CN1442004A - System and process for return channel spectrum manager - Google Patents

Abstract

A scanning receiver spectrum analyzer system is a system for monitoring the spectrum of RF energy on an upstream cable plant in order to operate a group of cable modems in the frequency bands that are the least disturbing. The spectrum analyzer measures the entire upstream spectrum (typically 5-42 MHz) to determine the noise level on each frequency and then weights this data with the current operating conditions (e.g., bit error rate) to determine the best possible alternative channel frequency for the modem at the upstream node, and thereafter waits for a trigger condition to occur indicating a need to cause the modem to change frequency.

Description

Be used for the system and the processing of return channel spectrum manager

Technical field

The present invention relates generally to network data processing system, and relate more specifically to the broadband network environment, for example, utilize SONET backbone network and Hybrid Fiber-Coaxial (Hybrid Fiber Coaxial network) (" HFC ") to connect the user to the environment of backbone network.The hardware/software standard that is used for the HFC environment of emerging in large numbers is the DOCSIS (data standard on the cable services interface) of CableLabs company.

Background technology

In the current structure that the data wide area is sent to HFC system (each system is connected to 200 family/clients), front-end server is connected to sonet ring road (referring to Fig. 1) by the multiplexer that is arranged on the sonet ring road.These multiplexers also need to spend 50000 dollars at present except front-end server, and along with the increase in size of group business may need new multiplexer and server.

Unit failure on the front-end server can cause whole " descending " (from headend equipment to the terminal use) subnet can not with world communication.Attempt system is carried out comprehensively, so that reduce cost and make system management simple and easy.Current integrated data transport system is illustrated among Fig. 2.Fig. 2 represents to have reverse path surveillance, Ethernet switch, router, modulator and upconverter, the system of supply of equipment system, phone parts and a plurality of CMTS (cable modem termination system).Such system generally has a plurality of suppliers (Vendor) and is used for its a plurality of systems, has different management systems, big coverage (footprint), high power requirement and high operating cost.

The network broadband cable system that typically is used for transmitting speech and data is illustrated in Fig. 3.Two OC-12 port interface servers all are connected to one of two P, and these two routers are connected to two switches again, and these switch networks are connected to the CMTS head end router.These CMTS head end routers are connected to a plurality of optical nodes.These switches also are connected to a plurality of telephone relay gateways, and these gateways are connected to public switched telephone network (PSTN) again.As for " integrated system " shown in Figure 2, such network generally also has a plurality of suppliers and is used for its a plurality of systems, has different management systems, big coverage, high power requires and high operating cost.

In order to help effective comprehensive solution need have the comprehensive diagnos system.From the upward signal of cable modem owing to a variety of causes has noise.Some noises can be predicted and the some of them noise can be avoided.When signal had too many noise, CMTS can not carry out work.Therefore, need to monitor upward signal and need correspondingly adjust the upstream data frequency range.

Wish to have scale, its power demand and the cost thereof that a kind of comprehensive solution reduces system and give data communication system bigger consistency.

The purpose of this invention is to provide electric interconnection system and the processing method that transmit in a kind of broadband that is used for high quality speech, data and video traffic.

Another object of the present invention provides system and the processing method that is used for the cable access platform, and this cable access platform has high network stabilization, has the ability of reliable support lifeline telephone service and provides speech linked together and the ability of data service.

Another object of the present invention provides a kind of system and the processing method that is used for the safe telescopic network switch of its scale.

Summary of the invention

The present invention utilizes a kind of return channel spectrum manager to solve at the close quarters that is used for integrated switch provides comprehensive frequency spectrum analyser to carry out the problem that speech and data transmit.

Scanning radio frequency spectrum analyser system is a kind of frequency spectrum that is used for monitoring RF energy on the rising main equipment so that the system of the one group of cable modem of frequency band operation that disturbs at tool least.This frequency spectrum analyser is measured whole uplink spectrum (being generally 5-42MHz), to determine the noise level on each frequency, and (for example utilize current operating condition subsequently, the error rate) these data is weighted, thereby determine on upstream node, to be used for the best possible replacement channel frequency of modulator-demodulator, and wait for that then the trigger condition that expression needs modulator-demodulator to change frequency occurs.

