Even as the global wireless subscriber base continues on its growth trajectory, the convergence of the mobile device with the internet and consumers’ demands for faster download speeds for numerous applications including mobile TV and video downloads, are driving the need for faster and better technologies.While 3G networks providing speeds of up to 2 Mbps are still being deployed across the globe, the industry has taken rapid strides in technology. Operators looking to increase network capacity and step up data download speeds are now in the process of trialling 4G technologies like long term evolution (LTE) and mobile Wi-Max.
3G
3G technologies have spearheaded making wireless broadband communication more economical in both developed and emerging markets like India and China. The factors that are encouraging countries to develop and deploy 3G services include high data speeds, access to multimedia content, video conferencing facilities, and facilitation of mobility and corporate solutions. Continuous enhancements in 3G technologies have given rise to advanced versions like EV-DO Rev. A, high speed downlink packet access (HSDPA) and femtocells. These provide outstanding capabilities, making 3G the technology platform of choice.
3G systems consist of two main standards ?? CDMA2000 and W-CDMA ?? as well as other 3G variants such as NTT DoCoMo’s freedom of mobile multimedia access and time division synchronous code division multiple access (TD-SCDMA), which is used primarily in China.
In Asia, Europe, Canada and the US, telecommunication companies use the WCDMA technology to operate 3G mobile networks. This belongs to the GSM/ UMTS family of standards.
Both CDMA2000 and W-CDMA use a coding scheme that separates each subscriber from others and use control channels to manage the network.
However, these technologies are not compatible as they have different chip rates. While W-CDMA uses a 5 MHz channel, CDMA2000 uses only a 1.25 MHz channel, but with CDMA2000 3x, three 1.25 MHz channels can be combined to form a super channel structure.
W-CDMA is synchronous, relying on mobile station time measurements between two base stations, while CDMA2000 uses a global positioning system (GPS).
In addition to providing faster data speeds on a per user basis, 3G technology is also helpful in providing greater overall capacity for voice and data users.
For example, most analysts are of the view that when 3G is launched in India, it will help alleviate the capacity constraints of existing 2G networks.
W-CDMA uses the same core network as GPRS does, thereby utilising existing infrastructure such as gateway GPRS support node (GGSN) and serving GSN. However, this technology requires new radio access network (RAN) infrastructure such as Node Bs (which replace base transceiver stations [BTSs]), and radio network controllers (RNCs) that replace base station controllers (BSCs). Ultimately, the W-CDMA core network will evolve to comprise a full mobile IP infrastructure including media gateway and media gateway controller equipment for voice over internet protocol (VOIP).
CDMA2000 starts with new channel cards and then migrates to a full mobile IP infrastructure requiring a new core network infrastructure such as the AAA (authentication authorisation accounting) server and packet data server node.
Femtocells
Poised for commercial launch by various telecom operators around the world in 2009, this new wireless mobile technology comprises compact cellular access points that provide premier cellular service inside homes, small offices and other environments where cellular penetration is restricted. Femtocells are an affordable solution for both subscribers and operators because they connect to the operator’s core network via an existing broadband connection, such as DSL or cable modem.
When a registered mobile device is within the femtocell’s proximity, the handset switches over transparently to the femtocell’s network. While connected to the femtocell, users can continue to use the mobile handset for all their usual voice and mobile data services, including sending text messages.
The only difference is that the traffic will be routed through the connected broadband network to the operator’s mobile network infrastructure. However, afemtocell will not work if internet connectivity is down. The actual number of mobile phones that can be supported per femtocell varies, but according to industry experts, the number lies between two and five phones ?? at least for the initial generation of equipment.
These access points deliver the traffic to the core network through the existing home broadband connection. They will play a key role in the growth of multimedia services such as IPTV by accommodating these data-hungry applications at home, while macrocells continue to provide coverage for users outside the femtocell site.
Wireless operators can maximise their quality of service, reduce macro network costs and provide a substitute for fixed line phone service in the residential users’ market. Femtocells reduce a carrier’s operation and deployment costs and allow for the equipment to be installed at individual sites to improve coverage and capacity.
