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NeMo CMTS
User Manual
93 pgs1.34 Mb0

Coresma NeMo CMTS User Manual

NeMo CMTS
User’s Guide
010804
NeMo CMTS User’s Guide
Important Notice
This guide is delivered subject to the following conditions and restrictions:
§ This guide contains proprietary information belonging to Coresma, Ltd. Such information is supplied solely for the purpose of explicitly assisting properly authorized users of NeMo CMTS System™.
§ No part of the contents may be used for any other purpose, disclosed to any person or firm or reproduced by any means, electronic and mechanical, without the express prior written permission of Coresma, Ltd.
§ The text and graphics are for the purpose of illustration and reference only. The specifications on which they are based are subject to change without notice.
§ The software described in this document is furnished under a license. The software may be used or copied only in accordance with the terms of that agreement.
§ Information in this document is subject to change without notice. Corporate and individual names and data used in examples herein are fictitious unless otherwise noted.
Copyright 2001 Coresma, Ltd.
NeMo CMTS, NeMo Modem are trademarks of Coresma Ltd. All other product names are trademarks or registered trademarks of their respective owners, and are hereby acknowledged.
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Safety Instructions
Caution! Risk of Electric Shock!
Do not open the cover under any circumstances.
§ Dangerous voltages inside.
§ No user serviceable parts inside.
§ Refer to qualified service personnel.
Explanation of Graphical Symbols:
This symbol is intended to alert the user to the presence of non-insulated "dangerous voltage" within the product's enclosure that may be of sufficient magnitude to constitute a risk of lethal electric shock to persons.
This symbol is intended to alert the user to the presence of important operating, maintaining and servicing instructions in the literature accompanying the appliance. Failing to comply with this instruction may result in a hazard.
NeMo CMTS User’s Guide
§ Power sources - Connect this unit only to power sources specified in the Operating Instructions, and as marked on the unit back.
§ This unit must be disconnected from power supply prior to servicing.
§ When disconnecting the AC power cord, pull it out by the AC power plug. Do
not pull the cord itself.
§ Never handle the AC power plug or cable with wet hands, as this could result in fire or an electrical shock.
§ Power cords should be routed to avoid being severely bent, pinched, or walked upon. Pay particular attention to the cord from the unit to the power socket.
§ To help prevent electric shock and fire hazard avoid connecting the unit through an extension cord.
§ Do not remove or at tach cables to the unit during a thunderstorm.
§ The CMTS must be installed near a wall power outlet.
§ Only a certified technician is allowed to connect and disconnect cables to the
CMTS.
§ Please install the CMTS on a stable horizontal surface that can support the weight of the CMTS, approximately 4.0 kg.
§ Do not place heavy objects on top of the box.
§ Do not try to bend the box.
Environmental Conditions for the NeMo CMTS
§ This unit must be installed in an office environment in a temperature-controlled location where the temperature is between 0° and 40° Celsius, far away from rain, water sources, heat sources, inflammable liquids, inflammable vapors, dust and flammable materials.
§ If installed in a rack, air ventilation should be provided for the CMTS. The surrounding temperature inside the rack around the CMTS should not be over 40º Celsius.
§ Do not impair the airflow around the CMTS especially near the air vents located at the sides of the unit as shown in the figure below. This may result in a hazard.
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§ The CMTS was designed to work at heights between –200 meters below sea level and to 2000 meters above sea level.
§ If the CMTS is brought in from a cold place to a hotter place, condensation may occur. Wait one hour before connecting to power.
NeMo CMTS User’s Guide
About This Guide
This guide describes how to prepare your site and install the NeMo CMTS system. It is intended for qualified engineers familiar with RF networks.
This guide contains the following chapters:
§ Chapter 1 – Introduction introduces the NeMo CMTS system, describes its components and provides technical specifications.
§ Chapter 2 - Site Preparation describes the hardware, software, and environmental requirements necessary for the installation at the headend and end-user sites.
§ Chapter 3 - Installing the NeMo CMTS describes the procedure for installing the NeMo CMTS system and testing an end-user site from your location.
§ Appendix A – Rlogin Commands describes the various system commands used to control the CMTS
§ Appendix B – NetHotel lists additional system commands for controlling the optional NetHotel software
§ Appendix C – Boot Parameters lists the parameters available during the boot sequence of the CMTS.
