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Smooth Evolution from CDMA to LTE

Development Trends in the Mobile Communication Market

Mobile data services account for an increasing percentage of worldwide mobile revenue, and havebeen a key point of competitive differentiation between mainstream operators. Since ARPU frommobile voice services has experienced slow or even negative growth in recent years, mobileoperators have begun to shift their focus of development to mobile data services. According toVerizons annual report, its revenue from wireless data services increased by 49% in 2009,accounting for 25.7% of its total revenue in the wireless business.

Moreover, with the expansion of the intelligent terminal market, huge potential exists for wirelessdata services, and demand for wireless bandwidth is predicted to double annually. Therefore,mobile data servicesespecially wireless broadband data serviceswill be a strong driving forcefor business growth.

Long Term Evolution (LTE) is widely accepted as the technology of choice for next-generationmobile networks. It has open standards, a sound industrial chain, and high-bandwidth and low-latency features as a result of OFDM, MIMO and a flat network structure.

CDMA to LTE Evolution

From the perspective of network deployment and subscriber development, CDMA to LTE networkevolution is a gradual process. CDMA Development Groups (CDG) estimation of global wirelesssubscriber growth shows that 2G, 3G and 4G technologies cannot simply substitute each other, butmust coexist and complement each other for an extended period (see Figure 1).

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CDMA2000 1X/EV-DO Rev.A is first upgraded to EV-DO Rev.B to meet the needs of currentusers. After conditions have matured, LTE networks are then deployed in urban hotspots, and thengradually LTE coverage is expanded. The CDMA and LTE networks complement each other; theCDMA network offers seamless coverage for voice and low-rate and medium-rate data services,while the LTE network provides hotspot area coverage for high-speed data services. They cancoexist for a long time.

ZTEs Uni-RAN Solution

In Radio Access Networks (RANs), smooth CDMA to LTE evolution requires utilizing existingCDMA base stations while evolving to LTE. CDMA and LTE networks can share the same basestation sites, the same transmission, and the same RF antenna feeder system. As the largest shipperof CDMA base stations worldwide, ZTE takes into full consideration the smooth evolution fromCDMA to LTE in its research and development into next-generation SDR-based base stations. Themanufacturer has rolled out a Uni-RAN solution that helps operators achieve sustainable evolutionwhile protecting their investments to the greatest possible extent.

Unified platform to minimize upgrade cost

ZTEs Uni-RAN solution adopts advanced SDR technology to support various systems includingCDMA, GSM, WCDMA, TD-SCDMA and LTE. The solution has the highest integrationalcapacity within the industry, and the lowest upgrade cost. ZTE took the lead by using aMircroTCA platform technology that brought about higher scalability and reliability for its BaseBand Units (BBUs). This satisfied the requirements for long-term wireless network upgrade and

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evolution. The unified and standard platform helps shorten the R&D cycle of new products so thatcustomer needs are promptly met.

Industrys highest integrational capability to save site space

Uni-RANs core innovation is its use of a single RAN to implement smooth network expansionand evolution; that is, to realize the coexistence of CDMA and LTE. These two systems share thesame base station sites, transmission, antenna feeder system, and network management system.This also extends life cycle of the system and reduces investment risks.

Both ZTEs indoor/outdoor macro base station and distributed base station adopt multi-mode BBUand RF units (including RSU and RRU). They are based on the same platform that allows smoothupgrade to LTE. The CDMA/LTE dual-mode base station has reached the same level of integrationas the CDMA2000 1X/EV-DO system. A single cabinet of the CDMA/LTE dual-mode base

station supports CDMA2000 1X, EV-DO, and LTE. This represents unique space savings. InNorth America, for example, where renting equipment rooms is costly, this solution helpsoperators greatly save on their OPEX. Figure 2 and Figure 3 show CDMA/LTE dual-mode BBUand RRU respectively.

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Shared transmission to enhance efficiency

Uni-RAN allows CDMA and LTE base stations to use the same physical transmission port in orderto share transmission bandwidth dynamically and realize statistical division multiplexing. Thisenhances transmission efficiency while saving rental fees for transmission bandwidth.

Shared RF Units to increase system capacity

When CDMA and LTE base stations are co-sited and operate on the same frequency band, Uni-RAN allows them to share the same RF units. This reduces insertion loss of the combiner by about3dB and increases air interface capacity by about 5%. Taking Verizon as an example, a singleCDMA/LTE base station can bring extra annual revenue of around $40,000.

Unified network management system to facilitate maintenance work

Uni-RAN adopts a unified network management platform for unified deployment and managementof different systems. This improves network maintenance and management efficiency. The unifiednetwork management structure for CDMA/LTE networks is shown in Figure 4.

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Environmental friendliness and energy saving to reduce OPEX

The RF is an important component in base station infrastructure, consuming about 80% of the totalenergy. Uni-RAN allows CDMA and LTE base stations operating on the same frequency band toshare the same RF units. This halves the number of RF units, and reduces energy consumption by50%. Moreover, its power amplifier adopts CFR, DPD, and Doherty techniques, which provide apower amplifier efficiency of over 35% in commercial use, and saves more than 30% of the totalenergy. For Verizon, a single CDMA/LTE base station can save up to $1000 in electricity per year,and 10,000 base stations save $10,000,000.

Conclusion

In todays telecom market, where mobile voice business is experiencing sluggish growth, mobiledata services will become the main source of operator revenue. The resulting expansion of mobiledata services will certainly increase the demand for data bandwidth. LTE has been chosen bymajor CDMA operators as their path to 4G evolution because of its open standards, soundindustrial chain, and high-bandwidth and low-latency features. Responding to the wireless trendtowards LTE, ZTE has launched a Uni-RAN solution that allows for smooth CDMA-to-LTE

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evolution. Uni-RAN takes into full account the need for low-cost evolution, multi-modeintegration, unified transmission, unified network management, and energy conservation. Thesehelp operators reduce their CAPEX and OPEX, and shorten the time to market of LTE.