Abstract:
A wireless telecommunications system that mitigates infrasymbol interference due to Doppler-shift and multipath and enables multiple access in one radio channel. Embodiments of the present invention are particularly advantageous for wireless telecommunications systems that operate in high-mobility environments, including high-speed trains and airplanes.

Description:
STATEMENT OF RELATED APPLICATIONS 
       [0001]    This application claims benefit of:
       U.S. provisional patent application No. 62/316,243, filed on 31 Mar. 2016, entitled “Robust Wireless Telecommunications System,” which is Attorney docket 3079-001pr1, and   U.S. provisional patent application No. 62/316,298, filed on 31 Mar. 2016, entitled “Orthogonal Time Frequency Space,” which is Attorney docket 3079-003 pr1,
 
both of which are incorporated by reference.
       
 
         [0004]    The following patent applications are incorporated by reference:
       U.S. patent application Ser. No. 15/146,987, filed on 5 May 2016, entitled “Wireless Telecommunications System for High-Mobility Applications,” which is Attorney docket 3079-001us1, and   U.S. patent application Ser. No. 15/215,007, filed on 20 Jul. 2016, entitled “Multiple Access in Wireless Telecommunications System for High-Mobility Applications,” which is Attorney docket 3079-002us1, and   United States patent application Ser. No. ______, filed on XX January 2017, entitled “Wireless Telecommunications System for High-Mobility Applications,” which is Attorney docket 3079-003us1.       
 
     
    
