Comparison between WCDMA and CDMA2000 network structure

comparison between WCDMA and CDMA2000 network structure

Author: Baoxiangwen Ma Xunong Wan Bing Jie
At present, the mobile communication system is developing towards the third generation, because there are two different 2G formats, so 2G to 3G evolution also exist two routes. GSM adopts WCDMA Evolution strategy and Narrowband CDMA adopts CDMA2000 Evolution strategy. WCDMA and CDMA2000 as the future mainstream technology, has been widely recognized by the industry. There are many similarities between WCDMA and CDMA2000 two kinds of standards, wireless technology and network technology, but there are many differences. This paper focuses on the similarity and difference of network structure.

The mobile communication system has undergone the first generation analog communication system and the second generation digital communication system (GSM, CDMA), and is developing to the third generation mobile communication system. Due to the existence of two different 2G formats, there are two corresponding routes in the process of 2G to 3G evolution. GSM adopts WCDMA Evolution strategy and Narrowband CDMA (IS95+ANSI41) adopts CDMA2000 Evolution strategy. As the mainstream technology in the future, WCDMA and CDMA2000 have been widely recognized by the industry. Under the dual function of technology innovation and Market drive, 3G is speeding up from concept to industrialization, the major equipment operators and manufacturers are actively tracking and developing 3G network products based on WCDMA or CDMA2000 technology, so it is very important to study and compare them. Whether it is wireless technology or network technology, WCDMA and CDMA2000 have a lot of similarities, but there are also differences between the two formats.

1, the gradual evolution of the two modes

The formulation of the two standard standards is very important to the gradual evolution of the concept, to ensure the smooth evolution of the entire network system, and for different operators to provide different solutions and networking strategies to meet the special needs of different operators. Because the standard is gradual evolution, so the standard formulation also must be phased. From the current standards, WCDMA divided into three relatively clear stage, namely R99, R4, R5. The stage division of CDMA2000 Standard is fuzzy, but it is divided into three stages, namely PHASE0, PHASE1/2, Phase3. This paper mainly discusses the second and third stages of the two modes.

2. WCDMAR4 Stage
For both modes, the second phase is the transition to a full IP network. In the second stage, the similarity of the two network structures is very strong, the main change is in the circuit domain (that is, voice), but the processing of the packet data changes very little. The following are mainly discussed for the circuit domain.
In the second phase, the Mobile Switching Center (MSC) and the mobile network Gateway (GMSC), which deal with voice, are split into two network elements, i.e. Mscserver/gmscserver and its controlled media Gateway (MGW). The server mainly completes the processing of signaling and call control, while MGW provides processing of voice streams and interconnection with external networks. The Gateway control protocol between server and MGW uses H.248,server and server-independent call Control Protocol (BICC). The signaling interconnection of the server and the external traditional network uses signaling gateways (SGW) to achieve interconnection and interoperability. Among them, T-SGW realizes the interconnection and interworking with the public Switched Telephone Network (PSTN) network, R-SWG realizes the interconnection and interworking with 2G mobile network.
The R4 network structure is directly evolved from R99, and some network elements (such as MGW, T-SGW, R-SGW) are added to the R4 network. and enhanced a part of the R99 network element functions (such as MSC, SGSN, GGSN, HLR), the core network can support the R99CS domain terminals, and allow the terminal in the R99 network and R4 network seamless roaming. This phase can be considered as a transition phase to a full IP network. Through a variety of media gateways and signaling gateways, the core network with 2G Network, PSTN and other external networks for interconnection and interoperability, to achieve 2G network and 3G network between the mutual roaming. 3G networks evolve from 2G networks, you can view 2G networks as an external network of 3G core networks.
The Intelligent network element is the most basic feature of the R4 networks, 3GPP has adopted a large number of traditional intelligent network protocols and made a lot of modifications in the process of making the Protocol, so that the network has powerful intelligent function. The function of Intelligent network is distributed in each network element, each network element has the function of Business Exchange point (SSP). Intelligent network functions can be seen as an integral part of the 3G core network.

For both modes, the second phase is the transition to a full IP network. In the second stage, the similarity of the two network structures is very strong, the main change is in the circuit domain (that is, voice), but the processing of the packet data changes very little. The following is mainly for the circuit domain ...

3. CDMA2000PHASE1/2 Stage

Throughout the evolution of the IP (Phase1), the CDMA2000 is the same as the WCDMA system, which splits the current ios4.x standard of MSC into Mscserver/gmscserver and MGW two functional entities and supports ATM/IP transmission.

