Telecommunications – Wireless distribution system
Reexamination Certificate
2001-03-09
2004-07-13
Tran, Pablo N. (Department: 2683)
Telecommunications
Wireless distribution system
C455S313000, C455S561000
Reexamination Certificate
active
06763221
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to wireless communications, and in particular to a radio subsystem for providing Local Multipoint Distribution Service (LMDS).
The ever-increasing demand for high-speed access to data networks, such as the Internet, continues to drive the need for new technologies in the computer and electronics industry. As the present day wireline telephone network strains under the demands of both corporate and individual need for high speed connections, a new world of computer communications will eventually break down into two domains, fiber networks and wireless networks.
Fiber networks provide a potential capacity for communication which is a factor of a thousand or even a million times greater than currently used copper cabling, while also providing signaling that is far less susceptible to errors. Wireless networks implemented using broadband technologies, such as LMDS, offer high capacity local access to remote networks that is less capital-intensive and faster to deploy than wireline solutions.
Through recent Federal Communication Commission (FCC) spectrum auctions in the United States, and similar activities in other countries, wireless networks implemented using LMDS are now becoming a reality for the delivery of a wide range of communication services. A point-to-multipoint radio access system implemented with LMDS is capable of providing services ranging from voice to high-speed data (e.g., speeds from T-1 up to OC-3) and serving customers ranging from small to large businesses.
Depending on the country, LMDS uses high frequency microwave signals in the frequency spectrum of 24 GigaHertz (GHz) to 44 GHz and higher for sending and receiving data signals (voice, video, Internet, etc.) wirelessly between radio equipment deployed at a central hub location and distributed remote locations. The radio equipment at the remote location is referred to as the customer premise equipment (CPE) and is typically located at the homes and buildings of LMDS subscribers. The radio equipment at the central hub location is referred to as the hub or base station equipment and is typically located at a central hub tower. Each central hub tower can serve hundreds or thousands of LMDS subscribers within a particular region (i.e., sector or cell site), while a master head-end coordinates the hub signals and connects the LMDS network to other networks via an Internet gateway and/or through land line cabling.
In a typical LMDS configuration, the primary functional modules of base station equipment are separated into an indoor unit (IDU) and an outdoor unit (ODU). The IDU includes digital equipment for transmission and reception of LMDS-compatible intermediate frequency (IF) signals. The IDU also performs the conversion between computer data signals of baseband frequency and the corresponding IF data signals. The IF data signals are typically transmitted between the IDU and the ODU over a coaxial cable connection. The ODU includes outdoor-mounted microwave equipment for wireless transmission and reception of LMDS RF data signals. The ODU also performs the conversion between LMDS-compatible IF data signals and the corresponding LMDS RF data signals.
In more detail, data transmission over an LMDS network involves an IDU that modulates computer data signals of baseband frequency into LMDS-compatible intermediate frequency (IF) signals having a frequency in the range between 10 MegaHertz (MHz) and 2 GHz using an LMDS modem module. LMDS modems are not typically provisioned to modulate baseband computer data signals directly into RF data signals having frequencies in the LMDS frequency spectrum. Instead, a coaxial cable connection carries the IF data signals from the IDU to an ODU where an IF/RF millimeter wave radio circuit performs a radio frequency (RF) up-conversion on the IF signals. The RF up-conversion shifts the carrier frequency of the IF data signals resulting in RF data signals having a frequency in the LMDS RF frequency spectrum. The RF signals are then transmitted wirelessly from an antenna packaged with the ODU to the associated customer premise equipment (CPE).
Conversely, data reception involves the antenna of an ODU receiving RF data signals transmitted wirelessly from the associated CPEs. The IF/RF millimeter wave radio circuit of the ODU performs an RF down-conversion on the RF signals resulting in intermediate frequency (IF) data signals suitable for demodulation by an LMDS modem module of an IDU. The intermediate frequency (IF) signals are forwarded over a coaxial cable connection to the IDU that demodulates them into corresponding baseband frequency data signals suitable for transmission over a computer network. The computer data signals are then transmitted to the computer network via an internetwork device (e.g., switch or router) or to a stand-alone computer.
SUMMARY OF THE INVENTION
Base station equipment in an LMDS network is physically separated into functional modules called indoor units (IDUs) and outdoor units (ODUs). The physical separation allows IDUs to directly interface with a computer network making installation and troubleshooting easier for network technicians. Similarly, ODUs can be installed up on a rooftop, tower, or pole above surrounding obstacles minimizing any signal interference during wireless transmission of LMDS RF data signals along a desired line-of-sight (LOS) propagation path within a sector or cell.
However, the separation of the base station equipment into indoor units (IDUs) and outdoor units (ODUs) makes managing this radio subsystem more complex. Since IDUs are directly connected to a computer network or stand-alone computer, IDUs can be easily managed from a network management system (NMS) server as another network device or end node. In contrast, however, ODUs are not directly connected to the network or stand-alone computer. Therefore, an NMS server indirectly manages an ODU through a communication path between an IDU coupled to the ODU.
Current deployment techniques involve complex and expensive cabling configurations in order to provide network management access to ODUs. In particular, common cabling configurations require direct cable connections capable of carrying network management signals between one or more IDUs and each ODU.
NMS servers provide the ability of managing and configuring devices through software. In the context of an LMDS wireless network, NMS servers are capable of obtaining status and telemetry information as well as providing command and control operation of base station IDUs and ODUs. An NMS server may be located on a computer network or may be a stand-alone computer. There may also be more than one NMS server on a computer network. NMS servers communicate with all of the equipment through the transmission of network management signals that implement a variety of proprietary and public management protocols, commonly SNMP. One or more IDUs typically serve as the interface for transmitting the network management signals between the NMS server and the ODUs.
FIG. 1A
is a block diagram illustrating a common cabling configuration for providing network management access to ODUs. IDUs are omitted in
FIG. 1A
for purposes of clarity. The base station equipment
100
includes four ODUs, one ODU receiver
30
and three ODU transmitters
35
-
1
,
35
-
2
, and
35
-
3
(collectively referred to as the ODU transmitters
35
). Each ODU
30
and
35
is coupled to an IDU via a power/data connection
25
-
1
,
25
-
2
,
25
-
3
, and
25
-
4
(collectively referred to as the power/data connections
25
) supplying DC power and carrying IF data signals. The power/data connections
25
are typically coaxial cables.
In addition to the power/data connections
25
, each ODU
30
and
35
is coupled to a separate network management connection
27
-
1
,
27
-
2
,
27
-
3
, and
27
-
4
(collectively referred to as the network management connections
27
) that extends from one or more IDUs. The network management connections
27
are typically multi-conductor shielded cables. An NMS server (not
Hamilton Brook Smith & Reynolds P.C.
Tran Pablo N.
YDI Wireless, Inc.
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