In 2006, many cellular operators began 3.5G network deployments (HSPA & EV-DO) and subsequently introduced very popular flat rate data tariffs. These operators now enjoy a growing subscriber data services penetration and the resulting growth in data traffic. In addition most of the devices available today feature the ability to play rich media content, access email and a number of mobile friendly sites such as Google, Yahoo, New York Times, etc. Application vendors are creating content, portals and new web browsing adapted to the mobile phone market.

These market forces combine to create an explosion of data demand on their networks, with many operators reporting triple digit year-on-year growth in network data traffic.

The deployment of 3.5G HSPA networks were critical for the adoption of mobile broadband but faced with the mobile broadband market success, operators must now consider the upgrade paths to support the continued growth with well performing network that provides sufficient capacity to offer subscriber a great mobile broadband user experience whatever the conditions.

The necessary upgrades to 3.5G networks often require increasing the backhaul capacity between the Radio Network Controller and Cell sites, UTRAN software and hardware upgrades to support higher speed HSPA, deploying a second and third carrier, additional NCs, and additional Packet Data Core capacity. Eventually, costly cell splitting will be needed in markets where the available spectrum is exhausted.

The growth in data traffic continues to increase at unprecedented rates (triple digit percentage increase has been observed in many instances), and many operators are already considering their options for near and long term growth. This paper studies various aspects of choosing an evolution path, with the particular focus on HSPA+ and LTE as the most common choices facing 3GPP operators.