WO1998052297A2

WO1998052297A2 - Parallel transmission method with diverse physical channel allocation

Info

Publication number: WO1998052297A2
Application number: PCT/US1998/009839
Authority: WO
Inventors: David C. Robb
Original assignee: Spectraplex, Inc.
Priority date: 1997-05-15
Filing date: 1998-05-13
Publication date: 1998-11-19
Also published as: AU7386598A; WO1998052297A3

Abstract

A throughput expansion method (10) for effectively increasing the throughput of a transmission medium (42). The transmission medium (42), which may be an available frequency spectrum (12) as of a telephone wire, is divided into a plurality of physical channels (16) and a data stream (20) is parsed into a plurality of virtual channels (22). The virtual channels (22) are multiplexed onto the physical channels (16) such that each of the virtual channels (22) will have a unique set of the physical channels (16) although each of the physical channels (16) will have data pertaining to more than one of the virtual channels (22) multiplexed thereonto. The physical channels (16) are communicated from an encoder (38) to a receiver (40) via the carrier (22) and the receiver (40) reconstructs the virtual channels (22) by separately summing the physical channels (16) which make up the virtual channels (22). In each such summation information that is common to all of a set of the physical channels (16) will be emphasized as the data of the receptive virtual channel (22) and other content of such physical channels (16) will tend to be self canceling.

Description

METHOD AND MEANS FOR INCREASING THROUGHPUT IN A CARRIER

TECHNICAL FIELD

The present invention relates to the field of data transmission and more specifically to a method and means for utilizing available bandwidth to effectively increase the effective throughput in a carrier. The predominant current usage of the present inventive throughput expansion method and means is for modem communications using a dedicated or assigned transmission means wherein it is desirable to effectively increase throughput within the fixed limitations of the transmission means.

BACKGROUND ART

In this "information age" it has become a nearly universal quest to try to squeeze as much throughput as possible from any and all available data communications means, throughput here being defined as the total amount of data which can be communicated in a given period of time. U.S. Patent No. 5,548,819, issued to this inventor, teaches a method and means for effectively increasing the number of available channels in a multichannel communications means such as a cellular telephone system. While such a system can correctly be said to effectively increase throughput, the inventor did not previously realize that some of the same principles and ideas could be used to increase the available throughput in a single channel, single user system.

In the case of communications between computers using modems to transmit and receive data via conventional telephonic transmission means (usually including wire transmission lines for at least a substantial portion of the transmission path), there is a relatively narrow bandwidth available for the transmission of data. Various compensation methods have been employed to attempt to make full use of the available physical bandwidth, and various data compression and encoding schemes and methods have been employed in an attempt to effectively increase the amount of data which can be transmitted via the available physical bandwidth. One reason why all such methods are limited is that the amount of data which can be accurately transmitted is a function not only of the overall bandwidth of a transmission means, but also of the signal to noise ratio attainable. Therefore, a method which could both effectively increase the throughput in a carrier medium while also actually effectively increasing the signal to noise ratio would be highly desirable. However, to the inventor's knowledge, no such method has existed prior to the present invention.

DISCLOSURE OF INVENTION

Accordingly, it is an object of the present invention to provide a method and means for increasing the effective throughput in a single carrier data transmission system.

It is still another object of the present invention to provide a method and means for increasing throughput which can be used with existing carriers, such as ordinary telephone wire carriers.

It is yet another object of the present invention to provide a data transmission method and means which will effectively increase the signal to noise ratio in a given carrier. It is still another object of the present invention to provide a data transmission method and means which can be used in conjunction with other methods for effectively increasing throughput, such as data compression schemes, and the like.

Briefly, the preferred embodiment of the present invention is method and means whereby the available bandwidth in a given carrier is allocated into a quantity of physical channels, and subsets of a plurality of the physical channels are assigned to be what will be referred to herein as "virtual" channels. The concept of a virtual channel will be better understood in light of the detailed description of the invention herein. Briefly, however, according to the present invention a virtual channel is channel in the sense that the data to be communicated is divided into a plurality of essentially parallel data portions, each comprising a virtual channel. In the presently preferred embodiment of the invention, an incoming serial data stream is parsed into a plurality of parallel data streams. A physical channel is the physical medium by means of which data is transmitted. In the best presently known embodiment of the present invention, the example of the physical channels will be divisible portions of the available frequency bandwidth. Accordingly, each of the physical channels will be modulated by a plurality, but not all, of the parallel data streams. At the receiving end, each of the parallel data streams is recovered by separately processing each of the sets of virtual channels. According to the present invention, each of the parallel data streams will be emphasized by summing its respective assigned set, while information relating to other of the parallel data streams which may be contained in some, but not all, of the physical channels in that virtual channel will tend to be self canceling. An advantage of the present invention is that throughput is effectively increased.

