Full-service broadband cable modem system

Full-service broadband cable modem system

FIELD OF THE INVENTION The present invention relates to a "last mile" broadband digital communication system capable of providing full services of voice, video and data to residential and commercial areas. More specifically, the present invention relates to the field of improvement measures in the media access control (MAC) protocol of a full-service cable modem system using multiple upstream and upstream channels. Other communication systems (e.g., fixed broadband wireless, broadband cellular, and two-way broadband satellite) can also benefit from the present invention.

BACKGROUND OF THE INVENTION In the past few years, cable modem systems based on data service specifications on cables have been accepted as the "last mile" high-speed data solutions for these consumers.

A two-way "hybrid fiber coaxial" (HFC) cable network is an infrastructure that can support multiple coverage services (for example, analog or digital video services, high-speed data and telephone technical services). These services use different frequency bands of the available spectrum in the downstream and upstream directions, and each service has its own operation and supply infrastructure. At customer premises (premises), full-service subscriptions require multiple components of customer premises equipment (CPE) (for example, set-top boxes, telephone network connection components, and cable modems). These coverage services will result in high infrastructure costs for supply and management, as well as the high cost of CPE and the inefficient use of upstream spectrum.

Convergent networks Therefore, there is a great need for a convergent network that can deliver voice, video, and data in a unified communications infrastructure.

Conventional data on cable media access control (MAC) protocols are based on shared upstream and downstream channels. Each cable modem or service is statically assigned to the upstream channel. Switching cable modems for load balancing or service balancing among multiple channels is complicated and slow.

Moreover, when it comes to supporting digital video services, cable modems have strict restrictions. Conventional digital video (on-demand broadcast or video) requires more stringent bit error rate and quality of service (QOS) than data services. A high bit rate of approximately 20Mbps per HDTV movie channel is required. Therefore, it is not sufficient to provide multi-program, well-defined digital video services in the same downstream channel used for conventional cable modulation data services.

Reverse flow restriction The reverse flow bandwidth of the HFC network is limited by two factors: First, the amount of available spectrum in the reverse flow signal in the conventional "sub-splitting" HFC cable equipment is 5 to 42 Mhz in North America. Due to incoming interference, an effective part of the spectrum is not suitable for broadband (for example, 3.2Mhz or 6.4Mhz/channel) and higher order modulation (for example, 16, 32, or 64QAM) in order to achieve high performance for the upstream channel in use. performance. If a 6.4Mhz channel is used, then only 6.4/(42-5)=17% of the reverse flow spectrum is used. The other 83% of the spectrum (especially for frequencies below 10 MHz) are often not used. In terms of the ability to "make full use of the upstream spectrum to maximize the capacity and provide the efficiency of QoS required by all these services", the conventional data MAC on the cable is greatly restricted.

Specifically, since each upstream channel must support data packets generated by different services with different QoS requirements, it is difficult to achieve high channel usage under conditions of dynamically changing traffic. In particular, the housekeeping operations (for example, bandwidth request and initial calibration) of these MAC management data packets will be important and will complicate the scheduling efficiency of the cable modem terminal system (CMTS).

Conventional data-on-cable MAC protocols rely on some form of polling method to achieve QoS goals that meet bandwidth, latency, and vibration requirements. Regarding a polling interval of 2 milliseconds, each upstream channel requires approximately 270 Kbps downstream bandwidth for the MAC operation. This represents a significant amount of bandwidth from the downstream channel. Therefore, the scalability of using multiple upstream channels in conventional data on cables is greatly restricted.

Broadcast quality digital video Although the HFC network has sufficient bandwidth to support the delivery of a complete series of services (including data, telephone technology, and video), these services are currently a separate infrastructure provided by service providers. As a result, these are the sub-optimal use of the HFC spectrum and the expensive copy of the equipment located at the headend and customer premises. "Online Voice Protocol" allows the concentration of voice and data. However, video services are still a separate infrastructure.

Therefore, there is an unmet need-a unified communication system that can meet all the needs of providing broadband Internet access, IP telephony technology, and broadcast quality digital video on the same HFC system.

Therefore, there is an unmet need-a MAC that can be used to implement a full-service cable modem system to realize the delivery of voice, video and data to homes and businesses in a cost-effective manner The full potential of the HFC network.

After the detailed description of the present invention, it will be realized how to overcome these limitations of conventional cable modem systems.

The full-service MAC described here makes full use of the upstream and downstream spectrums of conventional HFC cable equipment, allowing service providers to economically deploy a complete service series with voice, video and data without the need for forklift-type HFC cable equipment. upgrade.

The unified full-service communication system described here will effectively reduce the cost of "providing three separate supply systems for video, data, and voice at the headend", and at the same time, will reduce the amount of equipment in the building. Reduce from three to one.

The purpose of the present invention is to overcome various shortcomings of the original technology.

SUMMARY OF THE INVENTION The present invention achieves this and other objects. According to the present invention, a full-service cable modem (fsCM) system capable of delivering video, data and voice over a two-way hybrid fiber coaxial cable network is described.

The high-capacity, high-efficiency multi-channel full-service MAC capable of supporting multiple upstream and downstream channels allows the fcCM system 100 to provide a complete service series that currently requires multiple delivery systems. The video can be delivered by a combination of high-quality broadcast MPEG-2 audio/visual streams and "Internet Protocol" (IP) video streams.