§ Appendix D – Multiple MAC Modems describes using multiple NeMo modems in a network.
§ Appendix E – Glossary of Terms defines technical terms used in this document.
§ Appendix F – Technical Specifications lists the specifications of the NeMo CMTS
§ Contacting Coresma lists the various ways to contact Coresma Sales and
Support.
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Table of Contents
IMPORTANT NOTICE.......................................................................................................................................................I
SAFETY INSTRUCTIONS..............................................................................................................................................II
Explanation of Graphical Symbols:.....................................................................................................................ii
Environmental Conditions for the NeMo CMTS............................................................................................iii
ABOUT THIS GUIDE........................................................................................................................................................V
TABLE OF C ONTENTS....................................................................................................................................................VI
INTRODUCTION................................................................................................................................................................1
About this chapter:.................................................................................................................................................1
WHAT IS THE NEMO CMTS SYSTEM? ................................................................................................................... 1
System Components...............................................................................................................................................1
NEMO CMTS DIAGRAM..........................................................................................................................................4
OVERVIEW....................................................................................................................................................................5
HOW THE CMTS WORKS.........................................................................................................................................6
NEMO HEADEND UNIT............................................................................................................................................7
Configuring the CMTS.........................................................................................................................................8
MAIN FEATURES.........................................................................................................................................................8
ARCHITECTURE...........................................................................................................................................................8
OPERATION AND MAINTENANCE...........................................................................................................................8
INSTALLATION FEATURES.........................................................................................................................................9
INTRODUCING THE NEMO C ABLE MODEM..........................................................................................................9
SYSTEM ARCHITECTURE..........................................................................................................................................10
SYSTEM C ONNECTIVITY...........................................................................................................................................11
HEADEND HARDWARE...........................................................................................................................................13
CMTS Functionality ...........................................................................................................................................13
RF Transmitter.....................................................................................................................................................13
RF Burst Receiver ................................................................................................................................................14
NeMo Modem Transmitter ................................................................................................................................14
Channel Controller...............................................................................................................................................14
IP Host Address ....................................................................................................................................................14
NeMo CMTS User’s Guide
HEADEND SOFTWARE.............................................................................................................................................14
CMTS Embedded Code.......................................................................................................................................15
NEMO CABLE MODEM...........................................................................................................................................15
CM Controller......................................................................................................................................................16
Burst Transmitter................................................................................................................................................16
Downstream IF Receiver ....................................................................................................................................16
Tuner and Diplexer .............................................................................................................................................16
Multiple MAC Modems .....................................................................................................................................16
APPLICATIONS..........................................................................................................................................................16
SYSTEM WITHOUT MANAGEMENT.......................................................................................................................17
SYSTEM WITH M ANAGEMENT...............................................................................................................................17
SITE PREPARATION......................................................................................................................................................18
About this chapter:...............................................................................................................................................18
OVERVIEW..................................................................................................................................................................18
System Components ............................................................................................................................................18
BASIC CONFIGURATION..........................................................................................................................................19
PREPARING THE HEADEND SITE...........................................................................................................................21
Preparing the Management Computer............................................................................................................21
Preparing the RF Network .................................................................................................................................23
Preparing the Ethernet Network Parameters..................................................................................................25
PREPARING A LOCAL END-USER SITE.................................................................................................................26
Installation Configuration..................................................................................................................................27
INSTALLING THE NEMO CMTS................................................................................................................................ 29
About this Chapter...............................................................................................................................................29
PART 1: SETTING UP THE CMTS AND MODULATOR CONNECTION.............................................................29
Connecting the CMTS and Modulator............................................................................................................29
Calibrating the RF Signals and Connecting to the RF Network.................................................................31
PART 2. SETTING UP THE MANAGEMENT COMPUTER(S)................................................................................35
Configuring the CMTS for the First Time: CMTS Configuration.............................................................36
Configuring the CMTS Using FOCS..............................................................................................................40
PART 3: SETTING UP AN END-USER SITE............................................................................................................41
