# Patent

## Title
Systems/methods of conducting a financial transaction using a smartphone

## Abstract

Embodiments of inventive concepts are provided wherein a mobile device, such as a smartphone, may be configured to communicate with a base station, using a first mode, and to communicate with an access point using a second mode that comprises a level of security exceeding that of the first mode. The second mode communications between the mobile device and the access point are conducted over a short-range wireless link responsive to an identity of the mobile device and/or responsive to a biometric data being provided by a user of the mobile device. Such second mode wireless communications may include data relating to a financial transaction and/or other data that may require an increased level of privacy and/or security.

## Background
CLAIM FOR PRIORITY
This application is a continuation of U.S. patent application Ser. No. 14/504,027, filed Oct. 1, 2014, entitled Systems/Methods of Preferential Communications, which itself is a continuation of U.S. patent application Ser. No. 14/456,649, filed Aug. 11, 2014, entitled Systems/Methods of Adaptively Varying a Spectral Content of Communications, which itself is a continuation of U.S. patent application Ser. No. 14/287,473, filed May 27, 2014, entitled Systems/Methods of Transmitting Information Via Baseband Waveforms Comprising Frequency Content Agility and an Orthogonality Therebetween, which itself is a continuation of U.S. patent application Ser. No. 14/187,899, filed Feb. 24, 2014, entitled Systems and/or Methods of Wireless Communications, which itself is a continuation of U.S. patent application Ser. No. 13/011,451, filed Jan. 21, 2011, entitled Systems and/or Methods of Increased Privacy Wireless Communications, which itself is a continuation-in-part of U.S. patent application Ser. No. 12/372,354, filed Feb. 17, 2009, entitled Wireless Communications Systems and/or Methods Providing Low Interference, High Privacy and/or Cognitive Flexibility, which itself claims priority to U.S. Provisional Application No. 61/033,114, filed Mar. 3, 2008, entitled Next Generation (XG) Chipless Spread-Spectrum Communications (CSSC), and is a continuation-in-part (CIP) of U.S. application Ser. No. 11/720,115, filed May 24, 2007, entitled Systems, Methods, Devices and/or Computer Program Products For Providing Communications Devoid of Cyclostationary Features, which is a 35 U.S.C. §371 national stage application of PCT Application No. PCT/US2006/020417, filed on May 25, 2006, which claims priority to U.S. Provisional Patent Application No. 60/692,932, filed Jun. 22, 2005, entitled Communications Systems, Methods, Devices and Computer Program Products for Low Probability of Intercept (LPI), Low Probability of Detection (LPD) and/or Low Probability of Exploitation (LPE) of Communications Information, and also claims priority to U.S. Provisional Patent Application No. 60/698,247, filed Jul. 11, 2005, entitled Additional Communications Systems, Methods, Devices and Computer Program Products for Low Probability of Intercept (LPI), Low Probability of Detection (LPD) and/or Low Probability of Exploitation (LPE) of Communications Information and/or Minimum Interference Communications, the entirety of all of which are incorporated herein by reference. The above-referenced PCT International Application was published in the English language as International Publication No. WO 2007/001707.


FIELD OF THE INVENTION
This invention relates to communications systems and methods, and more specifically to wireless preferential communications systems and methods wherein communications with an access point (e.g., femtocell) are preferred to communications with a base station.
BACKGROUND
Wireless communications systems and methods are increasingly being used for voice, data and/or multimedia communications. As the use of such systems/methods continues to increase, available bandwidths may limit an ability to effectively transmit voice/data/multimedia content. Accordingly, access points other than base stations (e.g., femtocells) are increasingly being used to provide additional capacity and relieve base station load.
SUMMARY
Embodiments of preferential wireless communications systems/methods are provided. According to some embodiments, a method of communicating between a mobile device and a base station is provided wherein the method includes preferentially communicating between the mobile device and an access point that is installed in a residence/office. Specifically, according to some embodiments, the method comprises: preferentially communicating with the access point when proximate thereto and refraining from communicating with the base station when proximate to the access point even though communications with the base station are possible when proximate to the access point; and further, preferentially communicating with a first access point that is installed in a residence/office responsive to an identity of the mobile device and refraining from communicating with a second access point that is installed in a residence/office responsive to the identity of the mobile device.
In additional embodiments, the method further comprises: providing communications between a first device and the access point responsive to an identity of the first device and denying communications between a second device and the access point responsive to an identity of the second device.
In further embodiments, the method further comprises: receiving an identity from a device; authenticating the device responsive to the received identity; receiving a key from the device following said receiving an identity and following said authenticating; and establishing communications with the device responsive to said receiving a key from the device; wherein prior to said receiving a key from the device, the method further comprises: providing the key to the device responsive to said receiving an identity and responsive to said authenticating.
According to additional embodiments, the method further comprises: receiving an identity from a device; authenticating the device responsive to the received identity; transmitting a notification; and establishing communications with the device responsive to said receiving an identity, authenticating the device and transmitting a notification.
In yet further embodiments, the method comprises: providing an identity of the mobile device to the access point by accessing a web site and providing to the web site the identity of the mobile device; and relaying the identity to the access point by the web site.
Analogous systems embodiments are also provided. According to some such systems embodiments, a mobile device is configured to communicate with a base station and with an access point that is installed in a residence/office; wherein the mobile device is configured to: preferentially communicate with the access point when proximate thereto and refrain from communicating with the base station when proximate to the access point even though the mobile device is able to communicate with the base station when proximate to the access point; and wherein the mobile device is further configured to preferentially communicate with a first access point that is installed in a residence/office responsive to an identity of the mobile device and to refrain from communicating with a second access point that is installed in a residence/office responsive to the identity of the mobile device.
According to additional embodiments, the system further comprises the base station and/or the access point; wherein the access point is configured to provide communications service to a first device responsive to an identity of the first device and deny communications service to a second device responsive to an identity of the second device.
In other embodiments, the system further comprises a processor that is configured to: receive an identity from a device; authenticate the device responsive to the received identity; receive a key from the device following having received the identity and following having authenticated the device; and establish communications with the device responsive to having received the key from the device; wherein the processor is configured to provide the key responsive to having received the identity from the device and having authenticated the device.
In yet additional embodiments, the system further comprises a processor that is configured to: receive an identity from a device; authenticate the device responsive to the received identity; transmit a notification; and establish communications with the device responsive to having received the identity from the device, having authenticated the device and having transmitted the notification.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration of functions of a transmitter according to embodiments of the present invention.
FIG. 2 is a schematic illustration of further functions of a transmitter according to further embodiments of the present invention.
FIG. 3 is a schematic illustration of waveform generation according to additional embodiments of the present invention.
FIG. 4 is a schematic illustration of further functions of a transmitter according to further embodiments of the present invention.
FIG. 5 is a schematic illustration of additional functions of a transmitter according to additional embodiments of the present invention.
FIG. 6 is a schematic illustration of functions of a receiver according to embodiments of the present invention.
FIG. 7 is a schematic illustration of further functions of a transmitter according to further embodiments of the present invention.
FIG. 8 is a schematic illustration of spectrum used by a transmitter according to embodiments of the present invention.
FIG. 9 is a schematic illustration of further functions of a receiver according to further embodiments of the present invention.
FIG. 10 is a schematic illustration of a communications system based upon one or more transmitters and one or more receivers according to further embodiments of the present invention.
FIGS. 11 through 14 illustrate functions of a receiver according to further embodiments of the present invention.
FIG. 15 is a schematic illustration of further functions of a transmitter and receiver according to further embodiments of the present invention.
FIG. 16 is a flowchart of operations that may be performed according to some embodiments of the present invention.
FIG. 17 is a block diagram of a XG-CSSC system transmitter architecture according to various embodiments of the present invention.
FIG. 18 is a block diagram of a XG-CSSC system receiver architecture according to various embodiments of the present invention.
FIGS. 19(a)-19(c) illustrate a power spectral density of a XG-CSSC waveform in an interference-free environment, in interference avoidance mode illustrating a cognitive property, and following a square-law detector illustrating featureless (cyclostationary-free) nature, respectively, according to various embodiments.
FIG. 20 illustrates a power spectral density of a conventional QPSK waveform and a cyclostationary feature thereof.
FIG. 21 illustrates a constellation of a XG-CSSC waveform according to various embodiments.
FIG. 22 illustrates a histogram of transmitted symbols of a XG-CSSC waveform corresponding to the constellation of FIG. 21 according to various embodiments of the invention.
FIG. 23 graphically illustrates BER vs. ES/N0 for 16-ary XG-CSSC and 16-QAM spread spectrum according to various embodiments of the invention.
FIG. 24 graphically illustrates BER vs. ES/N0 for 16-ary XG-CSSC and 16-QAM Spread Spectrum subject to Co-Channel (“CC”) interference according to various embodiments of the invention. The CC interference considered is of two types: Wide-Band (“WB”) spanning the entire desired signal spectrum, and Band-Pass (“BP”) spanning only 20% of the desired signal spectrum. Interference and desired signal are assumed to have identical power.
FIG. 25 graphically illustrates BER vs. ES/N0 for 16-ary XG-CSSC and 16-QAM Spread Spectrum subject to Band-Pass (“BP”) Co-Channel interference according to various embodiments of the invention. The BP interference spans 20% of the desired signal spectrum. The term “Adaptive XG-CSSC” in the legend refers to the cognitive feature of XG-CSSC in sensing and avoiding the interference. Interference and desired signal are assumed to have identical power.
FIG. 26 is a block diagram of systems and/or methods of increased privacy wireless communications according to various embodiments of the present invention.
FIG. 27 is a block diagram of additional systems and/or methods of increased privacy wireless communications according to various embodiments of the present invention.