In addition, multiple channels can be used to multiplex all types of data packets, which is allowed by the true seamless channel change described in the present invention, thereby maximizing the statistical multiplexing gain. As required by the high-availability, fault-tolerant, voice-over-IP voice telephony technical service in the cable modem system, the packet-by-data channel switching allows rapid recovery from channel failures.

According to the preferred embodiment, as an example, the fsCM system 100 includes two downstream channels (DCPC and DPC1) and two upstream channels in the HFC cable device connecting the fsCMTS in the headend and the multiple fsCMs at the subscriber site. Payload channels (UPC1 and UPC2), three upstream control channels (UCC1, UCC2, UCC3).

fsCM uses DCPC for downstream MAC management messages and payloads ("MPEG-2 Transport Stream" (TS) or IP packets), and uses DPC1 for downstream payload channels to deliver high-quality MPEG-2 video or IP data pack.

The present invention further includes downstream MAC management messages MMAP 900 and MDCD 1000 to allow fsCMTS to allocate upstream transmission to any upstream channel of the plurality of upstream channels on a packet-by-packet basis, and allows the multi-channel MAC domain to change rapidly, To adapt to the changing traffic volume in the network.

The various methods and devices described here implement a novel and unique tool that specifies efficient access to a full-service cable modem network, which can simultaneously satisfy a large number of users on a conventional HFC network for Internet access, telephone technology, Interactive and demanding digital video communication needs.

Brief Description of the Drawings Figure 1 is a block diagram showing an embodiment of a full-service "cable modem system";

Figure 2 is a block diagram of a full-service cable modem; Figure 3 shows a plan view of the channel for an example full-service cable modem system; Figure 4 is a block diagram showing the structure of the SYNC message 500; Figure 5 is a block diagram showing the structure of the CREQ message 600 Structure; Figure 6 is a block diagram showing the structure of the CRSP message 700; Figure 7 is a block diagram showing the structure of the BREQ message 800; Figure 8 is a block diagram showing the structure of the MMAP message 900; Figure 9 is a block diagram showing the MDCD message The structure of 1000; Fig. 10 is a flowchart showing a typical fsCM initialization process; and, Fig. 11 is a flowchart showing a typical upstream data transmission process using arguments BREQ 800 and MMAP 900.

Detailed Description of the Invention For a preferred embodiment of the multi-channel fsCM system 100, please refer to FIG. 1. The fsCMTS 102, which is usually located at the head end 101, is connected to this optical fiber portion of the bidirectional HFC network 104 through an electrical-optical interface (not shown). The fsCM 106 in the remote location is connected to the coaxial line 402 portion of the HFC 104. The downstream frequency spectrum (usually 50-850Mhz) is usually divided into 6Mhz channels in the downstream signal for the NTSC cable system. In North America, the range of the countercurrent spectrum is usually 5 to 42Mhz; and the bandwidth of the countercurrent channel usually varies from 160KHz to 6.4Mhz. The structure and topology of modern two-way HFC cable equipment are known in this technical field and will not be repeated here.

In this example, referring also to Figure 3, there are two downstream channels and five upstream channels; the two downstream channels are: downstream control and payload channel DCPC 147, and downstream payload channel DPC1137; these five The two upstream channels are: upstream control channels UCC1 174, UCC2 176, UCC3 178, and upstream payload channels UPC1 182 and UPC2 184. Figure 3 shows these exemplary channel frequencies, where the channel center frequencies for DCPC 147, DPC1 137, UCC1 174, UCC2 176, UCC3 178, UPC1 182, and UPC2 184 correspond to f1, f2, f3, f4, f5, f6, f7. About DCPC 147 and DPC1 These center frequencies of 137 are controlled by corresponding frequency-flexible upconverters 146 and 136. The UCC's 174, 176, and 178 channel center frequencies and channel bandwidths are controlled by a burst transmitter 194. The center frequencies of 182 and 184 of the UPC and the channel bandwidth are controlled by another burst transmitter 196. As an illustration, the UCC uses a narrower channel bandwidth and a robust modulation scheme (for example, QPSK or BPSK that can be located in the noisier part of the upstream spectrum). This "cleaner" part of the upstream spectrum is generally used by UPC so that higher order modulation (e.g., 16-64QAM) can be reliably used for higher throughput with respect to payload. In an alternative embodiment, a single upstream frequency flexible programmable burst transmitter can multiplex the transmission of control and payload bursts.

Through the IP network interface 122, the fsCMTS 102 is connected to the video server 108 for MPEG-2 digital video services, and is connected to the managed voice network for connection with the "public switched telephone network" PSTN 113 or other IP-based voice networks for telephone technical services The Internet hub 112 is connected to the Internet hub 114 for high-speed data services, and is connected to the intranet IP network 116 for use of the provisioning and network management server as part of the operation of the fsCMTS system. The IP network interface is also connected to the video server 108, and is used to provide video-related network management and (as an example) IP connectivity for the upstream traffic generated by the set-top box 530.

Utilize the fsCMTS MAC message 160 (including SYNC 500, CREQ 600, CRSP 700, BREQ 800, MMAP900, MDCD 1000 and IP payload data packet 154 in the downstream transmitter 132, 142) output to the downstream modulator 134, 144 ) To multiplex the digital video traffic, which is generated by the video server 108 and grouped into MPEG-2 transport streams TS 150, 152. These intermediate frequency outputs of the modulators 134, 144 are up-converted to these required center frequencies by up-converters 136 and 146. Then, via the coaxial 402 part of the HFC 104, these radio frequency RF outputs of the upconverters 136 and 146 are transmitted to the downstream receivers 470, 420 of the fsCM 106 through the HFC device 104. It is generally stipulated that downstream modulators 134, 144 comply with ITU J83 appendix A, B or C depending on the country. There may be other modulation and transfer error correction (FEC) formats.

