Abstract:
A method of spatially-encoded wireless transmission using a wireless communications device that is configured with an electromagnetic radiator involves applying a modulated carrier to one or more radiator elements of the electromagnetic radiator. The radiator elements are selected based on instantaneous samples of baseband information, and the modulated carrier is generated from the baseband information. The modulated carrier is then transmitted via the selected radiator elements.

Description:
RELATED APPLICATIONS 
     This patent application claims the benefit of the filing date of U.S. provisional patent application Ser. No. 61/515,117, filed Aug. 4, 2011, entitled “Communication System for Spatially-Encoded Wireless Communications”. 
    
    
     FIELD OF THE INVENTION 
     This patent application relates to a method and system of wireless communication. 
     BACKGROUND 
     RF wireless communications devices include a RF antenna and transceiver that allows the communications device to transmit and receive wireless information via a wireless communications protocol. Known wireless communications protocols include long-range protocols (e.g. GSM, GPRS, CDMA, EDGE, UMTS, EvDO, HSPA) and short-range protocols (irDA, Bluetooth (IEEE 802.15), and WiFi (IEEE 802.11x)). None of these communications protocols make optimum use of the available communications bandwidth. 
     SUMMARY 
     This patent application describes a wireless communications device and associated communications protocol that allows the communications device to wirelessly transmit information by spatially-encoding an electromagnetic carrier (e.g. modulating the diameter and/or radial position and/or angular position of the carrier) with a portion of the information to be transmitted. 
     In accordance with a first aspect of the disclosure, there is provided a wireless communications device that comprises an electromagnetic radiator and a signal processor coupled to the radiator. The electromagnetic radiator comprises an array of electromagnetic radiator elements. The signal processor is configured to effect applying of a modulated electromagnetic carrier to one or more of the radiator elements selected, in real-time, based on instantaneous samples of baseband information, and to effect transmission of the modulated carrier via the selected radiator elements. The modulated carrier is generated from the baseband information. 
     In accordance with a second aspect of the disclosure, there is provided a method of wireless transmission of baseband information using a wireless communications device. The wireless communications device is configured with an electromagnetic radiator comprising an array of electromagnetic radiator elements. The method comprises the wireless communications applying a modulated carrier to one or more of the radiator elements of the electromagnetic radiator, and transmitting the modulated carrier via the selected radiator elements. The wireless communications device selects the one or more radiator elements, in real time, based on instantaneous samples of baseband information. The wireless communications device generates the modulated carrier from the baseband information. 
     The signal processor may be configured to select the one or more radiator elements so as to vary the diameter of the transmitted carrier based on the instantaneous baseband information. The signal processor may be configured to select the one or more radiator elements so as to vary the radial position of the transmitted carrier, relative to a centre of the transmission, based on the instantaneous baseband information. The signal processor may be configured to select the one or more radiator elements so as to vary the angular position of the transmitted carrier, relative to a reference angular position, based on the instantaneous baseband information. 
     Since a portion of the baseband data is encoded into the carrier by modulating the diameter and/or the radial position and/or the angular position of the carrier, the wireless communications device and the method of wireless transmission can make better use of the available communications bandwidth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An exemplary wireless communications device, and method of wireless transmission will now be described, with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic view of the communications device, depicting the signal processor, a local oscillator, and an electromagnetic radiator; 
         FIGS. 2   a  and  2   b  are respectively a top plan view and a side elevation of a first embodiment of the electromagnetic radiator; 
         FIG. 3  depicts a second embodiment of the electromagnetic radiator; 
         FIGS. 4   a  and  4   b  depict a third embodiment of the electromagnetic radiator; 
         FIG. 5  depicts a sample wireless transmission according to the method of wireless transmission in which the rate of change of angular position of the transmitted carrier varies based on the baseband information; 
         FIG. 6  depicts a sample wireless transmission in which the radial position of the transmitted carriers vary based on the baseband information; and 
         FIG. 7  depicts a sample wireless transmission in which the radial position and the rate of change of angular position of the transmitted carrier varies based on the baseband information. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a schematic view of a wireless communications device, denoted generally as  100 . Preferably, the wireless communications device  100  is a two-way wireless communications device. Depending on the exact functionality provided, the wireless communications device  100  may be referred to as a wireless data communication device, a wireless telephone, a portable computer, or a wireless base station, as examples. 
     The wireless communications device  100  includes a communication subsystem  102 , and may also include an input subsystem  104  and an output subsystem  106  both coupled to the communication subsystem  102 . The input subsystem  104  allows the user of the wireless communications device  100  to provide data and/or voice input to the wireless communications device  100 , and may include a keyboard and/or a microphone, as examples. The output subsystem  106  provides visual and/or sound output for the user of the wireless communications device  100 , and may include a LCD display and/or a speaker, as examples. 
     The communication subsystem  102  performs communication functions, such as data and voice communications, and includes a plurality of transceivers (transmitters/receivers)  112 , and a local oscillator  114 , an electromagnetic radiator  200  and a signal processor  120  coupled to the transceivers  112 . Electromagnetic signals are received by the electromagnetic radiator  200  and intended for receipt by the output subsystem  106  are input to the transceivers  112 , which perform functions such as frequency down conversion and analog to digital conversion, in preparation for more complex communication functions performed by the signal processor  120 . Conversely, data intended to be transmitted by the input subsystem  104  are processed by the signal processor  120  and input to the transceivers  112  in preparation for transmission via the electromagnetic radiator  200 . 
