Multiservice Pseudowire and ATM Access

Service providers are faced with an increasing demand from their enterprise customers for high speed connectivity with Quality of Service that adheres to service level agreements (SLAs). Service providers with either ATM-based networks or newly deployed packet-switched core networks can use ATM access devices to begin delivering next-generation services over their existing infrastructure. This provides immediate revenues from new service offerings while mitigating the technological and commercial uncertainties involved with wholesale migration to next-generation core networks.

At the same time, backhaul is one of the major contributors to the high cost of building out and running a mobile network. This is true whether the mobile operator owns the transport links or leases lines from a local carrier. It also applies if the operator is deploying a dedicated transport segment for 3G or planning to integrate several generations onto the same platform.

For many years, ATM has been chosen by carriers as the multiplexing and high speed switching technology that meets the requirements of broadband networks. ATM networks enable carriers to increase their service versatility and use a common infrastructure for the different services, while providing end-to-end service quality. ATM is a proven and widely deployed multiservice, high speed, scalable technology that is capable of supporting services with different transfer characteristics. It can simultaneously transport voice, data and video traffic at different data rates, starting at E1/ T1 up to STM-1/OC-3, STM-4/OC-12 and STM-16/OC-48, with various levels of service, quality assurance and sophisticated traffic engineering. ATM access equipment enables efficient access to ATM networks and provides tools for performance monitoring, diagnostics and traffic engineering in various ATM-based networks. Additional drivers for deployment of ATM access devices include the use of ATM-based DSL networks as the transport infrastructure for leased line services and the initial phase of UMTS (3G) build-out. RAD’s ATM access solutions provide efficient ATM access at the customer premises. They improve and lower the cost of ATMbased services by offering end-to-end management, QoS control, traffic management, fault localization, and rate and media conversion. RAD’s ATM access devices also support interworking with other services, such as circuit emulation services (for voice and TDM connectivity), IP and LAN, thus providing a single solution for service integration over ATM with guaranteed end-to-end quality.

RAD’s ATM products can also be used for smart demarcation between ATM networks or between ATM and IP networks. In addition, the products enable simple provisioning, diagnostics and traffic management in DSL networks that are based on ATM technology.

Multiservice Aggregation

Leveraging TDM-based networks – PDH and SDH/SONET – for cellular backhaul affords a large degree of investment protection for mobile operators with their own access networks. In addition to carrying legacy TDM streams, the TDM-based network is also suitable for ATM. At the same time, the ATM protocol can cope with the multiple technologies of various mobile generations and handle different traffic types with great efficiency. RAD offers a wide range of multiservice gateways and aggregators (ACE-3xxx – please refer to pages 68-71 and 73) that support aggregation of 2G TDM traffic as well as 3G ATM traffic and future Ethernet-based wireless services for efficient utilization of next-generation transport infrastructure.

Mobile network planners searching for a comprehensive solution encompassing future developments will take a good look at the packetswitched option. Metro Ethernet transport networks are mushrooming, and Ethernet-based wireless links have become viable alternative transport solutions for cellular backhaul. Handling legacy traffic – encapsulating 2G TDM traffic alongside 3G ATM streams – is presenting a challenge, however, for the emerging packet-switched network (PSN) transport alternatives. The answer to this challenge is RAD’s cell-site gateways and aggregators which pave the way for operators to adapt to PSN effectively. In the case of PSN transport, synchronization of the Radio Access Network (RAN) elements is accomplished by using advanced clock recovery algorithms. TDM/ATMoPSN gateways recover the clock transported over the packet network, achieving the desired timing accuracy and complying with ITU-T G.823, G.824 and G.8261 specifications in the presence of packet delay variation and packet loss.