Before transmitting the downstream signal, the unique data packet identifier PID (1FFE hexadecimal for the data on the cable) is used to encapsulate the IP data packet 154 into MPEG2-TS.

By periodically sending the captured time stamp value of the time stamp counter 130 driven by the time stamp frequency source 128, the time base in the fsCMTS 102 and the remote fsCM 106 are synchronized. The time stamp value is encapsulated in the MAC management message (SYNC 500), and before being delivered to the downstream modulator 134, the MAC management message is encapsulated in MPEG2-TS and combined with another TS. In this technical field, this synchronization method using time-stamped messages is known. SYNC 500 is transmitted in all downstream channels to allow seamless conversion of downstream channels.

DCPC 147 carries MAC management messages including MMAP 900 and MDCD 1000, which are essential for this multi-channel MAC operation; and, through the following detailed description, their importance will be understood.

Full-service MAC (fsMAC) has two parts: fsMAC-CM 192 and fsMAC-CMTS124; they are located in fsCM 106 and fsCMTS 102, respectively. The task of the fsMAC is: to coordinate the delivery of downstream IP data packets and fsMAC management messages; another task is to use two upstream pulse train transmitters 194 and 196 to coordinate the efficient and orderly transmission of upstream pulse trains. .

One of the transmitters 194 is used to transmit fsMAC management data packets (e.g., calibration and bandwidth request). Another transmitter 196 is used to transmit the payload of the IP data packet 199 received from the CPE interface 197.

More specifically, by using the burst feature table, the transmitter 194 can be used to transmit the burst to UCC1 174, UCC2 176, or UCC3 178. These burst feature tables are generated by fsMAC-CMTS 124 by sending MDCD 1000 down. Deliver to fsMAC-CM 106. Likewise, by using other burst feature tables, the transmitter 196 can be used to transmit the burst to the UPC1 182 or UPC2 184. The fsCM106 understands these burst feature table characteristics by listening to the MDCD message 1000, and uses the burst feature table and the transmission time by decoding the MMAP message 900.

At fsCMTS 102, corresponding to these transmitters in fsCM 106, there are matched frequency flexible programmable burst receivers including UCC burst receiver 172 and UPC burst receiver 180, which will receive, demodulate and recover These data packets received. These data packets (including collision detection information (if any)) will be input to fsMAC-CMTS 124.

Full Service Cable Modem Figure 2 is a block diagram showing an embodiment of fsCM 106. This RF signal enters the fsCM 106 at the coaxial line 402. The RF is divided into two paths by the RF splitter 404. The RF paths 406, 405 from the splitter 404 are connected to the co-direction duplex filters 410, 460, respectively. The co-direction duplex filter 410 passes the high-frequency downstream RF signal 412 to the DPC1 downstream receiver 420, and its output is the MPEG-2 transport stream TS 422 entering the packet identifier (PID) demultiplexing part 424. By checking the PID value, the demultiplexing part 424 separates the on-cable data TS 426 from the regular audio/video/data TS 423. The data TS 426 on the cable is identified by the value of 1FFE (hexadecimal). The audio/video/data TS 423 associated with a program (e.g., movie) is directed to a conventional MPEG-2 decoder 428 for generating audio/visible signals. The output from the decoder 428 may be related to a digital TV DTV 430, or a standard analog signal 434 (composite video or NTSC modulated RF) for connection with a conventional TV receiver or video monitor.

Alternatively, the TS 423 can be connected to the digital set-top box using IEEE 1394 (not shown) or other high-speed connections. Another alternative is to send the MPEG-2 audio/video/data TS 476 to the FSMAC-CM 192, where the TS is encapsulated in IP (MPEG-2 over IP) and is passed through the CPE interface 197 Forward to the home network 508. The digital set-top box 503 connected to the home network 508 can decode the MPEG-2 TS.

The other RF path 405 passes through the co-direction duplex filter 460. The downstream RF signal 462 is tuned to the DCPC 147 and processed by the second downstream receiver 470. The output is another MPEG-2 transport stream TS 472. The MPEG-2 transport stream TS 472 is input to the PID multiplexer. The component 424 is disassembled, and the data TS 476 on the cable is separated from another audio/video/data TS 473.

The on-cable data TS 426 is processed in the downstream processing unit 502 to recover the data packets (including MAC messages and IP payload data packets) of the data on the cable before entering the fsMAC-CM 192. The MAC message is processed by fsMAC-CM 192. Following the filtering rules of the CPE interface 197 (for example, an Ethernet network interface), the IP payload data packet is forwarded to the CPE device connected to the home network 508. Specifically, IP data packets obey the filtering rules in the data packet forwarding engine in the CPE interface 197 using bridging or routing rules. These IP data packets are forwarded to CPE equipment (for example, personal computer 514, Internet tool 512, "multimedia terminal adapter 516" for voice telephony technology 518 over IP, fax 522, video conference 520, and use home networking infrastructure 508 ( For example, other media streaming services such as 10/100Base-T Ethernet, USB, HPNA, wireless LAN, HomePlug, etc.).

The upstream IP data packets from the CPE devices 512, 514, 516, and 530 undergo filtering by the packet forwarder in the CPE interface 197, and then are queued at the upstream processing unit 586. There are two upstream burst transmitters in this embodiment: a "upstream control channel" (UCC) burst transmitter 194 and a "upstream payload channel" (UPC) burst transmitter 196. According to these stored burst feature tables sent from fsCMTS 102, each of these two transmitters includes FEC encoder, modulator, frequency flexible digital up-converter, RF front-end, etc., to allow the upstream spectrum Upstream burst transmission in any channel within.

