ZTE's BBU+RRU Solution
Release Date：2007-06-28 Author：ZTE Click：8876
Problems Confronting Operators
GSM was initiated as a European standard in 1982 and went into commercial
service in 1992. As the choice of 80 percent of all new mobile customers, it is
the world's most popular cellular standard. It is predicted that there will be
almost three billion GSM/EDGE subscribers by 2010, and GSM will still be the
leading standard. However, as subscribers continue to increase, new problems
have occurred and have to be addressed with urgency. These problems are
listed as follows:
With the capacity increase in GSM networks, it is necessary to add the
main and supplementary system equipment, which will surely present problems
such as insufficient equipment rooms and weight bearing. Meanwhile, the
equipment rooms are getting more and more difficult to obtain, and the
equipment rooms' rental and construction fees are becoming increasingly
expensive. The shortage of equipment rooms sets limits on the fast
development of GSM network and needs to be resolved.
The traffic load has the characteristic of periodic migration. In order to
maximize the efficiency of network resources, it is required that the radio
resources be shared, which can't be enabled by the existing integrated base
stations.
The focus on deep coverage and service quality in enclosed buildings has
given rise to the increasing need to provide indoor coverage. However, the
traditional indoor coverage solutions are costly and inflexible in terms of cabling
and capacity expansion.
The number of hot spots-temporary high density spots such as sports
stadium and exhibition halls-is increasing. The traditional base stations can't
flexibly and quickly adapt to the bursty traffic load.
Mobile operators, locked in intense competition, are seeking ways to
reduce CAPEX and OPEX. For operators who have GSM/EDGE networks, the
challenge will be to protect their existing investments while speedily and
economically deploying WCDMA/HSPA services.
New Technological Development
In order to create an open market for BTS equipment that ensures the
availability of standard modules and components, reducing product
development cycles and costs, base station vendors and module and component
manufacturers founded Open Base Station Architecture Initiative (OBSAI) in
October 2002. With 122 members including Nokia, Motorola and ZTE, OBSAI
aims to define a modular base station architecture and detailed specifications
for the interfaces between the modules. On the other hand, another industry
group called Common Public Radio Interface (CPRI) has been formed.
The OBSAI and CPRI initiatives and their specifications help manufacturers
focus on their core competencies and buy standard radio base station modules.
In return, operators will benefit from more extensive products, more flexible
base station solutions and more cost-effective network deployment.
SRRP Base Stations
By adopting advanced technologies, ZTE has launched a series of smart radio
resource pool (SRRP) base stations, which are based on the baseband unit
(BBU) + the remote radio unit (RRU) structure (Fig. 1).
BBU+RRU ( a narrowband transceiver)
BBU is in charge of GSM base station control and RF signals processing; it has
a maximum capacity of 48 carrier frequencies within a single rack. It uses the
same hardware platform as WCDMA and can support GSM and WCDMA mixed
inserts in one baseband board to achieve dual mode operation. The BBU, which
is 19 inches in width, can be flexibly installed. A single RRU supports two
carriers and can naturally dissipate heat, reduce the feeder line loss and
increase the coverage of the base station.
BBU+ RRU ( a broadband transceiver)
By adopting the broadband transceiver unit and Multi Carrier Power Amplifier
(MCPA), the solution provides a large bandwidth necessary for multiple carriers
and can flexibly configure and schedule the carriers. The RRU can transmit and
receive common-mode GSM/WCDMA signals, and when combined with the
multi-mode BBU, makes up the highly integrated multi-mode
GSM/EDGE/WCDMA products.
The miniBSC+BBU+ RRU (a broadband transceiver)
The BSC and BBU can be integrated into an intelligent base station that
accomplishes wireless transmission, administrates radio resources management
and realizes the integrated and intelligent scheduling of baseband and radio
frequency resources.
Dynamic Resources Pool
The ZXG10 SRRP system is based on the innovative GSM/WCDMA dual mode
BBU (B8048), the RRU (R8102) with low power consumption, and the dual
mode RRU. The BBU and RRU form the distributed base station system where
the baseband and radio frequency resources can be shared.
As the industrial and residential areas are currently separated, large traffic
loads tend to occur in different areas over different periods of time. The
traditional base station system needs to provide RF parts and baseband
resources to meet the maximum traffic demands in both areas. When traffic is
low in one area, the available network resources can't be shared and reused,
resulting in equipment investment waste. However, ZTE's BBU+RRU dynamic
resources pool structure enables sharing of baseband resources and greater
resource allocation flexibility (different resources scheduled at different times).
Benefits of BBU+RRU Structure
Saving costs on equipment rooms
With a small size, the BBU can be installed in residential and business
buildings. It can also be located in the integrated power cabinets, in a
basement, or in a 2G cabinet, solving the problem of insufficient equipment
rooms.
Reducing the feeder line losses by 2 to 3dB
Traditionally, the macro base station is connected to the antenna via 7/8-inch
feeder cable. The BTS output power lost in feeder lines is 2 to 3dB at an
average. In the BBU+RRU structure, the remote RF module is connected to the
antenna via the flexible jumper, avoiding feeder line losses.
Shortening the construction time
The BBU+RRU solution has no special needs for equipment rooms and
requires only the installation of the auxiliary antenna feeder systems, enabling
operators to speed up network construction to gain a first-mover advantage.
ZTE is devoted to offering innovative products and solutions in quick response
to customers' needs. Taking subscriber traffic, capacity, electricity, installation,
evolution, etc. into full consideration, ZTE's SRRP base stations and solutions
help effectively reduce operators' operating and capital expenses.
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