     FIELD OF THE INVENTION 
       [0008]    The present invention relates to wireless telecommunications in general, and, more particularly, to a wireless telecommunications system that can detect and mitigate impairments to its radio signals. 
       BACKGROUND OF THE INVENTION 
       [0009]    A radio signal can be impaired as it propagates from a transmitter to a receiver, and the value of a wireless telecommunications system is substantially dependent on how well the system mitigates the effects of those impairments. In some cases, the transmitter can take preventative measures, and in some cases the receiver can take remedial measures. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention is a wireless telecommunications system that avoids some of the costs and disadvantages associated with wireless telecommunications systems in the prior art. For example, the illustrative embodiments of the present invention use a modulated radio-frequency carrier signal to convey data items wirelessly through a radio-frequency environment that comprises natural and man-made radio-frequency carrier signal-path impairments (e.g., objects, etc.) that reflect, refract, diffract, and absorb the modulated radio-frequency carrier signal. 
         [0011]    A consequence of the presence of the signal-path impairments is that the radio receiver receives both direct-path and multipath images of the signal, which can cause infra-symbol and inter-symbol interference. The illustrative embodiments of the present invention are able to discriminate between direct-path and multipath images, which (substantially) prevents infra-symbol interference and enables the remediation of inter-symbol interference. Furthermore, the illustrative embodiments are also particularly effective remediating the effects of Doppler-shift impairments in the radio channel. 
         [0012]    The illustrative embodiment of the present invention modulates the radio-frequency carrier signal with waveforms that are constructed to (substantially) prevent infra-symbol interference and enable the remediation of inter-symbol interference and Doppler-shift impairments. 
         [0013]    As described in detail below, the nature of the waveforms is such that temporally-longer waveforms are better at preventing infra-symbol interference but introduce greater latency to the communications. Therefore, temporally-longer waveforms are less suitable for data items that are less latency tolerant (e.g., bi-directional voice communications, etc.) but more acceptable for data items that are high latency tolerant (e.g., broadcast uni-directional television, etc.). Temporally-longer waveforms are also advantageous as pilot signals and to discover the precise nature of the signal-path impairments. 
         [0014]    In contrast, temporally-shorter waveforms are less effective in preventing infra-symbol interference but are more suitable for low latency tolerant data items. The illustrative embodiments of the present invention enables temporally-longer waveforms and temporally-shorter waveforms to be used concurrently in the same communications channel. This is advantageous for several reasons, including but not limited to, the ability of the telecommunications system to adapt on-the-fly the mix of longer and shorter waveforms based on the latency tolerance of the data items queued for transmission. 
         [0015]    Furthermore, embodiments of the present invention enable a plurality of transmitters to simultaneously transmit (radiate) into the same radio channel to a single receiver in such a way that the receiver can separate the individual transmissions and properly associate them with their respective transmitters. This is widely called “multiple access” and is well known in other telecommunications systems (e.g., frequency-division multiple access, time-division multiple access, code-division multiple-access, etc.). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1A  depicts a block diagram of the salient components of wireless telecommunications system  100  in accordance with the illustrative embodiment of the present invention. 
           [0017]      FIG. 1B  depicts a block diagram of the salient components of base station  120  in accordance with the illustrative embodiment of the present invention. 
           [0018]      FIG. 1C  depicts a block diagram of the salient components of wireless terminal  130 - a , wherein aε{1, 2}, in accordance with the illustrative embodiment of the present invention. 
           [0019]      FIG. 2 a    depicts a flowchart of the salient tasks performed by base station  120 , wireless terminal  130 - 1 , and wireless terminal  130 - 2  in accordance with the illustrative embodiment of the present invention. 
           [0020]      FIG. 2 b    depicts a flowchart of the salient tasks performed by base station  120 , wireless terminal  130 - 1 , and wireless terminal  130 - 2  in the performance of task  201 . 
           [0021]      FIG. 3  depicts a waveform array Φ 1  is based on M1 orthogonal M1-ary stepped-pulse waveforms. 
           [0022]      FIG. 4 a    depicts a plot of where the energy associated with waveform φ 1 (1,1) of waveform array Φ 1 (M1=6, N1=4) beginning at superframe time interval 1 is deposited into a 10 MHz radio channel. 
           [0023]      FIG. 4 b    depicts a plot of where the energy associated with waveform φ 1 (1,1) of waveform array Φ 1  (M1=6, N1=4) beginning at superframe time interval 25 is deposited into a 10 MHz radio channel. 
           [0024]      FIG. 4 c    depicts a plot of where the energy associated with waveform φ 2 (1,1) of waveform array Φ 2  (M2=6, N2=8) beginning at superframe time interval 1 is deposited into a 10 MHz radio channel. 
           [0025]      FIG. 5 a    depicts a plot of where the energy associated with all of the waveforms from waveform arrays Φ 1  assigned to base station  130 - 1  is deposited beginning at superframe time interval 1. 
           [0026]      FIG. 5 b    depicts a plot of where the energy associated with all of the waveforms from waveform arrays Φ 1  assigned to base station  130 - 1  is deposited beginning at superframe time interval 25. 
           [0027]      FIG. 5 c    depicts a plot of where the energy associated with all of the waveforms from waveform arrays Φ 2  assigned to base station  130 - 1  is deposited beginning at superframe time interval 1. 
           [0028]      FIG. 5 d    depicts a plot of where the energy associated with all of the waveforms from waveform arrays Φ 1  assigned to base station  130 - 2  is deposited beginning at superframe time interval 1. 
           [0029]      FIG. 5 e    depicts a plot of where the energy associated with all of the waveforms from waveform arrays Φ 1  assigned to base station  130 - 2  is deposited beginning at superframe time interval 25. 
           [0030]      FIG. 5 f    depicts a plot of where the energy associated with all of the waveforms from waveform arrays Φ 2  assigned to base station  130 - 2  is deposited beginning at superframe time interval 1. 