Can best understanding the present invention from the detailed description of the embodiment of the invention shown in the following accompanying drawing and above and other advantages, wherein:

Brief description of the drawings

Fig. 1 represents the prior art network on the sonet ring road;

Fig. 2 represents the prior art data communication system;

Fig. 3 represents the prior art data transport network;

Fig. 4 is the block diagram of frame (Chassis) in accordance with the principles of the present invention;

Fig. 5 represents to have the composite cable foundation structure of the frame of Fig. 4;

Fig. 6 be application card in the frame of Fig. 4, base plate (backplane) and between the block diagram of part interconnection;

Fig. 7 is the schematic diagram with backplane interconnection of the netted connection of exchange;

Fig. 8 represents that difference is to the block diagram of the slot of connection between two exemplary slots (slot);

Fig. 9 is the block diagram of the MCC chip in the application module in accordance with the principles of the present invention;

Figure 10 is the figure of grouping sign;

Figure 11 is the block diagram of general switch packet header;

Figure 12 is the flow chart by the transfer of data of base plate;

Figure 13 is the block diagram of input ICL grouping;

Figure 14 is the block diagram of title that is used for the ICL grouping of Figure 13;

Figure 15 represents according to the principle of the invention the example mappings table of channel Mapping to the base plate slot;

Figure 16 is the block diagram that is connected the bus arbitraction application module in the base plate of the present invention;

Figure 17 is the state diagram of bus arbitraction in the application module of Figure 16;

Figure 18 is the block diagram of expression according to the frame of Fig. 4 of the subclass of the RF holding wire of the principle of the invention in base plate;

Figure 19 is the block diagram of the cable modem of the CMTS application module that connects by base plate according to the principle of the invention and embedding;

Figure 20 is the block diagram of frequency spectrum analyser in accordance with the principles of the present invention; With

Figure 21 is the chart of expression inlet characteristic.

The specific descriptions of preferred implementation

Fig. 4 represents the frame 200 according to principle of the invention operation.Frame 200 with a plurality of network applications comprehensively in single switching system.The present invention is the osi layer 3/4IP switch that full mesh connects, and it has high-performance grouping transmission, filtration and QoS/CoS (service quality/service type) ability of the rudimentary embedded software that uses the Cluster Administrator control that is subjected in the shelf controller.High-level software resides in the Cluster Administrator, this manager has routing server function (RIPv1, RIPv2, OSPF etc.), network management (SNMP V1/V2), maintains secrecy, DHCP, LDAP and long-range access software (VPN, PPTP, L2TP and PPP) and can easily make amendment or upgrade.

In present embodiment of the present invention, frame 200 has 14 slots that are used for module, and 12 slots among these 14 slots are used to keep application module 205, and two slots keep shelf controller module 210.Each application module have airborne DC-DC converter and each application module can " heat is inserted " frame in.Shelf controller module 210 is used for redundant system clock/bus arbitraction.Comprehensively the application example in frame is CMTS module 215, ethernet module 220, SONET module 225 and phone application 230.Another Application can be to make this frame be linked to link (ICL) port 235 between the frame of another frame.

Fig. 5 represents to have the composite cable foundation structure 260 of the frame 200 of Fig. 4.Frame 200 is the parts that are used for the local concentrator 262 (being also referred to as " headend equipment ") of speech and data transmission.Hub 262 comprises Video Controller application 264, video server 266, Web/ cache server 268 and operations support systems (OSS) 270, combiner 271 and frame 200.Frame 200 is as the IP access switch.Frame 200 is connected to the sonet ring road 272 that is positioned at hub 262 outsides, has to the Internet 274 connection and being connected to public switched telephone network (PSTN) 276.Frame 200 is used 264 with Video Controller and is connected to combiner 271.Combiner 271 utilizes HFC link 278 to be connected to the cable client and IP speech, data, video and fax services is provided.At least 2000 cable clients can be linked to headend equipment by HFC link 278.Frame 200 can support a plurality of HFC links and a plurality of frame also can nettedly to link together (as described below) to support thousands of cable client.

According to current convention, having a broad-band channel is used for to user's's (this can be desktop computer, facsimile machine or telephone set) transmission (download) and 4 much narrow that channel is used for (uploading), this utilizes the HFC that has duplex ability on the O/E node to stick into row and handles, and local HFC cable system or loop can be the coaxial cable distribution of net that is set on the cable modem.

Fig. 6 represents to be connected to the application module of base plate 420 of the frame 200 of Fig. 4.In current embodiment of the present invention, this base plate be embodied as 24 layers print terminal blocks and comprise 144 pairs unidirectional different from connecting, every pair directly with the input of each module among maximum 12 application modules and input that output is connected to each other module and output and self.Each application module utilizes these terminals to pass through netted communication chip (MCC) 424 backplane interface therewith.Each application module also is connected to rack management bus 432, and described bus provides to the connection of shelf controller 428,430 for these modules.Each MCC424 has 12 (12) serial link interface to base plate 420.11 serial links on each application module are used for application module is connected to each other application module of frame.Article one, link is used for module is connected with self, i.e. the loopback link.Base plate is that full mesh connects, and represents that each application module has the direct link by each other application modules of serial link to the frame.Only represent that in Fig. 6 the part of these connections is as example.The netted connection of base plate is illustrated among Fig. 7.

