WO2008080077A1

WO2008080077A1 - Method and apparatus to facilitate transmitting data using multiple optical data streams

Info

Publication number: WO2008080077A1
Application number: PCT/US2007/088589
Authority: WO
Inventors: Ovidiu Gabriel Vlad; Lawrence Carl Spaete, Jr.; Alfred Robert Zantow
Original assignee: Embedded Control Systems
Priority date: 2006-12-21
Filing date: 2007-12-21
Publication date: 2008-07-03
Also published as: WO2008080071A1

Abstract

One provides a source of data (101) along with a plurality of differing optical data streams (104). These differing optical data streams are then used, in parallel, to transmit the data over a shared optical transport media. By one approach, these differing optical data streams differ from one another with respect to their carrier frequencies. By this approach, a single optical transport media, such as a fiber optic cable, can now carry considerably more data than might otherwise be associated with a given upper switching speed for the enabling light emitters being employed.

Description

METHOD AND APPARATUS TO FACILITATE TRANSMITTING DATA USING MULTIPLE OPTICAL DATA STREAMS

Related Applications)

[0001] This application claims the benefit of U.S. Provisional application number

60/871,349, filed December 21, 2006, which is incorporated by reference in its entirety herein.

[0002] This application is related to co-pending and co-owned U.S. patent application number XXX (having attorney's docket number 8462/91290), entitled METHOD AND APPARATUS TO FACILITATE MULTIPLEXING LIGHT IN A SHARED OPTICAL CONDUIT and filed on even date herewith, which is incorporated by reference in its entirety herein.

Technical Field

[0003] This invention relates generally to the transmission of data using optical carriers.

Background

[0004] The use of optical carriers to transmit data comprises a known area of endeavor. In a typical scenario using fiber optic media, a light emitting element such as a Light Emitting Diode (LED) or laser is rapidly switched on and off for each bit of data to form a corresponding bitstream. That bitstream then typically incorporates and includes the payload data. A corresponding receiver detects these pulses of light and converts these received pulses to electrical counterparts to thereby facilitate recovering the optically encoded payload data bits.

[0005] Existing practices suffice for many application purposes. Indeed, relatively high switching rates, and hence relatively high data throughput rates, are often achievable. Nevertheless, present practices do not meet all potential requirements. In some application settings, for example, existing available data rates using these methodologies can be insufficient. Brief Description of the Drawings

[0006] The above needs are at least partially met through provision of the method and apparatus to facilitate transmitting data using multiple optical data streams described in the following detailed description, particularly when studied in conjunction with the drawings, wherein:

[0007] FIG. 1 comprises a flow diagram as configured in accordance with various embodiments of the invention;

[0008] FIG. 2 comprises a graph as configured in accordance with various embodiments of the invention;

[0009] FIG. 3 comprises a block diagram as configured in accordance with various embodiments of the invention;

[0010] FIG. 4 comprises a block diagram as configured in accordance with various embodiments of the invention;

[0011] FIG. 5 comprises a block diagram as configured in accordance with various embodiments of the invention;

[0012] FIG. 6 comprises a block diagram as configured in accordance with various embodiments of the invention; and

[0013] FIG. 7 comprises a block diagram as configured in accordance with various embodiments of the invention.

[0014] Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.

Detailed Description

[0015] Generally speaking, pursuant to these various embodiments, one provides a source of data along with a plurality of differing optical data streams. These differing optical data streams are then used, in parallel, to transmit the data over a shared optical transport media.

[0016] By one approach, these differing optical data streams differ from one another with respect to their carrier frequencies. By this approach, a single optical transport media, such as a fiber optic cable, can now carry considerably more data than might otherwise be associated with a given upper switching speed for the enabling light emitters being employed. If desired, however, available data rates can be shifted even higher by using optical data streams that are comprised of multi-bit symbols. Examples in this regard include pulse amplitude modulation symbols, quadrature amplitude modulation symbols, and so forth.

[0017] So configured and arranged, those skilled in the art will recognize and appreciate that these teachings provide an effective, efficient, and powerful mechanism for leveraging various existing approaches to effect a considerable increase in data throughput for a given optical transport media such as an optical fiber. It will further be recognized that these teachings are highly scalable and can be successfully applied over a very wide range of operating conditions and requirements.

[0018] These and other benefits may become clearer upon making a thorough review and study of the following detailed description. Referring now to the drawings, and in particular to FIG. 1, an illustrative process that is compatible with many of these teachings will now be presented.

