Innovative Distributed NodeB Solution

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Abstract: Network investment and network quality are contradictory. As
sites/equipment rooms are getting more difficult to obtain, and the leasing
cost is shooting up, the construction cost and the operation cost of 3G
network increase. The innovative distributed NodeB solution of Huawei can
greatly reduce the leasing cost, electricity, air-conditioning, and human
resource of the equipment room. According to statistics, it can save the
cost of the total investment by 30%.

1 Introduction of Distributed NodeB Solution

The coverage quality is critical for subscribers, operators are supposed to
keep improving the network quality by installing new sites. However, the
available sites and equipment room for new base stations are decreasing, and
the rental fees become more expensive. How to build a network quickly and
economically is the critical difficulty that the operators have to face.

Distributed NodeB solution is an economical and fast wireless network
deployment solution under the circumstances of no equipment room or less
ideal equipment room locales. The distributed NodeB solution adopts remote
RF technology. The Remote Radio Unit (RRU) can be installed near the antenna,
and connected with the BaseBand Unit (BBU) via optical fiber (as shown in
the following figure). The optical interface module implements clock
extraction and the multiplexing/demultiplexing of the baseband signals. The
I/O signals of the CPRI interface are modulated, digital/analog converted,
up-converted, filtered, and amplified before they are output to the antenna
feeder.

CPRI is an open standard interface. In April 2003, Ericsson, Huawei, NEC,
Siemens, and Nortel established the Common Public Radio Interface (CPRI)
cooperation organization. The organization focuses on the new form of the
WCDMA FDD NodeB, and produce new open standard interfaces, dividing NodeB
into radio equipment (RE) and radio equipment control (REC). In that way,
each part of the NodeB can better benefit from the technological progress
from different sources.

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2- Application of
Distributed NodeB Solution

2.1 Partial Outdoor Solution

Operators have their own sites or indoor space, but the equipment rooms are
spatially small, or have an insufficient weight bearing capacity, or have
less ideal locales (which may lead to excessively long cable feeder). In
such scenarios, DBS is more advantageous than the conventional macro NodeB.

BBU can be installed at any place within the building, connected with the
RRU on top of the building via optical fiber. It solves the problems of
equipment room space, insufficient weight bearing, less ideal equipment room
locales, and excessively long cable feeder. RRU can be powered on with the
-48V in the equipment room, or can adopt the 220V DC.

2.2
Stand-alone Outdoor Solution

Operators do not have their own equipment rooms. The adoption of MBA+BBU+RRU
or APM+BBU+RRU solution (MBA can accommodate lightning protection device,
power conversion, transmission, and BBU, without storage battery, used in
areas that do not require storage battery, e.g., Europe; APM includes
storage battery, maximally supporting 8 hours of backup power, used in areas
that require backup power) can replace the outdoor macro NodeB in most
cases.

The temperature range for normal working of this solution is: -40~45°C (MBA/APM
is equipped with heating device to ensure the startup of the equipment in
low temperatures).

2.3 Embedded Outdoor Solution

Operators have their own 2G outdoor base station sites and at the same time
the outdoor base station have available space (19″, 1U). The mode of
installing the BBU in the 2G outdoor base station can save the leasing of
equipment room. Compared with conventional outdoor macro NodeB solution, it
greatly reduces the leasing cost, project cost, and project implementation
time.

The site acquisition, manpower cost, and space leasing cost in the
international markets (especially Europe) are high, and there is a large
proportion of outdoor macro base station established in the 2G era. This
solution has a lot of significance for the carriers, and is widely applied
in Europe (almost networkwide application in Holland).

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2.4 Inter-Sites Sharing Solution

Operators have optical resource between sites (direction connection or
contour connection via an intermediate central site, less than 40km for a
single hop and max. 100km in the case of cascading). There are no equipment
rooms but there are optical fibers connected with other sites. The RRU can
be connected with the macro NodeB or BBU of other sites, with the baseband
resource shared by multiple sites. The typical application is shown in the
following schematic diagram.

In this solution, as the handover between sites is softer-handover, which
can improve the network quality. Furthermore, the daily maintenance and
future capacity expansion need to be done in the host NodeB equipment room.
This solution relies on the large amount of optical fiber resource the
operators have. Operators may find some center equipment rooms in the city
area, with other surrounding sites adopting RRU connected to the center
equipment rooms via optical fiber. In this way the demand for equipment
room, and operation & maintenance cost are reduced, the network quality is
improved, and centralized maintenance is possible.

3- Benefits of
Distributed NodeB for Operators

Distributed node B is an important option for the 3G network construction of
the operators. The adoption of the Huawei distributed NodeB solutions can
bring the following benefits:

1. Solving the problem of equipment rooms

When the operators construct the WCDMA network, the distributed NodeB can
reduce the requirement for equipment rooms when insufficient, or less ideal
locales. The baseband units can be placed in the center equipment room
available in a centralized manner, or the compact BBU3806 can be installed
in the corridor of the building, lift lobby, or underground chamber. The
RRUs are distributed at the sites according to the network planning.
Experiences show that the adoption of distributed NodeB can reduce 80% of
the equipment room demand.

2. Reducing the project implementation cost

The distributed node B features small size, light weight, direct
installation near the antenna, one-man installation and fast testing.
Experiences show that the project implementation cycle of the distributed
NodeB is only 30% of the conventional NodeB. Compared with the conventional
macro NodeB or outdoor NodeB, the installation cost of the distributed NodeB
is far less.

3. Reducing the operation cost

The distributed node B adopts high efficient amplifier, with the power
consumption of the RRU3801 less than 220W and that of the BBU3806 less than
60W. It reduced the power consumption of the peripheral equipment like
air-conditioner, which means that the carriers save a large amount of
electricity expenses.

The distributed node B has less demand for peripheral facilities such
equipment room, power, and air-conditioner, and saves project installation
and operation costs. Statistics show that distributed NodeB can sharply
reduce the investment by 68% in terms of project implementation, peripheral
facilities, equipment room, and electricity consumption. The distributed
NodeB shares the baseband processing resources of the center sites, saving
cable feeder and tower amplification module, or put altogether, saving the
equipment purchase cost.

4. Reducing the equipment cost

The Huawei distributed NodeB solution can solve the problem of burst traffic.
As the baseband sharing strategy is adopted, the surplus baseband resources
in the surrounding cells can be utilized to handle burst traffic in other
areas concerned.

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4-
Summary

Since 2002, Huawei started to develop distributed NodeB products( including
BBU and RRU). In 2003, Huawei released the first RRU product. In 2004,
Huawei released the BBU product, which is the smallest BB unit worldwide.
Huawei’s distributed NodeBs are widely applied in commercial networks,
especially in Holland, which is considered a major breakthrough on the 3G
network construction.

Huawei’s distributed NodeB solution can provide economical, fast deployment,
and at the same time provides better network quality. It is an ideal network
construction solution for mobile operators.

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About Huawei

Huawei is one of the leading players in the global telecom market.
specializing in the research and development, production, sales and
marketing of telecoms equipment, Huawei provide innovative, customized
equipment, service and solution in different telecom fields, creates long
term value for customer and realizes the customers’ potential growth.

Huawei has about 35,000 employees; its overseas services have covered more
than 90 Countries/regions, Huawei Technologies serves 22 of world’s top 50
operators. in 2004, the contract sales of huawei have reached USD 5.58
billion.