A further advantage of the present invention is that signal to noise ratio is effectively increased.

Yet another advantage of the present invention is that it can be used with existing data transmission and carrier means.

Still another advantage of the present invention is that it is relatively easy and inexpensive to implement.

These and other objects and advantages of the present invention will become clear to those skilled in the art in view of the description of the best presently known mode of carrying out the invention and the industrial applicability of the preferred embodiment as described herein and as illustrated in tile several figures of the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a flow diagram depicting some basic operations of the inventive throughput expansion method; Figure 2 is a frequency graph showing the division of an available telephonic frequency spectrum into a plurality of "physical" channels;

Figure 3 is an example of a data stream being parsed into virtual channels; Figure 4 is an example of assignments of physical channels to virtual channels in a single carrier means; and

Figure 5 is a block diagram of an example of a typical encoder and receiver for accomplishing the inventive method of Figure 1.

BEST MODE FOR CARRYING OUT INVENTION The best presently known mode for carrying out the invention is a throughput expansion method for increasing the effective throughput and signal to noise ratio in a given carrier means. The inventive throughput expansion method is depicted in a flow diagram in Figure 1 and is designated therein by the general reference character 10. Figure 2 is a frequency graph depicting an available frequency spectrum 12 in a typical telephonic wire carrier. The throughput expansion method 10 of Figure 1 has a divide frequency spectrum into physical channels operation 14 wherein the available frequency spectrum 12 is divided into a plurality of physical channels 16, with each of the physical channels 16 being a portion of the available frequency spectrum 12. In the example of Figure 2, the available frequency spectrum 12 is shown divided into ten physical channels 16, which are designated as PI through PI 0 in the diagram of Figure 2.

Following the divide frequency spectrum into physical channels operation 14 in the best presently known embodiment 10 or the present invention is a parse data stream into virtual channels operation 18. Figure 3 is a diagrammatic representation of a data stream 20 being parsed into a plurality of virtual channels 22. In the example of the best presently known embodiment 10 of the present invention, the quantity of virtual channels 22 is eighteen, which are designated as VI through VI 8 in the diagram of Figure 3. In actual practice, the quantity of virtual channels 22 into which the data stream is parsed might be greater or less than the quantity of this example. Similarly, the quantity of physical channels 16 into which the available frequency spectrum 12 is divided as depicted in the example of Figure 2 is an example only, and the quantity of physical channels 16 will vary according to such factors as the application and the type of communications medium available. The relevance of these quantities will be discussed in greater detail hereinafter. It should be noted that, since the divide frequency spectrum into physical channels operation 14 and the parse data stream into virtual channels operation 18 are essentially independent operations, these operations could be performed simultaneously or the order reversed as compared to the example of Figure 2.

In the example of Figure 3, the data stream 20 and the virtual channels 22 are depicted as an essentially random series of ones and zeros. The actual values are examples only and are of no significance. In the example of Figure 3, it should also be noted that the data stream 20 is being parsed in a serial fashion such that a bit from the data stream is assigned to the first VI virtual channel 22, the next bit is assigned to the second V2 virtual channel 22, and so on until a bit has been assigned to each of the eighteen virtual channels 22, the process is then started over such that the nineteenth bit will be assigned to the first VI virtual channel 22, and so on. One skilled in the art will recognize that other parsing methods are possible. Also, one skilled in the art will recognize that it will likely be desirable to buffer the inputs and/or outputs of the virtual channels such that an uninterrupted flow of data will be available for further operations as will be discussed hereinafter.