Utilize digital 0-11 mark to have 12 channels of the serial link of MCC, this is called channel id or CID.Slot on the base plate is also from 0 mark to 11 (slot ID or SID).But machine frame system does not need channel 0 rigid line to be connected to slot 0 on the base plate.Serial link can be connected to arbitrary slot.According to system topology dynamic-configuration slot ID.This provides free for the backplane wiring layout, otherwise just requires some layers except that 24 layers in noseplate.Application module reads the slot ID of this slot that it inserts.This application module will send from its serial transmission line in the idle stream of described that slot ID between transfer of data.This application module also comprises slot ID in each transfer of data.

Channel Mapping during Figure 15 represents to block is to the example of the mapping table of base plate slot.The part of every this table of card storage, that is, this table row relates to particular card, should show row and be stored among the MCC.

Figure 16 represents to be connected to the management bus arbitration application module of base plate.This base plate comprise two independently management bus be used for error protection.Each application module that has in the described frame of two shelf controllers and 12 application modules can use these two management buses or a bus wherein.

The low speed data that management bus is used in the frame transmits and generally comprises control, statistics, configuration information, the data that are sent to the application module of frame from the frame controller module.

The enforcement of management bus comprises one 4 Bit data path, tranmitting data register, tranmitting data register signal, collision control signal and 4 bits arbitration bus.As shown in figure 16, bus control unit has the 10/100MAC device, receives FIFO, bus transceiver logical circuit and programmable logic device (" PLD ").

Data path on the management bus is 4 bits (media independent interface) the MII standard interface that is used for 10/100 ethernet mac.But therefore the operation of bus mock standard 100Mbit industry ethernet interface can utilize the MAC function.Programmable logic device comprises the state machine of carrying out bus arbitraction.

Figure 17 represents to be used for the state diagram of state machine of the programmable logic device of management bus.The arbitration circuit utilizes the open collector logical circuit to determine this bus of which module controls.Draw (pull-up) program residence in the shelf controller module on the arbitration bus.Each slot is placed on the arbitration circuit its slot ID so that the request bus.Between the transmission period of the preposition part of the data that will send, destroyed if arbitrate, then bus control unit supposes that another slot asks this bus simultaneously, and the state machine in the PLD is effectively abandoned transfer operation by forcing the collision alarm that is used for this bus and local mac device.Detect collision alarm on this bus when effective in other module, force the collision circuit on each local mac to become collision status, this allows compensation (back-off) algorithm in the MAC to determine next delivery time.If do not detect collision, then with data latching in the reception FIFO of each module, and TX-Enable (sending permission) signal is used to quantize data from bus.State machine is waited for 4 clock circulations during the preposition part of transmit status, and waits for 4 clock circulations during collision status, to allow other modules state synchronized of bus therewith.

Base arrangement

Fig. 7 is illustrated among Fig. 6 the internal backplane structure with the current embodiment of the switch of the present invention shown in the exemplary forms.Characteristic is the full mesh interconnection between the slot shown in the zone 505.Utilize vertical line to express slot among Fig. 7.This utilization is embedded in the difference of 144 centerings in the base plate shown in Figure 8 to implementing.Each slot thereby have the full duplex serial path of each other slot to the system.In this system, has the individual non-loopback link of double n (n-1) (promptly, article 132, link) be used for base plate altogether 264 differences to the duplex of (or other double links are used for 528 circuits) to structure, so that generate the netted connection of base plate in current embodiment of the present invention, each difference is to supporting the data throughput greater than 1 mbit/.

In present enforcement of the present invention, clock signal is embedded in the serial signaling, thereby avoiding needing independent goes to be used for clock distribution to (four times).Because data path is independently, so the different right card in the frame can be exchange (ATM) cell and other exchanges (IP) grouping.It is useful characteristic that each slot can send for broadcasting on its whole 11 serial links at once, and all slots that send on its all serial links obtain the peak bandwidth of 132 mbit/.The bandwidth of being kept depends on system configuration.

The connection of fully redundance is provided between the netted application card that is connected in the base plate, and connection Shi Buhui that breaks down influences the communication capacity of these cards.Routing table is stored in the shelf controller.For example, if being connected between application module 1 and the application module 2 broken down, then upgrade routing table.Be reported in when not receiving data on the specific serial link to shelf controller at application module, upgrade these routing tables.Can route to the Another Application module for the data selection that is addressed to application module 2 by application module 1 input, for example, application module 3, this module sends these data to application module 2 then.

The baseplate zone 525 that bus connects comprises three bus systems, and management/control bus 530 is used for the out-of-band communication of signaling, control and management information.The redundancy backup of management bus fault will be a mesh interconnect structure 505.In the current embodiment, the management bus as packet bus provides 32 bit 10-20MHz to transmit.Arbitration concentrates on the system clock module 102 (clock A).Allow the communication of any-slot, also support broadcasting and multi-casting communication to any-slot.Bus driver is integrated on the system bus FPGA/ASIC.