           [0031]      FIG. 6  depicts a flowchart of the salient tasks associated with task  202 - a , wherein aε{1, 2}, in accordance with the illustrative embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]      FIG. 1A  depicts a block diagram of the salient components of wireless telecommunications system  100  in accordance with the illustrative embodiment of the present invention. Wireless telecommunications system  100  comprises: base station  120 , wireless terminal  130 - 1 , and wireless terminal  130 - 2 , all of which are situated in geographic region  110 . 
         [0033]    In accordance with the illustrative embodiment, base station  120  provides bi-directional wireless telecommunications service to wireless terminal  130 - 1  and wireless terminal  130 - 2 . 
         [0034]    In accordance with the illustrative embodiment, base station  120  provides telecommunications service by exchanging “data items” with wireless terminal  130 - 1  and wireless terminal  130 - 2 , which data items represent sound, images, video, data, and signaling. It will be clear to those skilled in the art how to make and use base station  120 , wireless terminal  130 , and wireless terminal  130 - 2  so that they can de-construct sound, images, video, data, and signaling into data items, and it will be clear to those skilled in the art how to make and use base station  120 , wireless terminal  130 , and wireless terminal  130 - 2  so that they can re-construct sound, images, video, data, and signaling from those data items. 
         [0035]    In accordance with the illustrative embodiment, each data item is represented by a complex number that corresponds to one symbol in a 16 quadrature-amplitude (“16 QAM”) signal constellation modulation scheme. It will be clear to those skilled in the art, however, after reading this disclosure, how to make and use alternative embodiments of the present invention in which each data item corresponds to a symbol in any digital modulation scheme (e.g., frequency-shift keying, amplitude-shift keying, phase-shift keying, etc.). 
         [0036]    In accordance with the illustrative embodiment, wireless telecommunications system  100  comprises one base station and two wireless terminals, but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that comprise any number of base stations and any number of wireless terminals. Furthermore, it will be clear to those skilled in the art how to partition the radio spectrum in an area into radio channels and to assign those channels to the base stations. 
         [0037]    In accordance with the illustrative embodiment, base station  120  is stationary and terrestrial, but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which each base station  120  is mobile or airborne, or mobile and airborne. 
         [0038]    In accordance with the illustrative embodiment, wireless terminal  130 - 1  and wireless terminal  130 - 2  are mobile, but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which each wireless terminal is either mobile or stationary. 
         [0039]    In accordance with the illustrative embodiment, geographic region  110  comprises natural and man-made radio-frequency objects (not shown) that reflect, refract, and diffract the carrier signals that propagate between base station  120  and wireless terminal  130 - 1  and wireless terminal  130 - 2 . Furthermore, some of the radio-frequency objects are stationary (e.g., trees, hills, buildings, etc.) and some are mobile (e.g., trucks, ships, airplanes, etc.). 
         [0040]    In accordance with the illustrative embodiment, the parameters that characterize the signal-path impairments in the radio channel between base station  120  and wireless terminal  130 - 1  and wireless terminal  130 - 2  are dynamic (i.e., change with respect to time). It will be clear to those skilled in the art, after reading this disclosure, how to make and use embodiments of the present invention in which the characteristics of the radio channel and the nature of the signal-path impairments are static (i.e., do not change with respect to time). 
         [0041]    In accordance with the illustrative embodiment, base station  120  and wireless terminal  130 - 1  and wireless terminal  130 - 2  exchange modulated radio-frequency carrier signals in a radio channel that is B=10 MHz wide. It will be clear to those skilled in the art, however, after reading this disclosure, how to make and use alternative embodiments of the present invention in which the radio channel has a different bandwidth (e.g., 2.5 MHz, 5.0 MHz, 12.5 MHz, 15 MHz, 20 MHz, 40 MHz, 80 MHz, etc.). 
         [0042]      FIG. 1B  depicts a block diagram of the salient components of base station  120  in accordance with the illustrative embodiment of the present invention. Base station  120  comprises: encoder  121 , modulator  122 , power amplifier  123 , and antenna  124 , low-noise amplifier  125 , demodulator  126 , decoder  127 , and processor  128 . 
         [0043]    Encoder  121  comprises the hardware and software necessary to compress, encrypt, and add forward error correction to the data items to be transmitted to wireless terminal  130 - 1  and wireless terminal  130 - 2 . It will be clear to those skilled in the art how to make and use encoder  121 . 
         [0044]    Modulator  122  comprises the hardware and software necessary to modulate a radio-frequency carrier signal with the data items from encoder  121  to generate a modulated radio-frequency carrier signal. The construction and operation of modulator  122  is described in detail herein and in the accompanying figures. 
         [0045]    Power amplifier  123  comprises the hardware necessary to increase the power of the modulated radio-frequency carrier signal for transmission via antenna  124 . It will be clear to those skilled in the art how to make and use power amplifier  123 . 
         [0046]    Antenna  124  comprises the hardware necessary to facilitate the radiation of the modulated radio-frequency carrier signal wirelessly through space to wireless terminal  130 - 1  and wireless terminal  130 - 2 . It will be clear to those skilled in the art how to make and use antenna  124 . 
         [0047]    Low-Noise amplifier  125  comprises the hardware necessary to increase the power of the modulated radio-frequency carrier signal received via antenna  124 . It will be clear to those skilled in the art how to make and use low-noise amplifier  125 . 
         [0048]    Demodulator  126  comprises the hardware and software necessary to:
       i. demodulate the modulated radio-frequency carrier signal received by antenna  124 , which is the sum of a first modulated radio-frequency carrier signal transmitted by wireless terminal  130 - 1  and a second modulated radio-frequency carrier signal transmitted by wireless terminal  130 - 2 , and   ii. recover one or more data items transmitted by wireless terminal  130 - 1  that are embodied in the modulated radio-frequency carrier signal and to associate those data items with wireless terminal  130 - 1 , and   iii. recover one or more data items transmitted by wireless terminal  130 - 2  that are embodied in the modulated radio-frequency carrier signal and to associate those data items with wireless terminal  130 - 2 .
 
