Quick Construction of Profitable Elaborate WCDMA Network in 3G Times

ZTE has the core network solution with large capacity, high integration and flat structure, the "Operation and Maintenance Factory " solution to wireless network deployment, and V3 series of WCDMA commercial products. Therefore, it helps operators to construct a profitable elaborate, guaranteed, mature, flexible and economical WCDMA networks.

    According to the characteristics of R4 Networks, ZTE puts forward a solution of building all-IP and flat structure and networking of large R4 local networks to construct the WCDMA core network.
The key idea of "Operation and Maintenance Factory" is to centralize the local base band processing equipment of the base station (also called the base band pool) to the operator´s building for operation and maintenance, and use optical fibers to connect the building with 3G sites distributed around the city.
V3 with high integration helps implement networks with large capacity, fewer offices and flat structure.

    Since 2004, the global 3G market has obviously recovered. It is inevitable that the competition of 3G will face operators with similar difficulties in future. Under such conditions, "how to construct a profitable elaborate WCDMA network" to improve the competence of 3G networks and services has become insiders´ common concern.
The cost of main equipment and the cost of equipment rooms should be the primary consideration when  constructing an economical and flexible WCDMA network. With a proper network building solution, operators may invest less in main equipment and equipment rooms, and costs of supporting facilities and operation and maintenance will accordingly be saved.

    ZTE has the core network solution with large capacity, high integration and flat structure, the
"Operation and Maintenance Factory" solution to wireless network deployment, and V3 series of WCDMA commercial products. Therefore, it helps operators to construct a profitable elaborate, guaranteed, mature, flexible and economical WCDMA networks.

1 Core Network Solution — High Integration and  Flat Structure
According to the characteristics of R4 Networks, ZTE puts forward a solution of building all-IP and flat structure and networking of large R4 local networks to construct the WCDMA core network. Moreover, ZTE proposes an economical and flexible network planning and construction strategy of "Planning in One Time, Implementation in Several Steps" to ensure the optimization of coverage and service and cost effectiveness.

    "Planning in One Time" ensures the implementation of the strategic goal of network planning. Using this solution, together with ZTE´s scalable and evolvable core network product series, operators can start their network building with the network planning. Furthermore optimization may be a method to consider how to reduce the influence of further network expansion on existing systems. Also make the core network easier for construction and maintenance as early as at the beginning of network construction. Since the core network is persistent in evolution, "Implementation in Several Steps" is a necessity to build evolvable network.

    Take China Mobile, the biggest mobile operator in China as an example.A networking solution of WCDMA R4 core network is to follow the current network architecture of GSM core network of China Mobile. That is to say, a 3-level network structure is adopted in most of the provinces and the municipalities directly under the central government of China.

    The Mobile Switching Center (MSC) server of the WCDMA network has a much greater capacity than MSC of the GSM network. Another way of the networking of WCDMA R4 core network just makes full use of this feature of the MSC server. Trunking Mobile Switching Center (TMSC) servers of the regional tandem centers are connected via primary tandem to realize nationwide toll connection. The regional TMSC servers are all interconnected.

    However, the MSC servers in a province are connected either by the TMSC server of the regional tandem center (as shown in Figure 1) or by setting a direct route between them, according to different connection requirements of calls.

    In the WCDMA R4 core network, due to the separation of bearing and controlling, bearing can be regarded as an interaction on a plane. End-to-end bearing can be set up through signaling working at MSC servers or TMSC servers. In a word, the TMSC server of the WCDMA R4 core network is only required to transit call control signaling to fix the calling route, free from the tandem of speech channels.

    In a word, for WCDMA R4 core networks, only with Time Division Multiplexing (TDM) based networking, the Trunking Media Gateway (TMGW) is required to do speech channel transit, but all the IP/ATM based R4 core networks can implement direct end-to-end interconnection, and the whole network structure is flat, which avoids net-like interconnection or layered tandem that exist in R99 networks.

2 Wireless Network Solution — "Operation and Maintenance Factory"
The investment of wireless networks occupies 80%-90% of that of the whole WCDMA network, so the selection of base stations and networking solutions is very important for decreasing the whole cost of WCDMA network construction and operation and maintenance.