TDM (time division multiplexing) structure 535 also is used for phone application.Selectable solution comprises the use of DSO structure, for example, uses and adopts the H.110 32TDM main line of standard (16 full duplexs, 2048FDX time slot or about 3 T3), or use SONET ATM (asynchronous transfer mode) structure.

The stationary singnal that mixes also can be distributed in the baseplate zone 540 of bus connection.Can transmit the signal of expression slot ID, clock failure and management bus arbitration fault.

Star interconnect area 545 provides and redundancy clock 102 and 103 irrelevant clock distributions.Stationary singnal on the backplane bus 540 tells that determine which system clock and bus arbitraction slot of system's mould is effective.Can support following two kinds of clock distribution of net: can synthesize the reference clock of other clocks and depend on the bus-structured TDM bus clock of selected TDM according to it.These two kinds of clocks are all synchronous with the BITS (setting up comprehensive regularly supply) that inner multilayer 3/4 oscillator or outside provide.

Fig. 8 represents first tie point on the MCC (that is, MCC A 350) on first module and second tie point and the connection between them 354,355,356,357 on the 2nd MCC on second module (that is MCC B 352).The netted connection 360 of base plate is passed in these connections according to the present invention.On each MCC 350,352, have transmitting channel 362,364 and receive channel 366,368, and each channel just has with negative and is connected.In a word, each point on mould is determined is connected owing to base plate is netted between other are put in it and each and has 4 connections.Control different transmission line impedance and length, to guarantee signal integrity and high speed operation.

Fig. 9 is the block diagram of MCC chip.F bus interface 805 is connected to fifo bus (F bus) with MCC 300.12 transmission FIFO 810 and 12 reception FIFO 815 are connected to F bus interface 805.Each sends FIFO and has data compressor (12 data compressor reducers altogether) 820, and each reception FIFO has data expander (12 data expanders altogether) 825.12 serializer/staticizers 830 are served data compressor 820 and expander 825, and each serializer/staticizer has a compressor reducer and an expander.Channel among the MCC is defined as serial link with its encode/decode logic, transmit queue and reception formation.Serial transmission line connects from these channels and leads to the netted connection of base plate.All channels can send data simultaneously.Current embodiment of the present invention adopts netted communication chip to utilize the serial link technology to reach 13 F bus with the interconnection of full mesh form.Each MCC has two F bus interface and 12 serial link interfaces.The mode that MCC increases progressively with the programmable size from 64 bytes to whole group on the F bus sends and receives grouping.It comprises 12 virtual transmission processors (VTP), and these processors obtain grouping and these groupings are sent to serial link from the F bus, thereby allows 12 output groupings simultaneously.VTP reads the MCC sign of grouping front and dynamically they oneself is linked together with the purpose slot shown in the title.

The specific specific MAC/PHY of processor, card/slot of card/slot communicates by letter on two-way F bus (or many unidirectional F buses) with MCC to (Ethernet, SONET, HFC etc.).The grouping transmit path is from PHY/MAC processor so far, subsequently more from then on processor stretch out to MCC and from netted connection.This processor carries out layer 3 in FIPP and layer 4 is searched, and to determine the destination and the service quality (QoS) of grouping, can revise title when needed, and before this grouping is sent to MCC the MCC sign is attached in this grouping in advance.

The grouping RX path is from the netted MCC of being connected to and proceeds to this processor, and then from then on processor stretches out to MAC/Phy and from channel.This processor was removed the MCC sign before sending to grouping on the MAC.

The first data flow con-trol mechanism among the present invention utilizes the duplex that connects in the base plate to structure and to the connection of module.MCC has the predetermined complete threshold value that is used for FIFO.Be filled into predetermined threshold if receive FIFO, then can send a code and stop to send data by the right transmitting channel of duplex.This code be designed to directly to be coupled on the balanced transmission line signal and can detect mistake.Code in the current embodiment of the present invention is the 16B/20B code, but can use other code within the scope of the invention.MCC sends has I1 or the I2 code that is set to be used to turn-off the XOFF bit of data flow.This message is included in the data flow that sends on the transmitting channel.If FIFO is lower than predetermined threshold, then MCC has the I1 of the XOFF bit that is eliminated or I2 code by transmission and is eliminated and stops message.Effectively current control prevents that low depth FIFO from transfiniting, thereby allows to use the little FIFO among the ASICS, for example, and 512 bytes.This reduces the microchip cost of system.

