Traditional wireless communication systems may have distributed antennas to expand the range of a centralized base station. Any signals received by the distributed antennas must be sent back to the centralized base station for processing regardless of where the ultimate destination of the signal is located. This causes unneeded transmission of signals and results in increased latencies for users of the system. Additionally, each remote antenna is required to share capacity with every other antenna connected to the centralized base station. This causes unacceptable disruption of services for some users of the system.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a distributed antenna system that effectively and efficiently processes wireless communication signals.
The above-mentioned problems of current systems are addressed by embodiments of the present invention and will be understood by reading and studying the following specification. The following summary is made by way of example and not by way of limitation. It is merely provided to aid the reader in understanding some of the aspects of the invention. In one embodiment, a distributed base station system for high speed data transmission is disclosed. The system includes a plurality of remote antennas, each antenna being coupled to a router. The plurality of remote antennas is coupled to each other and is arranged into a network.
The present invention can be more easily understood and further advantages and uses thereof more readily apparent, when considered in view of the detailed description and the following figures in which:
In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the present invention. Reference characters denote like elements throughout Figures and text.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific illustrative embodiments in which the device may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical and electrical changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense.
The present apparatus is a modular wireless platform that enables a system facilitator to easily and inexpensively adapt their wireless system for use with different data transport mechanisms, frequency bands, communication technologies, and intelligence distribution. This modular platform is made up of a reconfigurable host unit and a reconfigurable remote unit designed for use in a system with a central node and a plurality of distributed antennas. The host unit is located near the central node and facilitates transmission/reception of information to/from the remote units which are located remotely with an accompanying antenna. The remote units function to transmit/receive transmissions from the host unit and transmit/receive wireless signals over accompanying antenna to mobile costumers.
Host unit and remote unit have a modular design and defined interfaces that allow components to be removed and installed to adapt to the needs of the service providers. Both host and remote unit are designed around a serial radio frequency (SeRF) communicator and have a defined interface where different varieties of digital to analog radio frequency transceiver (DART) modules can be connected and disconnected. There are many different DART modules, and each DART module is designed for a particular technology and frequency band. Thus, technology and frequency band adjustments can be made by simply replacing the DART module in the host unit or remote unit. Additionally, host unit and remote unit are designed to allow different transport mechanisms between the host unit and remote unit. For example, the same host unit and remote unit that use fiber optic for inter-unit transmission can be adapted to use E Band wireless transmission instead of or concurrently with the fiber optic. Finally, wireless processing functionality can be placed all on a base station near the central node, or the functionality can be distributed throughout each of the remote units. The flexibility to modify the functionality of each remote unit allows the wireless platform to support centralized base stations and distributed base stations, either separately or concurrently.
In the transmission direction of transport, base station 103 performs baseband processing on IP data from IP gateway and places the IP data onto a channel. In one embodiment base station 103 is an IEEE 802.16 compliant base station. Optionally, base station 103 may also meet the requirements of WiMax, WiBro, or a similar consortium. In another embodiment, base station 103 is an 800 MHz or 1900 MHz base station. In yet another embodiment, the system is a cellular/PCS system and base station 103 communicates with a base station controller. In still another embodiment, base station 103 communicates with a voice/PSTN gateway. Base station 103 also creates the protocol and modulation type for the channel. Base station 103 then converts the IP packetized data into an analog RF signal for transmission over antenna 108. Base station 103 sends the RF signal to host unit 102. Host unit 102 converts the RF signal for long distance high speed transmission over transport mechanism 104. Host unit 102 sends the signal over transport mechanism 104, and the signal is received by remote unit 106. Remote unit 106 converts the received signal back into an RF signal and transmits the signal over antenna 108 to consumer mobile devices.
DART modules 208, 210, 212 provide bi-directional conversion to/from analog RF signals from/to digital sampled RF. In one direction of communication, DART module 208 receives an incoming analog RF signal from base station 103 and converts the analog signal to a digital signal for use by SeRF communicator 202. In the other direction DART modules 208, 210, 212 receive digital sampled RF data from SeRF communicator 202 and convert the data to analog RF for use by base station 103.
