Mobile Backhaul Evolution from TDM to Carrier Ethernet

The proliferation of smart mobile devices is driving a seemingly insatiable need for mobile backhaul bandwidth. Fiber is the only media capable of supporting virtually limitless growth, so Carriers are currently driving fiber to the edges of the network. Unfortunately, bandwidth is only part of the problem. Mobile technology is in the midst of a migration from 2G to 3G to 4G/5G/LTE. This means that Carriers providing backhaul must be able to satisfy the current need for TDM services while preparing for a seamless migration to an all Ethernet network in the future. While many options are available, Carriers must be able to support the migration in a scalable and cost-effective manner.

There are essentially three phases in the migration from legacy 2G to LTE mobile backhaul.

1. Legacy mobile backhaul networks are based on TDM
2. Current migration adds Carrier Ethernet to TDM network (Hybrid Mobile Backhaul)
3. The future requires Long Term Evolution (LTE) and Carrier Ethernet and fiber infrastructure

Mobile Backhaul Evolution Products

Migration from 2G to 3G to LTE

In these mobile backhaul application examples, a wireless operator is providing connectivity from a BSC/RNC to a cell tower via a fiber access network for a wireless carrier. Over time, the services evolve from multiple T1s (2G), to T1s and Ethernet (3G), to Carrier Ethernet (4G/LTE). These application examples show how the iConverter Multi-Service Platform enables a seamless transition from TDM to Ethernet services over the three phases in the migration from legacy 2G to 3G to 4G/LTE mobile backhaul.

Note that T1s and Ethernet over dark fiber are illustrated, but they can be transported over a switched cloud with the T1s and/or Ethernet transported over an Ethernet Virtual Connection (EVC).

2G – Multiple T1/E1 Circuits

This 2G application shows connectivity to a cell tower with multiple T1 circuits over a Radio Access Network (RAN) fiber link. At the BSC/RNC, groups of T1/E1 MUX modules are installed in a high-density 19-Module Chassis. Each group of modules transports up to 16 T1 circuits over a fiber access link using a GM4 NID as a fiber transport module. At the cell tower, a corresponding group of modules are installed in an iConverter 5-Module chassis that connects the T1 circuits to the 2G BTS cell tower. Both chassis conserve rack space and feature redundant AC or DC power supplies.

3G – Multiple T1/E1 Circuits and Ethernet

This 3G application shows connectivity to a cell tower with multiple T1 circuits over a RAN fiber link. At the BSC/RNC, the same groups of T1/E1 MUX modules are installed in a high-density 19-Module Chassis. Each group of modules transports up to 16 T1 circuits over a fiber access link using a GM4 NID as a fiber transport module. The GM4 NID module is now configured to transport Gigabit Carrier Ethernet with up to 16 T1 circuits. The GM4 NID has all the traffic management and Service OAM capabilities required for LTE, including Y.1564 Service Activation Testing, Y.1731 performance monitoring, 802.3ag fault management and 1588 synchronization. At the cell tower, a corresponding group of modules are installed in an iConverter 5-Module chassis that connects the T1 circuits and Gigabit Ethernet (via UTP or fiber) to the 3G nodeB cell tower.

4G/5G/LTE – Carrier Ethernet

This LTE application shows connectivity to a cell tower with Carrier Ethernet over a RAN fiber link. At the BSC/RNC, the T1/E1 MUX modules are decommissioned from the high-density 19-Module Chassis, and GM4 NIDs are used to transport Gigabit Carrier Ethernet. The GM4 NID has all the traffic management and Service OAM capabilities required for LTE, including Y.1564 Service Activation Testing, Y.1731 performance monitoring, 802.3ag fault management and 1588 synchronization. At the cell tower, a corresponding GM4 NID module installed in an iConverter 5-Module chassis connects the Carrier Ethernet (via UTP or fiber) to the 4G/LTE enodeB cell tower. The slots in each of the chassis that were occupied by the T1/E1 MUX modules can now be replaced with other modules, such as NIDs and CWDM multiplexers to deliver high-bandwidth services with advanced Quality of Service to the wireless subscribers.