Figure 10 represents the grouping sign, is also referred to as the MCC sign.The MCC sign is 32 bit flag, is used for to be a minute group selection route by the netted connection of base plate.The slot processor appended to this sign the front of this grouping before grouping is sent to MCC.This sign has 4 fields; Destination shielding (mask) field, precedence field, maintenance field and reserved field.So the destination mask field be used for keeping dividing into groups being destined to be sent to, to or can not be the field of shielding of the slot in forebay of the final destination of system.For sending grouping, MCC utilizes the destination mask field to determine the transmit queue that this grouping is destined to be sent to.For receiving grouping, MCC utilizes precedence field and keeps field to determine too much make a promise to abandon which grouping in (over-committed) slot at one.In current embodiment of the present invention, do not use reserved field.

MCC has two independently sending mode selector, slot-channel Mapping and virtual sending modes.In slot-channel Mapping, MCC is mapped to SID CID and software pellucidly needn't follow the tracks of this mapping.In virtual sending mode, MCC handles the multicast grouping translucently.MCC obtains the total linear flow of single F and directly sends them to a plurality of channels.The virtual transmission processor of transmit port addressing among the MCC (VIP) and not addressing slot.The F bus interface directly is sent to this grouping the virtual transmit path of selection.VIP preserves the destination mask field and sends this grouped data (comprising the MCC sign) to shown in the mask field of destination transmit queue group from the MCC sign.Follow-up 64 bytes of all of this grouping " piece (chunks) " utilize same port id to send by the slot processor, and therefore all directly send to same VTP.VTP sends grouping block to the transmit queue group of representing in the destination mask field of preserving from the MCC sign.When grouping block arrived and wherein is provided with the EOP bit, VTP removed its destination mask field.If be addressed to next grouping block of that port is not the beginning part of new grouping (that is, having the SOP bit of setting), and then VTP does not send this grouping block to any formation.

The destination mask field of MCC sign is by " latching " multicast transmission of effectively dividing into groups.This destination mask field comprises the code that is used for all appointment purpose slots.Therefore, if the grouping expression is used for all 12 slots, then only need to send a grouping.With this sign be sent in this mask field, encode the institute on purpose.If only the slot of some will receive grouping, these slots of then in the mask field of destination, only encoding.

MCC keeps one group and is used for stoping a plurality of VTP simultaneously grouping to be sent to " channel busy " bit of same CID by it.This conflict stops mechanism not to be intended for use the auxiliary busy channel of slot manager administration, but is used for preventing to divide into groups thoroughly to worsen when the slot processor sends to same slot with two groupings once in a while simultaneously.When VTP obtained new grouping, it will compare purpose CID mask field and channel busy bit.If arbitrary channel busy then will be removed this channel from the mask field of destination, and for mistake of that CID record.VTP all is provided with busy bit and sends this grouping for all remaining purpose channels subsequently.When being used at this VTP finding EOP on the F bus of this grouping, its removes the channel busy bit that is used for its purpose CID.

The F bus interface is carried out the I/O function between the remainder of MCC and application module.As shown in figure 10, this application module appends to 32 bit groupings signs (MCC sign) will select in each packet of route by netted connection.

The data that receive or send in the F bus are up to 64 bit widths.In transfer of data, the F bus interface appends to 4 status bits and sends on the data, to form 68 Bit data segmentations.The F bus interface is placed on 68 Bit data segmentations among the suitable transmission FIFO that determines from the grouping sign.To be transmitted to relevant data compressor from the data that send FIFO, in this data compressor, 68 Bit data segmentations be reduced to 10 bit segments.Send these data to relevant serializer then, in this serializer, these data are further reduced and be serial flow.Described serial flow is sent to base plate by serial link.

Come on the correlated channels by serial link from the data that base plate arrives.The serializer that is used for this channel expands to 10 Bit data segmentations with these data, and relevant data expander expands to 68 Bit data segmentations with these data, and this data sementation is sent to relevant FIFO and is sent to the F bus interface from FIFO subsequently.

Fast IP processor (FIPP) has the high-speed synchronous SDRAM of 32/64 Mbytes, the high-speed synchronous SRAM and the bootflash memory of 8 Mbytes.FIPP has 32 bit pci buss and 64 bit fifo bus (F bus).FIPP to the device that all F bus connects transmit grouped data or from these devices receiving block data, it provides IP to transmit with unicast communication and multi-casting communication pattern.Receive routing table by management bus from the frame routing server.FIPP also provides higher functions, such as filtering and CoS/QoS.

Each line card is useful on the Clock Subsystem of all clocks that produce each calorie requirement, and this will lock onto and utilize system clock and management bus arbitration to block on the reference clock that provides.

Every card all has heat to insert (hot-plug), on-reset circuit and Sanity Timer (demagnetization timer) function.All jigs have airborne DC-DC converter, so that from base plate-the 48V rail voltage is raised to and uses required any voltage.Some cards (such as the CMTS card) might have the power supply of two independences and isolation, so that performance the best of the simulation of this card part.