[0019] Pursuant to this process 100, one provides 101 a source of data. This source of data can essentially comprise any source of data including sources of static data and/or dynamically changing data. These sources can also comprise a longer term data storage facility or can comprise, for example, a component that develops the data in the first instance and then discards that information following a transmission of that information. The data itself can similarly vary as desired and can span the gamut from comprising non-executable discrete items of information to comprising executable software instructions. [0020] This process 100 will optionally accommodate, if desired, also providing 102 clock information. By one approach, this can comprise absolute time (that is, actual time as measured with respect to the time of day) or can comprise relative time (that is, a tracking of the passage of time with respect to some non-time-of-day point of reference. By another approach, this can comprise a marking of time by, for example, a periodic and regular series of pulses or other marks (akin, for example, to the passing of seconds or minutes) where there is no corresponding maintained count. The latter example finds numerous applications in settings where a so-called clock signal serves to permit two or more devices to synchronize their behaviors and activities and/or to establish the rate at which steps are taken, data pulses are formed, or the like. Numerous examples of such clock sources are known in the art and others are likely to be developed going forward. Accordingly, for the sake of brevity, further elaboration in this regard will not be presented here.

[0021] This process 100 will also optionally accommodate, if desired, also providing

103 protocol control signaling. As used herein, the expression protocol signaling will be understood to refer to data that serves to effectuate the transmission of a corresponding payload of data but is not, in and of itself, typically intended as the payload being directed to the target of the communication. Such control signaling typically relates, for example, to such activities as establishing a communication session between two entities, confirming the successful transmission and receipt of a corresponding data payload, establishing and maintaining a secure communication context, confirming a tearing down of the communication session, and so forth. In some cases, this protocol control signaling can comprise, at least in part, a so-called pilot signal by which a receiver can calibrate its decoding of the payload data.

[0022] The precise protocol control signaling so provided will of course vary with the particulars of a given application setting. Again, such practices are very well known in the art and require no further explanation here.

[0023] In any event, this process 100 then makes provision for providing 104 a plurality of differing optical data streams. By one approach, this can comprise providing a plurality of optical carriers that each have a different frequency from one another. By one approach, this can comprise different center frequencies (where the bandwidths of the different optical data streams are, for example, non-overlapping with one another). [0024] As will be described below in more detail, these differing optical data streams can make use of multi-bit symbols if desired. Such multi-bit symbols can comprise, for example, Pulse Amplitude Modulation (PAM) signals, Quadrature Amplitude Modulation (QAM) signals, and so forth. Other examples in this regard are possible as well. As one simple illustrative example in this regard, and referring momentarily to FIG. 2, a given one of the optical data streams can have any of a variety of relative intensity levels (i.e., brightness at some corresponding frequency or frequencies).

[0025] In this example, a first level 201 of intensity corresponds to a first data symbol, a second level 202 of intensity corresponds to a second data symbol, a third level 203 of intensity corresponds to a third data symbol, and a fourth level 204 of intensity corresponds to a fourth data symbol. By this approach, a single pulse of light can communicate any of four different symbols and hence a single pulse of light is capable of communicating more than a single bit of information. The number of levels utilized in a given application setting can vary with the needs and/or opportunities as tend to characterize a given application setting. For example, instead of four levels, a lesser or greater number of levels can be utilized as desired.

[0026] As noted above, these teachings will accommodate the transmission of a pilot signal. With continued reference to FIG. 2, such a pilot symbol can be optionally represented by, in this example, a fifth level 205 of intensity. By representing this pilot signal as a particular unique pattern of light emissions, a receiver can identify the pilot signal for what it is. This, in turn, can permit the receiver to note the intensity level of the received pilot signal and utilize that intensity level to calibrate its detection of the other accommodated intensity levels to thereby potentially improve the reliability by which the multi-bit symbols as correspond to these different levels can be properly detected.

[0027] Referring again to FIG. 1, this process 100 then provides for using 105 this plurality of differing optical data streams, in parallel with one another, to transmit the aforementioned data over a shared optical transport media. This reference to "parallel" utilization will be understood to refer to temporal considerations, such that these differing optical data streams are utilized, at least part of the time, at the same time as one another to so transport the data. This reference to a shared optical transport media can be met through any number of known conventions including, but not limited to, free space, glass optical fibers, plastic optical fibers, lightpipes of various type and material, and so forth. The data so conveyed will be understood to comprise, as suggested above, the data being provided by the source of data, the aforementioned clock information, the aforementioned protocol control signaling, or the like.