For CDMA2000, this is the first phase of the evolution to the full IP, the beginning of the signaling and transmission separate, core network and access network separate, independent development. In this phase, the core network in the circuit part of the signaling and load separation, signaling in the IP transmission, the bearer continues to use the original load mode. The group part and the access network develop independently. Access to the network part of the use of IP transmission (such as A3, A7, A9, A11, etc.). The air interface uses RELEASE0 or Releasea.

At this stage, the concept of "ipmultimediadomain" and "Legacymsdomainsupport" are introduced in all IP. The former deals with VoIP, multimedia, and the combination of both, which supports the traditional mobile phone in all IP. Through the roaming signaling processing of the original ANSI-41 Electric network business. "IP Multimedia Domain" Although also support the traditional mobile phone, but the signaling and business are transmitted on the IP, it and through the roaming signaling to solve the original user's business is a different concept. In the full IP because there are two domains of support, dual-mode mobile phone can according to their ability to choose the appropriate mode to the full IP Wireless access network (RAN) registration. Ran should support access to both domains. The air interface needs to increase the hosting of the Session Initiation Protocol (SIP) call signaling in IP domain in all IP, but the traditional mobile station (MS) support can continue to use the original interface.

In the RAN, the internal interface is open through full IP, especially the interface of the Voice encoder part should be open, so that the sound coder can move to the core network conveniently. The position of the acoustic encoder will eventually move from the base station controller (BSC) to the MGW. At this point, the A1, A2, A5 interfaces evolve into A1 ', A2 ' and A5 ' interfaces, and voice and SS7 signaling are transmitted by IP.

Ran is evolving toward full IP and more open direction, not only to support traditional MS, but also to support the core network's multimedia domain (Multimediadomain).

The main differences between the two-stage networks are as follows: A R-SGW the transaction processing capability Application Part (TCAP) and the mobile application part (MAP) of the two modes are different. b for packet data, WCDMA service GPRS support node (SGSN) and GPRS Gateway Support node (GGSN) mainly Adopt GPRS Tunneling Protocol (GTP), CDMA2000 The mobile IP (MIP) protocol is mainly used between the Group data Service node (PDSN) and the Attribution Agent (HA). c) The voice of the CDMA2000 base station and the core network is transmitted in the form of EVRC/RTP, and the voice between WCDMA base station and core network is ATMAAL2 loaded. D The AAA server is optional in WCDMA and is part of the network in CDMA2000.

4. WCDMAR5 Stage

The network is composed of wireless network, GPRS network, call control, all kinds of gateways connecting with external network and business framework. Wireless networks consist of mobile users, wireless links and wireless access. GPRS network is composed of GPRS support node, including providing SGSN of mobility management, providing packet data Protocol (PDP) activating context Management SGSN and providing attribution location Register (HLR) function of the user server (HSS). The network entity of the call control part includes some media gateways and signaling gateways, consisting mainly of the call State control function (CSCF), the Media Gateway control function (MGCF), the roaming signaling Gateway (R-SGW), the MGW, the transmission signaling Gateway (T-SGW), and the Media resource function (MRF). Complete the call control and signaling functions to achieve a variety of real-time mobile services.

5. CDMA2000PHASE3 Stage

This phase is the culmination of the evolution to the full IP network, at this stage, all become IP multimedia domain, no traditional Ms. IP will extend to all areas, air interface, access network and core network are IP bearer, including all signaling and business.

At present, MS's packet data service uses MSC to the corresponding HLR to identify the user's data service rights and instruct BSC to complete the packet data connection. In the multimedia domain, through the Mobility Management module (MM) in BSc, the local AAA and HOMEAAA are performed interactively. At this stage, the traditional mobile domain (LMSD) will no longer continue to evolve, and if the network is built directly from this stage, it will no longer support the traditional MS. But if the network is from the previous stage of development, operators can choose to retain the previous LMSD, and IP multimedia domain coexist to support the traditional Ms. At this stage, IP multimedia should be the dominant technology in the network to support new business or enhanced IP Multimedia services, and to meet enhanced business capabilities and QoS requirements.