The upstream MAC management burst data packets 498 are sent to the UCC channel transmitter 194, and they are output to the in-direction duplex filter 460 as the RF burst signal 490. The payload IP data packets 488 emerge from the upstream processing unit 506, and they are processed by the UPC burst transmitter 196 accordingly. The output burst RF signal 480 is coupled to the in-direction duplex filter 410 and used as the RF signal 406. It appears that the RF signal 406 is coupled to the HFC coaxial line 402 through the splitter 404, so as to flow backward to the head end where the fsCMTS 102 is located.

Now, the signal flow of the fsCM system 100 between the fsCMTS 102 and the fsCM 106 has been described. The following further description will show how fsMAC-CMTS 124 and fsMAC-CM 192 will coordinate the multiple access transmission of the upstream burst. First, the essential MAC management messages SYNC500, MDCD 1000, MMAP 900, CREQ 600, CRSP 700, and BREQ 800 will be described, and then the details of the fsMAC protocol will be described.

Full-service MAC management message·SYNC message FIG. 4 is a block diagram of a SYNC MAC message structure 500. The SYNC MAC message structure 500 includes a MAC management header 582, a time stamp snapshot 584 that captures the value of the sample value of the time stamp counter 130, an fsMAC domain identifier 586, and a downstream channel identifier 588.

Table 1 shows the description of each field of the SYNC message 500. However, in the SYNC message 500, fewer or additional fields can also be used.

Table 1. SYNC message 500 field parameter field parameter description

fsMAC message header This field allows fsCM-MAC 192 to uniquely identify and process 582 the SYNC management message 500.

Time Stamp Snapshot This field contains the sample 584 value of the time stamp counter 130.

fsMAC domain identifier This field uniquely identifies the fsMAC domain as defined in the MMAP message 900 586.

Downstream Channel Identifier This field uniquely identifies the downstream channel in which the fsMAC message is transmitted.

CREQ message FIG. 5 is a block diagram of a calibration request (CREQ) MAC message structure 600. The CREQ MAC message structure 600 includes a MAC management header 602, fsCM service identifier 604, fsMAC domain identifier 606, downstream channel identifier 608, fsCM Ethernet MAC address 610, fsCM type 612, and pre-equalizer training sequence 614.

Table 2 shows the description of each field of the CREQ message 600. However, in other embodiments, fewer or additional fields may be used in the CREQ message 600.

Table 2. CREQ message 600 field parameters Field parameter description fsMAC message header 602 This field allows fsCM-MAC 192 to uniquely identify and process CREQ message 600.

fsCM Service Identifier (SID) This field uniquely identifies the service process associated with the fsCM 106 in the fsMAC domain identified by the fsMAC domain ID 604 606.

fsMAC domain identifier (MAC This field uniquely identifies the fsMAC domain as defined by MMAP message 900ID) 606.

DCPC Channel Identifier 608 This field uniquely identifies the downstream control and payload channel (DCPC) into which the fsMAC message is passed.

Ethernet MAC Address 610 This field contains the 48-bit Ethernet MAC address associated with fsCM 106.

fsCM Type 612 This field contains information about the type and version of fsCM 106.

Pre-equalizer training sequence 614 This field contains the pre-equalizer training sequence for the fsCM transmitters 194, 196.

CRSP message FIG. 6 is a block diagram of the calibration response MAC message structure 700. CRSP MAC message structure 700 includes MAC management header 702, fsCM service identifier 704, fsMAC domain identifier 706, upstream channel identifier 708, timing adjustment 710, frequency adjustment 712, transmission power adjustment 714, transmitter pre-equalizer tap coefficients 716 and the redistributed fsMAC domain identifier 718.

Table 3 shows the description of each field of the CRSP message 700. However, in other embodiments, fewer or additional fields may be used in the CRSP message 700.

Table 3. CRSP message 700 field parameters Field parameter description fsMAC message header 702 This field allows fsCM-MAC 192 to uniquely identify and process CRSP message 700.

fsCM Service Identifier This field uniquely identifies the service process associated with the fsCM 106 in the fsMAC domain identified by the fsMAC domain ID (SID) 704-706.

fsMAC domain identifier (MAC This field uniquely identifies the fsMAC domain as defined by MMAP message 900ID) 706.

Reverse Channel Identifier 708 This field identifies the reverse channel CRSP 700 to which it responds.

Timing Adjustment 710 This field contains information for fsCM 106 to adjust its local clock to synchronize with the local clock of fsCMTS.

Frequency adjustment 712 This field contains information for the fsCM 106 to adjust the center frequency of its upstream transmitter to within the receiving frequency range of the fsCMTS receiver.

Transmit Power Adjustment 714 This field contains information for fsCM 106 to adjust its transmitter power amplifier gain to the correct level.

Transmit pre-equalizer tap system This field contains information for fsCM 106 to adjust its number 716 transmitter pre-equalizer to this new parameter.

Redistributed fsMAC domain identifier This field contains information about the new fsMAC domain identifier 718 (if any). After receiving this message, fsCM 106 will communicate with this new

fsMAC domain identifier association.

· BREQ message FIG. 7 is a block diagram of the bandwidth request (BREQ 800) MAC message structure 800, which includes the fsMAC message header 802, the fsCM service identifier 804, the fsMAC domain identifier 806, the framing header type 808 and the requested quantity 810.