It will be clear to those skilled in the art, after reading this disclosure, how to make and use demodulator  126 .
       
 
         [0052]    Decoder  127  comprises the hardware and software necessary to decompress, decrypt, and correct the data items transmitted by wireless terminal  130 - 1  and wireless terminal  130 - 2 . It will be clear to those skilled in the art how to make and use decoder  127 . 
         [0053]    Processor  128  comprises the hardware and software necessary to operate base station  120  and to interface with the cellular infrastructure (not shown in  FIG. 1B ). It will be clear to those skilled in the art, after reading this disclosure, how to make and use processor  128 . 
         [0054]      FIG. 1C  depicts a block diagram of the salient components of wireless terminal  130 - a , wherein aε{1, 2}, in accordance with the illustrative embodiment of the present invention. Wireless terminal  130 - a  comprises: encoder  131 - a , modulator  132 - a , power amplifier  133 - a , and antenna  134 - a , low-noise amplifier  135 - a , demodulator  136 - a , decoder  137 - a , processor  138 - a , and user interface  139 - a.    
         [0055]    Encoder  131 - a  comprises the hardware and software necessary to compress, encrypt, and add forward error correction to the data items to be transmitted to base station  120 . It will be clear to those skilled in the art how to make and use encoder  131 - a.    
         [0056]    Modulator  132 - a  comprises the hardware and software necessary to modulate a radio-frequency carrier signal with the data items from encoder  131 - a  to generate a modulated radio-frequency carrier signal. The construction and operation of modulator  132 - a  is described in detail herein and in the accompanying figures. 
         [0057]    Power amplifier  133 - a  comprises the hardware necessary to increase the power of the modulated radio-frequency carrier signal for transmission via antenna  134 - a . It will be clear to those skilled in the art how to make and use power amplifier  133 - a.    
         [0058]    Antenna  134 - a  comprises the hardware necessary to facilitate the radiation of the modulated radio-frequency carrier signal wirelessly through space to base station  120 . It will be clear to those skilled in the art how to make and use antenna  134 - a.    
         [0059]    Low-Noise amplifier  135 - a  comprises the hardware necessary to increase the power of the modulated radio-frequency carrier signals received via antenna  134 - a . It will be clear to those skilled in the art how to make and use low-noise amplifier  135 - a.    
         [0060]    Demodulator  136 - a  comprises the hardware and software necessary to demodulate a modulated radio-frequency carrier signal transmitted by base station  120  to recover the data items transmitted by base station  120 . It will be clear to those skilled in the art, after reading this disclosure, how to make and use demodulator  136 - a.    
         [0061]    Decoder  137 - a  comprises the hardware and software necessary to decompress, decrypt, and correct the data items transmitted by base station  120 . It will be clear to those skilled in the art how to make and use decoder  137 - a.    
         [0062]    Processor  138 - a  comprises the hardware and software necessary to operate wireless terminal  130 - a  and to interface with user interface  139 - a . It will be clear to those skilled in the art, after reading this disclosure, how to make and use processor  138 - a.    
         [0063]    User interface  139 - a  comprises the hardware and software necessary to enable a user (not shown) to interact with wireless terminal  130 - a . It will be clear to those skilled in the art how to make and use user interface  139 - a.    
         [0064]      FIG. 2 a    depicts a flowchart of the salient tasks performed by base station  120 , wireless terminal  130 - 1 , and wireless terminal  130 - 2  in accordance with the illustrative embodiment of the present invention. 
         [0065]    At task  201 , base station  120 , wireless terminal  130 - 1 , and wireless terminal  130 - 2  establish the parameters of two non-identical waveform arrays waveform arrays Φ 1  and Φ 2 —with which they will communicate. In accordance with the illustrative embodiment, base station  120 , wireless terminal  130 - 1 , and wireless terminal  130 - 2  establish the parameters of two non-identical waveforms arrays but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that establish the parameters of any number (e.g., three, four, six, eight, twelve, sixteen, thirty-two, sixty-four, etc.) of non-identical waveform arrays. Task  201  is described in detail below and in the accompanying figures. 
         [0066]    At task  202 , wireless terminal  130 - 1  and wireless terminal  130 - 2  each transmit (radiate) a modulated radio-frequency carrier signal in a radio channel to base station  120  in accordance with the parameters of waveform arrays Φ 1  and Φ 2 . Task  202  is described in detail below and in the accompanying figures. 
         [0067]    At task  203 , base station  120  receives a radio-frequency signal from the radio channel that is a sum of:
       1. the modulated radio-frequency carrier signal radiated by wireless terminal  130 - 1 , plus   2. the multipath images (if any) of the modulated radio-frequency carrier signal radiated by wireless terminal  130 - 1 , plus   3. the modulated radio-frequency carrier signal radiated by wireless terminal  130 - 2 , plus   4. the multipath images (if any) of the modulated radio-frequency carrier signal radiated by wireless terminal  130 - 2 , plus   5. noise.
 
As part of task  203 , base station  120  demodulates and decodes the radio-frequency signal to recover one or more data items transmitted by wireless terminal  130 - 1  (and to associate those data items with wireless terminal  130 - 1 ) and one or more data items transmitted by wireless terminal  130 - 2  (and to associate those data items with wireless terminal  130 - 2 ). It will be clear to those skilled in the art, after reading this disclosure, how to make and use base station  120  to be able to perform task  230 .
       
 
         [0073]    At task  204 , base station  120  transmits one or more data items associated with wireless terminal  130 - 1  and one or more data items associated with wireless terminal  130 - 2  to the cellular infrastructure (e.g., a mobile switching center, etc.), which is not shown in  FIG. 1B . 
         [0074]      FIG. 2 b    depicts a flowchart of the salient tasks performed by base station  120 , wireless terminal  130 - 1 , and wireless terminal  130 - 2  in the performance of task  201 . As part of task  120 , the parameters of waveform arrays Φ 1  and Φ 2  are chosen to:
       i. mitigate infra-symbol interference caused by Doppler-shift and multipath interference in the radio channel, and   ii. enable simultaneous multiple access by both wireless terminal  130 - 1  and wireless terminal  130 - 2  to base station  120 , and   iii. enable wireless terminal  130 - 1  to transmit waveforms of waveform arrays Φ 1  and Φ 2  into the radio channel at the same time (i.e., concurrently) while wireless terminal  130 - 2  transmits different waveforms of waveform arrays Φ 1  and Φ 2  into the same radio channel.       
 
