Application Note

2G BTS and 3G NodeB Backhaul over Ethernet or IP

Opportunity Recent studies show that 40% - 50% of the Operational Expenses (OpEx) incurred by mobile/wireless operators are associated with the costs of 2G BTS T1/E1 leased lines for the backhaul of traffic in the Radio Access Network (RAN). With the transition to 3G infrastructure, OpEx is expected to grow significantly as the additional leased lines required for the backhaul of 3G NodeB AAL2/5 traffic and PPP will increase the total number of leased lines by approximately three to four times. Therefore, optimizing the RAN and reducing backhaul expenses is imperative.

The cost-effectiveness of Ethernet transport provides new opportunities for mobile/wireless operators to reduce the recurring costs of TDM T1/E1 leased lines along with optimization of the RAN for 3G All-IP by enabling the backhaul BTS T1/E1 and NodeB AAL2/5 as well as PPP circuits over low-cost Ethernet or IP transport networks.

Solution

Axerras AXN1, AXN10, and AXN100 Pseudo-Wire Gateways and Access Devices, deployed at the BTS/NodeB cell sites, aggregate, and backhaul T1/E1, ATM AAL2/5 and PPP circuits to the BSC/RNC site using TDM, ATM AAL0/5 and PPP pseudo-wire encapsulation (CESoP/ATMoP/HDLCoP). Axerras AXN1600 or AXN800 carrier-class pseudo-wire gateways, deployed at BSC/RNC sites, aggregate, terminate, and groom multiple CES, AAL0/5 and PPP pseudo-wires into high-speed TDM and ATM links for cost-effective integration with BSCs and RNCs.

The Ethernet transport can be available by metro Ethernet, DOCSIS HFC, or cost-effective Ethernet radio. High accuracy clock synchronization, required for proper operation of the BTS, is transferred across the Ethernet network utilizing Axerras RTP-based High-Precision Clock Recovery (HPCR) mechanism. HPCR is compliant with G.823/G.824 and maintains 16 ppb FFoFF accuracy for both Maximum Relative Time Interval Error (MRTIE) traffic interface as well as Maximum Time Interval Error (MTIE) synchronization interface.

BSC

AXN1600 Abis

ETH GigE

ETH Fibre

nxT1/E1s

AXN1/10

BTS

ETH

AAL2/5

AXN1/10

NodeB

BTS nxT1/E1s AXN100

NodeB

AAL2/5

ETH Radio

ETH

RNC

Iub

ATM

Ethernet Transport

e.g. RPR/EoS

High Accuracy Primary Reference Source (PRS) Clock

e.g. GPS or Stratum 1

Cell sites are Synchronised to

PRS Clock

HPCR

BSS/RNS Site

HPCR

HPCR

TDM

Application Note

Benefits for Service Providers Enables TDM, ATM and PPP backhaul over a single Ethernet access link and thus reduces

providers OpEx on leased lines while optimizing the RAN for 3G All-IP

Enables more bandwidth at lower cost to support new high-speed data services while also decreasing dependency on costly T1/E1s from incumbent carriers

Ensures cellular network performance through Axerras HPCR, the industry most robust and accurate clock recovery over packet mechanism and low end-to-end delay