A kind of ethernet physical layer data transmission method, system and equipment
Technical field
The present invention relates to communication technical field, relate in particular to a kind of ethernet physical layer data transmission method, system and equipment.
Background technology
In the ethernet communication system, carry out transfer of data through physical layer between the equipment, wherein the encoding and decoding of data are to be realized by the PMD in the physical layer (Physical Medium Dependent, physical medium is relevant) sublayer.The PMD sublayer coded system of existing ethernet standard comprises: NRZ (Non-Return-to-Zero; Non-return-to-zero) coding, NRZI (Non-Return-to-Zero-Inverse; The non-return-to-zero anti-phase) coding, Manchester (Manchester) coding, MLT-3 (Multi-level Transmission-3 levels; Multilevel transmission-3 level) coding and PAM (Pulse Amplitude Modulation, pulse amplitude modulation) encode etc.The specific coding structure is as shown in Figure 1: the nrz encoding mode is used in the low-speed communication usually, by pulse clock in the cycle height of level represent that if high level, then expression numeral 1, if low level, then expression numeral 0; The nrzi encoding mode does not return 0 for meeting 1 upset; The Manchester coded system is for having saltus step in the middle of each binary digit, and with indicator bit value, for example, the logical zero value is indicated in from 1 to 0 saltus step, from 0 to 1 saltus step indication logical one value; The MLT-3 coded system be a kind of ambipolar coding (comprise+V, 0 ,-three level of V), signal can transition between adjacent two level, is 1 during saltus step, is 0 during not saltus step; The PAM coded system is the multilevel electrical level coded system, and each clock cycle is sent a symbol, and each symbol once comprises two positions; For example; For PAM-4, comprise 00,01,10 and 11, thereby its each code element (symbol) can load the data of 2bit; Therefore the frequency halving of symbol is suitable for transmitting higher chip rate when transmission phase same rate.
The chip rate of several kinds of coded systems commonly used is as shown in table 1 in the PMD sublayer coding of existing ethernet standard:
Table 1:
Coded system |
Chip rate (Symbol rate) |
Manchester(10BaseTX) |
20M baud/second |
MLT-3(100BaseTX) |
125M baud/second |
PAM-8(100BaseTX) |
41.7M baud/second |
Can know through table 1: the Manchester coding is represented a bit with two code elements; The efficient of coding has only 50%; Promptly need double transmission bandwidth (signal rate is 2 times of data rate), for example, transmission rate is the Manchester coded data that the Ethernet of 20Mb/s can only transmit 10Mb/s; Therefore, code efficiency is lower.But, all carry clock information in each code element of Manchester coding, so recovered clock only needing several code elements, resume speed is very fast.The PAM code efficiency is higher; But not to be each code element all carry tangible clock information for it; Therefore the speed of recovered clock is slow, and the initial clock synchronization time at communication two ends needs accurately recovered clock of tens code elements, the corresponding magnitude of absolute time about 100 μ s (microsecond).
In existing radio and television standard; EPCN (Ethernet Passive Coxial Network; Ether passive coaxial network) system uses the coaxial frequency band of TV to distribute from 5MHz~1GHz; Wherein 65MHz uses as programme channel to 1GHz, and 5MHz~65MHz uses as bidirectional data path.Distribute according to this channel, when base band Ethernet and TV programme are used the coaxial cable transmission, owing to the base band Ethernet can not interfering TV program transmission; Therefore can only be the frequency resource that takies below the 65MHz; But in the frequency resource below 65MHz,, can only carry out the Ethernet transmission (it takies 20MHz) of 10Mbps according to the transmitted symbol speed of present Ethernet; And the Ethernet transmission that can not carry out 100Mbps (is used the 8B/10B coding; Take 125MHz) because be in this moment on the above frequency band of 65MHz, the transmission of meeting interfering TV program.Therefore in the EPCN system,, can only be to adopt high efficiency coded system, reduce the frequency spectrum resource that transmission needs if consider and the transmission of TV conllinear.
In addition, the EPCN system is again the time division communication system of a point-to-multipoint (for example 48 points), comprises a CLT (Coxial Line Terminal, coaxial line terminal) and 48 CNU (Coxial NetworkUnit, coaxial network unit).Wherein, CLT is a local side apparatus, and CNU is a ustomer premises access equipment, and CLT is a down direction to CNU transmission data, and CNU is a up direction to CLT transmission data, and down direction sends data and up direction transmission data are time-division relations, such as the time period that takies 5ms separately.At down direction, because CLT never changes, promptly operational use time efficient is (5000 μ s-100 μ s)/5000 μ s=98%, and the system synchronization time, slow (like 100 μ s) were acceptables; But at up direction, establish 5ms in the time period, 48 CNU need send valid data one time to CLT; Send data because whenever change a CNU; CLT all need with this CNU again synchronously once, the time that promptly spends 100 μ s carries out physical layer synchronization and shakes hands, whole system is very long lock in time; Therefore operational use time efficient is (5000 μ s-48*100 μ s)/5000 μ s=4%, and this moment, system was available hardly.
