Patent Application
20130028600
Various types of signal transmission media are typically selected on the basis of a frequency bandwidth associated with a signal. For example, human voice generally occupies a frequency bandwidth on the low end of the frequency spectrum, and consequently, voice signals can be propagated through wires such as a twisted pair of wires as used in wire-line telephony. On the other hand, television signals occupy a frequency bandwidth that is significantly higher than that of voice signals. As a result, television signals are propagated through a cable medium rather than twisted pair wire media, because the cable medium can transport the television signal over a greater distance with less distortion and attenuation in comparison to twisted pair wire media. However, cable media cannot optimally support the transportation of higher frequency signals such as microwave frequency radio signals that are transmitted over the air. As can be appreciated, each type of transmission medium has an associated advantage as well as associated handicaps such as performance trade-offs and cost trade-offs.
Attention is drawn to
Splitter 115 routes the low frequency telephone voice signals to a telephone 120 and routes the computer data (carried in a digital subscriber line (DSL) frequency bandwidth that is located above human voice bandwidth) to a computer 130. Unfortunately, twisted pair wire-line medium 110 places delivery distance constraints upon the DSL frequency bandwidth, therefore limiting delivery of computer data to a certain radius around CO 105. As can be understood, it would be preferable to expand this radius in order to provide computer data service (e.g. Internet access) to more customers and earn more revenue based on such delivery.
Turning now to the other transmission medium shown in
The free-space transmission medium places certain limitations such as signal loss and/or signal quality degradation as a result of obstacles (rain clouds, trees, buildings etc.) in the propagation path. Naturally, it would be preferable to transport the television signals while minimizing or eliminating some of these handicaps.
The handicaps explained above have been mitigated to some extent by exploiting the wide bandwidth characteristics of optical fiber for transporting a variety of signals that are combined together using various schemes (modulation schemes, multiplexing schemes etc). This alternative approach does provide certain advantages. However, these advantages are obtained at a price—specifically a high price associated with hardware, software and/or operating costs.
To elaborate upon this aspect in some detail, as is known, the various signals that are to be combined together in order to take advantage of the wide bandwidth characteristics of optical fiber may be provided in a variety of different formats. For example, a first signal that is carried on the twisted pair wire-line medium 110 of
It is therefore desirable in view of the remarks above, that transmission media cost, equipment cost, and equipment complexity be minimized in communication systems catering to wideband, multi-format signals.
According to a first aspect of the disclosure, a configurable transceiver includes a duplex transceiver circuit, a simplex transceiver circuit, and two switches. The duplex transceiver circuit includes a first antenna operative over a first radio frequency band; a first transmitter configured to operate upon a first transmit signal having a first communication format; and a first receiver configured to operate upon a first receive signal having the first communication format. A first switch is operable to selectively couple the first antenna to the duplex circuit when the communication transceiver is configured to enable a duplex mode of operation, and to selectively decouple the first antenna from the duplex circuit when the communication transceiver is configured for disabling the duplex mode of operation. The simplex transceiver circuit includes a second antenna operative over a second radio frequency band; a second transmitter configured to operate upon a second transmit signal having a second communication format; and a second receiver configured to operate upon a second receive signal having the second communication format. A second switch is operable to selectively couple the second antenna to either the second transmitter, when the communication transceiver is configured to enable a transmit mode of operation in the second communication format, or the second receiver when the communication transceiver is selectively configured to enable a receive mode of operation in the second communication format.
According to a second aspect of the disclosure, a method of operating a configurable transceiver, includes enabling a duplex mode of operation by activating a first switch to couple a first antenna to a duplex transceiver circuit, wherein the duplex transceiver circuit includes a first transmitter configured to operate upon a first transmit signal having a first communication format; and a first receiver configured to operate upon a first receive signal having the first communication format. The method further includes enabling a first simplex mode of operation by activating a second switch to couple a second antenna into one of a) a second transmitter that is configured to operate upon a second transmit signal having a second communication format or b) a second receiver that is configured to operate upon a second receive signal having the second communication format.
