CN1522021A - An upward decoding control method and apparatus - Google Patents
An upward decoding control method and apparatus Download PDFInfo
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- CN1522021A CN1522021A CNA031153267A CN03115326A CN1522021A CN 1522021 A CN1522021 A CN 1522021A CN A031153267 A CNA031153267 A CN A031153267A CN 03115326 A CN03115326 A CN 03115326A CN 1522021 A CN1522021 A CN 1522021A
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Abstract
The invention discloses a method for controlling RS decoding positioning of burst data packet on receiving end comprising the steps of, determining the time of arrival on the receiving end for each of the uplink business allocated in each uplink business bandwidth allocation device on the receiving end, establishing the corresponding relation between the business arrival time and business coding length for the cycle using MAP as periodic time on the receiving end, determining demodulator time sequence based on the determined business arrival time, thus producing the positioning signal needed by the decoder. The invention also discloses an apparatus for controlling RS decoding positioning of burst data packet on receiving end.
Description
Technical field
The present invention relates to a kind of at the method and apparatus that adopts DOCSIS to realize to determine in the uplink traffic transmission process valid data and Reed_Solomon (RS) coding correspondence position in the burst packet, particularly relate to after sending burst packets and having increased the Reed_Solomon coding, the data after the demodulator demodulation are determined the method and apparatus of the correspondence position of valid data and RS coding in the burst packet.
Background technology
DOCSIS has stipulated to be positioned at the cable modem (CM) of user's building and has been positioned at physical layer and medium access control system (MAC) layer protocol between the cable modem termination device systems (CMTS) of carrier network.Be cable system between CM and CMTS, its minimum level is traditional two-way tree-shaped and branch's coaxial cable net.
DOCSIS is the high-speed bidirectional Data Transport Protocol on the hfc plant, and the frequency range of its up channel is 5～42MHz.The up channel of DOCSIS uses the combination of FDMA and two kinds of access waies of TDMA, and frequency division multiple access (FDMA) mode makes system have a plurality of up channels.Standard code the burst transfer form of time division multiple access (TDMA) when inserting, support modulation system, multiple transmission symbol rate and preamble bit flexibly, support the Frame of fixing and variable-length and programmable Reed-Solomon block encoding etc. simultaneously.The up flexibly FEC coding of DOCSIS makes the length of the own regulation corrected data packets of the operator of system energy and the corrected number of bit errors in each bag.
Owing to be vulnerable to the interference of other signal in the frequency range content of 5～42MHz, adopting the DOCSIS agreement is in the broadband wireless communication system of point-to-multipoint of over-the-air protocol, in order to improve the system wireless transmission performance, lower the error rate in the wireless transmission process, bursty traffic to up transmission has adopted the Reed_Solomon coding in Base-Band Processing, in order from the data flow behind the coding of Reed_Solomon, to extract active data, need to determine the position of Reed_Solomon coding in the uplink burst data at receiving terminal.Yet, in the present demodulation chip that adopts the DOCSIS agreement to realize the uplink burst bag, also do not have this decoding function.In addition, because dysmetria is true, the problem of dislocation appears in the location that exists uplink burst data.
Summary of the invention
After the purpose of this invention is to provide a kind of employing DOCSIS agreement uplink burst data being encoded, the method and apparatus of the correspondence position of Reed_Solomon decoding in the burst packet of receiving terminal control Reed_Solomon decoder location.
According to a first aspect of the invention, a kind of method that the RS decoding is located in receiving terminal control burst packet is provided, wherein classify to uplink burst is professional according to the DOCSIS agreement at transmitting terminal, according to upstream bandwidth and the requirement of system transmissions reliable rows, coded data to every kind of service selection appropriate length, described method comprises step: according to the DOCSIS agreement, determine that each uplink service that distributes in each uplink service allocated bandwidth (MAP) arrives the moment of receiving terminal at receiving terminal; At receiving terminal is to set up professional due in and operation code length corresponding relation the cycle with MAP; Determine the demodulator sequential according to determined professional due in; According to the position of the Luo Meng of Reed-institute code field in data flow in DOSCSIS uplink burst data bag characteristic and the demodulator sequential location uplink burst data, thereby produce the framing signal that decoder needs, the K/T value switching signal that provides decoder to need, wherein K is the length of data in the burst packets, and 2*T is the length of RS coding.