Summary of the invention
The embodiment of the invention provides a kind of ethernet physical layer data transmission method, system and equipment, requires inconsistent problem with physical layer up-downgoing time synchronized in the limited frequency spectrum in the solution prior art.
The invention provides the data transmission method of ethernet physical layer in a kind of ustomer premises access equipment, be applied to comprise in the communication system of a local side apparatus and at least two ustomer premises access equipments, said method comprising the steps of:
Data to be sent are encoded through first coded system, send to said local side apparatus;
Reception is from the coded data of passing through second coded system coding of said local side apparatus, and said coded data is decoded.
Said data to be sent are encoded through first coded system specifically comprises:
Obtain the code element clock that said first coded system is used;
Utilize said code element clock and said first coded system that said data to be sent are encoded.
Said code element clock obtains according to the coded data from said local side apparatus.
Said data to be sent are encoded through first coded system also comprises before:
Obtain said data to be sent from the media access control MAC layer of ustomer premises access equipment.
Said first coded system is the fireballing coded system of recovered clock, and said second coded system is the high coded system of code efficiency.
Said first coded system comprises Manchester Manchester coding, and said second coded system comprises pulse amplitude modulation PAM coding.
Said local side apparatus is a coaxial line terminal, and said ustomer premises access equipment is a coaxial network unit.
The present invention also provides the data transmission method of ethernet physical layer in a kind of local side apparatus, is applied to comprise in the communication system of a local side apparatus and at least two ustomer premises access equipments, said method comprising the steps of:
Data to be sent through second coded system coding, are sent to said ustomer premises access equipment;
Reception is from the coded data of passing through first coded system coding of said ustomer premises access equipment, and said coded data is decoded.
Said data to be sent are encoded through second coded system specifically comprises:
Obtain the code element clock that said second coded system is used;
Utilize said code element clock and said second coded system that said data to be sent are encoded.
Said code element clock is generated by said local side apparatus.
Said data to be sent are encoded through second coded system also comprises before:
Obtain said data to be sent from the MAC layer of local side apparatus.
Said first coded system is the fireballing coded system of recovered clock, and said second coded system is the high coded system of code efficiency.
Said first coded system comprises the Manchester coding, and said second coded system comprises the PAM coding.
Said local side apparatus is a coaxial line terminal, and said ustomer premises access equipment is a coaxial network unit.
The present invention also provides a kind of ustomer premises access equipment, comprising:
The user side coding unit is used for data to be sent through first coded system coding;
User side first transmitting element is used for the coded data that said coding unit generates is sent to local side apparatus;
User side first receiving element is used to receive the coded data from said local side apparatus;
The user side decoding unit is used for the coded data of passing through second coded system coding from said local side apparatus is decoded.
Also comprise:
User side second receiving element is used for receiving said data to be sent from the MAC layer of said user side;
User side second transmitting element is used for said decoded data is sent to the MAC layer of said user side.
Also comprise:
Code element clock acquiring unit is used for obtaining the code element clock from the coded data of said local side apparatus.
Also comprise code element clock memory cell, be used to store the said code element clock that obtains.
Said first coded system is the fireballing coded system of recovered clock, and said second coded system is the high coded system of code efficiency.
Said first coded system comprises the Manchester coding, and said second coded system comprises the PAM coding.
The present invention also provides a kind of local side apparatus, comprising:
The local side coding unit is used for data to be sent through second coded system coding;
Local side first transmitting element is used for the coded data that said coding unit generates is sent to ustomer premises access equipment;
Local side first receiving element is used to receive the coded data from said ustomer premises access equipment;
The local side decoding unit is used for the coded data of passing through first coded system coding from said ustomer premises access equipment is decoded.
Also comprise:
Local side second receiving element is used for receiving said data to be sent from the MAC layer of said local side apparatus;
Local side second transmitting element is used for said decoded data is sent to the MAC layer of said local side apparatus.
Said first coded system is the fireballing coded system of recovered clock, and said second coded system is the high coded system of code efficiency.
Said first coded system comprises the Manchester coding, and said second coded system comprises the PAM coding.
The present invention also provides a kind of ethernet physical layer data transmission system, comprising:
Ustomer premises access equipment is used for data to be sent are encoded through first coded system, sends to local side apparatus, and will decode from the coded data of passing through second coded system coding of said local side apparatus;
Local side apparatus is used for data to be sent are encoded through second coded system, sends to said ustomer premises access equipment, and will decode from the coded data of passing through first coded system coding of said ustomer premises access equipment.