         [0078]    At task  210 , and as is described in detail below, each waveform array Φj is characterized by two parameters Mj and Nj, wherein Mj and Nj are a positive integers greater than one and jε{1, 2} (i.e., waveform array Φ 1  is characterized by parameters M1 and N1 and waveform array Φ 2  is characterized by parameters M2 and N2). 
         [0079]    In accordance with the first illustrative embodiment, M1=M2=6, N1=4, and N2=8 (i.e., M1=M2 and N1≠N2). In accordance with the second illustrative embodiment, M1=16, M2=32, and N1=N2=8 (i.e., M1≠M2 and N1=N2). In accordance with the third illustrative embodiment, M1=16, M2=32, N1=32, and N2=8 (i.e., M1≠M2 and N1≠N2). In all three illustrative embodiments, M1·N1≠M21·12. 
         [0080]    It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention with any combination of values of M1, M2, N1, and N2. Furthermore, it will be clear to those skilled in the art, after reading this disclosure, that embodiments of the present invention are typically simplified and more efficient by making M2 an integral multiple of M1 (e.g., 2×, 3×, 4×, 5×, 6×, 8×, 12×, 16×, 32×, 64×, 128×, etc.). And still furthermore, it will be clear to those skilled in the art, after reading this disclosure, that embodiments of the present invention are typically simplified and more efficient by making N2 an integral multiple of N1 (e.g., 2×, 3×, 4×, 5×, 6×, 8×, 12×, 16×, 32×, 64×, 128×, etc.). 
         [0081]    In accordance with the illustrative embodiment, the parameters of waveform arrays Φ 1  and Φ 2  are established once when base station  120 , wireless terminal  130 - 1 , and wireless terminal  130 - 2  first establish communication, but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which base station  120 , wireless terminal  130 - 1 , and wireless terminal  130 - 2  periodically or sporadically re-establish the parameters of waveform array Φ 1  or waveform array Φ 2  or waveform arrays Φ 1  and Φ 2 . For example and without limitation, base station  120 , wireless terminal  130 - 1 , and wireless terminal  130 - 2  can re-establish the parameters of waveform arrays Φ 1  and Φ 2  when:
       i. the traits of the signal path from change, or   ii. the type of data represented by the data items changes, or   iii. the latency tolerance of the data items changes, or   iv. any combination of i, ii, and iii.       
 
         [0086]    As is described in detail below, waveform arrays Φ 1  and Φ 2  comprise waveforms that convey data items from wireless terminal  130 - 1  or wireless terminal  130 - 2  to base station  120 . In accordance with the illustrative embodiment, wireless terminal  130 - 1  and wireless terminal  130 - 2  convey low-latency tolerant data items using waveform array Φ 1  and high-latency tolerant data items using waveform array Φ 2 . It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which wireless terminal  130 - 1  and wireless terminal  130 - 2  use the waveforms in different waveform arrays for:
       i. different conditions of the signal path from wireless terminal  130 - 1  or wireless terminal  130 - 2  to base station  120 , or   ii. different types of data items, or   iii. different latency tolerance of the data items, or   iv. any combination of i, ii, and iii.       
 
         [0091]    Basic Waveforms—Waveform array Φj is based on an extension of Mj basic waveforms bj( 1 ), . . . , bj(mj), . . . , bj(Mj) that are orthogonal in Mj-dimensional vector space, where Mj is a positive integer greater than 1, and mj is a positive integer in the range mjε{1, . . . , Mj}. 
         [0092]    In accordance with all of the illustrative embodiments, basic waveform bj(mj) is waveform mj of a Mj-ary stepped-pulse waveform scheme, as depicted in  FIG. 3 . In accordance with all of the illustrative embodiments, each pulse is a band-limited raised-cosine pulse but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which each pulse has a different shape. 
         [0093]    Each pulse in basic waveform bj(mj) is band-limited, and, therefore, the duration of each pulse is 1/B seconds, wherein B is the bandwidth of the channel. Furthermore, the centers of adjacent pulses are separated by 1/B seconds. And still furthermore, the total duration of each basic waveform bj(mj) is Mj/B seconds. 
         [0094]    Although all of the illustrative embodiments uses stepped-pulse waveforms as the basic waveforms, it will be clear to those skilled in the art, however, after reading this disclosure, how to make and use alternative embodiments of the present invention in which waveform array Φj is based on any set of Mj orthogonal waveforms, bj( 1 ), . . . , bj(Mj). 
         [0095]    Structure of Waveform ArrayΦ—Waveform array Φj comprises Mj·Nj waveforms that are orthogonal in Mj·Nj-dimensional vector space. The Mj·Nj waveforms of waveform array Φj are denoted φ(1,1), . . . , φj(mj,nj), . . . , φj(Mj,Nj), where nj is a positive integer in the range njε{1, . . . , Nj}. 
         [0096]    Each waveform φj(mj,nj) is the sum of Nj waveforms yj(mj,nj,1), . . . , yj(mj,nj,pj), . . . , yj(mj,nj,Nj). 
         [0097]    Each waveform φj(mj,nj) is identically partitioned into Nj time slots  1 , . . . , pj, . . . , Nj, where pj is a positive integer in the range pjε{1, . . . , Nj}. Waveform yj(mj,nj,pj) occupies time slot pj in waveform φj(trj,pj) and equals: 
         [0000]        yj ( mj,nj,pj )= bj ( mj )· u ( nj,pj )  (Eq. 1)
 
