BWA-2000 System Description
All Broadband Wireless Access Systems are made up of three functional sub-systems.
- The RF System – the high-capacity, wireless pipeline for transmitting communications to and receiving communications from each subscriber.
- The Access System – packages the information for transport and manages the relationship between the subscriber and the operator.
- The Network Interface – represents the communication infrastructure, through which the provider connects to the application content; and the subscriber network infrastructure, through which the subscriber connects to the system.
The RF System consists of one or more transceivers, and antenna(s) at the base station and an integrated transceiver/antenna as part of the Customer Premises Equipment (CPE) at each subscriber site.
At the base station, the transmitter and receiver modules of the transceiver are connected on one side to the base station access equipment and on the other side to an omni-directional antenna providing 360 degrees of coverage or to a sector antenna providing 180, 90, or 45 degrees of coverage (depending on system requirements). The transceiver is sized and configured to handle both downstream and upstream channel loading requirements as determined by system analysis.
Customer Premises Equipment (CPE)
At the subscriber site, a CPE transceiver receives the downstream signal from the base station and passes it on to the subscriber modem. It simultaneously receives upstream traffic from the subscriber modem and transmits it to the base station.
The CPE transceiver is integrated with the antenna into a single weatherproof package designed for easy outdoor installation and alignment. A single coaxial cable connects the transceiver to the indoor subscriber modem. This cable carries:
- the downstream signal from the CPE transceiver to the modem,
- the upstream signal from the modem to the CPE transceiver,
- and feeds DC power to the outdoor transceiver.
The Access System serves as a data communications interface between the data network point of presence (e.g., Internet/ISP/Servers) at the base station and any modems installed at subscribers’ homes or offices. It is responsible for formatting and managing the signal traffic transported in either direction via the RF System.
The BWA-2000 is a cell-based “shared access” system. Subscribers “time-share” the downstream and upstream channels assigned to them in each cell or in each sector of each cell. Like most carrier-class, fixed-wireless systems, at the assigned downstream and upstream channel, the system provides access based on a TDM (Time Division Multiplexing) approach downstream using 64-QAM modulation, and a TDMA (Time Division Multiple Access) approach upstream using either QPSK or 16-QAM modulation.
This Access System consists of the Base Station Modem (sometimes referred to as the Cable Modem Termination System or CMTS) which modulates downstream traffic and demodulates upstream traffic; the subscriber modem, which does the converse; and the Network Management System (NMS), which configures and controls this activity.
Base Station Modem
The Base Station Modem is a router-based unit that manages the two-way data communication between the subscribers and the Internet world. It allows operation for all types of applications and protocols that are commonly used over the Internet. The major applications that are used with the system are Internet access, High-Speed access to information and multimedia servers, video conferencing and streaming and other advanced applications. Access to the PSTN (Public Switched Telephone Network) for VoIP applications can be provided via a VoIP Gateway.
Powerful QoS Features – The DOCSIS Standards Pave the Way
The Base Station Modem provides rich QoS support required to deliver multiple services. The system is based on DOCSIS 1.0, DOCSIS 1.1, DOCSIS 2.0, and PacketCable 1.0 standards. QoS classification is performed at wire speed on up to 16,000 cable flows – up to 8,000 downstream and up to 8,000 upstream. Most QoS features are fully integrated within the Base Station Modem, thus reducing the need for costly third-party QoS equipment.
The Base Station Modem enables operators to create QoS policies and service profiles that can be applied to a subscriber or groups of subscribers, resulting in the ability to implement end-to-end Service Level Agreements (SLAs). Subscriber management features are based on open systems interfaces and allow operators to establish and enforce policies for service usage on a per-subscriber basis. This simplifies the provisioning process and streamlines the addition of new customers.
The Base Station Modem can be configured as a router or as a bridge. This flexibility provides an operator with the ability to optimize performance based on the size of his network. For example, in the initial system deployment, when the network is small, the Base Station Modem can be configured as a bridge, which simplifies the network implementation. As the operator’s subscriber base grows, the Base Station Modem can be configured as a router to reduce broadcast traffic – better leveraging the services offered to subscribers – as well as adding the extended network security that a router provides.
The subscriber modem connects to the CPE transceiver via a single duplexed coaxial cable. It demodulates, decodes, and recovers the downstream data that arrives from the base station. When the subscriber sends data back to the base station, the subscriber modem modulates, codes, and processes the bursts of data that are sent to the CPE transceiver via the single duplexed coaxial cable.
The subscriber modems are DOCSIS-based and appropriate for residential, home office or small office use. Any DOCSIS-compliant cable modem product will work with the BWA-2000 system. Some models support up to 32 computers – 1 via a Universal Serial Bus (USB) connection and up to 31 through an auto sensing 10/100BaseT Ethernet connection (via a network connection – either a switch/hub or SOHO router).
Network Managment System
Control of the system is achieved through a Cisco-compatible Command Line Interface (CLI) for ease-of-use and interoperability with legacy infrastructure. The CLI supports full scripting capability, and ASCII-formatted command files can be uploaded, downloaded, and executed. However, the system architecture also supports Simple Network Management Protocol (SNMP) v1 and v3. It supports all appropriate standard MIBs and offers custom MIBs for the implementation of graphical user interfaces with varying levels of sophistication. Moreover, the system supports the standard TCP/IP Protocol for data transfer, and it can be seamlessly integrated into the existing network management infrastructure.
Flexible metering services can be provided to allow the use of various billing systems. With this information, operators can carefully track utilization and accurately generate invoices to maximize revenue from both subscribers and service provider partners. Operators can create profiles for each user. The Subscriber Management and Provisioning System communicates with directories that store service profiles and QoS policies as well as subscriber and provider information to enable interoperability with legacy systems.
The Network Interface represents the connection to the source of voice and data services that the BWA-2000 is able to provide. At the Base Station, the network interface is specific to the type of service.
- The data application consists of an edge router that converts and routes data packet from the Internet backbone data pipe.
- For VoIP applications, the typical components to interface with the PSTN are a telephony gateway and call management servers.
- For video applications, multicast IP video encoded from any video source can also be forwarded to the CMTS.
At the customer premises, the network interface consists of data modems for Internet access, MTAs (Media Terminal Adapters) for connection to standard telephone handsets and an STB (Set Top Box) for IP video equipment.