Before You Begin..................................................................................................................................................41
Installing the NeMo Modem..............................................................................................................................41
Installing and Using the NeMo Tool ...............................................................................................................42
RLOGIN C
OMMANDS
....................................................................................................................................................45
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INTRODUCTION.........................................................................................................................................................45
REQUIREMENTS.........................................................................................................................................................45
AUTHORIZATION......................................................................................................................................................45
RLOGIN PASSWORD..................................................................................................................................................46
SHELL COMMANDS..................................................................................................................................................46
dir ............................................................................................................................................................................46
cd .............................................................................................................................................................................46
show ........................................................................................................................................................................46
set ............................................................................................................................................................................46
help..........................................................................................................................................................................46
quit..........................................................................................................................................................................47
reboot......................................................................................................................................................................47
write........................................................................................................................................................................47
ls..............................................................................................................................................................................47
CONTROL VARIABLES..............................................................................................................................................47
Root directory........................................................................................................................................................47
Service directory ...................................................................................................................................................48
Upchan directory..................................................................................................................................................49
Freq_hopp_table directory...................................................................................................................................51
Downchan directory ............................................................................................................................................51
CMTS directory....................................................................................................................................................52
mgmt directory .....................................................................................................................................................54
Stats directory .......................................................................................................................................................55
ip_cfg directory.....................................................................................................................................................57
Boot_cfg directory ................................................................................................................................................58
Radius Directory ..................................................................................................................................................58
CM Operation Mode directory ..........................................................................................................................62
NETHOTEL .....................................................................................................................................................................65
NAT/SETTINGS DIRECTORY...................................................................................................................................65
BOOT PARAMETERS.....................................................................................................................................................69
M ULTIPLE MAC MODEMS.........................................................................................................................................71
PREFACE.....................................................................................................................................................................71
MULTIPLE MAC DETAILED DESCRIPTION..........................................................................................................71
MODEM I DENTIFICATION.......................................................................................................................................71
Modem Ethernet Operation Mode....................................................................................................................71
MAC ADDRESS TRANSLATION.............................................................................................................................72
NeMo CMTS User’s Guide
IP messages handling ..........................................................................................................................................72
ARP messages handling......................................................................................................................................72
DHCP messages handling..................................................................................................................................72
DHCP Block Mode..............................................................................................................................................72
MULTI MAC AUTHENTICATION IMPLICATIONS..............................................................................................73
MULTI MAC FORWARDER IMPLICATIONS.........................................................................................................73
GLOSSARY OF TERMS..................................................................................................................................................74
TECHNICAL SPECIFICATIONS ....................................................................................................................................76
NeMo CMTS ........................................................................................................................................................76
NeMo Modem.......................................................................................................................................................77
CONTACTING C ORESMA.............................................................................................................................................79
INDEX ..............................................................................................................................................................................80
NeMo CMTS User’s Guide
CHAPTER 1
Introduction
This chapter introduces the NeMo CMTS system, describes the system components, and presents a system diagram and lists its technical specifications.
About this chapter:
§ What is the NeMo CMTS System?, Describes the components and features of the NeMo CMTS system.
§ Technical Specifications, page 5, provides the technical specifications of the
NeMo CMTS and the NeMo modem.
What is the NeMo CMTS System?
The NeMo CMTS system is a high-speed two-way RF cable modem solution. NeMo is designed for a distributed node architecture for homes, multiple dwelling units, campuses, executive offices, and hotels. It is comprised of an intelligent RF bridge and can be managed remotely. This enables operators and ISP's to manage dispersed CATV networks from one control station.
System Components
The NeMo CMTS is comprised of the following components:
§ NeMo CMTS, page 1.
§ Management Software, page 2.
§ NeMo Modem, page 3.
NeMo CMTS
The NeMo CMTS resides at the headend and provides up to a 10Mbps connection for high-speed delivery of Internet content and other on-line services. The main objective of the NeMo CMTS is to emulate an Ethernet LAN over a cable television network, and connect subscribers' PCs and local servers via an IP router.