         [0000]    wherein u(nj,pj) is a phasor that equals: 
         [0000]        u ( nj,pj )=exp(2π( nj− 1)( pj− 1) i/Nj )  (Eq. 2)
 
         [0000]    The duration of waveform y(mj,nj,pj) defines the duration of time slot pj. 
         [0098]    The Mj·Nj waveforms of waveform array Φj partition the time-frequency space of the modulated radio-frequency carrier signal into 1/B second-long “time intervals” and Mj·Nj “frequency sub-bands.” Each waveform array Φj constitutes a “frame” of Mj·Nj time intervals, and the least common multiple of Mj·Nj for all j (e.g., the LCM(M1·N1, M2·N2) for jε{1, 2}) constitutes a “superframe” of time intervals. The temporal start of each waveform is specified relative to the first time interval in the superframe. 
         [0099]    A salient characteristic of the illustrative embodiment is that each waveform φj(mj,nj) in waveform array Φj deposits energy into:
       i. unique time-frequency portions the radio channel, and   ii. 1/Mj·Nj th  of the radio channel during the frame of waveform array Φj.
 
This is illustrated in  FIGS. 4 a , 4 b , and 4 c    for waveform array Φ 1  (M1=6, N1=4) and waveform array Φ 2  (M2=6, N2=8).
       
 
         [0102]    For example,  FIG. 4 a    depicts a plot of where the energy associated with waveform φ 1 (1,1) of waveform array Φ 1  (M1=6, N1=4) beginning at superframe time interval 1 is deposited into a 10 MHz radio channel. In  FIG. 4 a    the radio channel is depicted as divided into twenty-four (M1·N1=24) 416.66 KHz frequency sub-bands (B=10 MHz/M1·N1=24) and forty-eight [LCM(M1·N1, M2·N2)=24] 0.1 microsecond (1/B=10 MHz) time intervals. In  FIG. 4 a   , it can be seen that energy is deposited only in time intervals 1, 7, 13, and 19 and only in the frequency sub-bands 0-0.416 MHz, 1.666-2.083 MHz, 3.333-3.750 MHz, 5.000-5.417 MHz, 6.666-7.083 MHz, and 8.333-8.750 MHz in the channel. 
         [0103]      FIG. 4 b    depicts a plot of where the energy associated with waveform φ 1 (1,1) of waveform array Φ 1  (M1=6, N1=4) beginning at superframe time interval 25 is deposited into a 10 MHz radio channel. In  FIG. 4 a    the radio channel is depicted as divided into twenty-four (M1·N1=24) 416.66 KHz frequency sub-bands (B=10 MHz/M1·N1=24) and forty-eight [LCM(M1·N1, M2·N2)=24] 0.1 microsecond (1/B=10 MHz) time intervals. In  FIG. 4 b   , it can be seen that energy is deposited only in time intervals 25, 31, 37, and 43 and only in the frequency sub-bands 0-0.416 MHz, 1.666-2.083 MHz, 3.333-3.750 MHz, 5.000-5.417 MHz, 6.666-7.083 MHz, and 8.333-8.750 MHz in the channel. 
         [0104]    Similarly,  FIG. 4 c    depicts a plot of where the energy associated with waveform φ 2 (1,1) of waveform array Φ 2  (M2=6, N2=8) beginning at superframe time interval 1 is deposited into a 10 MHz radio channel. In  FIG. 4 a    the radio channel is depicted as divided into twenty-four (M1·N1=24) 416.66 KHz frequency sub-bands (B=10 MHz/M1·N1=24) and forty-eight [LCM(M1·N1, M2·N2)=24] 0.1 microsecond (1/B=10 MHz) time intervals. In  FIG. 4 c   , it can be seen that energy is deposited only in time intervals 1, 7, 13, 19, 25, 31, 37, and 43 and only in the frequency sub-bands 0-0.208 MHz, 1.666-1.875 MHz, 3.333-3.541 MHz, 5.000-5.208 MHz, 6.666-6.875 MHz, and 8.333-8.541 MHz in the channel. 
         [0105]    It will be clear to those skilled in the art how to determine when and where any given waveform φj(mj,nj) will deposit energy into a radio channel using Fourier analysis in well-known fashion. 
         [0106]    In accordance with the illustrative embodiment, base station  120  selects individual waveforms from waveform arrays Φ 1  and Φ 2  to convey data items from wireless terminal  130 - 1  and wireless terminal  130 - 2 , and selects those waveforms so that:
       I. no two waveforms overlap the time-frequency space of the modulated radio-frequency carrier signal (to prevent inter-symbol interference), and   II. all of the time-frequency space of the modulated radio-frequency carrier signal has energy deposited into it (to maximize spectral efficiency), and   III. waveforms from waveform array Φ 1  convey data items with low-latency tolerance and waveforms from waveform array Φ 2  convey data items with high-latency tolerance.
 
