Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
  • H04B10/25—Arrangements specific to fibre transmission
  • H04B10/2575—Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
  • H04B10/25752—Optical arrangements for wireless networks

Definitions

• the present invention relates generally to wireless and wired communication systems, and in particular relates to radio-over-fiber (RoF) communication systems that employ wired and/or wireless technology.
• RoF radio-over-fiber
• Wireless communication is rapidly growing, with ever-increasing demands for highspeed mobile data communication.
• so-called “wireless fidelity” or “WiFi'' systems and wireless local area networks (WLANs) are being deployed in many different types of areas (coffee shops, airports, libraries, etc.).
• Wireless communication systems communicate with wireless devices called “clients,” which must reside within the wireless range or “cell coverage area” in order to communicate with the access point device.
• clients wireless devices
• One approach to deploying a wireless communication system involves the use of "cells,” which are radio-frequency (RF) coverage areas.
• RF radio-frequency
• Cells can have relatively large radii (e.g., 1000 m) or can have relatively small radii ("picocells") in the range from about a few meters up to about 20 meters. Because a picocell covers a small area, there are typically only a few users (clients) per picocell. Picocells also allow for selective wireless coverage in small regions that otherwise would have poor signal strength when covered by larger cells created by conventional base stations.
• the essential components that make up a RoF wireless cellular system are a headend controller ("head end"), one or more optical fiber cables, and one or more transponders.
• the optical fiber cables are connected at one end to the head-end controller.
• the transponders are optically coupled to the optical fiber cables along the length of the cables.
• the optical fiber cables have downlink and uplink optical fibers that carry RoF optical signals between the transponders and the head end.
• the transponders convert RoF optical signals to electrical signals and vice versa to create the corresponding one or more cells.
• the transponders include one or more antennas that transmit and receive RF free-space electromagnetic (EM) signals to and from the client devices within the corresponding cell. Combining a number of transponders creates an array of cells that cover an area called a "cellular coverage area.” A closely packed array of picocells forms a picocellular coverage area that provides high per-user data-throughput.
• EM free-space electromagnetic
• RoF wireless cellular and picocellular systems are robust, it is desirable to be able to provide state-of-the-art wireless and wired services to end-users — for instance, in present day technology terms, a wireless RoF infrastructure with IEEE 802.1 la/b/g/n along with Gigabit Wireline Ethernet, and a wired infrastructure with IEEE 802.3/u./z (where IEEE 802.3 is 10 Mbps, IEEE 802.3u is 100 Mbps and IEEE 802.3z is 1 Gbps).
• IEEE 802.3 10 Mbps
• IEEE 802.3u 100 Mbps
• IEEE 802.3z is 1 Gbps
• One aspect of the invention is a hybrid transponder for distributing wireless and wired signals from a hybrid head end to at least one client device.
• the hybrid transponder includes a hybrid converter adapted to convert wireless and wired optical signals from the head-end unit to corresponding wired and wireless electrical signals, and vice versa.
• the hybrid transponder also includes a frequency multiplexer/demultiplexer (MfD) electrically connected to the converter and adapted to multiplex and demultiplex the wired and wireless electrical signals.
• An antenna system is electrically connected to the frequency M/D via a signal-directing element configured to allow the antenna system to transmit and receive wireless signals from the at least one client device.
• a wireline cable port such as a standard Ethernet port, is electrically connected to the frequency M/D and is adapted to connect to a wireline cable (e.g., an Ethernet cable) to carry wired electrical signals to and from the at least one client device.
• a wireline cable e.g., an Ethernet cable
• Further embodiments of the present invention comprise wireline cables and cable ports that carry optical signals to and from the at least one client device.
• the hybrid transponder thus allows for both wired and wireless communication between one or more client devices and the hybrid head end.
• one client device wirelessly communicates via the hybrid transponder while another client device wire- communicates via the hybrid transponder.
• the same client device both wire-communicates and wirelessly communicates via the hybrid transponder.
• Another aspect of the invention is a method of providing wired and wireless connectivity to at least one client device from a hybrid head-end.
• the method includes deploying at least one hybrid transponder optically coupled to the head-end unit and adapted to convert optical wired and wireless signals from the hybrid head-end into corresponding electrical wired and wireless signals.
• the method also includes, in the at least one hybrid transponder, directing the electrical wireless signals to a multiple-input/multiple-output (MIMO) antenna system so as to wirelessly communicate with the at least one client device.