Table 4 shows the description of each field of the BREQ message 800. However, fewer or additional fields can also be used.

Table 4. BREQ message 800 field parameters Field parameter description fsMAC message header 802 This field allows fsCM-MAC 192 to uniquely identify and process the BREQ message 800.

fsCM Service Identifier This field uniquely identifies the service process associated with the fsCM 106 in the fsMAC domain identified by the fsMAC domain ID 806 (SID) 804.

fsMAC domain identifier (MAC This field uniquely identifies the fsMAC domain as defined by MMAP message 900ID) 806.

Framing header type 806 This field contains the header type information for the fsCMTS to consider the MAC frame header housekeeping operations when allocating the bandwidth of the requested fsCM.

Requested Quantity 810 This field contains the amount of payload bandwidth requested by the fsCM (not including MAC header housekeeping operations), such as the number of bytes or the number of time slots (for example, very small slots).

MMAP message FIG. 8 is a block diagram of a multi-channel bandwidth allocation MAC message (MMAP) structure 900, which includes an fsMAC management message header 902, an fsMAC domain identifier 904, a broadcast grant list, a unicast grant list, and a pending grant list 910.

Table 5 shows the description of each field of the MMAP message 900. However, fewer or additional fields can also be used.

Table 5. MMAP message 900

Field Parameter Field Parameter Description fsMAC Message Header 902 This field allows fsCM-MAC 192 to uniquely identify and process MMAP message 900.

fsMAC domain identifier 904 This field uniquely identifies the fsMAC domain.

Broadcast Grant 906 This field contains the central bandwidth grant for the argument area in order to transmit bandwidth requests from any fsCM in the fsMAC domain. Table 6 gives examples given by the center broadcast.

Unicast grant 908 This field contains the bandwidth grant address to the individual fsCM. Table 7 gives examples of unicast delivery.

Pending grants 910 This field contains a list of pending grants for those BREQs successfully received by the fsCMTS, but these grants are postponed to a future MMAP 900. Table 8 gives examples of pending grants.

Table 6. Broadcast grant 906 example Broadcast grant field parameter description of the number of broadcast grant In this example, = 2 service ID (the beginning of the first broadcast grant). This field contains the SID of the broadcast address for all fsCMs.

Grant type bandwidth request BREQ 800 upstream channel ID. This field contains the channel ID assigned to the broadcast. The burst feature table ID. This field identifies the burst feature table of BREQ 800. Compensation start and end values. This field contains the selected argument. The compensation window of the decomposition algorithm The number of payloads in bytes The length of the BREQ 800 burst in bytes The length of the payload data length The number of bursts is about the number of BREQ 800 bursts given The transmission start time is the first one The service ID of the start transmission time of the BREQ 800 burst (the start given by the second broadcast). This field contains the SID about the broadcast address of a group of fsCMs.

Grant type calibration request CREQ 600 upstream channel ID. This field contains the burst feature table ID of the channel ID assigned to the broadcast. This field identifies the burst feature table compensation start and end values of CREQ 600. In this example, this field The compensation window containing the selected argument resolution algorithm The number of payloads in bytes The number of CREQ 600 bursts in bytes The length of the data payload Data length The number of bursts in relation to the number of CREQ 600 bursts given Transmission start time The start transmission time of the first CREQ 600 burst Table 7. Unicast grant 906 example Unicast grant field parameter description Unicast grant quantity in this example is 3SID-1 (the first single point Transmission of the beginning of giving). This field contains the SID of fsCM-1.

Give Type Variable Length Payload Packet Reverse Channel ID This field contains the channel ID to which the unicast is assigned, the burst feature table ID This field identifies the burst feature table of the packet, the burst framing header type, the The field contains the framing header type to allow fsCMTS to calculate the required housekeeping operations for the burst. The number of payloads in bytes. The length of the burst payload in bytes. The length of the data. Transmission start time. The first BREQ 800 The start transmission time of the burst

SID-2 (the beginning of the second unicast grant). This field contains the SID of fsCM-2.

Give Type Constant Bit Rate (CBR) Backstream Channel ID This field contains the channel ID to which the unicast is assigned Burst Characteristic Table ID This field identifies the Burst Characteristic Table Burst Framing Header Type for this burst This field contains the type of framing header to allow fsCMTS to calculate the housekeeping operations required for the burst. The number of payloads in bytes. The length of the burst payload. The length of the burst data in bytes. The given interval. This field contains two The time interval between adjacent grants. Transmission start time. The burst start transmission time SID-3 (the beginning of the third unicast grant). This field contains the SID of fsCM-3.

Grant Type Dedicated Channel Reverse Channel ID This field contains the channel ID for which the unicast is assigned. The number of payloads in bytes. The length of the burst payload in bytes. The data-carrying length. Grant period. This field contains The dedicated channel can be used to transmit the start time of the time transmission start time of the first burst start transmission time table 8. Pending grant 910 example Pending grant field parameter description broadcast grant In this example, = 2 number SID-a This field contains The pending SID of fsCM-a.

SID-b This field contains the pending SID of fsCM-b.

·MDCD message Figure 9 is a block diagram of the fsMAC domain channel descriptor (MDCD) MAC message structure 1000, which includes fsMAC message header 1002, fsMAC domain identifier 1004, acceptance of new fsCM registration mark 1006, number of downstream channels 1008, upstream Number of channels 1010, downstream channel change count 1012, upstream channel change count 1014, downstream channel identifier and "type-length-value" (TLV's) list 1026, upstream channel identifier and TLV's list 1028, and upstream List of burst feature table identifiers and TLV's 1030.