Referring again to the best presently known embodiment 10 of the present inventive method as depicted in Figure 1, in an allocate physical channels to virtual channels operation 24, the virtual channels 22 are distributed among the physical channels 16. An example of an allocation chart 26 is shown in Figure 4. Although it is specifically not a restriction of the present invention that no more than half of the physical channels 16 assigned to a given virtual channel 22 may be used in common with another of the virtual channels 22, this is the case in the example of Figure 4, since this will result in a superior signal to noise ratio. In the example of Figure 4 it can be seen that each of the physical channels 16 is modulated by six of the virtual channels 22. This results in two of the physical channels (those number 13 and 14 in the example of Figure 4) being used four times, while the remainder of the physical channels 16 are each used seven times. In the allocate physical channels to virtual channels operation 24, the assigned virtual channels 22 are multiplexed onto the appropriate physical channels 16. According to the best presently known embodiment 10 of the invention, such multiplexing is done by analog summation of the several virtual channels 22 assigned to each of the physical channels 16, followed by appropriate adjustment of the gain for each physical channel 16 such that the amplitude will be appropriate to the carrier means.

A transmit physical channels operation 28 simply designates that the several physical channels 16 are next transmitted on the carrier means. Since in the example of the best presently known embodiment 10 of the present invention, the carrier means used is the available frequency spectrum 12

(chosen for purposes of the example to be typical of a telephonic wire connection), this means that each of the separate frequency bands (the physical channels 16, in this example) are transmitted. Again, it should be remembered that alternative "physical channels" are within the scope of the invention. For example, a plurality of code channels or any other means now known, or to be developed in the future, for dividing a transmission means into a plurality of distinct carrier means or "channels" could be substituted for the example of the physical channels 16 discussed herein in relation to the best presently known embodiment 10 of the present invention. The above discussed operations of the best presently known embodiment 10 of the inventive throughput expansion method are part of a transmit operation 30. A receive operation 32 commences with the reception of the output from the transmit physical channels operation 28 and, where necessary (as in the present example), the separation of such output into the various physical channels 16. In the present example, the separation of the physical channels 16 is accomplished by using well known filtering methods to separate the several bands which are the physical channels 16. In a reconstruct virtual channels operation 34, an analog summation of each of the physical channels 16 that correlate to the respective virtual channels is accomplished and a decision is made as to whether each successive data bit in each such virtual channel is a one or a zero. By way of example, such decision is based, in the best presently known embodiment 10 of the invention, on the following criteria: Where the various physical channels 16 have been summed and the output adjusted such that the peak value of the output (not including aberrations) is set at one volt, then values greater than one half volt would be adjudged to be a "one" and values equal to or less than one half volt would be adjudged to be a "zero". It should be noted that these criteria are examples only, and more refined criteria may well be developed through experimentation and experience during development of future applications of the present invention.

Figure 5 is a block diagram of a simplified version of a throughput expansion encoder 38, receiver 40, and transmission medium 42 such as may be used for accomplishing the present inventive throughput expansion method 10. It will be recognized that the reconstruct virtual channels operation 34 (Figure 1) will require that the receiver 40 know which of the physical channels 16 being received have been allocated to each of the virtual channels 22. The simplest method will be to have a fixed assignment such as is depicted in the chart of Figure 4 and which is programmed or hard wired into the circuitry of both the encoder 38 and the receiver 40. Alternatively, the assignments for a particular communication might be transmitted from the encoder 38 to the receiver at the commencement of such communication. It is also conceivable, and perhaps highly desirable in some applications, that the quantity of virtual channels 22 (and, therefore, the distribution of virtual channels 22 to physical channels 16) be dynamically altered as such factors as traffic, instant signal to noise ratio, and criticality of data vary.

According to the above described example of the inventive throughput expansion method 10, since each of the virtual channels 22 is made up a set of the physical channels 16 such that all of the physical channels 16 which are examined to reconstruct a specific virtual channel 22 contain the information of that particular virtual channel 22. That is, using the example of the chart of Figure 4, to reconstruct the first VI virtual channel, the PI, P2, P3 and P4 physical channels 16 will be examined in the reconstruct virtual channels operation 34. Therefore, an analog summation of this set of physical channels 16 will cause the information of the VI virtual channel 22 to be cumulative and self emphasizing. Alternatively, information relating to the several other virtual channels 22 which use some, but not all, of the same set of physical channels 16 will tend to be random and, therefore, self canceling when an analog summation of the PI, P2, P3 and P4 physical channels 16 is accomplished.

Following the reconstruct virtual channels operation 34, is a reserialize data stream operation 36 wherein the data stream 20 is reconstructed from the data contained in the several virtual channels 22. One skilled in the art will recognize that this is essentially the reverse operation of the parse data stream into virtual channels operation 18 described previously herein.