• MIMO multiple-input/multiple-output
• the method also included directing the electrical wired signals to a wireline cable port and to the client device via a wireline cable operably connecting the transponder to the at least one client device.
• Another aspect of the invention is a hybrid RoF communication system capable of providing wireless and wired connectivity to at least one client device.
• the system includes a hybrid head-end adapted to transmit and receive wired and wireless optical signals over an optical fiber cable.
• At least one hybrid transponder is optically coupled to the optical fiber cable and is configured to convert wired and wireless optical signals to corresponding wired and wireless electrical signals and vice versa.
• the hybrid transponder is configured to wirelessly transmit the wireless electrical signals to the at least one client device via an antenna system, and to wire-transmit the wired signals to the at least one client device via a wireline cable that operably connects the hybrid transponder to the at least one client device.
• the system provides a wired connection to one client device and a wireless connection to another client device that both reside within a cell of the system.
• FIG. 1 is a schematic diagram of a generalized embodiment of a hybrid RoF wireless/wired communication system ("hybrid RoF system") according to the present invention showing a hybrid head-end optically coupled to at least one hybrid transponder via an optical fiber cable, and showing a cell (picocell) formed by one of the hybrid transponders and two client devices within the picocell;
• hybrid RoF system a hybrid RoF wireless/wired communication system
• FIG. 2 is a detailed schematic diagram of an example embodiment of the hybrid head-end of the hybrid RoF system of FIG. 1;
• FIG. 3 and FIG. 4 are the same as FIG. 2, and respectively show the various downlink and uplink wireless and wired signals;
• FIG. 5 is a detailed schematic diagram of an example embodiment of the hybrid transponder of the system of FIG. 1, showing the various optical and electrical downlink wireless and wired signals transmitted to and received from the hybrid head-end, and also showing the wireline cable that provides wired communication to a client device;
• FIG. 6 is a schematic diagram illustrating a hybrid transponder incorporated with the optical fiber cable that has downlink and uplink optical fibers, and showing an Ethernet- type wireline cable port in the transponder;
• FIG. 7 is the schematic diagram of FIG. 5, but showing the various uplink optical and electrical wireless and wired signals
• FIG. 8 is a schematic diagram of the transponder end of the hybrid RoF system of the present invention, showing two transponders and three client devices, including a multiple-input/multiple-output (MIMO) client device in wireless communication with one or both hybrid transponders, and two other client devices in wired communication with the respective hybrid transponders;
• FIG. 9 is a detailed schematic diagram of an example embodiment of a MIMO hybrid transponder;
• FIG. 10 is a schematic diagram of the transponder end of the hybrid RoF system of the present invention that includes the MIMO hybrid transponder of FIG. 9, illustrating the hybrid transponder providing MIMO wireless communication with one of the client devices as well as wired communication with the other two client devices;
• FIG. 11 is a schematic diagram of the transponder end of the hybrid RoF system of the present invention illustrating an example embodiment wherein some of the upstream hybrid transponders are connected to a remote power/data extender unit;
• FIG. 12A is a schematic diagram of the transponder-end of the hybrid RoF system of the present invention, illustrating an example embodiment of a drop-down configuration wherein the hybrid transponder drops down from the ceiling into a room from an optical fiber cable installed above the ceiling;
• FIG. 12B is similar to FIG. 12A, and illustrates an example embodiment wherein one client device wirelessly communicates through the hybrid transponder while another client device wire-communicates through the hybrid transponder;
• FIG. 13 is a schematic diagram similar to FIG. 12, illustrating an example embodiment of a drop down configuration wherein the hybrid transponder remains above the ceiling and wherein the wireline cable can plug into the transponder's wireline cable port and also plug into the client device to establish wired and/or wireless communication between the head-end and the client device;
• FIG. 14A is similar to FIG. 13 but shows two client devices, and illustrates an example embodiment wherein the wireline cable is connected directly to the transponder rather than to a wireline cable port in the hybrid transponder;
• FIG. 14B is similar to FIG. 14A and illustrates an example embodiment wherein a first wireline cable connects the transponder to a wall outlet, and a second wireline cable connects the client device to the wall outlet; and
• FIG. 15 is a close-up view of the hybrid transponder and wireline cable, showing the wireline cable connected directly to the transponder at the amplifier/filter electronics unit
• the present invention is directed to a hybrid wireless/wired RoF communication system (hereinafter “hybrid RoF system” for short) that provides both wireless and wired network connectivity.