Femtocells provide premium signal strength because they offer higher data rates from an access point positioned close to the handset, and do not rely upon the macro network for service, thus eliminating some common capacity challenges. Femtocells offer the quality and unsurpassed 3G coverage directly from the network into a home or small office. Home users will not experience slow and at-capacity network issues that can occur during peak times on the macro network, since their femtocell is connected directly through the IP network.
This technology is a nascent technology where the standards are still evolving. Nonetheless, it is developing rapidly with new upgrades and functionalities and will be critical in the mass adoption of 3G services, going forward.
4G technologies
4G is the next generation of future wireless networks that will replace 3G. It is an initiative to move beyond the limitations and problems of 3G. 3G performance may not be sufficient to meet the needs of future high performance applications like multimedia, full-motion video and wireless teleconferencing. 3G is essentially a wide-area concept. Moreover, there are multiple standards for 3G making it difficult to roam and interoperate across networks. There is a need for a network technology that extends 3G capacity by an order of magnitude and has hybrid networks that utilise both the wireless LAN (hotspot) concept and the base station wide area network design.
4G networks will address the future needs of a universal high speed wireless network that will seamlessly interface with wireline backbone networks. The two 4G technologies are mobile LTE and Wi-Max.
LTE
LTE is a 4G wireless broadband technology developed by the Third Generation Partnership Project, an industry trade group. It represents the next step (4G) in a progression from GSM ?? a 2G standard, to UMTS, a 3G technology based on GSM.
The LTE standard reached the functional freeze milestone in December 2008 and hardware designers have been designing chipsets, test equipment and base stations for some time now. LTE test equipment has been shipped from several vendors since early 2008.
LTE is aimed at minimising cost and power consumption while ensuring backward compatibility and a cost-effective migration from UMTS systems. Enhanced multicast services, enhanced support for end-to-end quality of service and minimising the number of options and redundant features in its architecture, are also being targeted. Spectrum efficiency in LTE downlink will be three to four times that of Release 6 HSDPA, while in the uplink, it will be two to three times that of Release 6 HSUPA. The handover procedure within LTE is intended to minimise interruption time to less than that of circuit switched handovers in 2G networks. Moreover, the handovers to 2G/3G systems from LTE are designed to be seamless.
The upper layers of LTE are based on the TCP/IP platform, which results in an all-IP network similar to the current state of wired communications. The technology incorporates multiple in, multiple out (MIMO) in combination with orthogonal frequency division multiple access (OFDMA) in the downlink and single carrier FDMA in the uplink, to provide high levels of spectral efficiency and end-user data rates exceeding 100 Mbps, coupled with major improvements in capacity and reductions in latency. The higher signalto-noise ratio at the receiver enabled by MIMO, along with OFDM, provides improved coverage and throughput, especially in dense urban areas.
This technology also offers a significant amount of flexibility as far as spectrum is concerned. It can be deployed in spectrum bands from 1.25 MHz to 20 MHz in multiple frequencies including 2.6 GHz. This flexibility is backed by the means to operate in both paired and unpaired spectrum using frequency division duplex, and enables operators to refarm GSM or CDMA bands, or leverage new spectrum for expansion.
Faced with the need for improved performance and lower costs, LTE’s architecture is simpler with fewer nodes and interfaces. The result is a reduction in both the processing overhead and latency. The architecture combines the time-critical functions from the RNC into the base station while integrating all the routing and inter-networking functions to a single node ?? the access gateway. There is also an interface between base stations, which need to communicate to support handovers.
LTE is clearly in a strong position to address rising data traffic and shrinking profit margin issues faced by operators, while enabling a more compelling user experience for the mass market.
Mobile Wi-Max
Mobile Wi-Max is a “last mile” IP-based broadband wireless solution that enables convergence of mobile and fixed broadband networks and like LTE, is based on OFDMA technology. This technology provides up to 70 Mbps symmetric broadband speeds over 31 miles, at higher bandwidths using MIMO technology, without the need for cables. Some players in the industry including both service providers and equipment vendors believe that LTE will replace or compete with Wi-Max.
However, others see Wi-Max as being able to coexist with 3G and LTE.
Nonetheless, as some markets get ready to launch 4G technologies and others have only just awarded their 3G licences and some have yet to do so, all these technologies will coexist and complement each other. These technologies will lead to new services and redefine how consumers use their mobile handsets.