DESCRIPTION OF EMBODIMENTS ACCORDING TO THE INVENTION
Specific exemplary embodiments of the invention now will be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It will be understood that two or more embodiments of the present invention as presented herein may be combined in whole or in part to form one or more additional embodiments.
It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It will be understood that although terms such as first and second are used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, a first element below could be termed a second element, and similarly, a second element may be termed a first element without departing from the teachings of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. The symbol “I” is also used as a shorthand notation for “and/or”.
Moreover, as used herein the term “substantially the same” means that two or more entities that are being compared have common features/characteristics (e.g., are based upon a common kernel) but may not be identical. For example, substantially the same bands of frequencies, means that two or more bands of frequencies being compared substantially overlap, but that there may be some areas of non-overlap, for example at a band end. As another example, substantially the same air interfaces means that two or more air interfaces being compared are similar but need not be identical. Some differences may exist in one air interface (e.g., a satellite air interface) relative to another (e.g., a terrestrial air interface) to account for one or more different characteristics that may exist between the terrestrial and satellite communications environments. For example, a different vocoder rate may be used for satellite communications compared to the vocoder rate that may be used for terrestrial communications (i.e., for terrestrial communications, voice may be compressed (“vocoded”) to approximately 9 to 13 kbps, whereas for satellite communications a vocoder rate of approximately 2 to 4 kbps, for example, may be used); a different forward error correction coding, different interleaving depth, and/or different spread-spectrum codes may also be used, for example, for satellite communications compared to the coding, interleaving depth, and/or spread spectrum codes (i.e., Walsh codes, long codes, and/or frequency hopping codes) that may be used for terrestrial communications.
The term “truncated” as used herein to describe a statistical distribution means that a random variable associated with the statistical distribution is precluded from taking-on values over one or more ranges. For example, a Normal/Gaussian distribution that is not truncated, allows an associated random variable to take-on values ranging from negative infinity to positive infinity with a frequency (i.e., a probability) as determined by the Normal/Gaussian probability density function. In contrast, a truncated Normal/Gaussian distribution may allow an associated random variable to take-on values ranging from, for example, V1 to V2 (−∞<V1, V2<∞) in accordance with a Normal/Gaussian distribution, and preclude the random variable from taking-on values outside the range from V1 to V2. Furthermore, a truncated distribution may allow an associated random variable to take-on values over a plurality of ranges (that may be a plurality of non-contiguous ranges) and preclude the random variable from taking-on values outside of the plurality of ranges.
As used herein, the term “transmitter” and/or “receiver” include(s) transmitters/receivers of cellular and/or satellite terminals with or without a multi-line display; Personal Communications System (PCS) terminals that may include data processing, facsimile and/or data communications capabilities; Personal Digital Assistants (PDA) that can include a radio frequency transceiver and/or a pager, Internet/Intranet access, Web browser, organizer, calendar and/or a Global Positioning System (GPS) receiver; and/or conventional laptop and/or palmtop computers or other appliances, which include a radio frequency transceiver. As used herein, the term “transmitter” and/or “receiver” also include(s) any other radiating device, equipment and/or source that may have time-varying and/or fixed geographic coordinates and/or may be portable, transportable, installed in a vehicle (aeronautical, maritime, or land-based) and/or situated/configured to operate locally and/or in a distributed fashion at any location(s) on earth, vehicles (land-mobile, maritime and/or aeronautical) and/or in space. A transmitter and/or receiver also may be referred to herein as a “terminal” As used herein, the term “space-based” component and/or “space-based” system include(s) one or more satellites and/or one or more other objects and/or platforms (such as airplanes, balloons, unmanned vehicles, space crafts, missiles, etc.) that have a trajectory above the earth at any altitude.
Some embodiments of the present invention may arise from recognition that it may be desirable to communicate information based upon a waveform that is substantially devoid of a cyclostationary property. As used herein to describe a waveform, the term “cyclostationary” means that the waveform comprises at least one signature/pattern that may be a repeating signature/pattern. Examples of a repeating signature/pattern are a bit rate, a symbol rate, a chipping rate and/or a pulse shape (e.g., a Nyquist pulse shape) that may be associated with a bit/symbol/chip. For example, each of the well known terrestrial cellular air interfaces of GSM and CDMA (cdma2000 or W-CDMA) comprises a bit rate, a symbol rate, a chipping rate and/or a predetermined and invariant pulse shape that is associated with the bit/symbol/chip and, therefore, comprise a cyclostationary property/signature. In contrast, a waveform that represents a random (or pseudo-random) noise process does not comprise a bit rate, a symbol rate, a chipping rate and/or a predetermined and invariant pulse shape and is, therefore, substantially devoid of a cyclostationary property/signature. According to some embodiments of the present invention, non-cyclostationary waveforms may be used, particularly in those situations where LPI, LPD, LPE, private, secure and/or minimum interference communications are desirable.
Conventional communications systems use waveforms that are substantially cyclostationary. This is primarily due to a methodology of transmitting information wherein a unit of information (i.e., a specific bit sequence comprising one or more bits) is mapped into (i.e., is associated with) a specific waveform shape (i.e., a pulse) and the pulse is transmitted by a transmitter in order to convey to a receiver the unit of information. Since there is typically a need to transmit a plurality of units of information in succession, a corresponding plurality of pulses are transmitted in succession. Any two pulses of the plurality of pulses may differ therebetween in sign, phase and/or magnitude, but a waveform shape that is associated with any one pulse of the plurality of pulses remains substantially invariant from pulse to pulse and a rate of pulse transmission also remains substantially invariant (at least over a time interval). The methodology of transmitting (digital) information as described above has its origins in, and is motivated by, the way Morse code evolved and was used to transmit information. Furthermore, the methodology yields relatively simple transmitter/receiver implementations and has thus been adopted widely by many communications systems. However, the methodology suffers from generating cyclostationary features/signatures that are undesirable if LPE/LPI/LPD and/or minimum interference communications are desirable. Embodiments of the present invention arise from recognition that communications systems may be based on a different methodology that is substantially devoid of transmitting a modulated carrier, a sequence of substantially invariant pulse shapes and/or a chipping rate and that even spread-spectrum communications systems may be configured to transmit/receive spread-spectrum information using waveforms that are devoid of a chipping rate.
A publication by W. A. Gardner, entitled “Signal Interception: A Unifying Theoretical Framework for Feature Detection,” IEEE Transactions on Communications, Vol. 36, No. 8, August 1988, notes in the Abstract thereof that the unifying framework of the spectral correlation theory of cyclostationary signals is used to present a broad treatment of weak random signal detection for interception purposes. The relationships among a variety of previously proposed ad hoc detectors, optimum detectors, and newly proposed detectors are established. The spectral-correlation-plane approach to the interception problem is put forth as especially promising for detection, classification, and estimation in particularly difficult environments involving unknown and changing noise levels and interference activity. A fundamental drawback of the popular radiometric methods in such environments is explained. According to some embodiments of the invention, it may be desirable to be able to communicate information using waveforms that do not substantially include a cyclostationary feature/signature in order to further reduce the probability of intercept/detection/exploitation of a communications system/waveform that is intended for LPI/LPD/LPE communications.
There are at least two potential advantages associated with signal detection, identification, interception and/or exploitation based on cyclic spectral analysis compared with the energy detection (radiometric) method: (1) A cyclic signal feature (i.e., chip rate and/or symbol rate) may be discretely distributed even if a signal has continuous distribution in a power spectrum. This implies that signals that may have overlapping and/or interfering features in a power spectrum may have a non-overlapping and distinguishable feature in terms of a cyclic characteristic. (2) A cyclic signal feature associated with a signal's cyclostationary property, may be identified via a “cyclic periodogram.” The cyclic periodogram of a signal is a quantity that may be evaluated from time-domain samples of the signal, a frequency-domain mapping such as, for example, a Fast Fourier Transform (FFT), and/or discrete autocorrelation operations. Since very large point FFTs and/or autocorrelation operations may be implemented using Very Large Scale Integration (VLSI) technologies, Digital Signal Processors (DSPs) and/or other modern technologies, a receiver of an interceptor may be configured to perform signal Detection, Identification, Interception and/or Exploitation (D/I/I/E) based on cyclic feature detection processing.
Given the potential limitation(s) of the radiometric approach and the potential advantage(s) of cyclic feature detection technique(s) it is reasonable to expect that a sophisticated interceptor may be equipped with a receiver based on cyclic feature detection processing. It is, therefore, of potential interest and potential importance to develop communications systems capable of communicating information devoid of cyclostationary properties/signatures to thereby render cyclic feature detection processing by an interceptor substantially ineffective.
FIG. 1 illustrates embodiments of generating a communications alphabet comprising M distinct pseudo-random, non-cyclostationary, orthogonal and/or orthonormal waveforms. As illustrated in FIG. 1, responsive to a “key” input (such as, for example, a TRANsmissions SECurity (TRANSEC) key input, a COMMunications SECurity (COMMSEC) key input and/or any other key input), a Pseudo-Random Waveform Generator (PRWG) may be used to generate a set of M distinct pseudo-random waveforms, which may, according to some embodiments of the invention, represent M ensemble elements of a Gaussian-distributed random (or pseudo-random) process. The M distinct pseudo-random waveforms (i.e., the M ensemble elements) may be denoted as {S(t)}={S1(t), S2(t), . . . , SM(t)}; 0≦t≦τ. The set of waveforms {S(t)} may be a band-limited set of waveforms having a one-sided bandwidth less than or equal to B Hz. As such, a number of distinct orthogonal and/or orthonormal waveforms that may be generated from the set {S(t)} may, in accordance with established Theorems, be upper-bounded by CτB, where C≧2 (see, for example, P. M. Dollard, “On the time-bandwidth concentration of signal functions forming given geometric vector configurations,” IEEE Transactions on Information Theory, IT-10, pp. 328-338, October 1964; also see H. J. Landau and H. O. Pollak, “Prolate spheroidal wave functions, Fourier analysis and uncertainty—III: The dimension of the space of essentially time-and band-limited signals,” Bell System Technical Journal, 41, pp. 1295-1336, July 1962). It will be understood that in some embodiments of the present invention, the key input may not be used and/or may not exist. In such embodiments, one or more Time-of-Day (TOD) values may be used instead of the key input. In other embodiments, a key input and one or more TOD values may be used. In still other embodiments, yet other values may be used.
In accordance with some embodiments of the present invention, the jth element of the set of waveforms {S(t)}, Sj(t); j=1, 2, . . . , M; may be generated by a respective jth PRWG in response to a respective jth key input and/or TOD value, as illustrated in FIG. 2. In some embodiments according to FIG. 2, each of the PRWG is the same PRWG and each key differs relative to each other key. In other embodiments, each key is the same key and each PRWG differs relative to each other PRWG. In further embodiments of FIG. 2, each key differs relative to each other key and each PRWG also differs relative to each other PRWG. Other combinations and sub-combinations of these embodiments may be provided. In still other embodiments, a single PRWG and a single key may be used to generate a “long” waveform SL(t) which may be segmented into M overlapping and/or non-overlapping components to form a set of waveforms {S(t)}, as illustrated in FIG. 3. Note that any τ-sec. segment of SL(t) may be used to define S1(t). Similarly, any τ-sec. segment of SL(t) may be used to define S2(t), with possibly the exception of the segment used-to define S1(t), etc. The choices may be predetermined and/or based on a key input.