Each DART module 208, 210, 212 has a common communication interface for communication with SeRF communicator 202, and a RF processing portion that is exclusive to one frequency band and communication technology. Each DART module 208, 210, 212, therefore, converts to/from one analog RF to the digital signal used by SeRF communicator. For example, DART module 208 is designed to transmit 850 MHz cellular transmissions. As another example, DART module 210 transmits 1900 MHz PCS signals. Some of the other options for DART modules 208, 210, 212 include Nextel 800 band, Nextel 900 band, PCS full band, PCS half band, BRS, WiMax, and the European GSM 900, DCS 1800, and UMTS 2100. By allowing different varieties of DART modules 208, 210, 212 to be plugged into DART interface 206, host unit 102 is configurable to any of the above frequency bands and technologies as well as any new technologies or frequency bands that are developed. Host unit 102, once installed, is field configurable to transmit a variety desired by insertion of a different DART module. Additionally, since SeRF communicator 202 is configured to communicate with multiple different DART modules 208, 210, 212, a single host unit 102 can transmit/receive multiple frequency bands or technologies.
SeRF communicator 202 provides bi-directional conversion to/from a SeRF stream from/to a high speed optical serial data stream. In one direction, SeRF communicator 202 receives incoming SeRF streams from DART modules 208, 210, 212 and sends a serial optical data stream over transport mechanism 104 to remote unit 106. In the other direction, SeRF communicator 202 receives an optical serial data stream from a remote unit 106 and provides SeRF streams to DART modules 208, 210, 212. In one embodiment, the SeRF stream between DART module 208 and SeRF communicator is a parallel stream. In another embodiment, SeRF stream is a serial data stream.
SeRF communicator 202 also allows multiple DART modules 208, 210, 212 to operate in parallel. SeRF communicator 202 actively multiplexes the signals from each DART module 208, 210, 212 such that they are sent simultaneously over a single transport mechanism 104. To accomplish this, SeRF communicator 202 re-clocks each DART module 208, 210, 212 to ensure synchronization.
In one embodiment, an optical multiplex module 214 is optically coupled to SeRF communicator 202. Optical multiplex module 214 performs multiplexing/de-multiplexing of an optical serial data stream to/from SeRF communicator 202 over transport mechanism 104. In this embodiment, optical multiplex module 214 performs wavelength division multiplexing.
In another embodiment, transport mechanism 104 is a wireless millimeter wave signal transceiver (e.g. E Band/70 GHz radio). In this embodiment, host unit 102 sends optical signals to the millimeter wave transceiver which converts the optical signals into millimeter waves and transmits the millimeter waves to a similar millimeter wave transceiver connected to remote unit 106. In yet another embodiment, transport mechanism 104 is a microwave radio transceiver. In still another embodiment, transport mechanism 104 is a T1 connection for transmission of IP data.
SeRF communicator 302 is designed and performs similar to SeRF communicator 202 of host unit 102. Likewise, DART modules 308, 309, 311 have the same features and design options as DART modules 208, 210, 212 of host unit 102. There is a slight difference from host unit 102, however, in the manner in which SeRF communicator 302 and DART modules 308, 309, 311 are connected. In this embodiment of remote unit 106, SeRF communicator 302 has a SeRF interface 304 which is used to link SeRF communicator to SeRF cables 305. SeRF cables 305 are used to allow DART modules 308, 309, 311 to be physically spaced from SeRF communicator 302 and from other DART modules. SeRF cables 305 connect to DART interface 306. DART modules 308 connected to DART interface 306 and communicate with SeRF communicator 302 through DART interface 306 over SeRF cables 305 and through SeRF interface 304. In another embodiment, SeRF interface 304, and SeRF cables 305 are eliminated and DART interface 306 is integrated into SeRF communicator 302.
DART modules 308 perform similar to DART module 208, except the ultimate destination/origination of the signals to/from DART modules 308 is antenna 108 and not base station 101 as in host unit 102. Optical multiplex module 314 also performs similarly to optical multiplex module 214 of host unit 102.