• the system is designed to provide a wireless connection with MIMO capability, such as IEEE 802.1 In, along with a high-data-rate wired connection, such as
• Wireline Ethernet or a fiber optic wireline cable An example of the hybrid RoF system of the present invention combines wireless and wired network infrastructures into a single hybrid RoF system (e.g., network) with multimode optical fibers carrying IEEE
• Ethernet signals (e.g., IEEE 802.3z @ 1 Gbps).
• a “wireless” signal is that associated with providing wireless communication
• a “wired” signal is that associated with providing baseband wired communication.
• Both “wireless” and “wired” signals can be electrical or optical, while the wireless signals can additionally be free-space electromagnetic signals of the type normally associated with “wireless” (i.e., non-wired) communications.
• LAN local area network
• WLAN wireless local area network
• FIG. 1 is a schematic diagram of a generalized embodiment of a hybrid RoF system 10 according to the present invention.
• Hybrid RoF system 10 includes a hybrid headend 20, at least one hybrid transponder unit (“transponder”) 30 configured to handle both wireless and wired signals, and an optical fiber cable 36 that optically couples the hybrid head-end to the at least one hybrid transponder.
• Hybrid head-end 20 is operably connected via a communication link 21 to an external source 22, such as an optical communication network or other network architecture backbone, the Internet, etc.
• an external source 22 such as an optical communication network or other network architecture backbone, the Internet, etc.
• optical fiber cable 36 includes one or more optical fibers, and in a particular example embodiment includes a downlink optical fiber 36D and an uplink optical fiber 36U.
• the present invention employs multi-mode optical fibers for the downlink and uplink optical fibers 36D and 36U.
• OM3 50 ⁇ m multi-mode optical fibers are used for downlink and uplink optical fibers 36D and 36U.
• downlink optical fiber 36D and/or uplink optical fiber 36U can comprise one or more individual optical fibers.
• individual optical fibers are shown for downlink and uplink optical fibers 36D and 36U by way of example and for ease of illustration.
• one of the optical fibers in 36D and/or in 36U is used for wireless signals, while another of the optical fibers in 36D and/or in 36U is used for wired signals.
• one of the optical fibers is used for one type of signal, while the other carries both signal types.
• downlink optical fibers in 36D are assumed to carry downlink optical wireless and wired signals from hybrid head-end 20 to hybrid transponder 30, while uplink optical fibers in 36U are assumed to carry uplink optical wireless and wired signals from the hybrid transponder to the hybrid head-end.
• Hybrid RoF system 10 forms at each hybrid transponder 30 a cell 40 substantially centered about the corresponding hybrid transponder.
• a cell 40 can be relatively large (e.g., 1000 m radius) or can be a picocell ranging anywhere from about a meter across to about twenty meters across.
• One or more cells 40 associated with the at least one hybrid transponder form a cellular coverage area 44.
• cell 40 is assumed to be a "picocell” and coverage area 44 is assumed to be a "picocell coverage area.”
• Hybrid transponder 30 is also adapted to provide wired communication via a wireline cable 50, such as an Ethernet wire-based cable or an optical fiber cable.
• Hybrid head-end 20 is adapted to perform or to facilitate any one of a number of RoF applications, such as radio-frequency identification (RFID), wireless local-area network (WLAN) communication (Ethernet signals), and/or cellular phone service.
• RFID radio-frequency identification
• WLAN wireless local-area network
• client device 45A includes two antennas 46A and 46B (e.g., a multi-antenna wireless card) adapted to receive and/or send free-space electromagnetic signals, while client device 45B is wire-connected to the transponder via wireline cable 50.
• Client device 45A is thus adapted for multiple-input/multiple-output (MIMO) communication with hybrid headend 20 via hybrid transponder 30.
• MIMO multiple-input/multiple-output
• hybrid RoF system 10 also includes a power supply 70 that generates an electrical power signal 71.
• power supply 70 is located at and is electrically coupled to head-end unit 20 via an electrical power line 72, and powers the power-consuming elements therein.
• an electrical power line 74 runs through hybrid head-end 20 and over to the at least one hybrid transponder 30 and powers not only the power-consuming elements in the hybrid head-end but also the power-consuming elements in at least one hybrid transponder, such as the OfE and E/O converters, as described below.