To accomplish this, base station  120  instructs wireless terminal  130 - 1  and wireless terminal  130 - 2  how to transmit waveforms from waveform array Φ 1  and waveforms from waveform array Φ 2  into the same channel at the same time with satisfactory guard waveforms (i.e., how to transmit waveforms from waveform array Φ 1  and waveforms from waveform array Φ 2  so that they:
   1. overlap in the 4.8 microsecond superframe “time space” of the radio channel, and   2. overlap in the 10 MHz “frequency space” of the radio channel, and   3. do not overlap in the “time-frequency space” of the radio channel.       
 
         [0113]    For example,  FIGS. 5 a , 5 b , 5 c , 5 d , 5 e , and 5 f    depict waveforms in which waveforms from waveform arrays Φ 1 (M1=6, N1=4) and Φ 2 (M2=6, N2=8) are either exclusively:
       1. assigned to base station  130 - 1  to transmit data items to base station  120 , or   2. assigned to base station  130 - 2  to transmit data items to base station  120 , or   3. reserved as guard waveforms (and not transmitted by either base station  130 - 1  or base station  130 - 2 .       
 
         [0117]    Base station  130 - 1  is assigned four waveforms from waveform array Φ 1  beginning at superframe time interval 1 and superframe time interval 25, as shown in Table 1 and as depicted in  FIGS. 5 a  and 5 b   , respectively. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Waveforms from Waveform Array Φ1  
               
               
                 Assigned to Base Station 130-1 
               
             
          
           
               
                   
                   
                 Beginning 
               
               
                   
                 Conveying 
                 Superframe  
               
               
                   
                 Waveform 
                 Time Interval 
               
               
                   
                   
               
               
                   
                 φ1(1, 1) 
                 1, 25 
               
               
                   
                 φ1(1, 2) 
                 1, 25 
               
               
                   
                 φ1(4, 3) 
                 1, 25 
               
               
                   
                 φ1(5, 3) 
                 1, 25 
               
               
                   
                   
               
             
          
         
       
     
         [0118]    Base station  130 - 1  is also assigned twelve waveforms from waveform array Φ 2  beginning at superframe time interval 1, as shown in Table 2 and as depicted in  FIG. 5 c   . 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Waveforms from Waveform Array Φ2  
               
               
                 Assigned to Base Station 130-1 
               
             
          
           
               
                   
                   
                 Beginning 
               
               
                   
                 Conveying 
                 Superframe 
               
               
                   
                 Waveform 
                 Time Interval 
               
               
                   
                   
               
               
                   
                 φ2(1, 1) 
                 1 
               
               
                   
                 φ2(1, 2) 
                 1 
               
               
                   
                 φ2(1, 3) 
                 1 
               
               
                   
                 φ2(2, 1) 
                 1 
               
               
                   
                 φ2(2, 3) 
                 1 
               
               
                   
                 φ2(2, 4) 
                 1 
               
               
                   
                 φ2(4, 5) 
                 1 
               
               
                   
                 φ2(4, 6) 
                 1 
               
               
                   
                 φ2(4, 7) 
                 1 
               
               
                   
                 φ2(5, 5) 
                 1 
               
               
                   
                 φ2(5, 6) 
                 1 
               
               
                   
                 φ2(5, 7) 
                 1 
               
               
                   
                   
               
             
          
         
       
     
         [0119]    It will be clear to those skilled in the art, after reading this disclosure, that base station  130 - 1  can transmit (in a single superframe) only those combinations of waveforms assigned to it that do not interfere with each other (i.e., do not put energy into the same “time-frequency space” of the radio channel). Furthermore, it will be clear to those skilled in the art, after reading this disclosure, which combinations of waveforms can be transmitted (in a single superframe) so as to not interfere with each other. 
         [0120]    Base station  130 - 2  is assigned four waveforms from waveform array  11  beginning at superframe time interval 1 and superframe time interval 25, as shown in Table 3 and as depicted in  FIGS. 5 d  and 5 e   , respectively. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Waveforms from Waveform Array Φ1  
               