[0028] Those skilled in the art will appreciate that the above-described processes are readily enabled using any of a wide variety of available and/or readily configured platforms, including partially or wholly programmable platforms as are known in the art or dedicated purpose platforms as may be desired for some applications. Referring now to FIG. 3, an illustrative approach to such a platform will now be provided.

[0029] In this illustrative example, the aforementioned data source 301 can be seen to potentially comprise a plurality of data sources. These data sources may be related to one another (for example, they may all provide data as stems from a common source) or they may be unrelated to one another (as when the data sources each provide different kinds of data in an independent manner from one another). A transmitter 302 operably couples to this data source 301 and serves to use a plurality of differing optical data streams, in parallel, to transmit this data over a shared optical transport media.

[0030] To effect these purposes, in this illustrative embodiment, a data parsing unit

303 receives the data from the data source 301 and parses this incoming data into multiple streams of data. These multiple streams of data can be parsed into separate physical pathways as suggested by the illustration or can be temporally separated from one another (using, for example, time division multiplexing to partition such data over time). In the simple example provided, an incoming data stream (represented as the sequentially received data A, B, C, D, and so forth) is parsed into two separate resultant data streams (a first comprising the data A, C, and so forth and a second comprising the data B, D, and so forth). The use of only two such resultant data streams serves to illustrate this concept with little complexity; it will be understood, however, that this example serves only in an illustrative capacity and that any larger number of resultant data streams can be accommodate in this manner.

[0031] Corresponding optical carrier sources 304, 305 receive these resultant parsed data streams. In this example, these optical carrier sources are represented by a first optical carrier source 304 through an Nth optical carrier source 305 (where N will be understood to comprise an integer greater than one). These optical carrier sources, in turn, serve to each source the aforementioned differing optical data streams. For example, the first optical carrier source 304 can source a first optical data stream having an optical carrier of a first frequency while the Nth optical carrier source 305 sources an Nth optical data stream having an optical carrier of an Nth frequency that is different from the first frequency.

[0032] There are various ways to realize these optical carrier sources. As one example in this regard, and referring momentarily to FIG. 4, by one approach an optical carrier source (such as the aforementioned first optical carrier source 304 which receives one of the bitstreams (A,C,...) from the data parsing unit 303 as described above) can comprise a light emitter 401 generates a corresponding optical carrier at a specific one of a plurality of the different carrier frequencies being employed in a given application setting. This specific frequency is denoted in FIG. 4 as Fi. Various LEDs, lasers, and the like are well suited to such an application. As another example in this regard, and referring momentarily now to FIG. 5, by another approach the optical carrier source can comprise a light emitter 501 that comprises a broadband light emitter that emits light over a relatively wide band of usable carrier frequencies (denoted in FIG. 5 as F_x through F_y). A light filter 502 of choice can receive this wideband output and serve to remove unwanted frequencies to thereby output the desired carrier frequency F₁. In either case, the light emitter 401, 501 can be modulated with the corresponding incoming data stream such that the resultant output data stream includes the data being transmitted.

[0033] As mentioned above, these teachings will compatibly accept the transmission of clock information along with the aforementioned payload data. Making momentary reference to FIG. 6, this can comprise, by one approach, combining 603 an incoming data stream with clock information from a clock information source 602 to yield resultant content that is then used to modulate the corresponding optical carrier source 601. It would also be possible, of course, to transmit such clock information using an optical carrier source that is dedicated to this purpose and apart from the transmission of any other data. With reference to FIG. 7 as well, much the same can be done to accommodate protocol control signaling as may be provided by a protocol control signaling source 701. For example, by one approach, this protocol control signaling source 701 can be substituted for the clock information source 602 as appears in FIG. 6 to thereby provide for the transmission of this protocol control signaling data.

[0034] Referring again to FIG. 3, and as mentioned above, one or more of these optical data streams can be comprised of multi-bit symbols. These can comprise PAM symbols, QAM symbols, or symbols of some other representation scheme of choice. By this approach, various controlled characteristics of the optical carrier sources are manipulated to thereby convey a greater quantity of individually discernable transmission events. Such characteristics can comprise, but are not limited to, light intensity, frequency phase shifts, and so forth.