• electrical power line 74 includes two wires 74A and 74B that carry a single voltage and that are electrically coupled to a DC power converter 180 at transponder 30 (DC power converter 180 is discussed in greater detail below in connection with FIG. 5).
• a power supply 70 is provided locally to one or more of the hybrid transponders and provides electrical power directly to one or more of the local hybrid transponders via electrical power line(s) 72 rather than via optical fiber cable 36.
• electrical power line 74 (or a branch thereof) is included in wireline cable 50, thereby allowing hybrid RoF system 10 to provide Power-over- Ethernet via hybrid transponder 30.
• hybrid RoF system 10 employs a known telecommunications wavelength, such as 850 nm, 1300 nm, or 1550 nm. In another example embodiment, hybrid RoF system 10 employs other less common but suitable wavelengths such as 980 nm.
• FIG. 2 is a detailed schematic diagram of an example embodiment of hybrid headend 20 of FIG. 1.
• Hybrid head-end 20 includes a switch 100 having first and second input/output (I/O) sides 102 and 104.
• I/O side 102 is operably coupled to communication link 21 at an I/O port 103.
• communication link 21 is or otherwise includes a high-speed (e.g., 10 Gbps) Ethernet link.
• I/O side 104 includes a number of I/O ports 106.
• I/O ports 106 are lower-speed ports (e.g., ten 1 Gbps ports to handle ten Gbps Ethernet signals from different wires carried by communication link 21).
• Two I/O ports 106A and 106B are shown for the sake of illustration.
• I/O port 106A is electrically connected to a wireless-signal converter 120, while I/O port 106B is electrically connected to a wired-signal converter 130.
• wireless-signal converter 120 includes an amplifier/filter electronics unit ("A/F electronics") 122 that amplifies and filters the wireless signals, as explained below.
• Hybrid head end unit 20 also includes a frequency multiplexer/demultiplexer (MfD) 138 that in an example embodiment includes a frequency combiner 140 and a frequency splitter 150. Frequency M/D 138 is electrically connected to A/F electronics 122 and converter 130.
• A/F electronics amplifier/filter electronics unit
• MfD frequency multiplexer/demultiplexer
• Hybrid head end 20 also includes an electrical-to-optical (E/O) converter 160 electrically coupled to frequency combiner 140 of frequency M/D 138.
• E/O converter 160 is adapted to receive electrical signals from frequency combiner 140 and convert them to corresponding optical signals, as discussed in greater detail below.
• E/O converter 160 includes a laser suitable for delivering sufficient dynamic range for RoF applications, and optionally includes a laser driver/amplifier (not shown) electrically coupled to the laser.
• E/O converter 160 examples include laser diodes, distributed feedback (DFB) lasers, Fabry-Perot (FP) lasers, and vertical cavity surface emitting lasers (VCSELs), such as 850 nm commercially available VCSELs specified for 10 Gbps data transmission.
• E/O converter 160 is optically coupled to optical fiber cable 36 and downlink optical fiber(s) 36D carried therein.
• Hybrid head-end 20 also includes an optical-to-electrical (OfE) converter 162 electrically coupled to frequency splitter 150 of frequency M/D 138 and to optical fiber cable 36 and uplink optical fiber 36U carried therein.
• O/E converter 162 is adapted to receive optical signals and convert them to corresponding electrical signals.
• O/E converter 162 is or otherwise includes a photodetector, or a photodetector electrically coupled to a linear amplifier.
• E/O converter 160 and O/E converter 162 constitute a converter pair unit (“converter unit") 166 that converts electrical signals to optical signals and vice versa.
• communication link 21 carries signals S21 that include downlink and uplink digital signals SD21 and SU2 1 .
• Downlink digital signals SD 21 originate, for example, from an external source 22.
• Digital signals S 21 may include a variety of different signal types, such as data, voice, video, etc. Certain types of these signals, such as high-bandwidth video signals, have relatively high data rates and so are best transmitted to an end-user via a wired connection. On the other hand, certain ones of these signals have relatively low data rates, such as low-bandwidth voice signals, and so can be transmitted to an end-user via a wireless signal.
• Downlink signals SD 21 enter hybrid head-end 20 and encounter switch 100.
• Switch 100 is adapted to direct certain signals SD 2 1 most suitable for wireless transmission to wireless-signal converter 120 and to direct the other signals SD 21 suitable for wired transmission to wired-signal converter 130.