It will be noted by one skilled in the art that some of the principles and ideas involved in this invention are similar to those involved in the U.S. Patent No. 5,548,819 referenced previously herein. However, as mentioned, prior to the present invention the inventor had not realized that an increase in throughput in a single user application was possible. This present invention relates to the earlier invention of U.S. Patent No. 5,548,819 in that the relationship of the quantity of physical channels 16 bears essentially the same relationship to the potential quantity of virtual channels 22 as does the quantity of physical channels (M) to the quantity of Communication Channels in the earlier invention, with the exception that the quantity of physical channels 16 used per virtual channel 22 in the present invention is not limited such that no more than one half of the physical channels used by any one virtual channel 22 is shared with another virtual channel.

Referring now again to the block diagram of Figure 5, it can be seen that the encoder 38 has a first filter 44 for accomplishing the divide available frequency spectrum into physical channels operation 14. The first filter 44 is an ordinary multiple band pass filter for separating the several physical channels 16 according to the best presently known embodiment 10 of the present inventive method, the construction of which will be known to one skilled in the art. As can be seen in the view of Figure 5, a parser 46 represents the division of the data stream 20 into the virtual channels 22 according to the parse data stream into virtual channels operation 18 as depicted in Figures 1 and 3. A multiplexor 48 is provided for accomplishing the allocate virtual channels to physical channels operation 24 as previously discussed herein. A transmitter 50 transmits the several physical channels 16 onto the transmission medium 42. In the case of the example of Figure 5, the transmitter 50 will simply recombine the physical channels 16 into the full available frequency spectrum 16 and couple its output to the transmission medium 42 which, in the present example, will be a telephone line although, as previously discussed, the invention is certainly not limited to the use of such medium. Within the receiver 40, a second filter 52 divides the received output from the transmitter 50 into the several physical channels 16. A plurality of correlation/summation units 54 (one per virtual channel) are provided to accomplish the reconstruct virtual channels operation 34 described previously herein in relation to Figure 1. The operation of the correlation/summation units 54 is described in substantial detail in U.S. Patent No. 5,548,819. A serializer 56 reconstructs the data 20 stream from the several virtual channels 22. The serializer 56 is merely a conventional device for accepting a parallel data input and providing the serial data 20 as an output.

The above description of the encoder 38 and receiver 40 is not purported to be an exhaustive list of the components which might be included in such devices. Indeed, one skilled in the art will recognize that applications other than that described in relation to the best presently known embodiment as described herein might require variations in the hardware needed to accomplish the inventive throughput expansion method 10. It should be noted that, although physical channels 22 have been described herein, in relation to the best presently known embodiment 10 of the present invention, as being frequency bands within an available frequency spectrum 12 of a physical wire transmission medium 42, the present invention is not limited to such carrier means. The physical channels 22 could be frequency bands in other carrier means, such as fiber optic channels or the like, or even separate radio "channels" having distinct carrier baseband frequencies. Alternatively, wherever inherently multiple physical channels are available, the present invention could be adapted to take advantage of such multiple physical channels. In this latter case, the divide available frequency spectrum into physical channels would not be required.

Various modifications may be made to the invention without altering its value or scope. For example, as discussed briefly previously herein, the quantity of physical channels 16 and/or the quantity of virtual channels 22 might be varied according to the needs of the application.

Although the best presently known embodiment 10 of the present invention is described herein, for the sake of simplicity, as a unidirectional data communications means, it will be recognized that bidirectional or multistation commumcations can be provided by providing the encoder 38 and receiver at each communications station.

All of the above are only some of the examples of available embodiments of the present invention. Those skilled in the art will readily observe that numerous other modifications and alterations may be made without departing from the spirit and scope of the invention. Accordingly, the above disclosure is not intended as limiting and the appended claims are to be interpreted as encompassing the entire scope of the invention.

INDUSTRIAL APPLICABILITY Although the present invention has been described in relation to a telephone transmission medium for modem communications, the scope of the invention extends to essentially any application wherein it is desired to increase the throughput and/or signal to noise ratio in a given communications medium. As described previously herein, the transmission of multiple bit streams in parallel can, according to the present invention, increase the total rate of data throughput over a single data stream using within the constraints of the same available bandwidth and using the same data encoding scheme as might otherwise be employed.