Table 9 shows the description of each field of the MDCD message 1000. However, fewer or additional fields can also be used.

Table 9. MDCD Message 1000 Field Parameters Field Parameter Description fsMAC Message Header 1002 This field allows fsCM-MAC 192 to uniquely identify and process MDCD message 1000.

fsMAC domain identifier 1004 This field uniquely identifies the fsMAC domain as defined in the MMAP message 900.

Accept the new fsCM registration flag. This field contains the flag bit. When set, 1006 the flag bit indicates that the fsMAC domain is accepting the new fsCM 106 registration.

Number of Downstream Channels 1008 This field contains the N number of downstream channels in the fsMAC domain.

Number of upstream channels 1010 This field contains the M number of upstream channels in the fsMAC domain.

Downstream Channel Change Count 1012 This field contains the change count in the downstream channel configuration. If this field is different from the count in the previous MDCD message 1000, the fsCM 106 in the fsMAC domain must update its downstream channel configuration to the current MDCD message 1000.

Upstream Channel Change Count 1014 This field contains the count of changes in the upstream channel configuration. If this field is different from the count in the previous MDCD message 1000, the fsCM 106 in the fsMAC domain must update its upstream channel configuration to the current MDCD message 1000.

Downstream Channel Identifiers and TLV's This field contains a list of N downstream channel identifiers and 1026 a list of the associated TLV's that define these channel parameters. Table 10 shows an example of a list of 2 downstream channels.

Upstream Channel Identifier and TLV's This field contains a list of M upstream channel identifiers and 1028 a list of the associated TLV's that define these channel parameters. Table 11 shows an example of a list of 5 upstream channels.

Identifier of the upstream pulse train characteristic table This field contains a list of X upstream pulse train characteristic identifiers and a list of TLV's 1030 identifiers and a list of the associated TLV's that define these pulse train parameters. Table 12 shows an example of a list of 3 burst feature tables.

Table 10. Downstream Channel Identifier and TLV's 1026 Example Number of Downstream Channels = 2 TLV Encoded Downstream Channel Type Length Value Description Parameters (1 (1 (L Type Byte) Byte) Byte) Downstream Channel 1 1 01 01 (channel identifier ID) downstream channel 1 1 1 1 (DCPC) type center frequency 3 4 f1 Hz symbol rate 4 1 0 0 (5.056941) FEC 5 1 1 1 (J83 appendix B) modulation 6 1 0 64QAM interleaving depth 7 2 16, 8 waiting time (I, J) =0.48 milliseconds downstream channel 1 1 02 02 identifier downstream channel 2 1 2 2 (DPC1) type center frequency 3 4 f2 Hz symbol rate 4 1 1 1 (5.360537 trillion symbols/sec) FEC 5 1 1 1=J83 Appendix B Modulation 6 1 1 256QAM Interleaving Depth 7 2 128,1 Latency (I, J) = 2.8 milliseconds Table 11. Reverse Channel Identifier and TLV's 1028 Example Number of Reverse Channels = 5 TLV encoding upstream channel type length value description parameter (1 (1 (L type byte) byte) byte) upstream channel 1 1 10 10 identifier upstream channel 2 1 0 0 (UCC1) type center frequency 3 4 f3 Hz symbol rate 4 1 3 3 (640 thousand symbols/sec) Reverse channel 1 1 11 Channel ID = 11 identifier Reverse channel 2 1 1 1 (UCC2) type center frequency 3 4 f4 Hz symbol rate 4 1 2 2( 320 thousand symbols/sec)

Reverse channel 1 1 12 Channel ID = 12 identifier. Reverse channel 2 1 2 2 (UCC3) type center frequency 3 4 f5 Hz Symbol rate 4 1 3 3 = 640 thousand symbols/sec. Reverse channel 1 1 13 Channel ID = 13 identification Symbol Reverse Channel 2 1 3 3 (UPC1) Type Center Frequency 3 4 f6 Hz Symbol Rate 4 1 6 6 = 5.12 Msymbols/sec Reverse Channel 1 1 14 Channel ID = 14 Identifier Reverse Channel 2 1 4 4 (UPC2) Type center frequency 3 4 f7 Hz Symbol rate 4 1 6 6 = 5.12 megasymbols/sec. Table 12. Identifiers and TLV's examples of upstream pulse train feature table. Number of upstream pulse train feature tables TLV code = 3 upstream pulse String parameter type length value description Number type (1 (1 (L byte) byte) byte) pulse train identification 1 1 11 pulse train characteristic table 1 modulation 2 1 0 0 = QPSK

Preamble 3 2 64 64-byte length section FEC code word 4 1 78 13 words (k) section FEC error correction 5 1 6 T=2 words (T) section encryption code 6 2 35 Seed sub=00110101 pulse Inter-series protection 7 1 5 5 symbols guard time pulse train identification 1 1 12 pulse train characteristic table 2 modulation 2 1 0 0=QPSK preamble 3 2 64 64-byte length section FEC code word 4 1 78 78 words (k) section FEC error correction 5 1 6 T=6 words (T) section encryption code 6 2 35 seed sub =00110101 inter-pulse string protection 7 1 5 5 symbols guard time pulse string identification 1 1 13 pulse string characteristic table 3 modulation 2 1 0 0 = 64QAM preamble 3 2 64 128 byte length section FEC code word 4 1 78 256 words (k) section FEC error correction 5 1 6 T = 10 (T) byte encryption code 6 2 35 seed Sub=00110101 inter-burst guarantee 7 1 5 5 symbols guard time full-service cable modem system operation Regarding this illustrated embodiment, the fsCMTS establishes the fsCM domain, and the fsCM domain includes: · 2 downstream channels 1. DCPC 147 is about all the broadcast channels of the fsCM 106 in the fsCM domain, and is modulated by 64QAM and configured as the ITU-T J83 Appendix B standard according to the center frequency of f1 Hz in the downstream spectrum as shown in FIG. 3. This channel is mainly used for data MAC management messages on the cable, IP traffic and (to a lesser extent) MPEG-2 video delivery.