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The NeMo CMTS features:
§ Excellent performance in noisy networks
§ Flexible installation and configuration
§ Ideal solution for MDUs, hotels, and campuses
§ Rack mount or stand alone design
Management Software
The FOCS management software resides at the headend and provides the services of a remote workstation through a classic, client -server SNMP web-based architecture and is comprised of the following components:
§ TFTP Services for software upgrades
§ Serial connection for local monitoring
§ The management software features:
§ Tracks and monitors network performance
§ Tracks and monitors the performance of NeMo modems
§ Collects performance and billing statistics
§ Enables authorization of all users
§ Assigns QoS
NeMo CMTS User’s Guide
§ Initiates alarms
§ Downloads software upgrades
NeMo Modem
The NeMo modem is a compact, user-friendly modem designed to suit the access needs of subscribers. Designed to plug and play, it does not require any software installation or preset attenuation. Once it is connected, the NeMo modem auto-downloads its operating software and is fully manageable and remotely diagnosed. The NeMo modem features:
§ ElastreamTM, a real-time resource allocation algorithm, delivers upstream packets at a higher success ratio than modems without such algorithms
§ Low cost, enables profitable operation in situations where density issues exist or where operators need a quick return to justify service commitments
§ Robust networking capabilities enable the modem to overcome the challenges of noisy upstream networks by providing QPSK modulation for both upstream and downstream, frequency hopping, frame correction, and packet fragmentation
§ Highly flexible QoS, enables operators to adjust the upstream and downstream bandwidth per subscriber depending on the class of service to which they are subscribed
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NeMo CMTS Diagram
NeMo CMTS User’s Guide
The NeMo CMTS diagram illustrates the following:
§ The NeMo CMTS resides at the headend site, offering access to high-speed delivery of Internet and other on-line services to subscribers. It handles the downstream and upstream channels. The CMTS also manages and controls the entire network in real time. It performs real time network management functions and controls upstream and downstream traffic intelligence.
§ The IF Agile Modulator connects to the NeMo CMTS and converts the IF input frequency into the desired RF channel output frequency.
§ The NeMo management software resides at the headend site. It controls the entire system in real time and off-line, and enables the system operator to perform monitoring and management functions.
§ The NeMo modem resides at the end-user’s site providing high-speed connectivity at speeds of up to 10Mbps via the existing cable infrastructure. It is connected to the Ethernet board in the end-user’s computer.
o The downstream channel goes from the NeMo CMTS at the
headend site to the NeMo modem at the end-user’s site.
o The data signal (measured at back of NeMo modem) should be
10 dBmV under the video signal in the CATV. The standard video signal is 10 dBmV, therefore the NeMo modem RF input should be 0 dBmV. ″The splitter at the end-user’s site splits the CATV connection. One of the splitter’s output cables is connected to the end-user’s TV, the other cable is connected to the NeMo modem at the end-user’s computer.
Overview
The NeMo CMTS system offers up to 10Mbps LAN access for high-speed delivery of Internet and other online services. The remote access capability makes the NeMo CMTS ideal for apartment complexes and high-rise residential or office buildings. The CMTS has a bandwidth of 1.8 MHz/2.56 Mbps on the upstream and 2.8 MHz/5.12 Mbps on the downstream. The main objective of the NeMo is to emulate an Ethernet LAN over a cable television network and connect subscribers' computers and local servers via an IP router.
The system is comprised of an intelligent RF bridge, managed by a remote Windows NT or UNIX workstation. The remote workstation manages all functions of authentication, network management, subscriber database and system configuration and control, while the NeMo CMTS distributes the Internet and other online services within the network. The NeMo CMTS has no distance limitations. It can be placed at a node in a neighborhood building, hotel basement or campus.
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How the CMTS Works
The NeMo CMTS system automatically performs software downloads, utilizes constant management messages, auto detects and keeps in memory the status of all modems in the network, detects noise and automatically advises NeMo modems to frequency hop in 10kHz increments on the upstream. Using Elastream
TM
, the NeMo CMTS system randomly and intelligently allocates time slots to every NeMo modem, based on demand, priority and system resources.
The design of the NeMo CMTS originates from its simplicity, scalability and management. With robust upstream and downstream QPSK modulation, system auto software download, auto attenuation, upstream techniques, and remote management, it can successfully operate in today's noisiest networks. With Elastream
TM
, Coresma's algorithm for managing real-time network activity, an ordinary network becomes elastic, enabling an operator to accommodate a growing number of users without creating the urgency to upgrade.
The following diagram illustrates the relationship between the NeMo CMTS and your computer.
The CMTS contains the following:
NeMo CMTS User’s Guide
NVRAM Parameters: The parameters needed to configure the CMTS.
Boot (ROM): The initial code that is activated when the CMTS is turned on. The CMTS
looks to the NVRAM parameters for its configuration. It then looks for a valid boot image (0 or 1) to determine whether to run the currently loaded software or to download new software files from the TFTP server.
CMTS Code Program: The Flash memory contains the CMTS application (ram.hex) and modem code (nsu.nmc, nsu.fdp).