According to a third aspect of the disclosure, a configurable transceiver includes a duplex transceiver circuit, a simplex transceiver circuit, and two switches. The duplex transceiver circuit includes a first antenna operative over a first radio frequency band; a first transmitter configured to operate upon a first transmit signal occupying at least a portion of the first radio frequency band; and a first receiver configured to operate upon a first receive signal occupying the at least a portion of the first radio frequency band. A first switch is operable to selectively couple the first antenna to the duplex transceiver circuit when the communication transceiver is configured to enable a duplex mode of operation, and to selectively decouple the first antenna from the duplex transceiver circuit when the communication transceiver is configured for disabling the duplex mode of operation. The first simplex transceiver circuit includes a second antenna operative over a second radio frequency band; a second transmitter configured to operate upon a second transmit signal occupying at least a portion of the second radio frequency band; and a second receiver configured to operate upon a second receive signal occupying the at least a portion of the second radio frequency band. A second switch is operable to selectively couple the second antenna to either the second transmitter or the second receiver.
Further aspects of the disclosure are shown in the specification, drawings and claims below.
Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Instead, emphasis is placed upon clearly illustrating the principles of the invention. Moreover, in the drawings, like reference numerals designate corresponding parts, or descriptively similar parts, throughout the several views and embodiments.
Throughout this description, embodiments and variations are described for the purpose of illustrating uses and implementations of the inventive concept. The illustrative description should be understood as presenting examples of the inventive concept, rather than as limiting the scope of the concept as disclosed herein. It will also be understood that the word “example” as used herein (in whatever context) is intended to be non-exclusionary and non-limiting in nature. Specifically, the word “exemplary” indicates one among several examples, and it must be understood that no special emphasis is intended or suggested for that particular example. A person of ordinary skill in the art will understand the principles described herein and recognize that these principles can be applied to a wide variety of applications using a wide variety of configurations and hardware elements.
The various embodiments described herein generally pertain to systems and methods related to a communication system that caters to multi-band, multi-format signals by using a configurable transceiver. The multi-band signals include many different signals, ranging from baseband frequencies to microwave frequencies and having a variety of formats. At this point, it may be pertinent to point out that terms such as “baseband,” “radio frequency (RF)” and “microwave” that are used herein are not necessarily defined by a rigid range of frequencies, but are instead flexibly definable in the context of various applications.
For example, when the various signals shown in
On the other hand, in another exemplary embodiment in accordance with the invention, analog or digital signals occupying a frequency spectrum below the very high frequency (VHF) band may constitute “baseband” frequencies, while signals in the VHF and ultra-high frequency (UHF) frequencies may constitute “RF” signals, and signals in the frequency spectrum above UHF frequencies (to whatever upper limit) may constitute the “microwave” frequencies, as referred to herein.
Furthermore, it should be notes that in accordance with a few embodiments described below, there are some references made to some standards such as, for example, 3G, 4G, WiMax, and LTE standards. As can be appreciated, communications-related standards evolve over time and are often modified. Nonetheless, it should be understood that changes to the various standards do not adversely affect the operability and the application of the various embodiments described herein. Furthermore, when such terms are used in the claims, the claims remain valid for all versions and evolutionary modifications of the various standards.
Attention is now drawn to
Central Office (CO) 105 houses a configurable transceiver 305 that accepts one or more signals occupying multiple frequency bands and one or more similar or dissimilar communication formats. An output port of configurable transceiver 305 is coupled to an optical fiber 310, which may be a single-mode or a multi-mode optical fiber in accordance with a desired operational bandwidth. At the other end of optical fiber 310, the one or more signals are received in configurable transceiver 325, which may be similar to configurable transceiver 305 in some embodiments, and different in other embodiments. Configurable transceiver 325 located in a remote housing 320, receives the one or more signals transmitted via the optical fiber 310 and routes the received signals to output ports that are coupled to suitable signal transmission elements (microwave dish antenna, RF antenna, coaxial cable etc).
