With the gradual development of All IP mobile network, IP becomes an inevitable choice for wireless access network. When introducing IP to 3G network, the network data ability can be greatly improved. Furthermore, IP can help 3G operators to alleviate current pressure from huge transmission requirement, especially the challenges brought by wireless broadband technologies such as HSPA.
Obvious trend of All IP mobile networks
The explosive increase of Internet services brings traditional transmission networks unprecedented revolutions in service development, traffic mode, and network operation. In view of the prospect of network protocols, IP is the only protocol that is compatible with all transport networks. Future transmission networks will gradually evolve to All IP. The huge success of the IP technology on the Internet indicates the prospect of IP in the mobile services and bearing networks. The future mobile communication will base on IP protocol from the network to the terminal, which means the whole process is IP based including control, bearing and services.
The IP technology in the mobile networks will firstly change the bearing way. Considering the system extendibility and network construction cost, IP based transmission will gradually be applied to core network and then wireless access network, and ended in the mainstream link-layer protocol of wireless access network. At present, IP technology has already applied widely in core network. 3GPP suggests introducing IP transmission in R5 stage, thus realizing evolution to All IP transmission both in core network and wireless access network. Therefore, IP transmission in the wireless access network has already become a hot spot in the industry.
Iub IP of radio access network is especially urgent
Nowadays, people are demanding more than voice service from the wireless telecommunication. So, high-speed, diversified and customized data services will lead the future. Meanwhile, developing mobile broadband technologies increase data rate of air interface unceasingly, so it brings higher requirements to wireless transmission bandwidth. Take the Iub transmission as an example, a 3 x 1 site in R99 network usually needs two E1s for Iub transmission, while in HSDPA early stage the transmission bandwidth demand increases to 3~5 E1s, in HSDPA mature stage the bandwidth demand is even higher.
With the rapid development of wireless broadband, more and more bandwidth is required on the radio access network. Therefore, the bandwidth of radio access network can not meet this increasing demand if it still relies on traditional ATM transmission solution. Moreover, because the data service has higher bandwidth requirement but lower returns ratio, the operation expense is possible to counteract the income from data service. IP is greatly concerned by operators because of its' characteristic on cost effectiveness, wide deployment and data service ability. So it is becoming the best choice for wireless access network.
When introducing IP transmission to radio access network, the Iub IP is especially urgent. Considering the construction and operation expense, the transmission cost between different network elements will normally account for a proportion of 20% of total expense. Moreover, because of the large total amount of the transmission links between Node B and RNC, Iub transmission expense becomes the main part of the total. Therefore, to save the Iub transmission cost is extremely significant.
Flexible Iub IP transmission solutions
In order to support high data rate packet services, the existing bearing network is now evolving to multiple services and higher bandwidth. The bearing network is diversified. It can be TDM or MSTP network, data network and even a combination of different networks. There is also a quite big difference between bearing networks of different operators. For example, when deploying 3G network, the traditional 2G operator generally depend on renting metro transmission resources or construct Microwave or other transmission networks, while integrated operators usually have abundant fixed transmission resources.
But which kind of Iub IP transmission solution to choose is greatly depending on operators' existing transmission resources. Huawei can provide customized Iub IP transmission solutions according to different bearing situations. After analyzing overall situation of transmission resources, Huawei brings forward 5 typical Iub IP transmission solutions: Iub IP networking based on TDM, MSTP, Data and even combined TDM/Data or TDM/xDSL.
TDM based Iub IP transmission This solution is mainly for operators with TDM network or 2G operators with spare TDM transmission resources. It is a convenient and cost-effective solution because the operator can entirely reuse the existing transmission resources. IP protocol is introduced to this solution, so it can smoothly evolve to All IP without replacing transmission board. Moreover, compared with the ATM protocol stack, applying IP protocol stack to the Iub interface can save 10%–20% transport expenses because of the higher efficiency of IP over E1 that adopts the standard compression protocols. The TDM transport network provides transparent transport for Iub data and ensures reliability, security, and QoS of the services.
MSTP based Iub IP transmission Iub IP networking based on MSTP is ideal for operators who have SDH networks or MSTP networks. SDH operators can provide Ethernet access as soon as they upgrade SDH to MSTP. In order to fully utilize transmission resources, the MTSP equipment encapsulates Ethernet frames into VC trunk whose bandwidth is shared by several Node Bs. VLAN enables hybrid transport between Node B and RNC. RNC and Node B label different VLAN tags to differentiate real-time services from non-real-time services. This solution can meet requirement of rapid service development very well because no physical link is required when expanding network capacity.
Data network based Iub IP transmission For operators who have or plan to construct data network, Data Network Based Iub IP Transmission Solution is preferred. This solution provide Iub interface with very high transmission capacity because a Node B is connected to a L2 switch or a L3 router via FE ports by cable or fiber connections. If the data network is based on RPR which has good reliability and switchover performance after failure, the service security and reliability are also guaranteed. Because this solution is based on the All IP network, the transmission network is ready to completely satisfy the evolution of 3G network from R99 to HSPA and to LTE. But in order to guarantee the quality of VP service, this solution also set a relatively stricter requirement on end-to-end QoS of Iub link.
TDM/Data based Iub IP transmission When restricted by performance of bearing network, single transmission network can not provide guaranteed QoS or precise synchronization clock, we can turn to a hybrid solution which is TDM/Data Based Iub IP Transmission Solution. There are two bearing networks between Node B and RNC. TDM network provides transmission channels for services of high QoS, such as Node B signaling, control data, and voice service. And data network provides transmission channels for services of low QoS, such as background services of HSDPA and R99. The solution can guarantee quality of high QoS service and clock by defaulted function of TDM network. On the other hand, it helps to provide low QoS data service with lower cost and higher bandwidth.
TDM/xDSL based Iub IP transmission This solution adopts xDSL as the last mile access of data network. For operators who have abundance copper cable resources, especially for some European operators with quality copper cable, TDM/xDSL Based Iub IP Transmission Solution is a cost-effective choice for Node B access. In xDSL networking, lines and modems are important because they are related to the reliability of the network. So Huawei provides a 1+1 redundancy solution that supports load-sharing and mutual backup for ADSL/ADSL2 + Modem.
Iub IP becoming a hot spot
Iub IP has become one of the key points of wireless network deployment, and received great attention from global mainstream operators. Operators like China Mobile, PCCW, Vodafone, Orange, T-Mobile and eMolile are very interested in Iub IP transmission. Many of them ask for on spot test or require IP transmission as an essential characteristic. Huawei's Iub IP transmission solution has passed performance test conducted by some European venders in Spain, France, and Italy.
With growing challenge of Iub transmission, leading 3G venders bring forward Iub IP transmission in response. As one of the leading vendors in telecommunications, Huawei has a full product line and accumulated abundant experience over Fixed-line network, Optical network and Datacom network over the years. Those accumulations provide Huawei great advantages over 3G transmissions. Huawei achieved to provide commercial Iub IP solution in the fourth quarter of 2006, and becomes the first vendor to provide Iub IP in the industry.
There are already two operators, eMolile and Etisalat, who have introduced Huawei's solution to their commercial networks, among which eMoblie's 3G network is the first 3G network based on All IP bearing in the world. The network deployment is still going on wheels and has already passed some tests required by eMobile. So far, some typical 3G services like video phone are provided. The commercial practices once again proved the advantages of Huawei Iub IP transmission solution, providing cost effective transmission for HSDPA best effort service, decreasing transmission construction and maintenance cost, helping operators strengthen operation ability.