Solution for Smooth Evolution of CDMA2000 to 3G

• Fully complies with ITU and 3GPP2 specifications
• Adopts advanced technologies and design concepts to achieve large capacity and high integration
• Enables easy migration to a next generation network
• Backward compatibility protects operators´ investment
• Uniquely designed super BTS supports a maximum of 120 carrier-sectors within a single site

More information at:
http://www.zte.com.cn/English/03product/more3.jsp

Analysis on the evolution and development trend of CDMA standards can be made on the radio and network sides. Accordingly, ZTE´s solution for the smooth evolution of CDMA2000 to 3G is proposed in the two aspects.

1 Evolution on Radio Side
The CDMA standards on the radio side include the 2G standard cdmaOne and the 3G standard CDMA2000. As a standard family, CDMA2000 includes CDMA2000 1x, CDMA2000 1x EV/DO and CDMA2000 1x EV/DV technologies.

  Besides the voice service, CDMA2000 1x can deliver data services with peak data rate of up to 307.2 kb/s within a wireless transmission bandwidth of 1.25 MHz. Currently CDMA2000 1x has been successfully put into commercial use in many countries and regions. It has turned out to be a field-proven technology.

  CDMA2000 1x EV/DO is a system optimized for data services with peak data rates of 2.4 Mb/s within 1.25 MHz bandwidth. It features high spectrum utilization. At present, CDMA2000 1x EV/DO system has also been applied on a commercial scale.
Combining the advantages of both CDMA2000 1x and CDMA2000 1x EV/DO, CDMA2000 1x EV/DV can offer voice and data services at data speeds of up to 3.09 Mb/s within 1.25 MHz bandwidth.

  Among all 3G technologies, CDMA2000 is the only one that has been commercially deployed. Moreover, it provides the highest packet data rate and the best spectrum utilization.
From IS-95 to CDMA2000, CDMA2000 1x EV/DO and CDMA2000 1x EV/DV, they are all backward compatible. Once deployed, they can be smoothly upgraded to new standards at low costs.
  The forward/backward compatibility of CDMA standards is one of the main advantages of the system, which can be specified in the following two aspects:
  (1) Next-generation mobile terminals can roam to the legacy network.
  (2) Legacy mobile terminals can roam to the next generation network.

  On the radio side, ZTE rolls out a CDMA2000 solution that supports all CDMA standards including cdmaOne IS-95, CDMA2000 1x, CDMA2000 1x EV/DO and CDMA2000 1x EV/DV. The solution also supports the smooth evolution of these standards.

  For the evolution solution ZTE offers on the radio side, changes are only made on BSS (Base Station Subsystem) while keeping the core network unchanged. Inside BSS, changes are only made on BTS (Base Transceiver Station), not on BSC (Base Station Controller). In BTS, changes are made on the baseband processing board, while no changes are required on other components such as the Abis interface unit, control unit and RF unit. A standard can be upgraded by replacing the baseband processing board and upgrading relevant software. Furthermore, ZTE´s CDMA equipment supports the coexistence of various standards in the same BTS and supports any combination of these standards. ZTE´s solution for smooth evolution among different standards depends on its excellent system features such as the high-capacity non-blocking switching and cross-carrier channel sharing.

2 Evolution on Network Side
Similarly, the CDMA standards on the network side require gradual evolution. The non-open internal interface can be developed into a half-open ATM interface, and finally into an all-open IP interface in a  so-called CDMA2000 all-IP network.

   Traditionally, IP is regarded as a low efficiency technology with poor QoS and can only be applied for data services. However, with the development of IP, technologies such as IEEE 802.1p, Virtual LAN, Type of Service and Differentiated Service are being used to improve the QoS of IP. In particular, IP has been able to provide sufficient bandwidth at a lower price. Besides, IP-based compression technologies are superior to AAL2/ATM protocols in terms of efficiency and time delay.

  With wide applications of IP technologies, it is an inevitable trend for CDMA standards on the network side to evolve to IP. This is the reason why both 3GPP and 3GPP2 select the all-IP network as the basic next generation network.

  The all-IP network comes from the existing network. The idea of separating the access and core networks has been introduced into the all-IP network architecture, which enables the access and core networks to independently evolve to all-IP networks. At the final stage, not only the equipment on the network side but also the terminals will evolve to all-IP mode. The future voice services will be developed using such new technologies as Voice IP, Robust Header Compression and so on.

  Being the first to put forward the concept of next generation mobile network based on Softswitch, ZTE is actively engaged in introducing and promoting the evolution of CDMA2000 to all-IP networks. ZTE has successfully developed an all-IP-based CDMA2000 access network, and put it into experimental operation. Shown in Figure1 is ZTE´s solution for smooth evolution of CDMA2000 to all-IP networks.

  In the initial design for a CDMA2000 all-IP network, ZTE has taken into full consideration its compatibility with the future all-IP network. The advantage is that the equipment can keep the architectures of both the core and access networks unchanged at any stages of evolution, even at the final stage of integrating the IP multimedia domain with the traditional MS domain.

   Taking the all-IP technology as a core for both BSC and BTS, ZTE´s CDMA2000 BSS can fully satisfy the  requirements of future all-IP networks.

   In addition to IP-based trunks, ZTE´s all-IP BSC can provide two kinds of built-in gateways: the ATM gateway and the self-defined packet gateway. They are used for the access of non-IP equipment, which provides users with good compatibility.

  ZTE´s CDMA2000 equipment on the network side supports a variety of networking modes. The Abis interface supports star, chain and ring networking topologies, and so does the baseband-RF interface. Furthermore, they all more performance advantages than both star and chain networkings.

3 Features of the Solution
ZTE has made a large investment in CDMA research and development. After the success in large-scale commercial deployment of its complete set of cdmaOne IS-95 equipment in China Unicom, ZTE has launched China´s first CDMA2000 1x mobile communications system and successfully developed the CDMA2000 1x EV/DO mobile communications system. It has made a breakthrough in critical product features, and is about to roll out its CDMA2000 all-IP products. Given below are the features of ZTE´s all-IP solution:
  (1) All-IP architecture for smooth evolution to future telecom networks and compatible with the existing ATM-based interfaces.
  (2) Huge ultimate-capacity, with BSS supporting 1.5 million voice subscribers (at 0.02 Erl) and data services at the speed of 2.0 Gb/s.
  (3) High integration of the all-IP base station, with a single rack (1.6 m in height) supporting both 8 carrier frequencies/3 sectors and 4 carrier frequencies/6 sectors.
  (4) Super-BTS architecture adopting ZTE´s patent technologies. (A single BTS site provides super powerful baseband processing capability for up to 120 carrier-sectors and is able to use remote RF units to cover an area that originally needs dozens of BTSs.)
  (5) Providing a series of BTS products such as the micro-BTS, remote RF module, super-BTS and macro-BTS, adopting a unified architecture.
  (6) Taking advantage of ZTE´s patent technologies to achieve chip-level resolution when channel elements are shared by up to 24 carrier-sectors.
  (7) Adopting the highly reliable ring networking at the baseband-RF interface and enabling a single fiber carrying all necessary information of 24 carrier-sectors.
  (8) Making use of cutting-edge technologies such as multi-carrier digital intermediate frequency and data predistortion technologies.
  (9) All-IP BTS supporting mixed insertion of CDMA2000 1x, CDMA2000 1x EV/DO and CDMA2000 1x EV/DV channel boards, providing great convenience for upgrade.

Manuscript received: 2003-10-08