• Wireless-signal converter 120 receives the signals SD21 directed to it and converts them into downlink "wireless signals" SlD. Specifically, wireless-signal converter 120 phase modulates and/or amplitude modulates signals SD 21 onto an RF carrier signal, e.g., a 2.4 GHz or 5 GHz RF carrier signal, resulting in downlink wireless signals SlD.
• Wireless-signal converter 120 also amplifies and filters wireless signals SlD using A/F electronics 122.
• wireless-signal converter 120 is configured to adapt the transmission protocol for wireless communication (e.g., Ethernet wireless protocol 802.3 to wireless LAN protocol 802.1 1).
• wired-signal converter 130 receives the signals SD 21 directed to it and processes (e.g., filters) these signals to make them compatible for transmission over the hybrid system.
• downlink signals SD 21 are twisted-pair transmit Ethernet data signals
• wired-signal converter 130 interfaces signals SD 2 1 to make them compatible with the corresponding single-ended signal versions, while rejecting any power-over-Ethernet DC signals that may be present. This results in downlink wired signals S2D.
• wireless signals SlD have a higher frequency than wired signals S2D so that these two signal types can be frequency multiplexed and demultiplexed. Accordingly, wireless signals SlD and wired signals S2D proceed to frequency M/D 138 and frequency combiner 140 therein, which combines (multiplexes) the different-frequency signals SlD and S2D onto a common electrical line connected to E/O converter 160 in converter pair unit 166. E/O converter 160 then converts downlink electrical wireless signals SlD into a corresponding optical signals SlD' and converts downlink electrical wired signal S2D into a corresponding optical signal S2D'. In an example embodiment, E/O converter 160 is configured to modulate the wireless and wired optical signals onto a single optical carrier. Both wireless and wired optical signals SlD' and S2D' are carried by downlink optical fiber 36D and travel to hybrid transponder 30.
• hybrid head-end 20 also receives uplink optical wireless signals SlU' and uplink optical wired signals S2U' from transponder 30, as described below. These signals travel from hybrid transponder 30 over uplink optical fiber 36U and are received by O/E converter 162 in converter unit 166, which converts these signals into corresponding uplink electrical wireless and wired signals SlU and S2U.
• Frequency splitter 150 in frequency M/D 138 splits (i.e., demultiplexes) these signals to follow two different electrical paths wherein that wireless signal SlU travels to wireless- signal converter 120, while wired signal S2U travels to wired-signal converter 130.
• Wireless- signal converter 120 then operates on the wireless signal S2U it receives and extracts signals SU 21 from the RF carrier.
• wired-signal converter 130 processes wired signals S2U it receives to form signals SU 21 .
• wired signals S2U are converted by wired-signal converter 130 to twisted pair receive Ethernet data signals.
• Signals SU 21 from converters 120 and 130 then travel to switch 100, which directs these signals onto communication link 21.
• not all signals SU 21 are directed to communication link 21.
• repeater-cellular signals would not need to go through switch 100 but rather would be directed to a separate processing unit (not shown).
• FIG. 5 is a schematic diagram of an example embodiment of hybrid transponder 30 according to the present invention.
• FIG. 6 is a schematic diagram of hybrid transponder 30 shown incorporated with optical fiber cable 36.
• Hybrid transponder 30 of the present invention differs from the typical access point device associated with wireless communication systems in that the preferred embodiment of the transponder has just a few signal-conditioning elements and no digital information processing capability with respect to the transmitted/received wired and wireless signals.
• Hybrid transponder 30 includes a converter unit 166 wherein O/E converter 162 is optically coupled to downlink optical fiber 36D while E/O converter 160 is optically coupled to uplink optical fiber 36U. O/E converter 162 is electrically connected to a frequency M/D 138 and specifically frequency splitter 150 therein.
• E/O converter 160 is also electrically connected to frequency M/D 138 and specifically to frequency combiner 140 therein. Both frequency splitter 150 and frequency combiner 140 are electrically connected to A/F electronics 122. Frequency splitter 150 of frequency M/D 138 is also electrically connected to port Pl of a three-port signal-directing element 200 having additional ports P2 and P3. In an example embodiment, signal-directing element 200 is a circulator. [0055] An antenna system 210 is electrically connected to input/output port P2 of signal- directing element 200, while frequency combiner 140 of frequency M/D 138 is electrically connected to output port P3. In an example embodiment, antenna system 210 includes one or more patch antennas, such as disclosed in U.S. Patent Application Serial No.