2. DPC1 137 is about all the broadcast channels of the fsCM 106 in the fsCM domain, and is modulated by 256QAM and configured as the ITU-T J83 Appendix B standard according to the center frequency of f2Hz in the downstream spectrum as shown in FIG. 3 . This channel is mainly used for broadcast quality MPEG-2 movie transport, but also transports IP data packets.

· 3 upstream control channels 1. UCC1 174 for all or a group of fsCM 106 argument bandwidth requests is modulated by QPSK and configured to be 640 thousand at the center frequency of f3 Hz in the upstream frequency spectrum as shown in FIG. 3 Symbol/second to operate.

2. UCC2 176 is used for the calibration and maintenance of all or a group of fsCM 106 arguments, and it is modulated by QPSK and is configured to be 320 thousand symbols/according to the center frequency of f4 Hz in the upstream spectrum as shown in Fig. 3 Seconds to operate.

3. UCC3 178 is used for Aloha arguments, pay-per-view or video-on-demand request bursts for all or a group of fsCM 106, and is modulated by QPSK and adjusted according to the center frequency of f5 Hz in the upstream spectrum as shown in FIG. 3 It is configured to operate at 640 thousand symbols per second.

· 2 upstream payload channels: 1. UPC1 182 is intended to be mainly used for voice CBR traffic over IP for all or a group of fsCM 106, and is modulated by 16QAM and is based on f6Hz in the upstream spectrum as shown in Figure 3. The center frequency of is configured to operate at 5.12 Msymbols/sec.

2. UPC2 184 is intended to be mainly used for high-speed data and media flow traffic about all or a group of fsCM 106, and is modulated by 16QAM and configured according to the center frequency of f7 Hz in the reverse flow spectrum as shown in FIG. 3 Operate at 5.12 trillion symbols per second.

When fsCMTS 102 is used for operation, periodically broadcast the following MAC management messages to all fsCM 106 in order to establish the fsCM domain in HFC 104 via DCPC 147: 1. SYNC 500, usually sent every 150-250 milliseconds, 2. MDCD 1000 is usually sent every 1 to 2 seconds, and 3. MMAP 900 is usually sent every 2 to 10 milliseconds.

SYNC 500 uses conventional time stamping methodology to establish network-wide clock synchronization of fsCMTS 102 and fsCM 106, which is known in the art. The MDCD 1000 uses the fsMAC domain identifier 1004 to establish the fsMAC domain. The MDCD 1000 also contains these parameters required by the fsCM 106 in order to join the fsMAC domain by setting up these channel and burst feature tables. By using a special burst feature table, transmission deadline, and at a special transmission start time, the MMAP 900 contains information about upstream transmission opportunities on a special channel. MMAP 900 also contains the opportunity for upstream transmission of fsCM 106 (usually once every 1 to 2 seconds), fsCM 106 hopes to join the network to transmit CREQ 600 to adjust its ranging offset, center frequency, transmitter power level and Transmitter pre-equalizer coefficients as part of this initialization process. Once initialized, the fsCM 106 starts to use the argument-based BREQ 800 to request the transmission of payload data packets.

Full-service cable modem initialization Referring to FIG. 10, when the fsCM 106 is powered on or reset, the fsCM initialization flowchart 1100 is entered at block 1102. In block 1104, the DCPC receiver 470 at fsCM 106 is continuously searching for a valid DCPC channel. If the MPEG-2 TS has a valid data PID on the cable (for example, 1FFE hexadecimal), the DCPC is considered valid; and once it is found, block 1106 is entered to search for a valid MDCD 1000. In MDCD 1000, if set, flag 1006 indicates that the DCPC is accepting new fsCM 106 registration, and block 1110 is entered. If the flag 1006 is not set, it means that the MDCD 1000 is not accepting new registrations, and the fsCM 106 will exit block 1106 and enter block 1104 to search for another valid DCPC.

In block 1110, all these parameters in MDCD 1000 are accepted by fsCM 106. The fsMAC domain ID 1004 will be used to match the domain identifier 586 in SYNC 500. If a valid SYNC 500 is received, the fsCM 106 will synchronize its time base with the fsCMTS time base in block 1114. The fsCM106 also initializes other upstream and upstream channels and these burst feature tables based on the information received in the MDCD 1000 in block 1114.

In block 1116, the fsCM 106 also monitors the MMAP 900 for the broadcast calibration grant as shown in Table 6. In this example, the second broadcast is given for CREQ 600. In block 1116, if a CREQ 600 grant is received, block 1118 will be entered, and fsCM 106 will construct a calibration based on the burst feature table and the payload information length as specified in the received broadcast grant 906 Burst.

