMI, as shown in Table 2 and Table 3.
5 Physical layer coding and modulation
5.1 Overview
This physical layer is based on the narrowband OFDM technology covering the frequency band of 3kHz~500kHz, and supports the continuous transmission of physical layer signal frames
Or power frequency synchronous zero-crossing time slot transmission mode.
5.2 Physical layer block diagram
The physical layer transmitter block diagram is shown in Figure 2.
The transmitter completes the conversion from the input data bits to the power line transmission signal. The input data bits to be sent are bit scrambled,
RS coding, convolutional coding, puncturing, bit repetition, interleaving, then bit-to-symbol constellation mapping, and then the mapped data and pilot
The data is modulated together with OFDM symbols, and the cyclic prefix is inserted and the window is overlapped, thus forming the frame body part of the data. Data frame body
Part of it is multiplexed with the preamble and frame header to form a transmission signal frame, which is finally injected into the power line for transmission through the analog front end.
5.3 Data preprocessing
5.3.1 CRC check
The MAC layer protocol data unit (MPDU) to be sent is passed to the physical via the PMI interface service primitive PHY-DATA.req
Layer, the data length is LMPDU bytes. The LMPDU byte data input to the physical layer becomes Ld byte after zero-filling according to formula (2) and represents
For DL. The Ld byte data becomes the data actually sent by the physical layer. At the sending end, calculate CRC-16 for Ld byte data, and add
The 16-bit CRC check word is appended to the back of the data block to form Ld 2 bytes.
The implementation structure of CRC-16 is shown in Appendix A.2, its initial value is 0xFFFF, and it is reset before encoding when each new MPDU is input.
5.3.2 Framing transmission
If the Ld 2 byte data exceeds the maximum data length BytesPerFrame that a single physical frame can carry, it needs to be split into
Multiple physical frames are sent. The physical layer encodes and sends each sub-frame independently. Framing consists of the Framing Sequence Number (FSN) in the physical frame header
To identify.
The framing process is as follows.
a) If sending Ld 2 bytes does not exceed BytesPerFrame, then a single frame is sent; BytesPerFrame is carried by a single frame at the physical layer
The maximum number of OFDM (MOFDM), modulation method, coding method, and number of subcarrier groups are determined. MOFDM=64.
b) Otherwise, split the Ld 2-byte data into multiple sub-frames for transmission. The framing processor determines the score according to BytesPerFrame
The number of frames and the number of bytes sent per frame.
c) Each sub-frame is encoded and sent independently, and is identified by FSN (see Table 5).
5.4 Physical layer frame format
5.4.1 Overview
The physical layer frame consists of a preamble, a physical frame header (PFH), an extended frame header (PFH_EXT) (if any) and a payload (Payload) group
As shown in Figure 3.
Figure 3 Physical layer frame structure
The preamble is used by the receiver for frame detection, frame synchronization and timing, and carries transmission mode recognition. The physical frame header carries the frame type, coding and modulation
Information such as control mode is provided for the receiver to demodulate and decode the received physical layer signal frame. Extended frame header (if any) carries subcarrier dynamics
Mapping table. The frame load field carries the MAC layer protocol data unit (MPDU), the length of which is variable.
5.4.2 Preamble
The preamble is mainly used for frame signal detection at the receiving end, frame synchronization, receiver timing synchronization, etc., and carries the transmission mode identifier. Local physical layer
Two transmission modes are supported. continuous transmission and power frequency synchronous zero-crossing time slot transmission. The sending end can use any of them, and the receiving end will automatically detect it.
The identification codes corresponding to the two transmission modes are.
5.4.3 Physical Frame Header (PFH)
The physical frame header is 30 bits of information, including frame type (FT, 1 bit) and frame control information (FCI, 29 bits).
This physical layer defines two frame types, namely data frame and confirmation frame. The definition is shown in Table 4.
Table 4 Frame type FT definition
Domain name bit width bit definition
Frame type (FT) 1 b0
0.data frame
1.confirmation frame
According to the different frame types, the meaning of FCI is also different, divided into data frame FCI and confirmation frame FCI.
When FT=0, the frame type is data frame, and the FCI definition of data frame is shown in Table 5.
5.4.4 Extended frame header (PFH_EXT)
When the frame header extension flag (EXT) in the physical frame header PFH is 1, PFH follows PFH_EXT.
PFH_EXT has a total of 36 bits, subcarrier dynamic mapping (TM) occupies 31 bits, and the extended frame header check word EHCS occupies 5 bits, as shown in Table 7.
The smallest unit of sub-carrier dynamic shielding is a sub-carrier super group. See 5.5.3 for the definition of subcarrier supergroup.
When multiple frames are continuously sent, if there is sub-carrier dynamic shielding, the first frame carries the sub-carrier dynamic mapping table through PFH_EXT, and the subsequent frames
No need to carry PFH_EXT repeatedly.
5.4.5 Payload
The payload carries user or high-level protocol data, that is, the physical layer service data unit (PSDU).