CMTS Application: The Modem Code area stores the latest NeMo modem application ready for download when both a new modem connects or when one with an older software version connects.
NeMo Headend Unit
The NeMo CMTS remotely manages all NeMo modems. The CMTS tracks and monitors the NeMo modems and network performance, collects performance and billing statistics, enables authorization of all users, assigns QoS, runs diagnostics, initiates alarms and downloads software upgrades.
The cable network has traditionally been a broadcast service, where the cable headend broadcasts signals to all subscribers. The CMTS therefore broadcasts the downstream traffic and each modem receives its appropriate data. The upstream, however, operates on a different topology. The headend can only receive data from one modem at a tim e. The analogy of a classroom may be used to illustrate this. The teacher (or headend) can speak to all students (modems) at once and be understood by all. Those who choose to listen can understand everything said and students (modems) may also choose to ignore the teacher when the teacher does not address them (modem). The teacher (headend), though, can only listen to one student at a time.
This architecture is flexible enough to manage varying network topologies at a cable node. By converting a cable node to a LAN, the system can accommodate a telco return solution at a node if required. This flexibility does not require each subscriber to tie up their phone lines, as is the case with typical telco return solutions. The router is configured to translate individual requests upstream via an inexpensive modem rack. This solution can serve a building, campus, hotel, hospital or any MDU, using in-feeds from satellite, microwave, wireless LANs or any type of DSL.
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Configuring the CMTS
Either a serial terminal or RLogin application can be used to remotely configure the CMTS and define its NVRAM parameters. However, first time configuration must be performed using a serial terminal, since the RLogin connection must be done via an IP address, and for the first time connection, the user is not familiar with the IP of the CMTS.
Main Features
§ The NeMo CMTS converts RF to digital signals (upstream) and digital signals to IF (downstream).
§ The RF chassis (What is the RF chassis? This is the first mention) contains signal control for frequency and timing coordination with the headend (CMTS?).
§ The CMTS connects to one downstream modulator and one upstream demodulator. (this is not a feature)
§ The NeMo CMTS separates the RF modules from the host (what is the host?), which enables better signal quality.
Architecture
§ Architecture flexibility to operate using NT or Unix OS
§ Requires one CMTS and any standard router
§ Equipment installed and operational at Cable Node
§ Supports 2-way HFC, 1-way satellite (telco return), 1-way microwave or wireless,
LMDS and MMDS
Operation and Maintenance
§ Varying levels of authentication.
§ IP filtering for secure packet delivery.
§ FOCS provides a built-in subscriber database.
§ QoS offers 64kbps increments with options on data rates per subscriber.
NeMo CMTS User’s Guide
§ Modem's plug and surf capabilities enable system to automatically download modem software.
§ Auto attenuation enables the headend to attenuate all modems in network.
§ SNMP management system enables diag nostics, troubleshooting, early warnings
and network alarms.
Installation Features
§ CMTS is only 1U high, 19" rack mountable, and may be installed at headend or node.
§ Modems connect to RF and Ethernet, and may be installed by subscriber.
§ Headend broadcasts auto-connect messages to all remote modems.
§ System DHCP or static IP enabled.
Introducing the NeMo Cable Modem
NeMo is a user-friendly modem ergonomically built to suit the access needs of subscribers. Designed to plug and play, it does not require any software installation or attenuation pre-settings. Once connected it auto-downloads its operating software and is fully manageable and remotely diagnosed. NeMo excels in upstream connectivity among modems of its class. With Elastream
TM
, a real-time resource allocation algorithm, the NeMo cable modem delivers upstream packets at a higher success ratio than modems without such algorithms. NeMo was built to sustain connectivity to thousands of online users simultaneously accessing Internet content.
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System Architecture
The diagram below illustrates the system architecture:
The system consists of the following elements:
Up Converter : Converts the RF frequencies' IF input to the correct channel frequencies output.
Diplexer and Splitter : Splits the output into multiple outputs.
Headend LAN: The LAN is the backbone of the cable network. It connects the local
server(s), the IP router and the cable network.
Note: The CMTS connects via Ethernet to the router or an Ethernet smart switch.
IP Router : enables communication from the cable network to and from the outside world
and the Internet.