An aspect of the invention not previously discussed is that the performance of the invention is improved when the several physical channels 16 are not entirely synchronous. This is because, where the physical channels

16 are not perfectly synchronized there often will occur a transition of state during the period of time when the state of the data in a virtual channel 22 using such physical channels 16. For example, if the data of a virtual channel 22 contained within a physical channel 16 were to transition states precisely in the middle of a sample period (and assuming that summation of state is linear throughout a sample period) then the effect of that particular physical channel 16 on that particular virtual channel 22 would be essentially zero.

Since the throughput expansion method 10 of the present invention may be readily produced into existing data communications systems and devices, and since the advantages as described herein are provided, it is expected that it will be readily accepted in the industry. For these and other reasons, it is expected that the utility and industrial applicability of the invention will be both significant in scope and long-lasting in duration.

Claims

IN THE CLAIMS:

1. A method for communicating data from an encoder to a receiver, comprising: a) providing a plurality of physical channels, each of said physical channels for communicating a signal from the encoder to the receiver; b) separating the data to be communicated into a plurality of virtual data channels; c) multiplexing each of said virtual data channels onto some but not all of said physical channels such that no two of said virtual channels shares an identical set of physical channels, each of said virtual data channels being then associated with a corresponding set of physical channels; d) transmitting the physical channels to the receiver; and e) summing each of said sets of physical channels at the receiver.

2. The method of claim 1, wherein: the physical channels are each a frequency ban within an available frequency spectrum.

3. The method of claim 1 , wherein: the physical channels are each a portion of the available frequency in a

telephonic communications medium.

4. The method of claim 1, wherein:

the data to be communicated is a digital serial data stream; and

the data to be communicated is separated into said plurality of virtual

data channels by parsing the serial data stream into said plurality of virtual

data channels.

5. The method of claim 4, wherein:

the serial data stream is parsed in one bit increments into said plurality

of virtual data channels.

6. The method of claim 1, and further including:

following the summing of each of said sets of physical channels, then

periodically determining if the result of the summing is indicative of a one data

bit or a zero data bit, such that each of said virtual channels is reconstructed in the receiver.

7. The method of claim 6, and further including:

serializing said virtual channels into a serial data stream.

8. A throughput expansion apparatus for increasing the throughput of a transmission medium, the apparatus comprising:

an encoder including a multiplexor for multiplexing a plurality of

virtual channels onto a plurality of physical channels such that each of the

physical channels will have multiplexed thereonto some, but not all, of the

virtual channels; and

a receiver including a correlation/summation unit for reconstituting the

virtual channels from the physical channels.

9. The throughput expansion apparatus of claim 8, and further including: a transmitter for transmitting the physical channels through the transmission medium.

10. The throughput expansion apparatus of claim 8, wherein:

the physical channels are each a portion of an available bandwidth of

the transmission medium; and

the transmitter transmits the combined physical channels.

11. The throughput expansion apparatus of claim 8, wherein:

the encoder further includes a first filter for dividing a carrier frequency into the physical channels.

12. The throughput expansion apparatus of claim 8, wherein:

the receiver further includes a second filter for dividing an input from the transmission medium into the physical channels.

13. The throughput expansion apparatus of claim 8, wherein:

the virtual channels are created by parsing a serial data stream into the

plurality of virtual channels.

14. The throughput expansion apparatus of claim 8, wherein:

in the receiver, the plurality of virtual channels are serialized into a

serial data stream.

15. A throughput expansion method for increasing the amount of data

which can be communicated within the constraints of a physical transmission

medium, comprising: dividing the physical transmission medium into a plurality of physical

channels;

dividing the data into a plurality of virtual channels; and

modulating each of the physical channels with some, but not all, of the

virtual channels.

16. The throughput expansion method of claim 15, wherein:

the physical transmission medium is divided into the plurality of physical channels by separating portions of the available frequency spectrum of the transmission medium into frequency bands.

17. The throughput expansion method of claim 16, wherein: the physical transmission medium is a telephonic communications

medium.

18. The throughput expansion method of claim 17, wherein:

the physical transmission medium is a telephone wire.

19. The throughput expansion method of claim 15, wherein:

the data is divided into the plurality of virtual channels by parsing the data into generally parallel data streams.

0. The throughput expansion method of claim 15, wherein: the data is information to be transmitted via a telephonic medium.