To elaborate upon this configuration, a baseband signal that is provided to configurable transceiver 305 may be combined with a radio frequency (RF) signal and/or a microwave signal that may also be provided to configurable transceiver 305, before the combined signal is injected into optical fiber 310. The manner in which this combining is carried out (which is described below in more detail) leads to an improvement in signal reach and system performance, and may also contribute to reduced system costs.
As explained above with reference to
Configurable transceiver 325 recovers the base-band frequency portion of the combined signal and transmits this baseband portion to residence 125, via transmission medium 340. Transmission medium 340 may be twisted pair wiring having the same length as the twisted pair of wires shown in
The microwave signal portion provided to configurable transceiver 305 (and carried over optical fiber 310 along with the baseband and the RF frequency signals) is processed in configurable transceiver 325 before transmission out of microwave dish antenna 225 to receiver dish antennae 230 and 235. As can be seen the adverse effect of obstruction 210 between transmitter dish antenna 225 and receiver dish antenna 235 has now been eliminated.
Also, the distance handicap between transmitter dish antenna 225 and receiver dish antenna 230 has also been eliminated.
For example, in certain embodiments, optical fiber 405 is a multimode optical fiber, optical transmitter device 410 is a light emitting diode (LED), and optical receiver device 415 is a relatively low-speed device selected in accordance with the low-speed, small-bandwidth nature of the signals propagated through optical fiber 405.
However, in certain other embodiments, optical fiber 405 is a single-mode optical fiber, optical transmitter device 410 is a laser device and optical receiver device 415 is a high-speed, wide bandwidth device selected in accordance with a high-speed, wide-bandwidth nature of the signals propagated through optical fiber 405. It will be understood that optical fiber 405 is not limited to the coupling configuration (central office 105 to remote housing 320) as shown in
Optical receiver device 415 is coupled to receive side circuitry contained inside each of duplex transceiver circuit 420, simplex transceiver circuit 425, and simplex transceiver circuit 430. Additional details pertaining to these circuits will be provided below using
Duplex transceiver circuit 420 is coupled to a switch 440, which in turn is connected to a first antenna 455. Antenna 455 may be a microwave antenna (as shown by antenna 225 in
Switch 440 may be implemented in various ways. For example, in a first implementation, switch 440 is an electro-mechanical device such as a single pole single throw (SPST) relay. In another implementation, switch 440 is a solid state device such as a FET-based switching device.
Simplex transceiver circuit 425 is coupled to a switch 445, which in turn is connected to a second antenna 460. Antenna 455 may be an RF antenna (as shown by antenna 335 in
Switch 445 may be implemented in various ways. For example, in a first implementation, switch 445 is an electro-mechanical device such as a single pole double throw (SPDT) relay. In another implementation, switch 445 is a solid state device such as a FET-based switching device.
Simplex transceiver circuit 430 is coupled to a switch 450, which in turn is connected to a third antenna 465. Switch 450 is operative under control of switching control circuit 435, to couple antenna 465 to one of two alternative connections into simplex transceiver circuit 430. Specifically, switch 450 is operative to couple antenna 465 to either link 411 or to link 412.
Switch 450 may be implemented in various ways. For example, in a first implementation, switch 450 is an electro-mechanical device such as a single pole double throw (SPDT) relay. In another implementation, switch 450 is a solid state device such as a FET-based switching device.
It will be understood that in other embodiments, in place of one duplex transceiver circuit and two simplex transceiver circuits, other combinations of such circuits may be used. For example, in one alternative embodiment, configurable transceiver 400 includes only one simplex transceiver circuit and one duplex transceiver circuit, while in another alternative embodiment, configurable transceiver 400 includes two duplex transceiver circuits and two simplex transceiver circuits. Furthermore, of these two duplex transceiver circuits and two simplex transceiver circuits, one duplex transceiver circuit and one simplex transceiver circuit may be used for redundancy purposes.