In some embodiments of the invention, a new set of waveforms {S(t)} may be formed periodically, non-periodically, periodically over a first time interval and non-periodically over a second time interval and/or periodically but with a jitter imposed on a periodicity interval, responsive one or more TOD values that may, for example, be derived from processing of Global Positioning System (GPS) signals, and/or responsive to a transmission of a measure of at least one of the elements of {S(t)}. In some embodiments, a processor may be operatively configured as a background operation, generating new sets of waveforms {S(t)}, and storing the new sets of waveforms {S(t)} in memory to be accessed and used as needed. In further embodiments, a used set of waveforms {S(t)} may be discarded and not used again, whereas in other embodiments, a used set of waveforms {S(t)} may be placed in memory to be used again at a later time. In some embodiments, some sets of waveforms {S(t)} are used once and then discarded, other sets of waveforms {S(t)} are not used at all, and still other sets of waveforms {S(t)} are used more than once. Finally, in some embodiments, the waveform duration τ and/or the waveform bandwidth B may vary between different sets of waveforms, transmission intervals and/or elements of a given set of waveforms.
Still referring to FIG. 1, the set of substantially continuous-time waveforms {S(t)}={S1(t), S2(t), . . . , SM(t)}; 0≦t≦τ; may, according to some embodiments of the present invention, be transformed from a substantially continuous-time representation to a substantially discrete-time representation using, for example, one or more Analog-to-Digital (A/D) converters and/or one or more Sample-and-Hold (S/H) circuits, to generate a corresponding substantially discrete-time set of waveforms {S(nT)}={S1(nT), S2(nT), . . . , SM(nT)}; n=1, 2, . . . , N; nT≦τ. A Gram-Schmidt orthogonalizer and/or orthonormalizer and/or any other orthogonalizer and/or orthonormalizer, may then be used, as illustrated in FIG. 1, to generate a set of waveforms {U(nT)}={U1(nT), U2(nT), . . . , UM(nT)}; n=1, 2, . . . , N; nT≦τ that are orthogonal and/or orthonormal therebetween. The GSO and/or other orthogonalization and/or orthonormalization procedure(s) are known to those skilled in the art and need not be described further herein (see, for example, Simon Haykin, “Adaptive Filter Theory,” at 173, 301, 497; 1986 by Prentice-Hall; and Bernard Widrow and Samuel D. Stearns “Adaptive Signal Processing,” at 183; 1985 by Prentice-Hall, Inc.).
It will be understood that the sampling interval T may be chosen in accordance with Nyquist sampling theory to thereby preserve by the discrete-time waveforms {S(nT)} all, or substantially all, of the information contained in the continuous-time waveforms {S(t)}. It will also be understood that, in some embodiments of the invention, the sampling interval T may be allowed to vary over the waveform duration τ, between different waveforms of a given set of waveforms and/or between different sets of waveforms. Furthermore, the waveform duration τ may be allowed to vary, in some embodiments, between different waveforms of a given set of waveforms and/or between different sets of waveforms. In some embodiments of the present invention, {S(nT)}={S1(nT), S2(nT), . . . , SM(nT)}; n=1, 2, . . . , N; nT≦τ may be generated directly in a discrete-time domain by configuring one or more Pseudo-Random Number Generators (PRNG) to generate S1(nT); n=1, 2, . . . , N; nT≦τ for each value of j (j=1, 2, . . . , M). The one or more PRNG may be configured to generate Sj(nT); n=1, 2, . . . , N; j=1, 2, . . . , M, based upon at least one statistical distribution. In some embodiments according to the present invention, the at least one statistical distribution comprises a Normal/Gaussian, Bernoulli, Geometric, Pascal/Negative Binomial, Exponential, Erlang, Weibull, Chi-Squared, F, Student's t, Rise, Pareto, Poisson, Binomial, Uniform, Gamma, Beta, Laplace, Cauchy, Rayleigh, Maxwell and/or any other distribution. In further embodiments, the at least one statistical distribution is truncated. In still further embodiments, the at least one statistical distribution depends upon a value of the index j and/or n (i.e., the at least one statistical distribution is a function of (j, n)).
In still further embodiments of the present invention, {S(nT)} may be generated by configuring one or more PRNG to generate real, imaginary and/or complex values that are then subjected to a linear and/or non-linear transformation to generate Sj(nT); n=1, 2, . . . , N; j=1, 2, . . . , M. In some embodiments of the present invention, the transformation comprises a Fourier transformation. In further embodiments, the transformation comprises an inverse Fourier transformation. In still further embodiments, the transformation comprises an Inverse Fast Fourier Transformation (IFFT). The real, imaginary and/or complex values may be based upon at least one statistical distribution. The at least one statistical distribution may comprise a Normal/Gaussian, Bernoulli, Geometric, Pascal/Negative Binomial, Exponential, Erlang, Weibull, Chi-Squared, F, Student's t, Rise, Pareto, Poisson, Binomial, Uniform, Gamma, Beta, Laplace, Cauchy, Rayleigh, Maxwell and/or any other distribution and the at least one statistical distribution may be truncated. In still further embodiments, the at least one statistical distribution depends upon a value of the index j and/or n (i.e., the at least one statistical distribution is a function of (j, n)).
The set {U(nT)}={U1(nT), U2(nT), . . . , UM(nT)}; n=1, 2, . . . , N; NT≦τ, may be used, in some embodiments of the present invention, to define an M-ary pseudo-random and non-cyclostationary alphabet. As illustrated in FIG. 4, an information symbol Ik, occurring at a discrete time k (for example, at t=kτ or, more generally, if the discrete time epochs/intervals are variable, at t=τk), and having one of M possible information values, {I1, I2, . . . , IM}, may be mapped onto one of the M waveforms of the alphabet {U1(nT), U2(nT), . . . , UM(nT)}; n=1, 2, . . . , N; NT≦τ. For example, in some embodiments, if Ik=I2, then during the kth signaling interval the waveform U2(nT) may be transmitted; n=1, 2, . . . , N; NT≦τ. It will be understood that transmitting the waveform U2(nT) comprises transmitting substantially all of the elements (samples) of the waveform U2(nT) wherein substantially all of the elements (samples) of the waveform U2(nT) means transmitting U2(T), U2(2T), . . . , and U2(NT). Furthermore, it will be understood that any unambiguous mapping between the M possible information values of Ik and the M distinct waveforms of the M-ary alphabet, {U1(nT), U2(nT), . . . , UM(nT)}, may be used to communicate information to a receiver (destination) provided that the receiver also has knowledge of the mapping. It will also be appreciated that the ordering or indexing of the alphabet elements and the unambiguous mapping between the M possible information values of Ik and the M distinct waveforms of the M-ary alphabet may be arbitrary, as long as both transmitter (source) and receiver (destination) have knowledge of the ordering and mapping.
In some embodiments of the invention, the information symbol Ik, may be constrained to only two possible values (binary system). In such embodiments of the invention, the M-ary alphabet may be a binary (M=2) alphabet comprising only two elements, such as, for example, {U1(nT), U2(nT)}. In other embodiments of the invention, while an information symbol, Ik, is allowed to take on one of M distinct values (M≧2) the alphabet comprises more than M distinct waveforms, that may, according to embodiments of the invention be orthogonal/orthonormal waveforms, {U1(nT), U2(nT), . . . , UL(nT)}; L>M, to thereby increase a distance between a set of M alphabet elements that are chosen and used to communicate information and thus allow an improvement of a communications performance measure such as, for example, an error rate, a propagations distance and/or a transmitted power level. It will be understood that in some embodiments, the number of distinct values that may be made available to an information symbol to thereby allow the information symbol to communicate one or more bits of information, may be reduced or increased responsive to a channel state such as, for example an attenuation, a propagation distance and/or an interference level. In further embodiments, a number of distinct elements comprising an alphabet may also change responsive to a channel state. In some embodiments, as a number of information symbol states (values) decreases a number of distinct elements comprising an alphabet increases, to thereby provide further communications benefit(s) such as, for example, a lower bit error rate, a longer propagation distance, reduced transmitted power, etc.
It will be understood that at least some conventional transmitter functions comprising, for example, Forward Error Correction (FEC) encoding, interleaving, data repetition, filtering, amplification, modulation, frequency translation, scrambling, frequency hopping, etc., although not shown in FIGS. 1 through 4, may also be used in some embodiments of the present invention to configure an overall transmitter chain. At least some of these conventional transmitter functions may be used, in some embodiments, in combination with at least some of the signal processing functions of FIG. 1 through FIG. 4, to specify an overall transmitter signal processing chain. For example, an information bit sequence may be FEC encoded using, for example, a convolutional encoder, interleaved and/or bit-to-symbol converted to define a sequence of information symbols, {Ik}. The sequence of information symbols, {Ik}, may then be mapped onto a waveform sequence {Uk}, as illustrated in FIG. 4. At least some, and in some embodiments all, of the elements of the waveform sequence {Uk} may then be repeated, at least once, to increase a redundancy measure, interleaved, filtered, frequency translated, amplified and/or frequency-hopped, for example, (not necessarily in that order) prior to being radiated by an antenna of the transmitter. An exemplary embodiment of a transmitter comprising conventional signal functions in combination with at least some of the signal processing functions of FIG. 1 through FIG. 4 is illustrated in FIG. 5.
A receiver (destination) that is configured to receive communications information from a transmitter (source) comprising functions of FIG. 1 through FIG. 4, may be equipped with sufficient information to generate a matched filter bank responsive to the M-ary alphabet {U1(nT), U2(nT), . . . , UM(nT)} of FIG. 4. Such a receiver may be substantially synchronized with one or more transmitters using, for example, GPS-derived timing information. Substantial relative synchronism between a receiver and at least one transmitter may be necessary to reliably generate/update at the receiver the M-ary alphabet functions {U1(nT), U2(nT), . . . , UM(nT)} and/or the matched filter bank to thereby provide the receiver with substantial optimum reception capability.
In some embodiments of the invention, all transmitters and receivers are substantially synchronized using GPS-derived timing information. It will be understood that a receiver may be provided with the appropriate key sequence(s) and the appropriate signal processing algorithms to thereby responsively form and/or update the M-ary alphabet functions and/or the matched filter bank. It will also be understood that a receiver may also be configured with an inverse of conventional transmitter functions that may be used by a transmitter. For example, if, in some embodiments, a transmitter is configured with scrambling, interleaving of data and frequency hopping, then a receiver, may be configured with the inverse operations of de-scrambling, de-interleaving of data and frequency de-hopping. An exemplary embodiment of a receiver, which may correspond to the exemplary transmitter embodiment of FIG. 5, is illustrated in FIG. 6.
FIG. 7 illustrates elements of a communications transmitter according to further embodiments of the invention. As shown in FIG. 7, following conventional operations of Forward Error Correction (FEC) encoding, bit interleaving and bit-to-symbol conversion (performed on an input bit sequence {b} to thereby form an information symbol sequence {Ik}), the information symbol sequence {Ik} is mapped onto a non-cyclostationary waveform sequence {Uk(nT)} using a first M-ary non-cyclostationary orthonormal alphabet (Alphabet 1). An element of {Uk(nT)} may then be repeated (at least once), as illustrated in FIG. 7, using a second M-ary non-cyclostationary orthonormal alphabet (Alphabet 2), interleaved, transformed to a continuous-time domain representation, filtered, amplified (not necessarily in that order) and transmitted. The repeat of an element of {Uk(nT)} may be performed using a different alphabet (Alphabet 2) in order to reduce or eliminate a cyclostationary feature/signature in the transmitted waveform. For at least the same reason, the at least two alphabets of FIG. 7 may be replaced by new alphabets following the transmission of a predetermined number of waveform symbols. In some embodiments, the predetermined number of waveform symbols is one. As stated earlier, a large reservoir of alphabets may be available and new alphabet choices may be made following the transmission of the predetermined number of waveform symbols and/or at predetermined TOD values.
According to some embodiments of the invention, the M-ary non-cyclostationary orthonormal alphabet waveforms may be broadband waveforms as illustrated in FIG. 8. FIG. 8 illustrates a power spectral density of a broadband waveform defining the M-ary non-cyclostationary orthonormal alphabet (such as, for example, waveform SL(t) of FIG. 3), over frequencies of, for example, an L-band (e.g., from about 1525 MHz to about 1660.5 MHz). However, FIG. 8 is for illustrative purposes only and the power spectral density of SL(t) and/or any other set of waveforms used to define the M-ary non-cyclostationary orthonormal alphabet may be chosen to exist over any other frequency range and/or interval(s). In some embodiments, different alphabets may be defined over different frequency ranges/intervals (this feature may provide intrinsic frequency hopping capability). As is further illustrated in FIG. 8 (second trace), certain frequency intervals that warrant protection (or additional protection) from interference, such as, for example, a GPS frequency interval, may be substantially excluded from providing frequency content for the generation of the M-ary non-cyclostationary orthonormal alphabets. It will be appreciated that the transmitter embodiment of FIG. 7 illustrates a “direct synthesis” transmitter in that the transmitter directly synthesizes a waveform that is to be transmitted, without resorting to up-conversion, frequency translation and/or carrier modulation functions. This aspect may further enhance the LPI/LPD/LPE feature(s) of a communications system.