In block 1120, the CREQ 600 burst will then be transmitted at the specified upstream channel and at the specified transmission start time (using the exponential compensation algorithm, and based on these compensation start and end values specified in the grant , To experience compensation). If the calibration response CRSP700 is received by the fsCM 106 in block 1122, the initial calibration is successful, and the fine calibration block 1124 is entered. If the CRSP 700 is not received in block 1122, then after a predetermined timeout, block 1116 will be entered, and the CREQ 600 process (not shown) will be retried.

In block 1124, by giving periodic unicast fine calibration to the fsCM 106 for each upstream channel, the fsCMTS will perform fine calibration on each of these upstream channels in the fsCM domain. In block 1124, after receiving the fine CRSP 700 from fsCMTS 102, and after fsCM 106 adjusts its upstream channel parameters including ranging offset, frequency, power level, and pre-equalizer coefficients, the fine calibration The process is complete. These parameters will be stored in the fsCM 106 upstream channel characteristics table, and they will be used to configure the channel before burst transmission. After the fine calibration, block 1126 is entered. In block 1128, fsCM 106 completes the modem registration process and becomes available for operation.

Refer to FIG. 11 for the transmission using the bandwidth request, which is a flowchart of the transmission using the argument-based bandwidth request 1200. In block 1204, one or more data packets are queued at fsCM 106. In block 1206, the fsMAC-CM 192 selects one or more data packets in the transmission data packet. Determine the number of bytes of the payload and the type of header (for example, short, long, or concatenated). In block 1208, the fsCM 106 waits until the broadcast grant 906 in the BREQ 800 is used to receive the MMAP 900 (example in Table 6). Entering block 1210, the fsCM 106 uses the compensation start and end values to calculate the initial compensation for the burst transmission (any compensation algorithm will work and is well known in the art). If the compensation algorithm determines that "the transmission opportunity exceeds the current grant", then fsCM 106 will postpone the transmission to the next MMAP 900; otherwise, referring to the first broadcast grant in Table 6, fsCM 106 calculates according to the following BREQ 800 burst transmission start time: (transmission start time) + (calculated and based on the length of the payload and header expressed in bytes and the burst period of the burst feature table) × (the delay calculated by the compensation algorithm The number of bursts) will transmit BREQ800 at the channel specified by the upstream channel ID and at the calculated time. Entering block 1212, fsCM 106 waits for the unicast grant or pending grant in the next MMAP 900. In block 1218, the next MMAP 900 is received, and, in block 1220, the next MMAP 900 is checked for a unicast grant with an SID corresponding to the SID in the original BREQ 800. The unicast grant will have the necessary information (burst feature table, header type, and burst feature table) to compile the burst in block 1226, and in block 1228, and at the specified upstream channel The transmission is carried out at the specified transmission start time (under compensation). If in block 1220, no unicast grant is received for BREQ 800, then MMAP 900 is checked for the existence of a pending grant.

In block 1224, if there is a pending grant, enter block 1208 to wait for the next MMAP900. If there is no pending grant in MMAP 900 in block 1224, then CREQ 600 is considered to be worn or conflicted, and block 1208 is re-entered to retry BREQ 800 transmission.

True seamless channel change In conventional data-on-cable systems, the conventional cable modem termination system (CMTS) may instruct the cable modem (CM) to change its upstream channel for communication load balancing, noise avoidance, or failed channel backup. The procedure for performing the channel change is as follows. When the CMTS determines to move the CM from the currently allocated upstream channel to another upstream channel, it sends a channel change request message to the CM. In response, the CM transmits a channel change response message on the currently allocated channel to signal that it is ready to use the new channel. After switching to this new channel, the CM usually performs recalibration of transmitter parameters (for example, ranging offset, power level, frequency, and pre-equalizer coefficients) before the new channel can be used. This channel switching mechanism can be very time-consuming, and can take a few seconds or longer, because full recalibration is often required.

According to the present invention, a truly seamless channel change can be realized in the fsCM system 100. True seamless channel changes on a packet-by-packet basis. The cable modem burst transmission directed by each CMTS can be at any of these upstream channels. They utilize these burst characteristics as defined in the MAC message MDCD1000 Any burst feature table in the table can be configured.

The fsCM 106 is added to accept the newly registered fsCM field in the MDCD message 1000. It also contains a list of downstream channels with channel characteristic table parameters, a list of upstream channel parameters and channel characteristic table parameters, and information about burst characteristic table parameters. The fields of the list. By using downstream, upstream and burst IDs, these feature table parameters are uniquely identified in the fsMAC domain. These parameters are stored in the fsCM along with the channel calibration parameters for each channel as a result of the calibration request/response process.

When receiving the upstream transmission grant from the MMAP 900, the grant contains sufficient information about the transmission channel ID, burst feature table, grant size, and header type to form the exact start time that will be specified in the same MMAP900. The transmitted countercurrent pulse train. In this way, the channel change is straightforward and indeed seamless.

Alternative Embodiments Those skilled in the art can utilize the multi-channel fsMAC in different modifications for further optimization. Examples are: If MPEG-2 video is not needed to further increase downstream capacity for additional users, or MPEG-2 video can be used for IP media streaming, then all downstream channels are used for IP packet streaming.

Use a single upstream control channel for channel calibration and bandwidth request.

Define different upstream payload channels (e.g., CBR channels, dedicated channels for achieving service quality and capacity goals).

Although the teachings of the present invention have been described in accordance with several preferred and alternative embodiments, those skilled in the art will understand that: without departing from the true spirit and scope of the appended claims Below, you can make numerous modifications, improvements and replacements that will perform the same function. All such modifications, improvements and substitutions are intended to be included within the scope of the appended claims here.