According to a second aspect of the invention, a kind of device that the RS decoding is located in receiving terminal control burst packet is provided, wherein classify to uplink burst is professional according to the DOCSIS agreement at transmitting terminal, according to upstream bandwidth and the requirement of system transmissions reliable rows, coded data to every kind of service selection appropriate length, described device comprises: the DOCSIS protocol processor, be used for determining according to MAP and system's ranging information which uplink service each MAP has distributed, and the K/T value of each uplink service correspondence and the relation table of professional due in and K/T; Medium access control apparatus, the formed relation data of storage DOCSIS protocol processor produces reference clock, and produces and the output Reed Luo Meng of institute (RS) decoding control signal and parameter; The burst demodulation device, the bursty traffic after decoder provides burst interface sequence and RS coding; With the RS decoder, the bursty traffic of burst decoder supply is decoded according to RS decoding control signal and parameter; And bursty traffic behind the output decoder and sequential.
The invention solves based on the orientation problem of the business datum RS decoding behind the up RS coding of DOCSIS, solved simultaneously, the problem of dislocation the location of uplink burst data occurred because dysmetria is true at receiving terminal.
Description of drawings
To make the above and other objects and advantages of the present invention clearer by describe the preferred embodiments of the present invention below in conjunction with accompanying drawing, wherein
Fig. 1 is a reception sequential chart of determining upstream demodulator;
Fig. 2 is the block diagram based on DOCSIS up decoding control of expression according to the embodiment of the invention;
Fig. 3 is the schematic diagram of expression according to the mini-slot benchmark generator of the embodiment of the invention;
Fig. 4 is the block diagram of expression according to the RS decoding control of the embodiment of the invention; With
Fig. 5 is the flow chart according to the RS decoding control and treatment of the embodiment of the invention.
Embodiment
Describe principle of the present invention and preferred embodiment in detail below in conjunction with accompanying drawing.
In the DOCSIS standard, medium access sub (MAC) is on the up physical layer (or descending transmission convergence sublayer), under the link safety sublayer.One of main feature of MAC agreement is to distribute upstream channel bandwidth by CMTS to CM.Up channel is made of mini-slot stream (mini-slots), has professional classification feature, and various message transmission rates are provided, and at data link layer virtual support LAN.
DOCSIS agreement one has four big class mac frames, comprises the mac frame based on bag, the ATM cell mac frame, the mac frame that keeps PDU, the mac frame in specific packet header, in addition, in the present invention, the DOCSIS agreement is expanded, increased a kind of special mac frame and transmitted the E1 business.In specific mac frame, comprise regularly mac frame (only being used for descending) again, managing MAC frame, request mac frame, segmentation mac frame, cascade mac frame.Mac frame such as UCD that the managing MAC frame has again surplus in the of 20 type, MAP etc.In addition,, be divided into the E1 business, IP operation, management information business, claim frame business, the professional five kinds of mac frames of distance measurement request frame top these mac frame classification.Five kinds of professional uplink bursts of forming are responsible for assigning to different characteristics, as different coding parameters.
According to upstream bandwidth and the requirement of system transmissions reliable rows, to the coded data of every kind of service selection appropriate length.Listed the selected coding parameter of characteristics in the following table 1, the uplink burst bag that different business is formed has been selected different Reed_Solomon coding parameters, under the situation of bandwidth availability ratio, to improve its error correcting capability according to the frame of different uplink services.Be to select the parameter correspondence table below.