In embodiments of the invention where a bandwidth of a signal to be transmitted by a transmitter (such as the transmitter illustrated in FIG. 7) exceeds a bandwidth limit associated with an antenna and/or other element of the transmitter, the signal may be decomposed/segmented/divided into a plurality of components, each component of the plurality of components having a bandwidth that is smaller than the bandwidth of the signal. Accordingly, a transmitter may be configured with a corresponding plurality of antennas and/or a corresponding plurality of other elements to transmit the plurality of components. Analogous operations for reception may be included in a receiver.
In some embodiments of the invention, a receiver (destination) that is configured to receive communications information from a transmitter (source) comprising the functionality of FIG. 7, may be provided with sufficient information to generate a matched filter bank corresponding to the transmitter waveform set of the M-ary alphabet {U1(nT), U2(nT), . . . , UM(nT)}. Such a receiver may be substantially synchronized with the transmitter using GPS-derived timing information (i.e., TOD). FIG. 9 illustrates elements of such a receiver, according to exemplary embodiments of the present invention. As illustrated in FIG. 9, following front-end filtering, amplification and Analog-to-Digital (A/D) and/or discrete-time conversion of a received waveform, a matched-filter bank, comprising matched filters reflecting the TOD-dependent waveform alphabets used by the transmitter, is used for detection of information. The receiver may have information regarding what waveform alphabet the transmitter may have used as a function of TOD. As such, the receiver, operating in substantial TOD synchronism with the transmitter, may know to configure the matched-filter bank with the appropriate (TOD-dependent) matched filter components to thereby achieve optimum or near optimum signal detection. Following matched-filter detection, symbol de-interleaving and symbol repeat combination, soft decisions of a received symbol sequence may be made, followed by bit de-interleaving and bit decoding, to thereby generate an estimate of a transmitted information bit sequence.
In accordance with some embodiments of the invention, a receiver architecture, such as, for example, the receiver architecture illustrated in FIG. 9, may further configure a matched filter bank to include a “rake” matched filter architecture, to thereby resolve multipath components and increase or maximize a desired received signal energy subject to multipath fading channels. Owing to the broadband nature of the communications alphabets, in accordance with some embodiments of the invention, a significant number of multipath components may be resolvable. Rake matched filter architectures are known to those skilled in the art and need not be described further herein (see, for example, John G. Proakis, “Digital Communications,” McGraw-Hill, 1983, section 7.5 starting at 479; also see R. Price and P. E. Green Jr. “A Communication Technique for Multipath Channels,” Proc. IRE, Vol. 46, pp. 555-570, March 1958).
FIG. 10 illustrates an operational scenario relating to a communications system that may be a covert communications system, in accordance with some embodiments of the present invention, wherein air-to-ground, air-to-air, air-to-satellite and/or satellite-to-ground communications may be conducted. Ground-to-ground communications (not illustrated in FIG. 10) may also be conducted. Modes of communications may be, for example, point-to-point and/or point-to-multipoint. A network topology that is predetermined and/or configured in an ad hoc fashion, in accordance with principles known to those skilled in the art, may be used to establish communications in accordance with any of the embodiments of the invention and/or combinations (or sub-combinations) thereof.
FIGS. 11 through 14 illustrate elements relating to a matched filter and/or a matched filter bank in accordance with exemplary embodiments of the invention, as will be appreciated by those skilled in the art. FIG. 15 further illustrates elements of a transmitter/receiver combination in accordance with further embodiments of the invention. The design and operation of blocks that are illustrated in the block diagrams herein and not described in detail are well known to those having skill in the art.
Embodiments of the present invention have been described above in terms of systems, methods, devices and/or computer program products that provide communications devoid of cyclostationary features. However, other embodiments of the present invention may selectively provide these communications devoid of cyclostationary features. For example, as shown in FIG. 15, if LPI/LPD/LPE and/or minimum interference communications are desired, then non-cyclostationary waveforms may be transmitted. However, when LPI/LPD/LPE and/or minimum interference communications need not be transmitted, cyclostationary waveforms may be used. An indicator may be provided to allow a receiver/transmitter to determine whether cyclostationary or non-cyclostationary waveforms are being transmitted or need to be transmitted. Accordingly, a given system, method, device and/or computer program can operate in one of two modes, depending upon whether LPI/LPD/LPE and/or minimum interference communications are desired, and/or based on other parameters and/or properties of the communications environment.
In still further embodiments of the present invention, a transmitter may be configured to selectively radiate a pseudo-random noise waveform that may be substantially devoid of information and is distributed in accordance with at least one statistical distribution such as, for example, Normal/Gaussian, Bernoulli, Geometric, Pascal/Negative Binomial, Exponential, Erlang, Weibull, Chi-Squared, F, Student's t, Rise, Pareto, Poisson, Binomial, Uniform, Gamma, Beta, Laplace, Cauchy, Rayleigh, Maxwell and/or any other distribution. The at least one statistical distribution may be truncated and the pseudo-random noise waveform may occupy a bandwidth that is substantially the same as a bandwidth occupied by a communications waveform. The transmitter may be configured to selectively radiate the pseudo-random noise waveform during periods of time during which no communications information is being transmitted. This may be used, in some embodiments, to create a substantially constant/invariant ambient/background noise floor, that is substantially independent of whether or not communications information is being transmitted, to thereby further mask an onset of communications information transmission.
It will be understood by those skilled in the art that the communications systems, waveforms, methods, computer program products and/or principles described herein may also find applications in environments wherein covertness may not be a primary concern. Communications systems, waveforms, methods, computer program products and/or principles described herein may, for example, be used to provide short-range wireless communications (that may, in accordance with some embodiments, be broadband short-range wireless communications) in, for example, a home, office, conference and/or business environment while reducing and/or minimizing a level of interference to one or more other communications services and/or systems that may be using the same, substantially the same and/or near-by frequencies as the short-range communications system.
Other applications of the communications systems, waveforms, methods, computer program products and/or principles described herein will also occur to those skilled in the art, including, for example, radar applications and/or cellular telecommunications applications.
In a cellular telecommunications application, for example, a cellular telecommunications system, in accordance with communications waveform principles described herein, may be configured, for example, as an overlay to one or more conventional cellular/PCS systems and/or one or more other systems, using the frequencies of one or more licensed and/or unlicensed bands (that may also be used by the one or more conventional cellular/PCS systems and/or the one or more other systems) to communicate with user equipment using broadband and/or Ultra Wide-Band (UWB) waveforms. The broadband and/or UWB waveforms may be non-cyclostationary and Gaussian-distributed, for example, in accordance with the teachings of the present invention, to thereby reduce and/or minimize a level of interference to the one or more conventional cellular/PCS systems and/or to the one or more other systems by the overlay cellular telecommunications system and thereby allow the overlay cellular telecommunications system to reuse the available spectrum (which is also used by the one or more conventional cellular/PCS systems and/or the one or more other systems) to provide communications services to users.
According to some embodiments of the present invention, a cellular telecommunications system that is configured to communicate with user devices using communications waveforms in accordance with the transmitter, receiver and/or waveform principles described herein, is an overlay to one or more conventional cellular/PCS systems and/or to one or more other systems and is using the frequencies of one or more licensed and/or unlicensed bands (also being used by the one or more conventional cellular/PCS systems and/or the one or more other systems). The cellular telecommunications system may be further configured to provide communications preferentially using frequencies of the one or more licensed and/or unlicensed bands that are locally not used substantially and/or are locally used substantially as guardbands and/or transition bands by the one or more conventional cellular/PCS systems and/or the one or more other systems, to thereby further reduce a level of interference between the cellular telecommunications system and the one or more conventional cellular/PCS systems and/or the one or more other systems.
As used herein, the terms “locally not used substantially” and/or “locally used substantially as guardbands and/or transition bands” refer to a local service area of a base station and/or group of base stations and/or access point(s) of the cellular telecommunications system. In such a service area, the cellular telecommunications system may, for example, be configured to identify frequencies that are “locally not used substantially” and/or frequencies that are “locally used substantially as guardbands and/or transition bands” by the one or more conventional cellular/PCS systems and/or the one or more other systems and preferentially use the identified frequencies to communicate bidirectionally and/or unidirectionally with user equipment thereby further reducing or minimizing a measure of interference. While the present invention has been described in detail by way of illustration and example of preferred embodiments, numerous modifications, substitutions and/or alterations are possible without departing from the scope of the invention as described herein. Numerous combinations, sub-combinations, modifications, alterations and/or substitutions of embodiments described herein will become apparent to those skilled in the art. Such combinations, sub-combinations, modifications, alterations and/or substitutions of the embodiments described herein may be used to form one or more additional embodiments without departing from the scope of the present invention.
Embodiments of the present invention have been described above in terms of systems, methods, devices and/or computer program products that provide communication devoid of cyclostationary features. However, other embodiments of the present invention may selectively provide communications devoid of cyclostationary features. For example, as shown in FIG. 16, if LPI/LPD/LPE communications are desired, then non-cyclostationary waveforms may be transmitted. In contrast, when LPI/LPD/LPE communications need not be transmitted, cyclostationary waveforms may be used. An indicator may be provided to allow a receiver to determine whether cyclostationary or non-cyclostationary waveforms are being transmitted. Accordingly, a given system, method, device and/or computer program can operate in one of two modes, depending upon whether LPI/LPD/LPE communications are desired.
The present invention has been described with reference to block diagrams and/or flowchart illustrations of methods, apparatus (systems) and/or computer program products according to embodiments of the invention. It is understood that a block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, and/or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer and/or other programmable data processing apparatus, create means (functionality) and/or structure for implementing the functions/acts specified in the block diagrams and/or flowchart block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the function/act specified in the block diagrams and/or flowchart block or blocks.
The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the block diagrams and/or flowchart block or blocks.
Accordingly, the present invention may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.). Furthermore, the present invention may take the form of a computer program product on a computer-usable or computer-readable storage medium having computer-usable or computer-readable program code embodied in the medium for use by or in connection with an instruction execution system. In the context of this document, a computer-usable or computer-readable medium may be any medium that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.