    In the coming construction of 3G networks, the performance and maturity of network equipment and terminals will not be the bottleneck of network deployment any more. The most significant problem operators will meet in their network construction is, how to get suitable 3G equipment rooms in proper places at the lowest cost, which is especially severe in developed regions.

    With good understanding of the demands of operators on 3G network construction, ZTE has put forward a brand-new networking solution of "Operation and Maintenance Factory" that uses a large scale of base band pools and Radio Remote Units（RRU）, making RRU equipment a main part for coverage. As shown in Figure 2, the key idea of "Operation and Maintenance Factory" is to centralize the local base band processing equipment of the base station (also called the base band pool) to the operator´s building for operation and maintenance, and use optical fibers to connect the building with 3G sites distributed around the city. RRU equipment at each 3G site receives base band signals transferred from the base band pool, and then convert them into wireless signals and send them out. The
"Operation and Maintenance Factory" features centralized deployment and distributed coverage.

    Compared with the traditional wireless networking, "Operation and Maintenance Factory" brings more benefits for operators in multiple aspects.

(1) The solution saves lots of investment in equipment rooms and supporting facilities.
    According to ZTE´s national survey in China, Chinese operators who adopted the solution of "Operation and Maintenance Factory" can save more than 70% of investment in equipment room construction, supporting facilities and power.

(2) The solution helps reduce the waste of feeder cables and improve the coverage efficiency. 
    The feeder required between RRU of "Operation and Maintenance Factory" and the antenna is considerably shorter than that between the macro base station and its antennae. According to the link budget formula in 3G network planning, this solution is able to reduce the feeder waste by 2-3 dB in the link budget. Therefore, the output power at the equipment top is decreased, and the cost of main equipment and relevant supporting facilities at base stations is accordingly reduced.

(3)  It accelerates network construction.
    By adopting the "Operation and Maintenance Factory" networking mode, the operators are able to resolve the  problem of equipment rooms. Then, they can focus their human resources on quick network deployment and operation. Therefore, they gain time to develop more users, to improve their ARPU and to quickly balance their costs. On the side of network construction speed, "Operation and Maintenance Factory" is similar to the Personal Handy-phone System (PHS) network.

(4) It greatly saves the operators´ Operating Expenditure (OPEX).
    Compared with the traditional networking model, this solution greatly reduces expenditure of equipment room construction or lease. Besides, equipment power consumption is also considerably less than that of macro sites. All these make great savings on the operators´ OPEX.

    In addition, the solution supports the networking of "a small base band pool + RRU" or "a macro base station with the capability of supporting RRU + RRU". Such a small "Operation and Maintenance Factory" avoids the problems caused by building the equipment room in a small area.

3 ZTE´s V3 Series— First Choice for WCDMA Network Construction
ZTE issued its WCDMA V3 commercial product series to the world at the Beijing Communication Exhibition in 2004. Based on the V2 commercial series, the V3 series takes the latest demands on 3G equipment during the practical network construction into full consideration. It adopts an optimized all-IP hardware and software architecture and multiple advanced technologies. Compared with V2, the V3 series has reached the top level of the industry with great improvement in performance indexes, equipment reliability and equipment maintainability.

    The development of V3 is based on 3GPP R4, and V3 is backward compatible with R99. Moreover, ZTE fully considered about the operators´ possible selection of different WCDMA versions, and so its V3 core network and wireless network products support smooth evolution and scalability. According to the demands of the operator the V3 series is able to do flexible networking and upgrade on different versions no matter it is R99,
R5/R6 or some ones in future. Hence, it effectively reduces the network construction cost and protecting the investment of the operators.

    V3 with high integration helps implement networks with large capacity, fewer offices and flat structure, which makes the network architecture more clear, reduces alternative speech routes, improves transmission utility, makes maintenance and management easier, and decreases the comprehensive cost of the network.

    The base station products of V3 series make the deployment and construction of wireless networks much easier. All the indoor macro base station products support installation by wall, which effectively save space of the equipment room. The V3 series also includes base band pool equipment with large capacity and RRU equipment, which gives a powerful equipment support to the solution of "Operation and Maintenance Factory".

Manuscript received: 2005-03-10