In the transmission direction, once a signal is converted to analog RF by DART module 308, the signal is sent through RF interface 322 (explained below) to power amplifier 310. Power amplifier 310 amplifies the RF signal received from DART module 308 for output through duplexer/linear amplifier 312 to antenna 108. Similar to DART modules 308, 309, 311, power amplifier 310 is designed for a certain frequency band and technology. Power amplifier 310 is, therefore, removable and is plugged into a power amplifier connector on remote unit 106 which is configured to receive power amplifier 310. Power amplifier connector is configured to couple power amplifier to duplexer/linear amplifier 312 and to DART module 308. Power amplifier 310 also has an alarm and control line that is connected to DART interface 306 for communication to SeRF communicator 302.
Once the signal is amplified by power amplifier 310, duplexer/linear amplifier 312 provides duplexing of the signal which is necessary to connect transmit and receive signals to a common antenna. Duplexer/linear amplifier 312 also provides low noise amplification of received signals and rms power detection of incident and reflected RF power in transmission signal. Similar to DART modules 308, 309, 311 and power amplifier 310, duplexer/linear amplifier 312 is frequency band and technology specific, and is removable. Duplexer/linear amplifier 312 plugs into a connector in remote unit 106 configured to receive duplexer/linear amplifier 312. Furthermore, the connector is configured to couple duplexer/linear amplifier 312 to power amplifier 310 and to antenna 108. Duplexer/linear amplifier 312 also has a control and alarm line that is connected to DART interface 320 for communication to SeRF communicator 302. In this embodiment, the frequency band and technology allow use of a single power amplifier 310 and duplexer/linear amplifier 318 by both DART module 308 and DART module 309. In this embodiment, a RF interface 322 is placed between power amplifier 310, duplexer/linear amplifier 312 and DART modules 308, 309. RF interface 322 provides RF splitting/combining of the RF transmit and receive signals necessary to allow connection of two DART modules 308, 309 to a single power amplifier 310 and duplexer/linear amplifier 312.
In one embodiment, DART links 508 and corresponding connectors on a DART interface carry 6 slots of digitized RF payload for reading and writing DART FPGA registers from SeRF FGPA 506. Each slot consists of 16 bits: 15 bits of digitized RF and 1 overhead bit used to transfer FPGA register data. The slots are framed in groups of 6 16-bit words, with each slot repeating at the sampling rate of 15.36M samples per second. A “superframe” of 32 frames encapsulates the data payload and provides synchronization. Thus, in this embodiment DART links 508 are 16-bit parallel data streams. In another embodiment, DART links 508 are serial. FPGA 506 has eight SERDES to serializer and deserializers each data stream. Thus, there is one SERDES for each DART link 508 and optical input/output 502.
In one direction, SeRF communicator 500 receives incoming SeRF streams over DART links 508 from DART modules, assembles data frames, and sends an outgoing optical serial data stream through optical input/outputs 502. In the other direction, SeRF communicator 500 receives an optical serial data stream from another SeRF communicator at optical input/outputs 502. SeRF communicator 500 then disassembles the frames of the serial data stream, and provides SeRF streams over DART links 508 to DART modules. SeRF communicator 500 also performs splitting and summing for digital simulcast, and provides a user interface for alarm, status, or configuration management. SeRF communicator 500 also provides bi-directional conversion to/from OBSAI protocol data received at optical input/outputs 502 from/to RF sampled data for DART modules. Additionally, SeRF communicator 500 has at least one RJ-45 connector 216 for receiving IP packets. In one embodiment, RJ-45 connector 216 supports Gigabit Ethernet.