Compared with prior art, the embodiment of the invention has the following advantages:
In the embodiments of the invention; Adopt up direction and the asymmetric Ethernet coding method of down direction; Down direction adopt the code efficiency height and lock in time long coded system; Up direction adopts code efficiency low and coded system that lock in time is short makes under limited frequency spectrum resources, can accomplish the two way high speed data communications of point-to-multipoint.
Description of drawings
Fig. 1 is an ethernet physical layer coding structure sketch map in the prior art;
Fig. 2 is ustomer premises access equipment side data transfer process figure among the present invention;
Fig. 3 is local side apparatus side data transfer process figure among the present invention;
Fig. 4 is a kind of ethernet physical layer data transmission system of the present invention structure chart;
Fig. 5 is a user side ethernet physical layer equipment structure chart among Fig. 4 of the present invention;
Fig. 6 is a local side ethernet physical layer equipment structure chart among Fig. 4 of the present invention.
Embodiment
Below in conjunction with accompanying drawing and embodiment, specific embodiments of the invention describes in further detail:
The invention provides a kind of data transmission method of ethernet physical layer, be applied to comprise in the communication system of a local side apparatus and at least two ustomer premises access equipments, this method is taked asymmetric Ethernet coding method at up direction and down direction.
Wherein, ustomer premises access equipment side data processing procedure is as shown in Figure 2, may further comprise the steps:
Step s201, ustomer premises access equipment is encoded data to be sent through first coded system, and the data after will encoding send to local side apparatus.Data to be sent are comprised through first coded system detailed process of encoding: ustomer premises access equipment receives data to be sent from MAC (Medium Access Control, medium access control) layer; Ustomer premises access equipment with the system clock of this equipment as the code element tranmitting data register; Utilize this code element clock and first coded system that data to be sent are encoded; This system clock obtains from local side apparatus usually; For example, extract clock coded data of sending from local side apparatus or the out of Memory as code element clock (also can the clock that extract be handled through frequency multiplication or frequency division and obtain the code element clock), certainly; This system clock also can be stored in the subscriber terminal equipment in advance, and is regularly synchronous with local side apparatus.Wherein, first coded system is the fireballing coded system of recovered clock, for example, includes but not limited to Manchester coding etc., and ustomer premises access equipment includes but not limited to coaxial network unit, and local side apparatus includes but not limited to coaxial line terminal.
Step s202, ustomer premises access equipment receive the coded data of passing through second coded system coding from local side apparatus, and this coded data is decoded, and decoded data is sent to the MAC layer of this equipment.The decoding process that ustomer premises access equipment adopts is corresponding with second coded system.Wherein, second coded system is the high coded system of code efficiency, for example, includes but not limited to PAM coding etc.
Step s201 and step s202 do not have strict sequence requirement in the present embodiment.
Local side apparatus side data processing procedure is as shown in Figure 3, may further comprise the steps:
Step s301, through second coded system coding, the data after local side apparatus will be encoded send to ustomer premises access equipment to local side apparatus with data to be sent.Data to be sent are comprised through second coded system detailed process of encoding: local side apparatus receives data to be sent from this equipment MAC layer; Local side apparatus as the code element tranmitting data register, utilizes this code element clock and second coded system that data to be sent are encoded the system clock of this equipment.Wherein, second coded system is the high coded system of code efficiency, PAM coding etc. for example, and ustomer premises access equipment includes but not limited to coaxial network unit, local side apparatus includes but not limited to coaxial line terminal.
Step s302, local side apparatus receive the coded data of passing through first coded system coding from ustomer premises access equipment, and this coded data is decoded, and decoded data is sent to the MAC layer of this equipment; The decoding process that local side apparatus adopts is corresponding with first coded system.Wherein, first coded system is the fireballing coded system of recovered clock, for example, and Manchester coding etc.
Step s301 and step s302 do not have strict sequence requirement in the present embodiment.
The present invention also provides a kind of ethernet physical layer data transmission system; As shown in Figure 4; Comprise ustomer premises access equipment 100; Be used for data to be sent are encoded through first coded system, send to local side apparatus 200, and the coded data of passing through second coded system coding from local side apparatus 200 is decoded; Local side apparatus 200 is used for data to be sent are encoded through second coded system, sends to ustomer premises access equipment 100, and will decode from the coded data of passing through first coded system coding of ustomer premises access equipment 100.Wherein, first coded system is the fireballing coded system of recovered clock, includes but not limited to Manchester Manchester coding; Second coded system is the high coded system of code efficiency, includes but not limited to pulse amplitude modulation PAM coding.In addition, ustomer premises access equipment 100 includes but not limited to coaxial network unit, and local side apparatus 200 includes but not limited to coaxial line terminal.