Table 1
| Business Name | Frame length (byte) | RS encoded K value | RS coding T value |
| IP operation | 88-1524 | ?128 | ?4 |
| The E1 business | 2-514 | ?64 | ?3 |
| Management information | 30-1534 | ?128 | ?4 |
| | 6 | ?6 | ?2 |
| Distance measurement request | 30 | ?30 | ?3 |
According to the DOCSIS agreement, determine that each uplink service that distributes among each MAP (uplink service allocated bandwidth) arrives the moment of receiving terminal at receiving terminal, this is a unit with the mini-slot constantly, is the absolute time of benchmark during with system's benchmark.At receiving terminal is to set up professional due in and operation code length corresponding relation the cycle with MAP.Determine the demodulator sequential according to determined professional due in.According to the position of Reed_Solomon code field in data flow in DOSCSIS uplink burst data bag characteristic and the demodulator sequential location uplink burst data, produce the framing signal that decoder needs, the K/T value switching signal that provides decoder to need.Wherein K is the length of data in the burst packets, and 2*T is the length of Reed_Solomon coding.The requirement of choosing coding parameter is in guaranteeing the scope that aerial transmission error rates allows, and improves transmission bandwidth as much as possible.For example, distance measurement request business datum length is 30, and choosing coding parameter K is 32, and T is 2, and promptly the utilance of effective information is 30/ (2+2*2) when transmission, and wherein K is a valid data length, and 2*T is an encoded byte length.
In the DOCSIS agreement, the delivery time of uplink service is to be defined by descending MAP.Define the transmission opportunity of transmitting terminal business by MAP, and determined the moment of professional arrival receiving terminal according to the time-delay of range finding.If specifying the delivery time of an IP frame among the MAP is the X moment, last line delay is Y, and the moment that arrives receiving terminal so is the X+Y moment.Based on this, can determine that uplink service arrives the moment of receiving terminal.Business among each MAP (IE) arrives the moment of receiving terminal with corresponding one by one to the coding parameter K/T of this IE distribution.
Fig. 1 shows the reception sequential chart of determining upstream demodulator.Be that CLOCKOUT is a demodulation clock, DATA_VALID indication demodulating data is effective, and DATA is data.Its relation is at DATA_VALID effectively therebetween, at the trailing edge of CLOCK data is adopted.
Below with reference to the device of Fig. 2 explanation according to the up RS decoding of the control DOCSIS of embodiment of the invention correspondence position.This device comprises processor 1, and medium are got involved controller (MAC) 2, burst demodulation device 3 and RS decoder 4.Processor 1 and medium are got involved controller 2 and are connected by bus, and burst demodulation device 3 passes through the demodulator interface signal line and is connected with RS decoder 4.As an example, processor 1 can adopt personal computer, PowerPC (MC8240) for example, but the invention is not restricted to this.As an example, burst demodulation device 3 can adopt 9257 demodulators.Medium are got involved between controller 2 and the RS decoder 3 and are connected by interface line.Processor 1 is the DOCSIS protocol processor, mainly to the processing of DOCSIS agreement, determines according to MAP and system's ranging information which uplink service each MAP has distributed, and the K/T value of every middle uplink service correspondence, and the relation table that reaches professional due in and K/T.The relation data that the main storage of processor 1 of MAC2 forms produces reference clock, and produces and export control signal and the parameter that is used to control the Reed_Solomon decoder.
Fig. 3 is according to mini-slot benchmark generator of the present invention, is used to provide reference clock.The markers counter is one 32 a counter, counting clock is 1024Mhz, provides reset signal Start_Clear from processor 1 to markers counter 5, and mini-slot counter 6 is synchronous with markers counter 5, the 5 every increases by 256 of markers counter, the mini-slot counter adds 1.