It should also be noted that in some alternate implementations, the functions/acts noted in the blocks of the block diagrams/flowcharts may occur out of the order noted in the block diagram/flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Moreover, the functionality of a given block of the flowcharts/block diagrams may be separated into multiple blocks and/or the functionality of two or more blocks of the flowcharts/block diagrams may be at least partially integrated.
Next Generation (XG) Chipless Spread-Spectrum Communications (CSSC)
Introduction & Executive Summary
According to some embodiments of a neXt Generation (XG) Chipless Spread-Spectrum Communications (CSSC) system, described further hereinbelow and referred to as “XG-CSSC,” XG-CSSC provides extreme privacy, cognitive radio capability, robustness to fading and interference, communications performance associated with M-ary orthonormal signaling and high multiple-access capacity. XG-CSSC uses spread-spectrum waveforms that are devoid of chipping and devoid of any cyclostationary signature, statistically indistinguishable from thermal noise and able to cognitively fit within any available frequency space (narrow-band, broad-band, contiguous, non-contiguous).
According to some embodiments, XG-CSSC maintains some or all desirable features of classical direct-sequence spread-spectrum communications while providing new dimensions that are important to military and commercial systems. For military communications, XG-CSSC combines M-ary orthonormal signaling with chipless spread-spectrum waveforms to provide extreme covertness and privacy. Military wireless networks whose mission is to gather and disseminate intelligence stealthily, in accordance with Low Probability of Intercept (LPI), Low Probability of Detection (LPD) and Low Probability of Exploitation (LPE) doctrine, may use XG-CSSC terrestrially and/or via satellite. In situations where armed forces face difficult spectrum access issues, XG-CSSC may be used to cognitively and covertly utilize spectrum resources at minimal impact to incumbent users.
Commercially, XG-CSSC may be used to provide opportunistic communications using spectrum that is detected unused. As spectrum usage continues to increase, it may become important to equip networks and user devices with agility to use opportunistically any portion (or portions) of a broad range of frequencies that is/are detected as unused or lightly used. A regime is envisioned wherein primary usage of spectrum and secondary (opportunistic) usage of the same spectrum co-exist on a non-interference, or substantially non-interference, basis.
XG-CSSC Fundamentals:
In accordance with XG-CSSC, a Gram-Schmidt Orthonormalization (GSO) procedure, or any other orthonormalization or orthogonalization procedure, may be applied to a set of “seed” functions, to generate an orthonormal/orthogonal set of waveforms. According to some embodiments, the seed functions may be discrete-time functions, may be constructed pseudo-randomly in accordance with, for example, Gaussian statistics (that may be truncated Gaussian statistics) and in accordance with any desired power spectral density characteristic that may be predetermined and/or adaptively formed based on cognitive radio principles. The GSO operation performed on the seed functions yields a set of Gaussian-distributed orthonormal waveforms. The set of Gaussian-distributed orthonormal waveforms may be used to define a signaling alphabet that may be used to map an information sequence into spread-spectrum waveforms without resorting to chipping of the information sequence.
Referring to FIG. 17, a Power Spectrum Estimator (PSE) may be used to identify frequency content being radiated by other transmitters. This may be accomplished by, for example, subjecting a band of frequencies, over which it is desired to transmit information, to a Fast Fourier Transform (FFT). Responsive to the output of the PSE, a “Water-Filling Spectrum Shape” (WFSS) may be formed in the FFT domain. Each element (bin) of the WFSS FFT may be assigned a pseudo-random phase value that may be chosen from (0, 2π). An Inverse Fast Fourier Transform (IFFT) may be applied to the WFSS FFT, as illustrated in FIG. 17, to generate a corresponding Gaussian-distributed discrete-time function. (The technique is not limited to Gaussian distributions. However, the Gaussian distribution is of particular interest since waveforms that have Gaussian statistics and are devoid of cyclostationary features are substantially indistinguishable from thermal noise.) The process may be repeated M times to produce a set of M independent Gaussian-distributed discrete-time functions. Still referring to FIG. 17, the output values of the IFFT may be limited in amplitude, in accordance with a truncated Gaussian distribution, in order to minimize non-linear distortion effects in the amplification stages of the radio.
We let the set of M independent Gaussian-distributed discrete-time functions be denoted by {S(nT)}={S1(nT), S2(nT), . . . , SM(nT)}; n=1, 2, . . . , N. We also let a one-sided bandwidth of {S(nT)} be limited to B Hz. As such, a number of orthogonal waveforms that may be generated from {S(nT)} may, in accordance with established theorems, be upper-bounded by 2.4τB; where τ=NT. (See P. M. Dollard, “On the time-bandwidth concentration of signal functions forming given geometric vector configurations,” IEEE Transactions on Information Theory, IT-10, pp. 328-338, October 1964; also see H. J. Landau and H. O. Pollak, “Prolate spheroidal wave functions, Fourier analysis and uncertainty—III: The dimension of the space of essentially time-and band-limited signals,” BSTJ, 41, pp. 1295-1336, July 1962) Accordingly, {S(nT)} may be subjected to a GSO in order to generate a set of M orthonormal waveforms {U(nT)}≡{U1(nT), U2(nT), . . . , UM(nT)}; n=1, 2, . . . , N.
The set of orthonormal waveforms {U1(nT), U2(nT), . . . , UM(nT)} may be used to define an M-ary orthonormal Gaussian-distributed signaling alphabet whose elements may be used to map an M-ary information sequence {Ik}; Ik{I1, I2, . . . , IM} into a spread-spectrum waveform sequence {Uk(nT)}. (The discrete-time index “k” relates to the signaling interval whereas the discrete-time index “n” refers to the waveform sampling interval. A signaling interval includes N waveform sampling intervals.)
Thus, in accordance with M-ary signaling, a block of L bits (2L=M) may be associated with one element of {U1(nT), U2(nT), . . . , UM(nT)}. Alternatively, since the system comprises M orthogonal channels (as defined by the M orthonormal waveforms) two or more of the orthonormal waveforms may be transmitted simultaneously. In this configuration, each one of the transmitted orthonormal waveforms may be modulated by either “+1” or “−1.”, to reflect a state of an associated bit, thus conveying one bit of information. The following example illustrates a trade off between M-ary orthogonal signaling and binary signaling.
As stated earlier, a number of orthogonal waveforms that may be generated from a set of seed waveforms {S(nT)} is upper-bounded by 2.4τB. Let us assume that each seed waveform is band-limited to B=500 kHz (one-sided bandwidth) and that the signaling interval τ=NT is 1 ms. Thus, M≦2.4τB=2.4*(10−3)*(0.5*106)=1200. Assuming that a number of 1024 of orthonormal waveforms can be constructed, transmitting one orthonormal waveform may relay 10 bits of information. Thus, the M-ary signaling approach may yield a data throughput of 10 kbps (since the signaling interval is 1 ms). Turning now to the binary signaling approach, each one of a plurality of orthonormal waveforms may be modulated by either “+1” or “−1” and transmitted, conveying 1 bit of information. If all 1024 orthonormal waveforms are used, the data throughput may be 1024 bits per τ=10−3 seconds or, 1.024 Mbps. It is seen that the two approaches differ in data throughput by 20 dB but they also differ in Eb/N0 performance. Since the M-ary signaling scheme conveys 10 bits of information per transmitted waveform, while the binary signaling approach conveys one bit of information per transmitted waveform, the M-ary signaling approach enjoys a 10 dB Eb/N0 advantage over the binary signaling approach. (Assuming the probability of error associated with a channel symbol is kept the same for the two signaling schemes.) Thus, whereas the binary signaling scheme may be ideally suited for high-capacity multiple-access military and/or commercial communications, the M-ary signaling scheme may be preferred for certain special operations situations that require extreme covertness and/or privacy.
A receiver that is configured to receive information from the transmitter of FIG. 17, may be equipped with sufficient information to generate a matched filter bank corresponding to the M-ary signaling alphabet {U1(nT), U2(nT), . . . , UM(nT)}. FIG. 18 illustrates key functions of such a receiver. The receiver may further be optimized for fading channels by using “rake” principles. In some embodiments, the receiver may be configured to detect lightly used or unused frequencies and instruct one or more transmitters, via a control channel message, to transmit information over the detected lightly used or unused frequencies. This may be accomplished, in some embodiments of the invention, by configuring the receiver to instruct the one or more transmitters by transmitting frequency-occupancy information, via the control channel, over a predetermined, known to the one or more transmitters, frequency interval, that may contain interference. The predetermined frequency interval may, according to some embodiments, be changing with time responsive to, for example, a Time-of-Day (ToD) value and/or any other input. The frequency-occupancy information may be of relatively low data rate and the predetermined frequency interval may be relatively large in bandwidth so as to provide sufficient processing gain to overcome the interference. In further embodiments of the invention, one or more elements of the M-ary signaling alphabet may be precluded from being used for wireless transmission and this may be used to provide a receiver with error detection and/or error correction capability, as will be appreciated by those skilled in the art.
Preliminary Computer Simulations:
Transmission and reception of information based on XG-CSSC waveforms has been simulated using 16-ary Gaussian-distributed orthonormal alphabets that were constructed in accordance with the principles described herein. FIG. 19(a) is a Power Spectral Density (“PSD”) of a transmitted XG-CSSC carrier in an interference-free environment (or in the presence of interference but without the cognitive function having been activated). In contrast, FIG. 19(b) shows the impact of a radio's cognitive function. As seen from FIG. 19(b), responsive to a detection of interference (indicated in FIG. 19(b) by the red or lighter trace), the PSD of a XG-CSSC carrier is “molded” around the interference. That is, the radio's cognitive function senses the power spectrum distribution of interference and forms a 16-ary signaling alphabet with spectral content that avoids the interference. FIG. 19(c) shows the PSD of the XG-CSSC carrier (of FIG. 19(a) or 19(b)) following square-law detection, illustrating a featureless (non-cyclostationary) nature thereof. By comparison, the first and second traces of FIG. 20 show a PSD of conventional QPSK and a PSD of conventional QPSK following square-law detection, illustrating a cyclostationary signature of conventional QPSK.
FIG. 21 shows a constellation associated with transmission of 20,000 16-ary symbols of the XG-CSSC carrier (of FIG. 19(a) or 19(b)) and FIG. 22 represents a histogram thereof. It is seen from FIGS. 19, 21 and 22 that XG-CSSC transmissions may be substantially featureless and substantially indistinguishable from thermal noise.
Communications performance has also been evaluated. FIG. 23 shows a Bit Error Rate (“BER”) vs. a Symbol Energy to Noise Power Spectral Density (“ES/N0”) for uncoded 16-ary XG-CSSC and uncoded spread-spectrum 16-QAM. (See Donald L. Schilling et al. “Optimization of the Processing Gain of an M-ary Direct Sequence Spread Spectrum Communication System,” IEEE Transactions on Communications, Vol. Com-28, No. 8, August 1980.) Spread-spectrum 16-QAM was chosen for this comparison in order to keep a number of transmitted bits per symbol invariant between the two transmission formats. The ES/N0 advantage of XG-CSSC is apparent, owing to its orthonormal signaling alphabet. It is seen that at 10−2 BER, XG-CSSC enjoys almost a 5 dB advantage over 16-QAM.
FIG. 24 shows BER performance subject to Co-Channel (“CC”) interference. The two systems (16-ary XG-CSSC and spread-spectrum 16-QAM) remain uncoded as in FIG. 23. Two types of CC interference are considered: Wide-Band (“WB”) and Band-Pass (“BP”). The WB interference is modeled as wideband complex Gaussian noise and its PSD spans the entire desired signal spectrum. The BP interference is modeled as band-pass complex Gaussian noise and its PSD spans only 20% of the desired signal spectrum. The power of interference (whether WB or BP) is made equal to the power of the desired signal. In FIG. 24, the cognitive aspect of XG-CSSC is not activated. As a consequence, the interference spectrum and the XG-CSSC spectrum remain co-channel impairing BER performance.
FIG. 25 focuses on the impact of BP interference and displays XG-CSSC system performance with and without cognition. The two systems remain uncoded, as above, and the power of interference remains equal to the power of the desired signal. In the legend of FIG. 25, the term “Adaptive XG-CSSC” indicates that the associated curve represents XG-CSSC with the cognitive feature active. It can be observed that performance of XG-CSSC subject to the cognitive feature (interference avoidance) is indistinguishable from the interference-free case (the blue [square points] and green [star points] curves are on top of each other).