Figure 11 represents to be used for the general switch title of integrated switch.It is that route is selected in packet that this title is used for by system.The final destination can be in the frame or between the frame.

The topic Types field represents that being used for by the network with one or more machine frame systems is the topic Types that divides the group selection route.Usually, this topic Types field be used to decode this title and provide grouping to transmit needed information.Particularly, this topic Types field can be used for representing that purpose structure interface address has logic port.Actually or this topic Types field also is used for this grouping of expression broadcasting clean culture.This topic Types field is used for representing the relevant field of title.

Keep field to represent whether can abandon grouping owing to crowding.

The segmented segment table shows whether packet segmentation and this grouping are made of two frames.

Precedence field is used to represent packet-priority.

Encap (encapsulation) type field is one and is illustrated in to transmit whether need before to divide into groups further layer 2 bit field of handling.If this bit is set, L2 then appears.If this bit is not set, L2 does not then appear.

Mcast (multicast) type field is that an expression is a bit field of broadcasting or multicast grouping.Can use or can not use this field according to environment.

Dest FIA (structure interface address) type field represents that purpose FIA is short-form (promptly＜frame/slot/port 〉) or microscler formula (that is,＜frame/slot/port/logic port 〉).Can use or can not use this field according to environment.This field can with the topic Types field combination together.

Src FIA type field is that expression source FIA is a bit field of short-form (promptly＜frame/slot/port 〉) or microscler formula (promptly＜frame/slot/port/logic port 〉).Can use or can not use this field according to environment.This field can with the topic Types field combination together.

Data type field is the X bit field, is used to utilize the application-application communication of exchange layer.This field identification grouping destination.

Transmitting information field is the X bit field, it keeps transmission table version is next jump field of transmission information (being next jump of switch), and which port it exports from forward-table-entry Key/id (transmitting table entry key/identification) identification grouping.

Dest FIA is the x bit field of the final destination of expression grouping, and it comprises frame/slot/port and comprises logic port information sometimes.The frame of value 0 (zero) represents to keep the frame of master agent.The port value of 0 (zero) represents that the receiver that divides into groups is an application module.Logic port can be used for representing which storehouse/entity of this card will receive this grouping.Therefore all edge ports and ICL port are based on " 1 ".

Src FIA field is the X bit field, the source of its expression grouping.Routing server utilizes this field to discern the source of input grouping.

Figure 12 is that general packet transmits the flow chart of handling.When receiving grouping on one of application module of switch, this module check BAS title is if a title determines whether grouping is addressed to the frame that this module connects.If not, this application module is searched the purpose frame and this grouping is sent to correct frame in routing table.If this grouping 3 is addressed to this frame, this application module is checked title, whether has been addressed to this module (or slot) to determine this grouping.If not, this application module is searched the purpose slot and is sent this grouping to correct application module in mapping table.If this grouping is addressed to this application module, then this application module compares transmission Table I D in the title and local transmission table version.If their unanimities, then this module utilizes the pointer in this title that this grouping is sent to its next destination.

The clean culture that receives from the ICL port already is equipped with

Figure 13 is the chart of input ICL grouping.This grouping has the BAS title, encapsulation fields, the IP field of (L2 or NULL sky) can be set or not be provided with and be used for the data field of data.

Figure 14 is the chart of title of the grouping of Figure 12.Topic Types can be 1 or 2.Topic Types 1 expression be used for destination and source, have a FIA field that form is frame/slot/port.Topic Types 2 expression be used for destination and source, form is the FIA field of frame/slot/port/logic port.Do not use the maintenance field.Do not use precedence field.Do not use the segmentation field.Do not use next jump field.Encapsulation fields is 0 or 1, does not use the multicast field.DST FIA type field can be 0 or 1.SRC FIA type field can be zero or 1.Do not use the BAS ttl field.Use and transmit information field, and use DST and SRC FIA field.

The cable modem that embeds

Cable Modem Terminal System comprises an asymmetric communication system, and it has two chief components: front end part and client part.The front end part that is called Cable Modem Terminal System (CMTS) sends with it gives this CM from the different basically signal of the signal of cable modem (CM) reception.CMTS sends 5,000,000 baud 64/256QAM in the 54-850MHz band signal and CM sends 160 kilobauds to 2.56, million baud QPSK/16QAM in the 5-42MHz band signal.Because it is different with received signal to send signal, so can not carry out the physical layer loopback for self diagnostic test.

The frame 200 of Figure 18 presentation graphs 4, it has from 215,900,902,904 of CMTS passes the RF signal line 906 of base plate 420 to shelf controller module 908.In fact, the RF signal line from each application slot to each shelf controller 908,910.For brevity this figure is simplified.

Each shelf controller 908,910 has the cable modem system 912,914 of embedding, and it can and generate inverse signal from one of CMTS received signal and give transmission CMTS.The cable modem that embeds also comprises diagnostic function.