• antenna system 210 is configured for MIMO communication with one or more client devices within picocell 40 (or more generally within the picocell coverage area 44 formed by one or more transponders). Antenna system 210 is discussed in greater detail below.
• A/F electronics 122 is electrically coupled to a wireline cable port 220, which in an example embodiment is or otherwise includes an Ethernet cable port. Cable port 220 is adapted to receive a cable connector 230 of a wireline cable 50, such as an Ethernet cable connector (plug) and Ethernet cable, that leads to a wired client 45 (see FIG. 1).
• cable port 220 is a gigabit Ethernet wireline port and wireline cable 50 is an Ethernet cable.
• electrical power line 74 is operably accessible at cable port 220 and wireline cable 50 includes a section of electrical power line 74 so as to provide Power-over-Ethernet via transponder 30 at the wireline cable port.
• aforementioned DC power converter 180 is electrically coupled to converter unit 166 and changes the voltage or levels of electrical power signal 71 to the power level(s) required by the power-consuming components in transponder 30.
• DC power converter 180 is either a DC/DC power converter, or an AC/DC power converter, depending on the type of power signal 71 carried by electrical power line 74.
• electrical power line 74 includes standard electrical-power-carrying electrical wire(s), e.g., 18-26 AWG (American Wire Gauge) used in standard telecommunications and other applications.
• electrical power line 72 (dashed line) runs from a local power supply 70 to hybrid transponder 30 (e.g., through a section of optical communication link 36 or straight to the hybrid transponder) rather than from or through head end 20 via optical fiber cable 36, such as electrical power line 74.
• electrical power line 72 or 74 includes more than two wires and carries multiple voltages.
• Hybrid transponder 30 is configured to provide both a wireless and wired connection to at least one client device 45.
• downlink optical wireless and wired signals SlD' and S2D' travel from head end unit 20 over downlink optical fiber 36D to O/E converter 162 in converter unit 166 of the hybrid transponder.
• O/E converter 162 converts optical signal SlD' and S2D' back into their electrical counterparts SlD and S2D.
• Signal-directing element 200 directs signal SlD to antenna system 210, causing it to transmit a corresponding downlink free-space electromagnetic wireless signal SlD".
• signal SlD is received by client device antenna 46A or 46B (say, antenna 46A), which antennas may both be part of a wireless card, or a cell phone antenna, for example.
• Antenna 46 A converts electromagnetic signal SlD" into its counterpart electrical signal SlD in the client device (signal SlD is not shown therein).
• Client device 45A then processes electrical signal SlD, e.g., stores the signal information in memory, displays the information as an e-mail or text message, etc. Meanwhile, wired signals S2D travel over wireline cable 50 to client device 45B (see FIG. 1) and are processed therein.
• client device 45A (FIG. 1) generates an uplink electrical wireless signal SlU (not shown in the client device), which is converted into a corresponding free-space electromagnetic signal SlU" by antenna 46A. Because client device 45A is located within picocell 40, electromagnetic signal SlU" is detected by transponder antenna system 210, which converts this signal back into electrical signal SlU. Meanwhile, client device 45B also transmits wired uplink signals S2U to hybrid transponder 30 via wireline cable 50.
• Signal SlU is then directed by signal-directing element 200 out of port P3 to frequency M/D 138 and frequency combiner 140 therein.
• signal S2U is amplified and filtered by A/F electronics 122 and provided to frequency M/D 138 and to frequency combiner 140 therein.
• Frequency combiner 140 combines (multiplexes) signals SlU and S2U and provides them to E/O converter 160.
• E/O converter 160 converts these electrical signals into corresponding optical signals SlU' and S2U'. These optical signals then travel over uplink optical fiber 36U to hybrid head-end unit 20, where they are received and processed in the manner described above.
• hybrid RoF system 10 is configured to support MIMO operation.
• FIG. 8 is a schematic diagram of the transponder end of hybrid RoF system 10 illustrating an example embodiment of the system, where client device 45A includes two antennas 46A and 46B. This configuration allows for 2x2 MIMO wireless communication with client 45A while also providing wired communication with clients 45B and 45C with downlink and uplink electrical wired signals S2D and S2U.
• Hybrid RoF system 10 can be set to one of a number of various MIMO configurations, such as 1x2, 2x1, 2x3, 3x2, 3x3 3x4, 4x3, 4x4, etc., depending on particular antenna system 210 configurations and the number of antennas available on the particular client device(s).
