4G Network Characteristics and Requirements

Several 4G network characteristics have been established by international standards development organizations and forums. These requirements and performance targets are shown in the following table, along with their impact on air interface and/or infrastructure equipment. 4G standards are generally characterized by superior bandwidth, which sacrifices some of the mobility attributes.

While most of the target 4G characteristics directly relate to the family of air interface standards, many directly influence the backhaul infrastructure requirements. These include:

• Scalability
• Resiliency
• Topological flexibility
• Improved economics

Scalability Requirements

Improved customer scalability. Each successive wireless generation has experienced significant customer growth. Some early 4G network markets have seen end station counts (measured in Media Access Control addresses) that are two to five times higher than initial estimates. Therefore, the 4G wireless backhaul infrastructure must be able to support tens and hundreds of thousands of MAC addresses per market.

IP transport. IPv6 is an important network layer technology for 4G networks given the number of wireless and mobile devices moving to IP-based services. A Layer 2 transport backhaul infrastructure using IPv4 for management enables use of IPv6 network layer scalability without requiring network address translation (NAT).

Base stations. Markets require diverse numbers of base stations/towers. The 4G wireless backhaul infrastructure must be able to handle growing base station counts while retaining address and customer scalability.

Resiliency Requirements

Stability. As 4G networks are deployed and expanded, the stability during backhaul infrastructure expansion and maintenance is a critical issue. Current stopgap implementations are prone to mis-configuration, causing traffic storms and costly network outages. There must be resilient, reliable backhaul infrastructure stability.

Predictable low-latency data transmission. Voice and other services reliant on fixed circuit-switched network delay require packet-based, low-latency, predictable data transmission.

Multi-vendor interoperability. Legacy Ethernet implementations often use vendor-specific proprietary control plane protocols to attempt to solve diverse backhaul architectures.

Optimized bandwidth plan. Traditional Ethernet backhaul technologies use loop prevention control plane protocols (e.g., IEEE 802.1w Rapid Spanning Tree, etc.). Often, half of the backhaul capacity/paths are disabled when these protocols are used. In order to maximize backhaul utilization, enhanced techniques to manage redundant paths and overall bandwidth engineering are required.

Deterministic bandwidth guarantees. Some network redundancy schemes result in overloaded paths during fault conditions. In order to provide deterministic bandwidth, 4G wireless backhaul infrastructure must have predictable failover and resiliency schemes.

Pre-defined failover actions. Legacy Ethernet’s connectionless nature weakens bandwidth and QoS configurability.

Topological flexibility requirements

Base station site interconnect technology. Wireless and mobile operators face myriad challenges when interconnecting base stations. In some cases, copper or fiber access is available. In many instances, microwave links are more economical and readily deployable. 4G mobile backhaul infrastructure must have the flexibility to accommodate wireline copper, fiber, or wireless microwave and free space optical connectivity.

Economic requirements

Cost effective. Given the competitive nature of wireline and wireless operators, it is imperative the backhaul infrastructure solution is cost effective to deploy, maintain and operate.

Simplified provisioning. Since mobile networks are constantly evolving through expanding markets, growing numbers of base stations, and customers, network and service provisioning must be simple yet powerful.

Automated network monitoring. While many legacy technologies (e.g., TDM) contain extensive monitoring capabilities, traditional Ethernet lacks troubleshooting and fault detection. 4G wireless backhaul infrastructure requires network and service monitoring, as well as fault detection, isolation, repair, and verification capabilities.

• Part 1:
  Introduction
• Part 2:
  Wireless Evolution to 4G
• Part 3:
  4G Network Characteristics and Requirements
• Part 4:
  Using PBB-TE in 4G Wireless Backhaul Networks
• Part 5:
  Summary