Embodiments of the present invention have been described above in terms of systems, methods, devices and/or computer program products that provide communication devoid of cyclostationary features. However, other embodiments of the present invention may selectively provide communications devoid of cyclostationary features. For example, as shown in FIG. 16 if LPI/LPD/LPE communications are desired, then non-cyclostationary waveforms may be transmitted. In contrast, when LPI/LPD/LPE communications need not be transmitted, cyclostationary waveforms may be used. An indicator may be provided to allow a receiver to determine whether cyclostationary or non-cyclostationary waveforms are being transmitted. Accordingly, a given system, method, device and/or computer program can operate in one of two modes, depending upon whether LPI/LPD/LPE communications are desired.
Privacy and security are paramount concerns for military/government communications systems. Privacy and security are also important concerns for civilian/commercial systems owing to the proliferation of e-commerce and other sensitive information of a personal and/or corporate/business/financial nature. Theft of sensitive and/or proprietary information, for example, by interception of signals, is on the rise and can be very costly to businesses and/or individuals. People often discuss sensitive information over wireless networks providing opportunities for illegal interception and theft of secrets. Accordingly, wireless communications systems/methods/devices that increase privacy and security of information and reduce or eliminate the possibility of unauthorized interception thereof would be valuable to corporations/businesses, government/military, and civilians who desire added privacy and security.
Additional embodiments of systems/methods/devices that increase privacy, security, covertness and/or undetectability of signals, such as wireless signals, will now be presented. At least some of the additional embodiments are based upon a realization that a XG-CSSC technology (i.e., a XG-CSSC-based communications system, method and/or air interface/protocol), as described hereinabove, or one or more variations thereof, may be used alone, or in combination with one or more other conventional technologies (conventional communications systems, methods and/or air interfaces/protocols), to provide the added privacy, security, covertness and/or undetectability of signals, that may be, according to embodiments of the invention, wireless signals. The XG-CSSC technology is described in U.S. application Ser. No. 12/372,354, filed Feb. 17, 2009, entitled Wireless Communications Systems and/or Methods Providing Low Interference, High Privacy and/or Cognitive Flexibility, and in the U.S. and International Applications cited and incorporated therein by reference and assigned to the Assignee of the present Application (EICES Research, Inc.) as well as in the Provisional Applications cited and incorporated therein by reference and assigned to the Assignee of the present Application, all of which are incorporated herein by reference in their entirety as if set forth fully herein.
Further, the XG-CSSC technology may include aspects/embodiments, in part or in whole, as described in U.S. application Ser. No. 12/748,931, filed Mar. 29, 2010, entitled Increased Capacity Communications for OFDM-Based Wireless Communications Systems/Methods/Devices, and in the U.S. and International Applications cited and incorporated therein by reference and assigned to the Assignee of the present Application (EICES Research, Inc.) as well as in the Provisional Applications cited and incorporated therein by reference and assigned to the Assignee of the present Application, all of which are incorporated herein by reference in their entirety as if set forth fully herein. It will be understood that the term “XG-CSSC technology” as used herein refers to any type of communications (wireless or otherwise) using a waveform, system, method, air interface and/or protocol that is based upon and/or uses a pseudo-randomly generated signaling alphabet and wherein the communications can comprise a reduced cyclostationary signature, a reduced detectability feature and/or increased privacy/security/covertness compared to conventional waveforms/technologies of, for example, TDM/TDMA, CDM/CDMA, FDM/FDMA, OFDM/OFDMA, GSM, WiMAX and/or LTE. Further, it will be understood that the term “conventional waveforms/technologies” as used herein refers to communications using a waveform, system, method, air interface and/or protocol that is not based upon and/or does not use a pseudo-randomly generated signaling alphabet.
Accordingly, a user device may be configured to include a XG-CSSC mode, comprising a XG-CSSC technology/air interface, and at least one additional mode (technology/air interface), such as, for example, a LTE (Long Term Evolution)-based technology/air interface. A user of such a device who desires the added privacy, security, covertness and/or undetectability of signals may elect to activate/use the XG-CSSC mode of the device by providing, for example, a key-pad command and/or a voice command to the device. In some embodiments, instead of the above or in combination with the above, the XG-CSSC mode of the device may be activated responsive to at least a time value, position value, proximity state, velocity, acceleration, a biometric value (that may be a biometric value associated with the user of the device and/or some other entity) and/or signal strength value (as may be sensed by the device and/or other device, such as, for example, an access point). Following activation of the XG-CSSC mode, the user device may be configured to establish communications with a base station and/or access point using the XG-CSSC mode, while refraining from using, at least for some elements/portions of the communications, the at least one additional technology and/or air interface.
It will be understood that the base station and/or access point (which, in some embodiments may be a femtocell) is/are also configured to include a XG-CSSC mode. Also, it will be understood that establishing communications between the user device and the base station and/or access point using a XG-CSSC mode may be more expensive to the user (i.e., may be offered by a service provider at a premium) compared to establishing communications between the user device and the base station and/or access point using the at least one additional technology and/or air interface. It will further be understood that the service provider may not charge a premium for XG-CSSC mode communications between an access point (e.g., femtocell) and a user device, thus encouraging access point deployments and usage, for example, to relieve capacity bottlenecks within conventional wireless infrastructure of the service provider.
Accordingly, in some embodiments, the user device may be configured to preferentially use the XG-CSSC mode responsive to a classification/sensitivity and/or a privacy level of information to be communicated being above a predetermined threshold and/or responsive to a first time value, a first position, a first proximity state, a first velocity, a first acceleration, a first biometric measurement and/or a first signal strength and to preferentially use the at least one additional technology or air interface responsive to the classification/sensitivity and/or privacy level of information to be communicated being equal to or below the predetermined threshold and/or responsive to a second time value, a second position, a second proximity state, a second velocity, a second acceleration, a second biometric measurement and/or a second signal strength. In multimedia communications, for example, wherein sensitive as well as non-sensitive information may need to be communicated simultaneously and/or sequentially, the user device may be configured to communicate the sensitive information using the XG-CSSC mode and to use the at least one additional technology and/or air interface (simultaneously with using the XG-CSSC mode and/or at different times) to communicate the non-sensitive information. It will be understood that the term “XG-CSSC mode” as used herein refers to communications using a waveform, system, method, air interface and/or protocol that is based upon and/or uses a pseudo-randomly generated signaling alphabet and wherein the communications can comprise a reduced cyclostationary signature, a reduced detectability feature and/or increased privacy/security/covertness compared to conventional waveforms, systems and/or methods of, for example, TDM/TDMA, CDM/CDMA, FDM/FDMA, OFDM/OFDMA, GSM, WiMAX and/or LTE.
As has been stated earlier, a signaling alphabet that may be associated with the XG-CSSC mode (i.e., an M-ary signaling alphabet comprising at least two elements that are pseudo-randomly generated and may be orthogonal therebetween) may be determined pseudo-randomly responsive to a statistical distribution based upon a key (seed) and/or a Time-of-Day (“ToD”) value. In some embodiments, the key may be a network defined key (e.g., defined/determined by an element/unit of the service provider) and may be used by one or more base stations of the network and by a plurality of user devices associated therewith. In other embodiments, instead of the above, or in combination with the above, a key that is associated with a user device may be defined (or determined) by a user of the user device and/or by the user device. In further embodiments, a user device may include a network defined key and a user defined key.
In order for the user (and/or the user device) to define the user defined key, the user (and/or the user device) may access a web site, that may be associated with the service provider, and access an individual account associated with the user (and/or the user device) by providing, for example, an on-line ID, a user name and/or a password. Following authentication of the user (and/or user device) by the web site, the user (and/or the user device) may define the user defined key by specifying, for example, a sequence of letters, numbers and/or other characters. The web site may be connected (wirelessly or otherwise) to a network element thus providing the user defined key to one or more access points and/or one or more base stations of the network. Also, the user may have to provide the same user defined key to the user device. Accordingly, the network and the user device may, responsive to the same key, derive the same signaling alphabet and may thus be able to communicate via the XG-CSSC mode (i.e., the same XG-CSSC mode). In some embodiments, the signaling alphabet may only/solely be based upon the user defined key. In other embodiments, the signaling alphabet may be based upon a combination of the user defined key and the network defined key. In further embodiments, the signaling alphabet may only/solely be based upon the network defined key. The user defined key may be changed by the user and/or by the user device (that is, may be re-defined by the user and/or by the user device) as often as the user desires thus providing additional security and privacy to the user. In some embodiments, upon accessing said web site and upon accessing said individual account associated with the user/user device, the web site may be configured to offer a key (i.e., a new unique key) to be used by the user/user device as a new “user defined” key. The user/user device may accept the offer or decline it, and, in the event the offer is declined, the user/user device may proceed to define the user defined key as described earlier. In the event the offer is accepted, the user may have to insert/activate the new “user defined” key provided by the web site into the user device.
In some embodiments, a forward link, from an access point and/or a base station to the user device, may be based upon the network defined key while a return link, from the user device to an access point and/or a base station, may be based upon the user defined key. In further embodiments, a system element (e.g., an access point and/or a base station) may relay to a first user device a user defined key that is associated with a second user device and may require/instruct the first user device to initiate communications using the user defined key of the second user device or to hand-over communications from communications that are based upon a first key being used by the first user device to communications that are based upon the user defined key of the second user device. In some embodiments, said relay to a first user device a user defined key that is associated with a second user device may occur responsive to an orientation and/or distance of the first device relative to the second device. In further embodiments, the second user device, whose user defined key is relayed to the first user device, is selectively and/or preferentially chosen from a group of user devices that are authorized to communicate with an access point that the first user device may also be authorized to communicate with. Said relay to a first user device a user defined key that is associated with a second user device may take place using communications that are based upon the first key that is being used by the first user device (the first key being a network defined key and/or a user defined key of the first device).
It will be understood that any of the principles/embodiments (in whole or in part) described above regarding network defined and/or user defined keys may relate to an XG-CSSC mode and/or to one or more other conventional waveforms/modes such as, for example, TDM/TDMA, CDM/CDMA, FDM/FDMA, OFDM/OFDMA, GSM, WiMAX and/or LTE, in order to provide user defined and/or network defined encryption and/or data scrambling therein and increase a privacy/security level thereof. Further, it will be understood that an XG-CSSC mode may comprise the user defined key and/or the network defined key, as already described, for forming the signaling alphabet, and may also comprise a “special” user defined key and/or a “special” network defined key, that differs from the user defined key and/or network defined key already discussed above, for encryption/scrambling of data prior to transmission thereof. The special user/network defined key may be defined by the user/network and/or user device along the same lines as discussed earlier for the user/network defined key but, wherein the user/network defined key may be shared by a plurality of devices, as already discussed above, the special user/network defined key may not be shared. Accordingly, in some embodiments of the present invention first and second devices may be communicating with a given base station and/or a given access point (e.g., femtocell) using the same user/network defined key for constructing/generating the signaling alphabets thereof and may be communicating with the given base station and/or given access point using respective first and second different special user/network defined keys for encryption and/or scrambling of data.