• An example embodiment of a client device having multiple antennas and MIMO capability is a laptop computer with a multiple-antenna MIMO wireless card.
• downlink electrical wireless signals SlD and corresponding uplink signals SlU are in the form of bit streams.
• each transponder antenna system and each client antenna system serve as both transmitting and receiving antennas that transmit and receive bit-stream segments.
• each transponder antenna system 210 receives the various portions of the entire uplink electromagnetic free-space wireless signal SlU" (i.e., the bit stream segments) transmitted by each transmitter antenna 46A and 46BA so that a jumbled bit stream is received at each receiver antenna.
• each antenna 46A and 46B receives the various portions of the corresponding downlink signal SlD" (i.e., the bit stream segment) transmitted from each transmitter antenna system 210.
• hybrid head-end station 20 provides the downlink signal SlD simultaneously to the different hybrid transponders 30, though the downlink signal bit stream is divided up among the hybrid transponders according to the MIMO signal processing.
• the client device simultaneously transmits the uplink signal bit streams to the different antenna systems 210, though the uplink signal bit stream is divided up among the client device antennas according to the MIMO signal processing.
• hybrid head-end 20 is adapted to perform MIMO signal processing of the electrical downlink and uplink signal bit streams by carrying out mathematical algorithms that properly divide a given downlink bit stream signal into the separate downlink bit stream signals for each transponder antenna system 210 to achieve MIMO gain.
• hybrid head-end 20 is adapted to properly recombine the otherwise jumbled uplink signal bit streams received by each antenna system 210.
• Client device 45A also preferably has MIMO signal processing capabilities so that it can communicate with antenna systems 210 using MIMO techniques.
• wireless-signal converter 120 includes a MIMO chip 124 adapted to perform the aforementioned MIMO signal processing.
• MIMO chip suitable for use in head-end unit 20 to provide MIMO capability is a 802.1 In-compatible MIMO chip, such as is available from Broadcom, Inc., Irvine, CA, as part number BCM2055.
• FIG. 9 is a schematic diagram of an example embodiment of hybrid transponder 30 according to the present invention that is configured to provide 2xN MIMO capability.
• Transponder 30 includes two antenna systems 210.
• FIG. 10 is a schematic diagram of the hybrid transponder 30 of FIG. 9 as used to perform MIMO wireless communication with client device 45A as well as wired communication with neighboring client devices 45B and 45C.
• the MIMO wireless communication includes downlink free-space electromagnetic signals SlD" and their counterpart uplink free-space electromagnetic signals SlU". These signals are processed in the manner described above.
• optical fiber cable 36 includes two sets of downlink and uplink optical fibers 36D and 36U to handle two different wireless signals (e.g., wireless signals having different frequencies).
• hybrid transponder 30 of FIG. 9 and hybrid head-end 20 are configured to frequency multiplex the different-frequency downlink and uplink wireless signals onto the same downlink and uplink optical fibers.
• FIG. 11 is a schematic diagram of the transponder end of RoF network system 10 illustrating an example embodiment wherein electrical power is provided locally rather than entirely from head end 20 via electrical power line 74 carried by optical fiber cable 36 (FIG. 1), and wherein wired signals (e.g, Ethernet wireline signals) are converted to wireless signals upstream of hybrid head end 20.
• wired signals e.g, Ethernet wireline signals
• the example embodiment of hybrid RoF system 10 of FIG. 11 includes a power/data extender unit 260 that includes a power supply 70 that provides electrical power via electrical power signal carried by a (multi-wire) local electrical power line 72.
• Local electrical power line 72 carries electrical power to hybrid transponders 30 on an upper cable span 302, which is farthest from hybrid head-end 20, while the hybrid transponders on a lower cable span 301 closer to hybrid head-end 20 are powered by power line 74 carried by link 36.
• power supply 70 is powered by (or is itself) an electrical outlet 308 via an electrical cord 310 and plug 312.
• power/data extender unit 260 includes a wired-to-wireless converter unit (e.g., a WLAN router) 322 adapted to convert downlink wired signals S2D (e.g., Ethernet-coded wireline signals) carried on lower cable span 301 into multiple downlink wireless signals SlD in upper cable span 302.
• power/data extender unit 260 is adapted to convert uplink wireless signals SlU carried on upper cable span 302 to uplink wired signals S2U that travel back to hybrid head-end 20 via lower cable span 301.