Below with reference to Fig. 2 and 4 are operating process of control RS decoder 4.Provide reset signal Start_Clear from processor 1 to markers counter 3.The counting clock of markers counter 3 is 1024Mhz.High 24 corresponding mini-slot counters 2 of markers counter 3 low 24, the counting clock of a mini-slot counting is 25us.Processor 1 writes 4-I and 6-I in the corresponding stored district in the mac controller 2 when producing first uplink service due in and professional K/T correspondence table according to MAP, and then writes an enabling signal (MAPSTART).This signal is as the address reset signal of professional due in memory and K/T memory, and making initial address is zero-address.Read the professional due in and the K/T value of corresponding address, when the mini-slot count value reaches when business arrives from moment that memory is read (by comparator 1), producing together, artery dashes, this signal one arrives, produce coding switching signal (RSC0 by decoder 15, RSC1), the K/T of 7 and 5 address generator control simultaneously memory is read the address, professional due in storage address adds one, whether effectively this signal enabling detects the next data useful signal (DATA_VALID) of demodulator (14) (high level is effective), when effective, start K*8 counter 12, and to put the RS coding control signal be low, when this counter meter during to K*8, starts 2*T*8 counter 13, put the RS coding control signal simultaneously for high, this signal period produces up to DATA_VALID signal step-down.
In order to realize the periodic Control of MAP, when the most-significant byte of the data of reading when professional due in memory was 0xFF, professional due in memory and K/T value memory read first address and switch in the next memory cell in the ping-pong structure (among 4-II and the 6-II).If the IE item among the MAP is 256, reads the address and be increased to 255 or the switching of rattling automatically of 511 o'clock addresses.
Below with reference to Fig. 5 description control RS process of decoding flow chart.Wherein classify to uplink burst is professional according to the DOCSIS agreement, according to upstream bandwidth and the requirement of system transmissions reliable rows, to the coded data of every kind of service selection appropriate length at transmitting terminal.At first, at step S51, produce system's reference clock.Because the reference clock that system realizes is a unit with digit time slot (25us), and the DOCSIS system clock is 10.24Mhz, adopt the mini-slot reference generating circuit that mini-slot clock and system clock are carried out strict synchronism.At step S52, in mac controller 2FPGA, distribute one to be used for the moment that each IE of store M AP (information element) arrives receiving terminal, reallocation is used for storing the uplink burst data RS coding parameter K/T value that corresponding MAP distributes corresponding IE.For the periodicity that realizes MAP sends control, to store the moment that IE (information element) arrives receiving terminal being used to, the memory that reaches the K/T value all distributes can store two MAP amount of information.In realization, adopt the table tennis method to switch.Table 2 has been listed the characteristic that service area distributes among the MAP:
Contention requests district wherein, the competition distance measurement zone, initialization range finding three districts, clean culture district only distribute a due at receiving terminal, arrive but have a plurality of burst packets in this zone, the encoding characteristics that is defined in this regional burst packets that arrives is identical, and has identical coding parameter (K/T value).Cycle distance measurement zone unitcast request district, a due in is only distributed at receiving terminal in the data field, in this zone, has only burst packets to arrive at most.
| Unexpectedly strive the request district | The competition distance measurement zone | Initialization range finding clean culture district | The cycle distance measurement zone | The unitcast request district | The data field |
At step S53, the sequential according to demodulator produces produces the switch-over control signal that sends the K/T value to decoder in burst packets preamble field (32 Clock) in the time.At step S54, according to the sequential that demodulator produces, the moment that valid data arrive in the uplink burst bag of location, the moment that promptly begins to export RS decoding positioning control signal.At step S55, according to the position of RS code field in data flow in DOSCSIS uplink burst data bag characteristic and the demodulator sequential location uplink burst data, thereby produce the framing signal that decoder needs, the K/T value switching signal that provides decoder to need, wherein K is the length of data in the burst packets, and 2*T is the length of RS coding.In the data valid period, output RS decoding control signal obtains the correspondence position that RS decodes in the burst packet according to K/T.(preferably can be described in more detail) to decoding process.
So far in conjunction with the preferred embodiments of the present invention the present invention is had been described in detail, those skilled in the art can make various improvement and variation under the situation of the scope and spirit essence that does not break away from claims.
