The Transformation to NGN in the Wireless Backhaul

Wireless BackhaulA number of leading mobile carriers in Asia/Pacific, in countries such as Australia, Hong Kong, India, Japan, Korea, Japan, Philippines, and Singapore, are already starting to connect parts of their metropolitan 3G/HSPA backhauls with Carrier Ethernet over fiber.

The main driver of this transformation is the need for mobile operators to provide scalable, high-bandwidth, web 2.0 video and audio content, and internet access services for both mobile and fixed users in incremental CAPEX outlays.

Mobile operators in the region are faced with five key challenges that are driving the need for more bandwidth to the end-user devices (downlink and uplink):
  • Enhancing coverage spanning dense urban, suburban, and rural areas.
  • In markets where pre-paid services is dominant, value added data services need to be geared to lower-speed bandwidth while post-paid centric markets must typically target premium value added services.
  • Potentially exponential increases in data traffic once higher speeds are enabled will not necessarily translate into higher data average revenue per user (ARPU).
  • Declining voice ARPU means that data ARPU must be increased in the long-term.
  • Network OPEX will need to be carefully contained so that it does not grow disproportionately with traffic demand growth.
The combination of the third and fourth challenges means that operators need to offer scalable bandwidth but at tariff schedules that resemble a combination of flat-rate plateaus with specific usage caps. Without the scalable bandwidth in the backhaul, operators will not be able to balance OPEX and CAPEX, and could find themselves in the noncompetitive situation of not being able to offer new multimedia-rich wireless services because of incremental bandwidth constraints.

Without such a transformation of the wireless backhaul, the promise of 3.5G and 4G systems such as LTE will not be feasible. The emergence of bandwidth hungry devices such as Apple's 3G iPhone and Google's Android-operating system based devices means that mobile operators need to begin the transformation to NGN in the backhaul urgently in order to avoid being branded as obsolete.

Green IT will put additional pressure on radio access network (RAN) and backhaul designs to become more energy efficient which means that equipment vendors will need to balance computational power at the basestation versus that in the local exchanges and mobile switching centers. Basestations that have router functionality will be able to provide peer-to-peer communications within the network. The multitude of radio standards is also putting pressure on vendors to implement re-configurable software solutions in the basestation. If operators delay the revamp of their mobile core networks to an all-IP platform, they will be left behind. The reductions in OPEX will justify the effort during the current economic downturn.

The rapid emergence of converged mobile devices with 3.5G HSDPA and WiFi, dual-mode support and the imminent entry of 802.16e Mobile WiMAX devices mean that operators are facing a situation where users will expect 1Mbps speed all the time, anywhere and everywhere. This is in stark contrast to the existing 2G/2.5G/3G networks of today, which have hotspot like coverage for high-speed wireless data services. An all-IP infrastructure only exists in some of the next-generation fixed-line networks in Asia/Pacific, some of the early mobile WiMAX networks, and in recently constructed greenfield 3G networks. In most cases in the Asia/Pacific region, the 3G UMTS (WCDMA) radio basestations are connected via E1/T1 leased lines aggregated in groups of 1-8, in an effort to provide up to 15Mbps per cell site. HSPA or 3.5G, CDMA2000 EV-DO, and mobile WiMAX operate with a theoretical maximum of 10-30Mbps per sector depending on the amount of frequency allocated to the operator.

With LTE just around the corner, which could see peak capacity of over 100-150 Mbps per cell site, operators who choose to deploy LTE in dense urban areas could be facing huge bandwidth requirements that will invariably put enormous stress on the existing backhaul and transport infrastructure. Femto LTE and HSPA access points can help alleviate backhaul congestion in markets where FTTX or xDSL is widely deployed but in the rest of the markets, the backhaul will need to be a combination of fiber and NGN microwave/Fixed WiMAX.