5.5 Subcarrier
5.5.1 Subcarrier type
Subcarriers are divided into the following types.
a) Unavailable subcarriers (FSC). specified according to national or regional frequency band policies or for other purposes (e.g. guard band)
Frequency not allowed. FSC should be set to 0.
b) Usable subcarrier (USC). Subcarriers other than FSC. However, the subcarriers used in a specific application situation and the application situation
It is related to the specific working frequency band. Therefore, USC is further divided into.
1) In-band sub-carrier (IBSC). The sub-carrier contained in the working frequency band of the application situation, which is further divided into.
① Data subcarrier (DSC). Load data bits, used to transmit data information;
② Pilot subcarrier (PSC). load special known data bits for receiver timing recovery, channel estimation, etc.;
③ Masked subcarrier (MSC). The subcarrier that is masked and cannot be used in the band is set to 0.
2) Out-of-band sub-carrier (OBSC). The available sub-carrier not included in the working frequency band, set to 0.
5.5.2 Subcarrier group
10 consecutive subcarriers form a subcarrier group.
5.5.3 Subcarrier Super Group
A sub-carrier super group is composed of 4 consecutive sub-carrier groups.
5.5.4 Subcarrier shielding
Subcarrier shielding is divided into static shielding and dynamic shielding. Static shielding refers to the sub-carriers that the transmitter and receiver have agreed and are not used. move
State shielding means that the sender changes the subcarrier used at any time according to the channel conditions, and the subcarrier shielding information needs to be notified to the receiver through the frame header
end. Static shielding applies to preamble, physical frame header, extended frame header (if any) and payload, and dynamic shielding only applies to payload.
When statically shielding in-band subcarriers, the entire subcarrier group in which the subcarrier is located and its left and right adjacent groups should be shielded, which is called the masked subcarrier.
Carrier Group (MSG). The subcarrier group that is not masked in the band is called the effective subcarrier group (ASG). An effective subcarrier group includes 1
Pilot sub-carrier (PSC), the remaining sub-carriers carry data bits, namely data sub-carrier (DSC).
When using dynamic sub-carrier shielding within the working bandwidth, the minimum shielding unit is a sub-carrier super group.
5.5.5 Frequency scheme
The frequency plan (FrequencyPlan) refers to the specific working frequency band of the application. It can start from any subcarrier, but always contains the whole
Several sub-carrier groups. The specific number of subcarrier groups determines the bandwidth of the frequency plan. The starting subcarrier of the frequency scheme corresponds to the frequency Fstart, and the end
The sub-carrier corresponds to the frequency Fend. See Appendix B for the frequency plan.
5.6 Channel coding
5.6.1 Bit scrambling
In order to increase the randomness of the transmitted data, bit scrambling is used to scramble each sub-frame data stream.
The bit scrambling code is a binary pseudo-random sequence. The generator polynomial is shown in equation (4).
G(X)=X9 X4 1 (4)
The structure of the bit scrambling code is shown in Appendix C, and its initial value is 0x1FF.
5.6.2 RS coding
The scrambled bit stream is then subjected to RS coding. The RS encoder supports the following RS codes.
a) RS(k 8,k), generated by truncation of the original RS(255,247);
b) RS(k 16,k), produced by truncating the original RS(255,239).
5.6.3 Convolutional coding
The output data of the RS encoder is converted into a bit stream (LSB first) and input to the convolutional encoder, and finally 6 zeros are added (flushing bits).
The convolutional code adopts convolutional coding with a constraint length of 7 and a coding efficiency of 1/2.Its generator polynomial is (133,171). See Appendix D for its encoder structure.
5.6.4 Punch
Puncturing the data after convolutional coding realizes different coding efficiency. The relationship between code rate and puncturing position is shown in Table 8.In the table,
"1" means sending the bit data at this position, and "0" means not sending the bit data at this position.
5.6.5 Bit repetition
Bit repetition refers to the repetition of a certain multiple of data bits after convolutional coding, and the repetition multiple can be 1, 2, 4, or 6.Repeated
The rule is. each bit of the convolution output is repeated and sent to the interleaver in turn.
5.6.6 Interleaving
5.6.6.1 Interleaver
The data after bit repetition is first filled with random bits (see 5.6.6.2 for the filling rules) and the data volume is 9×G×b×n bits.
Where G is the available subcarrier group, b is the number of subcarrier loading bits, and n is the number of OFDM symbols.
The stuffed data is written into the interleaver column by column in the form of a bit stream. The structure of the bit interleaver is shown in Figure 4.The interleaver has m columns and
n rows, where the maximum m is 216.If there is remaining data when the interleaver is full, first output the interleaver, and then repeat the above for the remaining data
The steps are interleaved.
5.6.6.2 Bit stuffing
If the number of data bits carried by the physical frame header, extended frame header (if any) or payload part of the integer OFDM symbols is greater than the actual number of data to be transmitted
To send data, the data to be sent needs to be filled appropriately, that is, pseudo-random bits are appended to the data bits to be sent in the interleaver;
The random bits used for ...
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