NeMo CMTS. The NeMo CMTS is the RF bridge that handles downstream and upstream termination. The CMTS consists of one downstream QPSK burst transmitter of 10Mbps and 1 to 2 upstream burst QPSK receivers. In addition, it converts data from digital-to-
NeMo CMTS User’s Guide
analog and analog-to-digital. The CMTS acts as a gateway as well as system manager, enabling IP traffic over RF, IP delivery and modem management. In addition, the CMTS supports the RADIUS protocol for Accounting and Authentication.
The CMTS also manages and controls the entire network in real-time. It performs real­time network management functions and controls upstream and downstream traffic intelligence. It houses Coresma's core Elastream
TM
algorithm that runs real-time system intelligence on time slot allocation and priority scheduling. The CMTS performs the following functions:
Media Access Control (MAC) Protocol Management. The CMTS is responsible for upstream bandwidth allocation and downstream data forwarding. Residing in the heart of a CATV network segment, the CMTS can receive messages from all NeMo modems connected to its downstream channel frequency. The CMTS controls a set of one downstream and one upstream channel.
Ethernet Bridging. The CMTS performs Ethernet bridging between the CATV network and the CATV Ethernet backbone, which enables the usage of any Ethernet LAN application over a CATV network.
Spectrum Management. The CMTS performs Spectrum Management system tasks and allocates upstream and downstream frequencies to different channels. The Network Management component also performs the tasks of Spectrum Management. It allocates upstream and downstream frequencies to each channel. It monitors the upstream channel quality and if necessary changes the upstream frequency if the noise threshold is reached. In addition, it detects for collision and counters with corrective action.
TFTP Server . The TFTP server application is used to auto-update the CMTS and modem software. The TFTP server can be installed on the CATV Ethernet backbone or anywhere on the Internet network.
System Connectivity
The following diagram illustrates the connections and data flow of the NeMo CMTS System.
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CATV
NEMO
BRIDGE
Downstream
Normal
RF
Network
Do wn str ea m
Connect to the
End-user Computer
(Ethernet board)
Downstream
Upstream
1
Sp litt
er
Sp litt
er
Management
Software
2
3
7
5
4
6
Upstream
This diagram illustrates the following:
The NeMo CMTS resides at the headend site, offering access for high-speed delivery of Internet and other on-line services to subscribers. It handles the downstream and upstream termination. The CMTS also manages and controls the entire network in real time. It performs real-time network management functions and controls upstream and downstream traffic intelligence. The upstream connection to the NeMo CMTS from the end-user site requires a signal power of between 0 to - 4 dBmV.
The IF Agile Modulator connects to the NeMo CMTS and converts the RF frequencies IF input to the correct channels’ frequencies output.
NeMo CMTS User’s Guide
The NeMo CMTS software resides at the headend site. It controls the entire system, both on-line and off-line and enables the system operator to perform monitoring and management functions.
The NeMo modem resides at the end-user site providing high-speed connectivity at speeds of up to 10Mbps via the existing cable infrastructure. It is connected to the Ethernet board in the end-user’s computer. The upstream connection from the NeMo modem to the splitter requires a signal power of between 30 and 57 dBmV.
The downstream channel goes from the NeMo CMTS at the headend site to the NeMo modem at the end-user site.
At the CATV television outlet at the end-user site, the data signal (NeMo client) should be 10 dBmV under the video signal in the CATV. The standard video signal is 10 dBmV. Therefore, the NeMo modem RF input should be 0 dBmV.
The splitter at the end-user site splits the CATV connection. One cable is connected to the end-user’s TV, and the other cable is connected to the NeMo modem.
Headend Hardware
The NeMo CMTS can be configured as a desktop unit on a shelf or tabletop, or it can be placed in a 19-inch rack. The CMTS contains various LEDs, which enable it to be easily monitored.
The following diagram displays the components of the NeMo CMTS and lists some of the salient features:
CMTS Functionality
The CMTS translates Ethernet packet traffic into/from cable TV packets. The translation is transparent to the adjacent router/gateway. The NeMo modem reverses the operation of the CMTS at the end-user side. The NeMo CMTS and modem together extend an Ethernet segment, using the CATV network as a WAN media.
RF Transmitter
The NeMo CMTS uses a QPSK modulator enabling bit rates up to 9.5 Mbit/sec, and power levels up to 53 dBmV. The transmitter is frequency-agile between 5-45 MHz. An external up-converter is required to position the transmitted signal into an available 6 MHz TV channel. The downstream signal power at the end-user side should be at or around 0 dBmV.