Claims (6)
1. a up decode control method is wherein classified to uplink burst is professional according to the DOCSIS agreement at transmitting terminal, and according to upstream bandwidth and the requirement of system transmissions reliable rows, to the coded data of every kind of service selection appropriate length, described method comprises step:
According to the DOCSIS agreement, determine that each uplink service that distributes among each uplink service allocated bandwidth MAP arrives the moment of receiving terminal at receiving terminal;
At receiving terminal is to set up professional due in and operation code length corresponding relation the cycle with MAP;
Determine the demodulator sequential according to determined professional due in;
According to the position of the Luo Meng of Reed-institute code field in data flow in DOCSIS uplink burst data bag characteristic and the demodulator sequential location uplink burst data, thereby produce the framing signal that decoder needs, the K/T value switching signal that provides decoder to need, wherein K is the length of data in the burst packets, and 2*T is the length of RS coding.
2. up decode control method according to claim 1, be divided into E1 business with mac frame wherein said uplink service classification is comprised, IP operation, management information business, claim frame business, the professional five kinds of media access control (MAC) frames of distance measurement request frame.
3. up decode control method according to claim 1 and 2, wherein saidly determine that each uplink service arrives the step in the moment of receiving terminal and comprises: according to the delivery time of uplink service in the DOCSIS agreement regulation by descending MAP definition, determine the delivery time of transmitting terminal business by descending MAP, and then determine the moment of professional arrival receiving terminal according to the time-delay of range finding.
4. a up decoding control device is wherein classified to uplink burst is professional according to the DOCSIS agreement at transmitting terminal, and according to upstream bandwidth and the requirement of system transmissions reliable rows, to the coded data of every kind of service selection appropriate length, described device comprises:
The DOCSIS protocol processor is used for determining according to MAP and system's ranging information which uplink service each MAP has distributed, and the K/T value of each uplink service correspondence and the relation table of professional due in and K/T;
Medium access control apparatus, the formed relation data of storage DOCSIS protocol processor produces reference clock, and produces and the output Reed Luo Meng of institute (RS) decoding control signal and parameter;
The burst demodulation device, the bursty traffic after decoder provides burst interface sequence and RS coding; With
The RS decoder is decoded to the bursty traffic of burst decoder supply according to RS decoding control signal and parameter; And bursty traffic behind the output decoder and sequential.
5. up decoding control device according to claim 4, wherein said medium access control apparatus comprise mini-slot counting generator, are used to produce the mini-slot with the system clock strict synchronism.
6. up decoding control device according to claim 5, wherein said medium access control apparatus comprises a plurality of look-up tables, is used for storing respectively the different business data from the input of DOCSIS protocol processor.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101682722A (en) * | 2007-04-10 | 2010-03-24 | Lg电子株式会社 | Digital broadcasting system and a data processing method |
| CN101110676B (en) * | 2006-07-18 | 2010-06-02 | 美国博通公司 | Method and system for ordering uplink bandwidth authorization |
| US8335975B2 (en) | 2007-04-10 | 2012-12-18 | Lg Electronics Inc. | Digital broadcasting system and data processing method |
| CN104813591A (en) * | 2012-12-27 | 2015-07-29 | 英特尔公司 | Systems and methods for implementing soft-decision reed-solomon decoding to improve cable modem and cable gateway performance |
-
2003
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101110676B (en) * | 2006-07-18 | 2010-06-02 | 美国博通公司 | Method and system for ordering uplink bandwidth authorization |
| CN101682722A (en) * | 2007-04-10 | 2010-03-24 | Lg电子株式会社 | Digital broadcasting system and a data processing method |
| CN101682722B (en) * | 2007-04-10 | 2012-10-03 | Lg电子株式会社 | Digital broadcasting system and a data processing method |
| US8335975B2 (en) | 2007-04-10 | 2012-12-18 | Lg Electronics Inc. | Digital broadcasting system and data processing method |
| CN104813591A (en) * | 2012-12-27 | 2015-07-29 | 英特尔公司 | Systems and methods for implementing soft-decision reed-solomon decoding to improve cable modem and cable gateway performance |
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| CN100502383C (en) | 2009-06-17 |
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