Along with being configurable to communicate on different frequency band/sub-bands and with different technologies, host unit 102 and remote unit 106 are configurable to perform more or less of the wireless processing of the RF signal. Host unit 102 and remote unit 106 are configurable into three different functional configurations. The first configuration is illustrated in
Referring back to
Remote Unit 106, in this embodiment, has a baseband unit 602 which is connected to a slot of DART interface 306. In this configuration, baseband unit 602 is in fact a remote WiMax base station which replaces the functionality of base station 103 in the first configuration. SeRF communicator 302 converts the packetized optical data received into 25-75 Mbps data and sends the data over to baseband unit 602. Baseband unit 602 performs baseband processing to put the IP data onto a channel. Baseband unit 602 also creates the protocol and modulation type for the channel. Baseband unit 602 then converts the data to match the OBSAI protocol. This OBSAI data is sent back into an optical input/output 502 of SeRF communicator 302. SeRF communicator 302 uses software to convert the OBSAI protocol data into digital RF sampled data and sends the digital RF data to DART module 308 for transmission over antenna 108. In another embodiment, baseband unit 602 converts IP data to/from common public radio interface (CPRI). Alternatively, any digital baseband protocol, including standard and proprietary protocols, or any software defined radio interface could be used by baseband unit 602 and SeRF communicator 302.
Since host unit 102 and remote unit 106 have multiple input/outputs and can have multiple types of DART modules connected to each, host unit 102 and remote unlit 106 are configured to multiplex different functional configurations through different input/outputs simultaneously. Thus, in one embodiment, a first input/output of host unit 102 and remote unit 106 function as a range extender for a base station. A second input/output of host unit 102 and remote unit 106 function to transmit ‘midhaul’ data. At the same time a third input/output of host unit 102 and remote unit 106 functions to transmit fronthaul data and remote unit 106 performs baseband processing upon the data.
The modular design of modular wireless communications protocol allows many different combinations of transport mechanisms, frequency bands, communication technologies, and processing functionality to operate simultaneously on the same host unit and remote unit.
Placing a base station at a remote wireless communication stations such as described with the configuration of
Distributed base station system 800 has many advantages over traditional centralized base station systems. For example, remote stations 806, 806 which are equipped with a base station do not need to transmit signals back to central node 801 for base station processing. Instead, when an RF signal is received via antenna 826 at remote station 806, for example, remote station 806 processes the RF signal with remote unit 818, which is configured as a base station. Processing the RF signal forms a second RF signal which is then routed toward the destination of the RF signal. In this embodiment, the RF signal received at remote unit 806 is from a first mobile device which is in communication with a second mobile device which is the destination of the second RF signal. In another embodiment, the RF signal is received from a fixed internet user and the destination of the second RF signal is on the internet via IP gateway at central node 801. In this embodiment, the second mobile device is within transmission range of remote station 812. Thus, after processing by remote unit 818 at remote station 806, routers 828 at remote stations 806, 810, 812 route the second RF signal through remote station 810 to remote station 812. Thus, distributed base station system 800 simplifies and speeds up the processing of wireless signals.
In addition, there are many other advantages of a distributed base station system. For example, since each remote station 802, 804, 806, 808, 810, 812 includes a router, a best path is found to the from the origination remote station to the destination remote station. This decreases the latency of communication transmission, and also reduces unnecessary network traffic. In addition, in one embodiment where each remote station 802, 804, 806, 808, 810, 812 is equipped with a base station, each remote station 802, 804, 806, 808, 810, 812 obtains dedicated capacity to the system. Dedicated capacity refers the allocation of an unvarying amount of bandwidth to each remote station 802, 804, 806, 808, 810, 812. For example, in one embodiment, each remote station 802, 804, 806, 808, 810, 812 is allocated 25 Mbps of bandwidth. This is not possible in previous systems, because each remote station shares the capacity of a single central base station.
In one embodiment, remote stations 802, 804, 806, 808, 810, 812 are set up in a ring configuration as shown in
In yet another embodiment, a plurality of remote stations is set up in a daisy chain configuration. Alternatively, any combination of ring, tree, or daisy chain configurations could be used to network a plurality of remote stations.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
This application is related to the following commonly assigned applications filed on even date herewith, each of which is hereby incorporated herein by reference: U.S. patent application Ser. No. ______ (Attorney Docket No. 100.828US01), entitled “MODULAR WIRELESS COMMUNICATIONS PLATFORM” (the '828 application).