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RF Burst Receiver
In the CMTS, a software controlled QPSK receiver for burst transmission receives signals in the range of 5-65 MHz, depending on the symbol rate, in the power range of –7 dBmV up to +23dBmv for Burst QPSK Bit Rate of 2.56 Mbps and –4 dBmV up to +26dBmv for Burst QPSK Bit Rate of 5.12 Mbps, with maximum ± 6 db burst -to-burst. The flexibility of the receiver allows for signal optimization in noisy environments.
NeMo Modem Transmitter
A cable modem’s upstream signal level is affected by the upstream symbol rate and the internal, software controlled attenuator. The attenuation level used can be applied in the range of 0 to 30 dB. For example, at 15 MHz and 1.28 Meg symbol –rate (2.56 bit-rate), the modem upstream signal level can vary between approximately 30dBmV (at 30 dB Attenuation) and 60dBmV (at 0 dB Attenuation). Operators of HFC networks can have sensitive equipment (e.g. lasers) that can be damaged on high levels of upstream power. Two parameters define a ‘minimum attenuation’ for the modems. Using these parameters operators can configure their modems to never go above a certain attenuation level.
Channel Controller
The channel controller board runs the software and hardware managing the upstream channel sharing, and relays information between the CATV plant and the Ethernet local network.
IP Host Address
The CMTS has an IP host address, enabling access to the CMTS from other IP hosts. This interface is not used for IP forwarding between CATV and Ethernet. The IP address of the CMTS can be changed from the remote or serial shell interfaces.
Headend Software
NeMo Headend Software consists of the CMTS Embedded Code, FOCS Shared Module, FOCS Client, and NeMo Mediator.
The NeMo Headend Software is a set of software modules that operate the cable modem system. It enables the system operator monitor, and controls the entire system, both on­line and off-line. The following diagram displays the relationship between the software components.
NeMo CMTS User’s Guide
CMTS Embedded Code
Two separate codes are stored in the CMTS. The first code stored in the CMTS is the CMTS Boot Code. This code tells the CMTS how to boot and how to utilize the TFTP protocol. The second code is the runtime code that provides the CMTS with its functionality. There are two files that are stored in the CMTS:
ram.hex: CMTS runtime code.
nsu.fdp: Modem runtime code.
NeMo Cable Modem
The NeMo Cable Modem provides high-speed connectivity at speeds of up to 10Mbps, via the existing cable infrastructure. With its highly intelligent upstream allocation algorithm, noise detection trigger systems, unique Quality of Service ability, billing ­ready structure, and Virtual LAN services, the NeMo Cable Modem converts an HFC cable environment into a highly flexible, elastic and network-ready service env ironment.
Data Transmit Data Receive Power
It has standard ports: Ethernet, RF and power, and an on/off switch. In addition, it has a serial outlet for gadget expansion. It is QPSK modulated both upstream and downstream. Downstream it uses a full 6MHz channel and upstream it can range from
1.8Mhz to 2.6Mhz. Bandwidth ranges up to Ethernet speeds of 10Mbps downstream, and up to 5.12Mbps upstream, per modem.
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The modem is easy to install. Once powered it initializes without any manual intervention. It contains one ROM chip that downloads its operating software. That software can be modified to contain features required by any cable operator. For example, if a cable operator needs to adjust its service parameters at a later stage, the software could be modified to address that requirement.
The NeMo Cable Modem has four main components:
§ CM Controller.
§ Burst Transmitter.
§ Downstream IF Receiver.
§ Tuner and Diplexer.
CM Controller
The Controller interfaces with the user premises via its 10Base -T Ethernet ports. It interfaces either directly to the user PC or through a local HUB. The controller receives downstream data from the downstream receiver and sends data to the upstream burst transmitter. The controller is responsible for the overall control of the Tuner, Transmit and Receive.
Burst Transmitter
The Transmitter is STANFORD TELECOM STEL-1109.
Downstream IF Receiver
The Receiver is STANFORD TELECOM STEL-2105.
Tuner and Diplexer
The Tuner and Diplexer can be monitored and controlled by the CMTool software provided to the cable operators' technicians.
Multiple MAC Modems
The modem supports up to 4 IP address machines connected via a HUB.
Applications
The following diagrams represent possible applications for the NeMo CMTS system:
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