6, WCDMA and CDMA2000 in the third phase of the similarities between

The third generation mobile communication WCDMA system is based on GSM and GPRS, and its specification is based on inheriting Phase1, PHASE2 and phase2+ protocol standards, with the change of technology and business, new and modified some technical specifications, There are many GSM and GPRS protocols that are directly referenced by 3GPP and converted to R99 phase protocols. Generally speaking, R99 as the first stage of WCDMA technical specifications, compared with GSM (PHASE1/PHASE2/PHASE) technical specifications, whether it is in the wireless access network part or the core network parts have very big changes. In the wireless network side, GSM and GPRS are all using TDMA technology, while in the R99, it uses the revolutionary CDMA technology. At the core network side, the circuit switching and packet switching technology are introduced, and ATM is used as the IU interface, which can be compatible with the second generation of Base station subsystem (BSS) and the core network of GSM and GPRS, and can interconnect with PSTN, ISDN and IP network. In other words, the 3G core network should be able to support both the wireless network subsystem (RNS) and BSS two types of access, while supporting 2G and 3G users and related businesses.

The core network of WCDMA can be divided into CS domain and PS domain in general, corresponding to the circuit switching part and GPRS part of GSM system, the PS domain basically inherits GPRS design idea. MSC/VLR is responsible for processing CS domain related business, SGSN and GGSN is responsible for processing PS domain related business. Compared with the original GPRS system, WCDMA significantly improves the utilization of wireless resources, simplifies the protocol stack of the core network, and pushes the processing work to the wireless network Controller (RNC). The main technical breakthroughs in the core network are the introduction of ATM switching technology with AAL2 and AAL5 adaptation, IP technology, AMR codec technology, transcode Technology and IU interface technology based on CS/PS domain. Compared with the second generation, the core network has been designed in the aspects of the user customization Application (CAMEL) service and the positioning Service (LCS) system of mobile network enhanced logic.

3G backbone network also needs to interact with a series of networks (such as PSTN, ISDN, Internet, other 2G plmn, other 3G PLMN, multimedia network, etc.) to realize various interworking business. Compared with the second generation of GSM, WCDMA has a relatively large network change due to the introduction of a new wireless format. Among them, the RNC and the NodeB and the second generation of BSc and BTS Compare, in the wireless format, transmission, protocol has a fundamental change. The core network has been greatly changed due to the introduction of new wireless and transmission technologies on the wireless side. The most essential change of WCDMAR99 's core network is the introduction of ATM transmission in IU port (equivalent to the original GSM interface of A and GB). The WCDMAR5 phase and the CDMA2000PHASE3 phase are all real IP networks. For the third stage, both networks introduce media control separation technology based on h.248 protocol and IP Multimedia session control technology in order to realize voice and multimedia service in the packet domain. has realized the IP technology from the mobile terminal to the network transmission and the business realization. For the superposition evolution, there may be some network elements in the second stage. For a completely gradual evolution of the network, all using IP Multimedia technology implementation. The HLR in the CDMA2000 network was completely replaced by AAA. WCDMA evolves to HSS, and becomes the center of Network user management business realization. The two kinds of standards in the packet domain to achieve voice services are very similar.

7, WCDMA and CDMA2000 of the third phase of the difference

The main difference between the two modes in this phase: A for R-SGW, the R-SGW is different in software because of the difference between the TCAP and map signaling used in the two formats. b) for packet data, WCDMA SGSN and GGSN mainly use GTP, and the CDMA2000 Pdsn and HA are mainly adopted MIP protocol. C for WCDMA, the function of HLR will be enhanced, the evolution of HSS, but AAA server is still optional. For CDMA2000, HLR will be degraded and its functionality will be implemented in an enhanced AAA server, with AAA becoming the center of Wireless user management, wireless resource management, and business development across the network. D for WCDMA, a multimedia processing subsystem is superimposed on the GGSN GI interface to achieve voice service on packet data. And CDMA2000 is through the pdsn or ha IP streaming to the media gateway, in order to achieve voice service in packet data.

8. Concluding remarks

At present, the world's major equipment manufacturers are actively tracking and research and development based on WCDMA 3G network products, Japan's DoCoMo early in 1991 to start the WCDMA research and development work, and in the second half of 2001 launched a WCDMA commercial system and product prototype. Global operators to participate in the WCDMA positive attitude, several major domestic operators are also actively fighting for the 3G license plate, and compete to launch the WCDMA network test for WCDMA operations to do preliminary preparation. How China Telecom operators integrate and utilize their existing resources and develop new business after acquiring 3G licenses, the author thinks that on the basis of discussing network structure, we need to solve a series of problems such as network construction cost, marketing and business strategy, and long-term scale benefit. Under the condition of weighing various factors, the operators choose which one of the three kinds of standard, which is the important problem related to the future development of the enterprise.