[0035] So configured and arranged, these teachings provide a powerful and cost effective approach to greatly leveraging the availability of a given optical pathway (such as an optical fiber) by greatly increasing the quantity of data that can be reasonably conveyed over a given period of time via that optical pathway. Those skilled in the art will appreciate that these teachings can be scaled as desired to accommodate a great number of parallel paths and to further accommodate a variety of multi-bit symbol encoding techniques towards these ends.

[0036] Those skilled in the art will recognize that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the spirit and scope of the invention, and that such modifications, alterations, and combinations are to be viewed as being within the ambit of the inventive concept.

Claims

We claim:

1. A method comprising: providing a source of data; providing a plurality of differing optical data streams; using the plurality of differing optical data streams, in parallel, to transmit the data over a shared optical transport media.

2. The method of claim 1 wherein providing a plurality of differing optical data streams comprises using a plurality of optical carriers having different frequencies.

3. The method of claim 2 wherein using a plurality of optical carriers having different frequencies comprises using a plurality of light emitters that each generate a corresponding optical carrier at one of the different frequencies.

4. The method of claim 2 wherein using a plurality of optical carriers having different frequencies comprises using a plurality of broadband light emitters in combination with light filtering to thereby provide the plurality of optical carriers having different frequencies.

5. The method of claim 1 further comprising: providing clock information; and wherein using the plurality of differing optical data streams, in parallel, to transmit the data over a shared optical transport media comprises using the plurality of differing optical data streams, in parallel, to transmit the data and the clock information over a shared optical transport media.

6. The method of claim 1 further comprising: providing protocol control signaling; and wherein using the plurality of differing optical data streams, in parallel, to transmit the data over a shared optical transport media comprises using the plurality of differing optical data streams, in parallel, to transmit the data and the protocol control signaling over a shared optical transport media.

7. The method of claim 1 wherein providing a plurality of differing optical data streams comprises providing a plurality of differing optical data streams comprised of multi-bit symbols.

8. The method of claim 7 wherein the multi-bit symbols comprise quadrature amplitude modulation symbols.

9. The method of claim 7 wherein the multi-bit symbols comprise pulse amplitude modulation symbols.

10. The method of claim 7 wherein providing a plurality of differing optical data streams comprised of multi-bit symbols comprises providing a plurality of differing optical data streams comprised of multi-bit symbols in combination with at least one pilot signal by which a receiver can calibrate its decoding of the multi-bit symbols.

11. An apparatus comprising: a source of data; a plurality of differing optical data streams; a transmitter operably coupled to the source of data and the plurality of differing optical data streams, wherein the transmitter is configured and arranged to use the plurality of differing optical data streams, in parallel, to transmit the data over a shared optical transport media.

12. The apparatus of claim 11 wherein the transmitter is further configured and arranged to provide a plurality of differing optical data streams by using a plurality of optical carriers having different frequencies.

13. The apparatus of claim 12 wherein the transmitter is further configured and arranged to use a plurality of optical carriers having different frequencies by using a plurality of light emitters that each generate a corresponding optical carrier at one of the different frequencies.

14. The apparatus of claim 12 wherein the transmitter is further configured and arranged to use a plurality of optical carriers having different frequencies by using a plurality of broadband light emitters in combination with light filtering to thereby provide the plurality of optical carriers having different frequencies.

15. The apparatus of claim 11 further comprising: a source of clock information; and wherein the transmitter is further configured and arranged to use the plurality of differing optical data streams, in parallel, to transmit the data over a shared optical transport media by using the plurality of differing optical data streams, in parallel, to transmit the data and the clock information over a shared optical transport media.

16. The apparatus of claim 11 further comprising: a source protocol control signaling; and wherein the transmitter is further configured and arranged to use the plurality of differing optical data streams, in parallel, to transmit the data over a shared optical transport media by using the plurality of differing optical data streams, in parallel, to transmit the data and the protocol control signaling over a shared optical transport media.

17. The apparatus of claim 11 wherein the transmitter is further configured and arranged to provide a plurality of differing optical data streams by providing a plurality of differing optical data streams comprised of multi-bit symbols.

18. The apparatus of claim 17 wherein the multi-bit symbols comprise quadrature amplitude modulation symbols.

19. The apparatus of claim 17 wherein the multi-bit symbols comprise pulse amplitude modulation symbols.

20. The apparatus of claim 17 wherein the transmitter is further configured and arranged to provide a plurality of differing optical data streams comprised of multi-bit symbols by providing a plurality of differing optical data streams comprised of multi-bit symbols in combination with at least one pilot signal by which a receiver can calibrate its decoding of the multi-bit symbols.