Wherein, ustomer premises access equipment 100 is as shown in Figure 5, specifically comprises: user side second receiving element 110 is used for receiving data to be sent from the MAC layer of user side; User side coding unit 120 is used for data to be sent through first coded system coding; User side first transmitting element 130 is used for the coded data that coding unit generates is sent to local side apparatus 200; User side first receiving element 140 is used to receive the coded data from local side apparatus 200; User side decoding unit 150 is used for the coded data of passing through second coded system coding from local side apparatus 200 is decoded; User side second transmitting element 160 is used for decoded data is sent to the MAC layer of user side; Code element clock acquiring unit 170 is used for obtaining the code element clock from the coded data of local side apparatus 200; Code element clock memory cell 180 is used to store the code element clock that obtains.
Wherein, local side apparatus 200 is as shown in Figure 6, specifically comprises: local side second receiving element 210 is used for receiving data to be sent from the MAC layer of local side; Local side coding unit 220 is used for data to be sent through second coded system coding; Local side first transmitting element 230 is used for the coded data that local side coding unit 220 generates is sent to ustomer premises access equipment 100; Local side first receiving element 240 is used to receive the coded data from ustomer premises access equipment 100; Local side decoding unit 250 is used for the coded data of passing through first coded system coding from ustomer premises access equipment 100 is decoded; Local side second transmitting element 260 is used for decoded data is sent to the MAC layer of local side.
Data transmission procedure between ustomer premises access equipment 100 and the local side apparatus 200 specifically comprises:
At up direction; User side second receiving element 110 receives data to be sent from the MAC layer of user side; Encode with first coded system by user side coding unit 120; And coded data is sent to local side first receiving element 240 in the local side apparatus 200 through user side first transmitting element 130; 250 pairs of coded datas of passing through first coded system coding from ustomer premises access equipment 100 of local side decoding unit are decoded then, and decoded data are sent to the MAC layer of local side by local side second transmitting element 260.
At down direction; Local side second receiving element 210 receives data to be sent from the MAC layer of local side; By local side coding unit 220 data to be sent are encoded through second coded system; And the coded data that local side coding unit 220 generates is sent to user side first receiving element 140 in the ustomer premises access equipment 100 through local side first transmitting element 230; 150 pairs of coded datas of passing through second coded system coding from local side apparatus 200 of user side decoding unit are decoded then, and decoded data are sent to the MAC layer of user side by user side second transmitting element 160.
The present invention will be described with the EPCN system below, and the transmission of Ethernet is used the CLT of different physical layer encodes in the EPCN system respectively and CNU communicate by letter with receiving, and sends the physical layer encodes mode different with the reception use.When CLT sends data to CNU, adopt slow PAM coded system of high efficiency, lock in time; When CNU sends data to CLT, adopt fast Manchester coded system lock in time.
Detailed process comprises: at the transmitting terminal of CLT, physical chip adopts the transmission of encoding of high efficiency PAM physical layer encodes mode; The corresponding receiving terminal at CNU, physical chip adopt high efficiency PAM physical layer decoding process decoding to receive.At the transmitting terminal of CNU, physical chip adopts the transmission of encoding of fast Manchester physical layer encodes mode of clock synchronization time; At the receiving terminal of CLT, physical chip adopts the fast Manchester physical layer decoding process decoding of clock synchronization time to receive.At this communication direction, fully take into account the upper limit of usable spectrum simultaneously, improve bandwidth as far as possible.Such as, up usable spectrum is 65MHz in the existing system, therefore can adopt the Manchester coding, carries out the ethernet communication of 30Mbps transmission rate.
In addition, the EPCN system clock is to come from CLT, and CNU need use and from the data that CLT sends, recover the clock of coming out, as the tranmitting data register of CNU.Therefore, there is certain correlation in the master clock that CLT sends and CNU sends.For example, CLT send to use the PAM-8 coding to carry out the transfer of data of 100Mbps, and corresponding code element clock is 33M, and promptly the CNU clock that from data, recovers to come out is 33M.At this moment; CNU can use this clock (or variable frequency clock of this clock; Like two divided-frequency etc.) carry out transfer of data as the code element clock; According to the Manchester code efficiency, can the traffic carried message transmission rate be 16.5Mbps, can accomplish the high speed data transfer of descending 100Mbps, up 16.5Mbps.
Therefore, adopt the asymmetric coded system of up-downlink direction, both taken into account CLT, can take into account the data communication of two-forty again, promptly reach on coaxial cable any the high-speed bidirectional transfer of data of multiple spot with CNU shakes hands fast synchronously.
The above only is a preferred implementation of the present invention; Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; Can also make some improvement and retouching, these improvement and retouching also should be regarded as protection scope of the present invention.