It will also be understood that the signals propagated through the various duplex and simplex transceiver circuits may occupy a wide variety of bandwidths and a wide variety of communication formats. Towards this end, antenna 455 is pictorially depicted by a larger symbol than antenna 460, which in turn is pictorially depicted by a larger symbol than antenna 465, for purposes of convenience to indicate that the range of frequencies and formats in the three antennae are diverse in nature.
In one exemplary embodiment, antenna 455 is selected to be effective for receiving/transmitting signals in a frequency division duplex (FDD) mode of operation. Referring back to
In contrast, antenna 460 is selected to be effective for receiving/transmitting signals in a time division duplex (TDD) mode of operation wherein different time slots are used to propagate different signals in each of the upstream and downstream direction. It should also be understood that in certain embodiments, configurable transceiver 400 may incorporate elements, such as wide band amplifiers and passive devices that are format agnostic, thereby interchangeably accommodating signals in any of multiple formats such as FDD and/or TDD.
In one specific exemplary embodiment, antenna 455 is selected to be effective for receiving/transmitting signals that confirm to cellular industry standards that are known to persons of ordinary skill in the art by 4G, LTE and WiMax terminology. In this specific exemplary embodiment, antenna 460 is selected to be effective for receiving/transmitting signals that confirm to cellular industry standards that are known to persons of ordinary skill in the art by 3G, WCDMA and DECT terminology. Furthermore, in this specific exemplary embodiment, antenna 465 is selected to be effective for receiving/transmitting signals that confirm to standards that are known to persons of ordinary skill in the art by 60 GHz, WiGig terminology.
As indicated above, though each of these standards are evolving and changing over time, the operative features of configurable transceiver 400 remain equally pertinent and valid for each of these variants. For example, the 4G, 3G and 60 GHz standards not only incorporate different data transfer rates as well as different signaling formats but also change over time. The corresponding antenna and transceiver circuits may be modified suitably to accommodate these changes.
Switching control circuit 435 provides control signals that are used to operate the various switches, via links 413, 414 and 416. In certain embodiments, these control signals maybe provided infrequently on as as-needed basis. For example, the control signals may be provided during an initial set-up procedure and not changed subsequently. One example of such a process is described below using
In other embodiments, the control signals provided by switching control circuit 435 on one or both links 413 and 414, for example, may be referred to as real-time signals. For example, the control signal on line 414 may vary in accordance with a TDD format, thereby coupling antenna 460 to link 408 for a first period of time and then to link 409 for a different period of time. In other words, the control signal provided on link 414 places simplex transceiver circuit 425 in a transmit mode of operation whereby a signal is transmitted out of antenna 460 for a certain period of time, and then places simplex transceiver circuit 425 in a receive mode of operation whereby a signal is received from antenna 460 for another period of time, the two periods of time defined by a TDD operating mode.
Attention is now drawn to
Duplex transceiver circuit 420 includes duplexer 422 which accommodates bi-directional signal propagation by allowing antenna 455 to concurrently transmit a signal of a first frequency and to receive a signal of a different frequency (FDD mode of operation). The signal received from antenna 455 is coupled from duplexer 422 into a buffer/driver 421 which drives this signal (via another buffer 470) into optical transmitter device 410, which in turn drives this signal as a radio-over-fiber (RoF) signal into optical fiber 405.
In the opposite direction, an RoF signal received by optical receiver device 415 from optical fiber 405 is coupled into duplexer 422 via an impedance matching circuit 423 and a buffer/driver 424. Impedance matching circuit 423 is selected in accordance with the nature of optical receiver device 415 and the nature (bandwidth, wavelength, frequency etc) of the RoF signal received from optical fiber 405 and detected in optical receiver device 415.
Duplexer 422 may be implemented in a variety of ways based on the nature of the signals propagated through duplexer 422. For relatively lower frequency/bandwidth signals, duplexer 422 may be a coupling transformer and/or a pair of op-amps suitably interconnected to each other. On the other hand, for higher frequency/bandwidth signals, duplexer 422 may be a microwave device such as a circulator and/or a coupler.