Signal line 906 in the base plate transmits radio frequency (RF) signal from CMTS and also returns for the CM that embeds again.Such, in base plate is implemented, require high degree of care at the RF signal of selecting route on the base plate, do not pollute these RF signals to guarantee any digital signal on the base plate.

Figure 19 represents to be connected to by base plate 420 the CMTS application module 215 of the cable modem 912 of embedding.CMTS application module 215 has downstream modulator 920 and 4 upstream modulator 922,924,926,928.Packet transaction and backplane interface 930 transmit and receive data on base plate 420.Data are handled on CMTS MAC layer 932.The cable modem 908 that embeds is gone up at first 12 position deferred mount 936 (it has a position for each application module) and receive downstream signal from CMTS application module 215.The cable modem 912 that embeds sends inverse signal to CMTS application module 215 by second 12 position delay circuit 937.The cable modem 912 that embeds also receives the CMTS signal so that diagnose on the 2 12 position delay circuit 937.

In cable modem, descending RF signal also passed through first adder 940 earlier subsequently by first variable attenuator 938 before carrying out demodulation on the downstream demodulator 942.On cable modem MAC layer 944, handle this signal.This signal from MAC layer 944 can be handled on CM packet transaction and backplane interface 946, and can send grouping subsequently to base plate 420.This signal also can send by a up pulse modulator 948 that is used to modulate inverse signal.Inverse signal sends by the second adder 950 of following second variable attenuator 952 thereafter then, and subsequently by the 2 12 position delay circuit 937, this signal is back to CMTS application module 215 by the RF signal line in this delay circuit 937.

Signal from CM packet transaction and backplane interface 946 can directly be sent to system interface 955, and in a preferred embodiment of the invention, diagnostic software resides in this system interface.In the of the present invention first interchangeable embodiment, diagnostic software can reside in the shelf controller of the cable modem outside that is arranged in embedding.In the of the present invention second interchangeable embodiment, diagnostic software can reside on the application module such as the CMTS module in the frame.In the of the present invention the 3rd interchangeable embodiment, diagnostic software can reside on the position outside other the long-range frame of central network manager or some.

The cable modem 912 that embeds has calibrated broadband noise source 954, and it generates an energy and is appending on the downstream signal on the first adder 940 and can append to noise signal on the upward signal on second adder 950.Calibrated noise source 954 is used to generate the test signal of carrying out carrier wave-noise diagnostics.

In operation,, these groupings are modulated on the carrier wave that scope is 54-850MHz in this modulator to CMTS MAC 932, to CMTS downstream modulator 920 from CMTS backplane interface 930 output stream of packets.Select to route to the coaxial hybrid network of external fiber (HFC) for resulting signal subsequently, in this network, this signal is sent to the descending CM of cable modem with embedding.In the scope of 5-42MHz, upstream packet modulated and from CM with embed and send these the cable modem and be grouped on the HFC, wherein this HFC is connected to one of uplink port of CMTS by cable, and signal selects to route to one of upstream demodulator for this reason on this port.The cable modem that embeds can be carried out diagnosis and generate test signal to supply with CMTS the uplink and downlink signal.

In interchangeable embodiment of the present invention, the cable modem of embedding can reside on each CMTS application module.Perhaps, the cable modem of embedding itself can be an application module.

Return frequency spectrum analyser

Scanning radio frequency spectrum analyser system 960 in the cable modem 912 that Figure 19 represents to embed.Comprehensive frequency spectrum analyser is to be used for monitoring that the frequency spectrum of RF energy on the rising main equipment is so that operate the system of one group of cable modem at the frequency band that least has interference.Frequency spectrum analyser is measured whole uplink spectrum (being generally 5-42MHz), to determine the noise level on each frequency, and (for example utilize current operating condition subsequently, the error rate) these data is weighted, with the channel frequency of the best possible replacement that is identified for the modulator-demodulator on the upstream node, and wait for that then the trigger condition that an expression needs one or more upstream modem and corresponding user's modulator-demodulator thereof to go to change the frequency on the upstream node occurs.A node is equivalent to physical circuit or optical fiber, accumulates on this node and is sent to the port of CMTS from the signal of a plurality of user's modulator-demodulators.

Figure 20 is the concrete block diagram of the frequency spectrum analyser system of Figure 19.Except having outside 4 receiver/demodulators 922,924,926,928, CMTS application module 215 also has 4 A/D converters 970,972,974,976.In fact receiver/demodulator is multiplexed into the A/D converter.For simplicity's sake this figure is simplified.The frequency spectrum analyser system picked out the signal of each up channel between A/D converter and the receiver/demodulator in 960 minutes.