FIGS. 26 and 27 illustrate additional embodiments of the present invention. As is illustrated in FIG. 26, a wireless network may comprise a plurality of base stations, only one of which is illustrated in FIG. 26, and a plurality of access points, installed in homes, offices and in/at any other place, as deemed necessary/desirable, to provide additional privacy/security while off-loading capacity from one or more near-by base stations (only one access point of the plurality of access points is illustrated in FIG. 26). A user device (e.g., a radioterminal; first user device of FIG. 26) may be configured to detect proximity to an access point, such as the access point illustrated in FIG. 26, and establish communications preferentially with the access point while refraining from communicating with a base station even though the user device is within a service region of the base station (such as the base station illustrated in FIG. 26) and can communicate with that base station. The first user device illustrated in FIG. 26 may further be configured, according to embodiments of the invention, to establish communications preferentially with the access point and to preferentially use the XG-CSSC mode to communicate with the access point. In some embodiments, the first user device is configured to use the network defined key and/or the user defined key corresponding to the first user device. In other embodiments, the first user device is provided (by the wireless network via the access point and/or the base station) a user defined key of another user device that may be already engaged in communications with an access point and/or a base station or is getting ready to engage in communications with an access point and/or base station. A user device (e.g., a radioterminal) may be configured to detect proximity to an access point by, for example, detecting a signal being radiated by the access point and/or by detecting a position that the user device has reached. It will be understood that in the event that communicating preferentially with the access point is not possible, due to a network malfunction and/or other reason, then the user device may be configured to communicate with the base station.
FIG. 26 also illustrates a second user device that is not proximate to the access point and/or is not allowed to communicate with the access point (e.g., the access point is privately owned and has not provided access to the second user device). Accordingly, the second user device is configured to communicate with the base station and may do so by using one of the conventional air interface standards/protocols (such as an LTE mode, as is illustrated in FIG. 26) if the information that is being communicated has not been deemed sensitive, and to communicate with the base station using the XG-CSSC mode if the information that is being communicated has been deemed sensitive and needs a higher level of protection and/or privacy. In some embodiments, a first portion of the information to be communicated may be deemed sensitive, requiring extra protection, while a second portion of the information to be communicated may not be deemed sensitive. Accordingly, in some embodiments, the first portion of the information is communicated using the XG-CSSC mode while the second portion of the information is communicated, concurrently with the first portion or otherwise, using a mode other than XG-CSSC (e.g., LTE, WiMAX, GSM, etc.). Providing access of a user device to an access point comprises, according to some embodiments, providing to the access point an identity of the user device. The identity of the user device may be provided to the access point manually by interacting directly with the access point and/or remotely by providing the identity of the user device to a web site (e.g., along the lines discussed earlier in connection with providing the user defined key) and then having the web site, which is connected to the access point, provide the identity of the user device to the access point. Similarly, a user device may be deleted from having access to an access point by either manually interacting with the access point and deleting/erasing the identity of the user device from a memory of the access point and/or by doing so remotely via the web site that is connected to the access point.
Whether a user device is communicating with the access point and/or with the base station (wherein the “and” part of the immediately preceding “and/or” may be occurring in order to provide diversity, added communications link robustness and/or a “make before break” connection in handing-over communications from the access point to the base station or vice versa) the user device, the base station and/or the access point may be configured to initiate and implement a hand-over from communications that are based upon the XG-CSSC mode and a first key to communications that are based upon the XG-CSSC mode and a second key, wherein the first key is at least one of: a user defined key relating to the user device, a user defined key relating to another user device and a network defined key; and wherein the second key differs from the first key.
Referring now to FIG. 27, additional embodiments of the present invention will be described. FIG. 27 illustrates four user devices communicating with a base station. The user devices are labeled “1,” “2,” “3” and “4,” respectively, wherein user devices 1 and 2 (indicated as “group 1” in FIG. 27) are proximate therebetween and user devices 3 and 4 (indicated as group 2 in FIG. 27) are proximate therebetween but are not proximate to user devices 1 and 2. Accordingly, responsive to a distance between group 1 and group 2 approaching and/or exceeding a predetermined value, the base station may be configured, according to some embodiments, to communicate with group 1 using a first antenna pattern and to communicate with group 2 using a second antenna pattern that is substantially different than the first antenna pattern, as illustrated in FIG. 27. Antenna pattern discrimination may thus be provided to group 1 and to group 2, reducing a level of interference therebetween and allowing reuse of resources (frequencies, keys, alphabet elements) between the two groups. It will be understood that the number of groups being served by a base station (or a base station sector) may be more than two and a number of user devices per group may exceed two or be less than two (i.e., one). The antenna patterns that are illustrated in FIG. 27 may be formed by the base station using any one of the principles/teachings/embodiments (in whole or in part) of U.S. patent application Ser. No. 12/748,931, filed Mar. 29, 2010, entitled Increased Capacity Communications for OFDM-Based Wireless Communications Systems/Methods/Devices, which is hereby incorporated herein by reference in its entirety as if set forth fully herein, including all references and definitions cited therein.
Still referring to FIG. 27, user device 1, communicating with the base station via link 1, and user and user device 2, communicating with the base station via link 2, may be communicating with the base station concurrently and co-frequency therebetween while relying on alphabet element discrimination (e.g., code discrimination) to maintain a level of interference therebetween at or below an acceptable level. Each one of the wireless communications links that are established and served by the first antenna pattern, link 1 and link 2, may be using (may have been allocated) different, substantially orthogonal, alphabet elements of a XG-CSSC mode, wherein the XG-CSSC mode may be based upon a network defined key and/or a user defined key (as described earlier). Accordingly, a signaling alphabet of the XG-CSSC mode, based upon a network/user defined key and a statistical distribution, comprising a plurality of orthogonal waveform elements, may be distributed by the base station over a plurality of links (e.g., link 1 and link 2) that are being served by a common antenna pattern and do not/cannot rely upon antenna pattern discrimination for acceptable performance. That is, the base station may allocate at least a first element of the plurality of orthogonal waveform elements of the signaling alphabet to, for example, link 1 while allocating at least a second element of the plurality of orthogonal waveform elements to link 2. Similar arguments hold relative to the user devices of group 2 communicating with the base station via links 3 and 4 of the second antenna pattern, as is illustrated in FIG. 27.
The base station(s), access point(s) and/or mobile device(s) that have been discussed/illustrated herein and/or in the references provided herein may be configured, according to embodiments of the present invention, to execute a handover during a communications session between a first signaling alphabet that is associated with a first key and a second signaling alphabet of a second key, responsive to a physical orientation between at least two mobile devices and/or responsive to a level of interference. We stress that by using pseudo-randomly generated signaling alphabets to provide communications (wireless and/or wireline), an extra level of encryption/scrambling is provided that is over and above the conventional encryption/scrambling that is provided at the bit level. Accordingly, embodiments of the present invention provide what may be termed “concatenated” encryption/scrambling, at the bit level and at the signaling alphabet level. Each one of these two encryption/scrambling components may be based upon a user defined key and/or a network defined key.
In additional embodiments of the present invention, a system/method such as that illustrated in FIG. 17 (or a variation thereof), that may comprise performing a FFT and a IFFT in order to generate an M-ary signaling alphabet, may be combined (in whole or in part) with a system/method such as that illustrated in FIG. 5 (or a variation thereof). It will be appreciated by those skilled in the art that the “I” and/or “Q” output signals of the block labeled “Symbol to Waveform Mapping” of FIG. 17 may correspond to the output signal of the block labeled “Bit-to-Symbol Conversion” of FIG. 5 and/or to the input signal of the block labeled “Symbol Repeat” of FIG. 5. It will be understood that the blocks of FIG. 5 that are labeled “Symbol Repeat” and/or “Symbol Interleaver” may be bypassed in some embodiments. Accordingly, in some embodiments, said “I” and/or “Q” output signals (or a variant thereof) may be used as an input to the “MODULATOR” of FIG. 5. In some embodiments, the “I” and/or “Q” output signals (or a variant thereof) may be subjected to a FFT (or a IFFT) before being presented to the “MODULATOR” of FIG. 5, whereby a frequency-domain representation thereof is used by the “MODULATOR” of FIG. 5. This may reduce a peak-to-average ratio of a signal to be amplified and transmitted.
It will be understood that generating pseudo-randomly a communications alphabet, as has been discussed hereinabove, may also be applied to a system/method wherein the communications alphabet comprises a constellation of points and not a set of functions (time-domain and/or frequency-domain functions).
Finally, those skilled in the art will appreciate that by leaving some elements and/or dimensions of a communications alphabet un-utilized for transmission of data, thus giving-up capacity, BER performance may be improved by increasing a size of a decision space that may be associated with a correct decision at a receiver. For example, in QPSK, if the constellation points of the second and fourth quadrants, were to be left un-utilized for transmission of data, the decision space for a correct decision at a receiver would grow from one fourth of the two-dimensional plane to one half of the two-dimensional plane.
The present invention has been described with reference to block diagrams and/or flowchart illustrations of methods, apparatus (systems) and/or computer program products according to embodiments of the invention. It is understood that a block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, and/or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer and/or other programmable data processing apparatus, create means (functionality) and/or structure for implementing the functions/acts specified in the block diagrams and/or flowchart block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the function/act specified in the block diagrams and/or flowchart block or blocks.
The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the block diagrams and/or flowchart block or blocks.
Accordingly, the present invention may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.). Furthermore, the present invention may take the form of a computer program product on a computer-usable or computer-readable storage medium having computer-usable or computer-readable program code embodied in the medium for use by or in connection with an instruction execution system. In the context of this document, a computer-usable or computer-readable medium may be any medium that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.
It should also be noted that in some alternate implementations, the functions/acts noted in the blocks of the block diagrams/flowcharts may occur out of the order noted in the block diagram/flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Moreover, the functionality of a given block of the flowcharts/block diagrams may be separated into multiple blocks and/or the functionality of two or more blocks of the flowcharts/block diagrams may be at least partially integrated.
In the specification and the Figures thereof, there have been disclosed embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation; the scope of the invention being set forth in the following claims.