• An advantage of the hybrid RoF system 10 of the present invention is that it can be installed in the same manner as a wireless picocellular system is installed, with transponders hanging down to desktop height at a corner of a room for easy access to the wireline Ethernet connection.
• a user has broadband wireless connectivity anywhere in the office, along with a wired "worry free" fast wireline Ethernet connectivity- all from a single hybrid transponder.
• FIG. 12A is a schematic diagram of the transponder end of hybrid RoF system 10 wherein hybrid transponder 30 drops down via optical fiber cable 36 into a room 400 (e.g., an office, library space, etc.) from above a ceiling 402.
• a client device 45 is shown resting upon a table 406 in room 400.
• This drop-down configuration allows for wireless communication with client device 45 as well as for convenient wired communication via wireline cable 50.
• the MIMO antenna system 210 shown in FIG. 12A includes patch antennas for the sake of illustration.
• the drop-down configuration of FIG. 12A allows for a system user to easily plug wireline cable 50 into client device 45 as well as into port 220 of transponder 30 to obtain a wired connection.
• FIG. 12B is similar to FIG. 12A, and illustrates an example embodiment wherein one client device 45 wirelessly communicates through hybrid transponder 30 while another client device 45 wire-communicates through the hybrid transponder via wireline cable 50.
• FIG. 13 is a schematic diagram similar to FIG. 12, illustrating an example embodiment wherein hybrid transponder 30 remains above ceiling 402 and wireline cable 50 plugs into wireline cable port 220. Wireline cable 50 drops down through ceiling 402 (e.g., through a hole 410 formed therein) so that it can be plugged into client device 45.
• This configuration hides transponder 30 and is convenient so long as access to the transponder is available, or if wireline cable 50 is plugged into the hybrid transponder and dropped down from the ceiling so that the user need not have to plug wireline cable 50 into the hybrid transponder.
• FIG. 14A is a schematic diagram similar to FIG. 13, except that wireline cable port 220 is not provided. Rather, wireline cable 50 is connected directly to hybrid transponder 30, e.g., at amplifier/filter unit 122, as illustrated in the close-up partial view of the hybrid transponder shown in FIG. 15.
• FIG. 14A also illustrates an example embodiment wherein one client device 45 wirelessly communicates through hybrid transponder 30 while another client device 45 wire-communicates through the hybrid transponder.
• FIG. 14B is a schematic diagram similar to FIG.
• wall outlet 420 includes two or more sockets (e.g., RJ- type sockets) 422 so that a number of client devices can be wire-connected to transponder 30.
• Hybrid transponder 30 and the hybrid RoF system 10 that includes at least one of the hybrid transponders offer a number of advantages over transponders and RoF communication systems that separately provide wireless and wired connectivity.
• hybrid RoF system 10 eliminates the need for separate wired and wireless network infrastructure and instead provides wireless and wired connectivity in a single integrated architecture.
• any new network deployment can be carried out with one fiber cable network.
• the hybrid nature of the system has lower installation costs relative to having separate wired and wireless infrastructure deployments.
• the hybrid RoF system of the present invention facilitates the migration from wired to wireless connections on a user-by-user basis without having to overlay new cabling.
• Hybrid RoF system 10 also provides improved connection reliability achieved through the guaranteed wireline connection provided at desired locations.
• Hybrid RoF system 10 also extends the maximum data reach of a traditional cellular network through the use of the additional wireline data being converted to a wireless data stream for the next section of traditional RoF cable.
• Hybrid RoF system 10 also extends the maximum power reach of the traditional cellular network through local powering of the drop down Wireline Ethernet cable.
• Both the wired and wireless features of the present invention can be easily upgraded as technology progresses.
• MIMO capability can be updated as needed, such as from 1x2 MIMO to 2x3 MIMO or to 4x6 MIMO, etc., using cell bonding, as described in U.S. Patent Application Serial No. 1 1/357,640 filed February 17, 2006, which is incorporated by reference herein.
• Hybrid RoF system 10 is also relatively easy to deploy into an existing building infrastructure. For example, it can be deployed in the same manner as optical fiber cables are deployed atop ceiling tiles rather than, for example, within building walls.
• Hybrid RoF system 10 can be deployed in the same manner as optical fiber cables are deployed atop ceiling tiles rather than, for example, within building walls.

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