Frequency spectrum analyser system 960 has digital switch or multiplexer 986, frequency spectrum analyser 992, the error rate (BER) measuring appliance 994, peak detector 996, power detector 998, AM demodulator 1000, frequency subsets demodulator 978 and auto-correlation processor.Frequency spectrum analyser 992 has tuning circuit (variable band-pass filter) 988 and signal detector 990 so that come detected amplitude.This system has to the figure output of graphical user interface 1002 with to listened to the output that can listen user interface 1004, and these allow the user to observe noise spectrum.This system also comprises can be set to the alarm output 1006 that triggers when the scheduled period noise level surpasses predetermined level.

Frequency subsets demodulator 978 is excute phase, frequency, SSB, amplitude or other demodulation process in the uplink spectrum of selecting subclass, listen to noise to allow the user by listening user interface 1004, thereby help to determine its source.The sample value of auto-correlation processor 980 processing RF frequencies, and the indication of the position of modulated nonrandom interference is provided, thus assisted user is determined the signal source of undesired signal.The AM demodulator is configured to go determine the AC hum level of arbitrary part of the RF spectrum on the present node.

Frequency spectrum analyser system branch picks out the digital uplink signal among the CMTS.Utilize digital switch can change this 4 channels.Frequency spectrum analyser be tuned to the spectral range that is used to analyze.The threshold value of noise in the BER measuring appliance inhibit signal.If noise exceeds threshold value, then the BER measuring appliance calculates this noise, thereby draw the good code element in the signal and the ratio of bad code element, why to detect impulsive noise by this way, this be because the scan-filtering analyzer for sometime the section need remain on the certain limit so that can suitably analyze this scope.

The signal to noise ratio and the error rate on the current channel of frequency spectrum analyser system monitoring.When noise ratio and the error rate surpassed configurable threshold value, this system utilized channel selecting method to obtain new channel frequency, and the indication modulator-demodulator moves to this frequency.

Selecting the method for new channel frequency to comprise is weighted various inputs.The frequency spectrum analyser system determines that subsequently which frequency can provide the killer opportunity of the bit error rate performance that improves the modulator-demodulator in the current upstream node with statistical.The factor of checking when selecting new channel frequency is: the instantaneous noise level on each frequency, the peak power that adds up in time on each frequency, average noise level on each frequency, the error rate of the estimation that when signal operation is on that selection frequency, will produce, the data histogram of such time total amount (noise level in this time range on each frequency all surpasses one group of predetermined level), forbid frequency band (forbidding that on these frequencies cable modem goes to operate according to user's configuration), and histogram data (these data for example can be used to search the frequency that only just has strong noise during some time period of one day) in the past.

Figure 21 represent to enter the mouth chart of characteristic.The frequency spectrum analyser system can be with graphical display spectrum analysis result on graphical user interface.Two types inlet can be isolated: impulsive noise and frequency domain inlet.Can utilize pulse duration, amplitude and repetition rate to come the indicating impulse characteristics of noise.Utilize bandwidth, amplitude and the duration of modulation to represent the feature that frequency domain enters the mouth.These parameters can be carried out relevant with the bad grouping occurrence rate in time in one day.This information for definite which frequency least tool to disturb be useful.This information for provide about the time in relative one day of the serious disturbance source and the graph data of the relative packet loss in serious disturbance source also be useful.

In current embodiment, be the part of the embedding cable modem on the shelf controller with the frequency spectrum analyser system description.In interchangeable embodiment, the frequency spectrum analyser system can be arranged in the CMTS application module, or itself is application module, or is inserted in the application module in the shelf controller and does not have the modulator-demodulator of embedding.

Should understand the foregoing description is the signal of the principle of the invention.Those skilled in the art can implement the principle of the invention and fall into spirit of the present invention and scope in various and other modifications and variations.

Claims (2)

1. A method for optimizing the upstream transmission frequency of a plurality of physical cable modem channels comprising the steps of: a) sampling the uplink transmission signals of these channels before demodulation; b) analyzing said samples for noise exceeding a threshold value; c) monitor noise on alternative frequencies for each channel; and d) adjusting the transmission frequency of a channel whose noise exceeds said threshold value to a frequency indicated by said monitoring to be less noisy; Wherein at least steps (a)-(c) are performed without human intervention. 2. A device for optimizing the frequency of upstream transmissions for a plurality of physical cable modem channels, comprising: a) interconnection means suitable for connection to upstream transmission signals of these channels prior to demodulation; b) a multiplexer for selectively connecting said interconnect means to a tunable bandpass filter; c) analysis equipment, which is connected to the output of said bandpass filter, this analysis equipment has: i) a noise threshold detector for providing an indication that a predetermined threshold has been exceeded; and ii) a signal amplitude recorder to provide an indication of signal quality; and d) Interconnection means adapted to connect said indication of exceeding said predetermined threshold value and said indication of signal quality to a logic circuit for adjusting the transmission frequency of these channels.

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