               
                 Assigned to Base Station 130-2 
               
             
          
           
               
                   
                   
                 Beginning 
               
               
                   
                 Conveying 
                 Superframe 
               
               
                   
                 Waveform 
                 Time Interval 
               
               
                   
                   
               
               
                   
                 φ1(1, 3) 
                 1, 25 
               
               
                   
                 φ1(2, 3) 
                 1, 25 
               
               
                   
                 φ1(4, 1) 
                 1, 25 
               
               
                   
                 φ1(5, 1) 
                 1, 25 
               
               
                   
                   
               
             
          
         
       
     
         [0121]    Base station  130 - 2  is also assigned twelve waveforms from waveform array F 2  beginning at superframe time interval 1, as shown in Table 4 and as depicted in  FIG. 5 f   . 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Waveforms from Waveform Array Φ2  
               
               
                 Assigned to Base Station 130-2 
               
             
          
           
               
                   
                   
                 Beginning 
               
               
                   
                 Conveying 
                 Superframe 
               
               
                   
                 Waveform 
                 Time Interval 
               
               
                   
                   
               
               
                   
                 φ2(1, 5) 
                 1 
               
               
                   
                 φ2(1, 6) 
                 1 
               
               
                   
                 φ2(1, 7) 
                 1 
               
               
                   
                 φ2(2, 5) 
                 1 
               
               
                   
                 φ2(2, 6) 
                 1 
               
               
                   
                 φ2(2, 7) 
                 1 
               
               
                   
                 φ2(4, 1) 
                 1 
               
               
                   
                 φ2(4, 2) 
                 1 
               
               
                   
                 φ2(4, 3) 
                 1 
               
               
                   
                 φ2(5, 1) 
                 1 
               
               
                   
                 φ2(5, 2) 
                 1 
               
               
                   
                 φ2(5, 3) 
                 1 
               
               
                   
                   
               
             
          
         
       
     
         [0122]    It will be clear to those skilled in the art, after reading this disclosure, that base station  130 - 1  can transmit (in a single superframe) only those combinations of waveforms assigned to it that do not interfere with each other (i.e., do not put energy into the same “time-frequency space” of the radio channel). Furthermore, it will be clear to those skilled in the art, after reading this disclosure, which combinations of waveforms can be transmitted (in a single superframe) so as to not interfere with each other. 
         [0123]    The remaining waveforms which were not assigned to either base station  130 - 1  or base station  130 - 2  are reserved as guard waveforms in order to reduce inter-symbol interference from multi-path images and Doppler shifts. 
         [0124]    It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that assign any combination of waveforms for conveying data items and any combination of waveforms for use as guard waveforms. Furthermore, it will be clear to those skilled in the art, after reading this disclosure, how to partition the waveforms in waveform array t among any number of wireless terminals and guard waveforms. 
         [0125]    At task  211 , base station  120  transmits the waveform array Φ parameters to wireless terminal  130 - 1  and wireless terminal  130 - 2  along with a command to transmit into the radio channel using the assigned waveforms. 
         [0126]    At task  212 , wireless terminal  130 - 1  receives the waveform array Φ parameters and the command to use the waveforms assigned to it. 
         [0127]    At task  213 , wireless terminal  130 - 2  receives the waveform array Φ parameters and the command to use the waveforms assigned to it. 
         [0128]      FIG. 6  depicts a flowchart of the salient tasks associated with task  202 - a , wherein aε{1, 2}, in accordance with the illustrative embodiment of the present invention. 
         [0129]    At task  1601 , wireless terminal  130 - a  establishes a one-to-one relationship between each data item it will transmit to base station  120  and each waveform φ(m,n) in waveform array Φ that has been assigned to it. As part of task  1601 , wireless terminal  130 - a  modulates a radio-frequency carrier signal with each waveform assigned to it and the corresponding data item to generate a modulated radio-frequency carrier signal. It will be clear to those skilled in the art, after reading this disclosure, how to make and use embodiments of the present invention that perform task  1601 . 
         [0130]    At task  1602 , the modulated radio-frequency carrier signal is radiated into the radio channel via antenna  134 - a  for reception by base station  120 . It will be clear to those skilled in the art, after reading this disclosure, how to make and use embodiments of the present invention that perform task  1602 . 
       Markman Definitions 
       [0131]    Orthogonal—For the purpose of this specification, two waveforms are orthogonal if their inner product is zero over the time interval of interest. 
         [0132]    Identical Waveform Arrays—For the purposes of this specification, waveform array Φ 1 (M1, N1) and waveform array Φ 2 (M2, N2) are identical if M1=M2 and N1=N2. 
         [0133]    Non-identical Waveform Arrays—For the purposes of this specification, waveform array Φ 1 (M1, N1) and waveform array Φ 2 (M2, N2) are non-identical if they are not identical.