Switch 605 is a 3-position switch that provides an alternative exemplary implementation whereby antenna 465 may be connected to one of links 411 or 412, or disconnected from both links. When disconnected from both links 411 and 412, simplex transceiver circuit 430 may be defined as being in a disabled/inactivated state. Switch 610 is also a part of an alternative exemplary implementation that permits power to be disconnected from simplex transceiver circuit 430, say for example, when simplex transceiver circuit 430 is in the disabled/inactivated state.
Similar switches and other switching arrangements may be made on simplex transceiver circuit 425, as well as on duplex transceiver circuit 420, when it is desired to place configurable transceiver 400 in a power conservation condition.
In the exemplary configured state shown in
With switch 440 in the closed position, duplex transceiver circuit 420 in conjunction with antenna 455 operates on various types of RoF signals that may be propagated through optical fiber 405. Such signals include FDD signals, frequency division multiple access (FDMA), and code division multiple access (CDMA) signals, that are typically bi-directional in nature.
In contrast, with switch 445 coupled to link 408, simplex transceiver circuit 425 in conjunction with antenna 460 operates on various types of RoF signals that are transmitted into optical fiber 405, but not signals that are transmitted from optical fiber 405 into simplex transceiver circuit 425.
In an alternative configuration, switch 445 is coupled to link 409, thereby allowing simplex transceiver circuit 425 to provide to antenna 460, various types of RoF signals that are received by simplex transceiver circuit 425 from optical fiber 405. In this alternative configuration, no signals are provided by simplex transceiver circuit 425 to optical fiber 405.
Simplex transceiver circuit 430 may not only be configured in the manner described above with reference to simplex transceiver circuit 425, but as a result of using a 3-position switch 605, may be also entirely disconnected from antenna 465.
It will be understood that though the description above (using
Furthermore, the description below makes reference to various elements described above using
In block 705, a determination is made if duplex transceiver circuit 420 is to be enabled. If enablement is desired, in block 710, switch 440 (
In block 715, a determination is made if simplex circuit 425 is to be enabled. If simplex circuit 425 is not to be enabled, flow chart operation is terminated. On the other hand, if enablement is desired, in block 720, another determination is made whether a transmit mode of operation is to be enabled.
If enablement is desired, in block 725, switch 445 (
If enablement of transmit mode is not desired in block 720, action flows to block 730, followed by termination of flowchart operations. In block 730, switch 445 (
It will be understood that though the flow chart indicates a termination of operations after blocks 730 and 725 are implemented, in various alternative embodiments, additional blocks may be implemented prior to termination. For example, such additional blocks may be directed at configuring a third simplex transceiver circuit 430 and/or a second duplex transceiver circuit, when such circuits are incorporated into configurable transceiver 400.
The person skilled in the art will appreciate that the description herein is directed at explaining merely a few aspects of a configurable multi-format, multi-band transceiver in accordance with the invention.
While the systems and methods have been described by means of specific embodiments and applications thereof, it is understood that numerous modifications and variations could be made thereto by those skilled in the art without departing from the spirit and scope of the disclosure.
Accordingly, it is to be understood that the inventive concept is not to be limited by the specific illustrated embodiments, but only by the scope of the appended claims. The description may provide examples of similar features as are recited in the claims, but it should not be assumed that such similar features are identical to those in the claims unless such identity is essential to comprehend the scope of the claim. In some instances the intended distinction between claim features and description features is underscored by using slightly different terminology.
The present application claims priority to U.S. Provisional Patent Application No. 61/512,903, filed Jul. 28, 2011, and entitled “HYBRID RoF STRUCTURE FOR MULTI-BAND OPERATION USING ONE OR MORE SWITHCES AND DUPLEXERS,” which is hereby incorporated in its entirety as if fully set forth herein.
| Number | Date | Country | |
|---|---|---|---|
| 61512903 | Jul 2011 | US |