## Claims

1. A mobile device comprising a processor that is configured to control the mobile device to perform operations comprising:
communicating using a first communications mode comprising a first level of security/privacy and a first wireless communications link that is based upon radio frequency emissions comprising a first air interface, a first power level, a first cyclostationary signature and a first detectability measure that is based upon the first power level and the first cyclostationary signature;
communicating using a second communications mode comprising a second level of security/privacy that is greater than the first level of security/privacy and a second wireless communications link that is based upon radio frequency emissions comprising a second power level that is less than the first power level, a second air interface that differs from the first air interface, a second cyclostationary signature that differs from the first cyclostationary signature and comprises a reduction relative to the first cyclostationary signature and a second detectability measure that is less than the first detectability measure based upon the second power level being less than the first power level and based upon the second cyclostationary signature comprising said reduction relative to the first cyclostationary signature;
using the first communications mode to communicate information that is associated with the first level of security/privacy while refraining from using the second communications mode to communicate information that is associated with the first level of security/privacy; and
using the second communications mode to communicate information that is associated with the second level of security/privacy while refraining from using the first communications mode to communicate information that is associated with the second level of security/privacy;
wirelessly communicating with a base station, at a first distance from the base station, using the first communications mode comprising the first level of security/privacy; and
wirelessly communicating with an access point, at a second distance from the access point that is less than the first distance, using the second communications mode comprising the second level of security/privacy that is greater than the first level of security/privacy, responsive to a proximity condition having been satisfied by the mobile device relative to the access point.

2. The mobile device according to claim 1, wherein the processor is further configured to control the mobile device to perform further operations comprising:
concurrently using the first communications mode and the second communications mode to communicate information responsive to the information comprising said first level of security/privacy and said second level of security/privacy.

3. The mobile device according to claim 1, wherein the processor is further configured to control the mobile device to perform further operations comprising:
communicating with the base station and with the access point by using respective first and second signaling alphabets comprising a plurality of waveforms that are orthogonal therebetween.

4. A communications method comprising:
communicating using a first communications mode comprising a first level of security/privacy and a first wireless communications link that is based upon radio frequency emissions comprising a first air interface, a first power level, a first cyclostationary signature and a first detectability measure that is based upon the first power level and the first cyclostationary signature;
communicating using a second communications mode comprising a second level of security/privacy that is greater than the first level of security/privacy and a second wireless communications link that is based upon radio frequency emissions comprising a second power level that is less than the first power level, a second air interface that differs from the first air interface, a second cyclostationary signature that differs from the first cyclostationary signature and comprises a reduction relative to the first cyclostationary signature and a second detectability measure that is less than the first detectability measure based upon the second power level being less than the first power level and based upon the second cyclostationary signature comprising said reduction relative to the first cyclostationary signature;
using the first communications mode to communicate information that is associated with the first level of security/privacy while refraining from using the second communications mode to communicate information that is associated with the first level of security/privacy; and
using the second communications mode to communicate information that is associated with the second level of security/privacy while refraining from using the first communications mode to communicate information that is associated with the second level of security/privacy;
wirelessly communicating by a mobile device with a base station, at a first distance from the base station, using the first communications mode comprising the first level of security/privacy; and
wirelessly communicating by the mobile device with an access point, at a second distance from the access point that is less than the first distance, using the second communications mode comprising the second level of security/privacy that is greater than the first level of security/privacy, responsive to a proximity condition having been satisfied by the mobile device relative to the access point.

5. The communications method according to claim 4, further comprising:
concurrently using the first communications mode and the second communications mode to communicate information responsive to the information comprising said first level of security/privacy and said second level of security/privacy.

6. The communications method according to claim 4, further comprising:
communicating with the base station and with the access point by using respective first and second signaling alphabets comprising a plurality of waveforms that are orthogonal therebetween.

7. A computer program product comprising:
a non-transitory computer readable storage medium having computer readable program code embodied in the medium, that when executed by a processor of a mobile device controls the mobile device to perform operations comprising:
communicating using a first communications mode comprising a first level of security/privacy and a first wireless communications link that is based upon radio frequency emissions comprising a first air interface, a first power level, a first cyclostationary signature and a first detectability measure that is based upon the first power level and the first cyclostationary signature;
communicating using a second communications mode comprising a second level of security/privacy that is greater than the first level of security/privacy and a second wireless communications link that is based upon radio frequency emissions comprising a second power level that is less than the first power level, a second air interface that differs from the first air interface, a second cyclostationary signature that differs from the first cyclostationary signature and comprises a reduction relative to the first cyclostationary signature and a second detectability measure that is less than the first detectability measure based upon the second power level being less than the first power level and based upon the second cyclostationary signature comprising said reduction relative to the first cyclostationary signature;
using the first communications mode to communicate information that is associated with the first level of security/privacy while refraining from using the second communications mode to communicate information that is associated with the first level of security/privacy; and
using the second communications mode to communicate information that is associated with the second level of security/privacy while refraining from using the first communications mode to communicate information that is associated with the second level of security/privacy; and
wirelessly communicating with a base station, at a first distance from the base station, using the first communications mode comprising the first level of security/privacy; and
wirelessly communicating with an access point, at a second distance from the access point that is less than the first distance, using the second communications mode comprising the second level of security/privacy that is greater than the first level of security/privacy, responsive to a proximity condition having been satisfied by the mobile device relative to the access point.

8. The computer program product according to claim 7, wherein the computer readable program code is further configured to control the mobile device to perform further operations comprising:
concurrently using the communications first mode and the second communications mode to communicate information responsive to the information comprising said first level of security/privacy and said second level of security/privacy.

9. The computer program product according to claim 7, wherein the computer readable program code is further configured to control the mobile device to perform further operations comprising:
communicating with the base station and with the access point by using respective first and second signaling alphabets comprising a plurality of waveforms that are orthogonal therebetween.