     Preferably, the electromagnetic radiator  200  comprises an array of electromagnetic radiator elements. Each radiator element is configured to transmit and/or receive electromagnetic radiation. Multiple embodiments of the electromagnetic radiator  200  are envisaged. In one embodiment, depicted in  FIGS. 2   a  and  2   b , the electromagnetic radiator  200  may comprise an RF antenna array, and the electromagnetic radiator elements are configured as a plurality of grounded monopoles which comprise a ground plane  210 , and a plurality of elongate conductors  212 . Each elongate conductor  212  may be electrically isolated from the ground plane  210 , but extending through the ground plane  210  from a respective radiator feed point  214  that is disposed below the ground plane  210 . 
     In the embodiment of  FIGS. 2   a  and  2   b , the elongate conductors  212  are substantially equidistantly spaced about the surface  210 . In another embodiment, depicted in  FIG. 3 , the elongate conductors  212  define a plurality of concentric circles. Moreover, the density of elongate conductors  212  in each circle may be greater in the inner circles than in the outer circles. For instance, each circle may include the same number of elongate conductors  212 , with the result that the distance between adjacent conductors  212  in the inner circles is less than the distance between adjacent conductors  212  in the outer circles. 
     In another embodiment, depicted in  FIGS. 4   a  and  4   b , the electromagnetic radiator  200  may again comprise an RF antenna array, but the electromagnetic radiator elements are configured as a plurality of patch antennas which comprise a conductive layer  206 , the ground plane  210 , and the plurality of elongate conductors  212 . A dielectric substrate  208  may be disposed between the conductive layer  206  and the ground plane  210 . In this embodiment, the conductive layer  206  and the ground plane  210  are disposed on opposite faces of the dielectric substrate, and the conductive layer  206  is provided as a plurality of planar antenna elements that are electrically isolated from each other. Preferably, the conductive layer  206  is oriented substantially parallel to the ground plane  210 . Each elongate conductor  212  is electrically isolated from the ground plane  210 , but extends through the ground plane  210  and the dielectric, from a respective radiator feed point  214  that is disposed below the ground plane  210 , and terminates at a respective planar antenna element. 
     In each embodiment, preferably the ground plane  210  comprises a planar ground plane, and the elongate conductors  212  are disposed about the ground plane  210 , perpendicular to the ground plane  210 , to thereby provide a planar antenna array. Alternately, the ground plane  210  may comprise an arcuate ground plane, and the elongate conductors  212  are disposed about the ground plane  210  to thereby provide an arcuate antenna array. Further, each radiator feed point  214  is coupled to a respective one of the transceivers  112 , and each transceiver  112  is connected to the signal processor  120  via a local bus. 
     Alternately, the electromagnetic radiator  200  depicted in  FIGS. 2   a ,  2   b ,  3 ,  4   a  and  4   b  may comprise a laser array, with the electromagnetic radiator elements being configured as laser transmitter/receivers  212 . Each laser transmitter/receiver  212  may mounted on a substrate  210 , and may be connected to a respective radiator feed point  214  that is disposed below the substrate  210 . As an example, each laser transmitter/receiver  212  may comprise a semiconductor laser diode that is closely-mounted or integrated with a laser phototransistor. Preferably, each semiconductor laser diode is configured to produce a beam of monochromatic, low divergent, singularly-polarized light, and the wave-front of each light beam is coherent over the distance between the electromagnetic radiator  200  and the corresponding receiver. Similarly, preferably each laser phototransistor is configured to detect a beam of monochromatic, low divergent, singularly-polarized light directed at the phototransistor. 
     The signal processor  120  is configured with computer processing instructions which, when executed by the signal processor  120 , implements a signal processing procedure. The operation of the signal processing procedure will be discussed in greater detail below. However, it is sufficient at this point to note that the signal processing procedure is configured to initiate electromagnetic (RF or laser) transmission of baseband information received from the input subsystem  104  by selecting one or more of the transceivers  112  (and their associated radiator elements) for transmission by the electromagnetic radiator  200 , based on the received baseband information. The signal processing procedure is also configured to facilitate delivery of baseband information to the output subsystem  106  based on the transceivers  112  (and the associated radiator elements) from which the signal processor receives demodulated electromagnetic (RF or laser) transmissions. It should also be understood that although the signal processing procedure may be implemented as a set of computer processing instructions, the functionality of the signal processing procedure may be implemented in electronics hardware instead. 
     When the communication subsystem  102  is in signal transmission mode, the signal processor  120  receives the baseband information from the input subsystem  104  as a series of digital values, and uses a portion of the received baseband information to select one or more transceivers  112  and transmits the baseband information to each of the selected transceivers  112 . Each selected transceiver  112  performs digital to analog conversion on the baseband information, and uses the analog baseband information to modulate the amplitude and/or phase of the carrier generated by the local oscillator  114 . Each transceiver  112  applies the modulated carrier to the associated radiator feed point(s)  214 . As a result, the modulated carrier is only transmitted (as a RF or laser transmission) from the radiator elements that are associated with the selected radiator feed points  214 . 
     The signal processor  120  selects transceivers  112  and varies the selection thereof (and hence also varies the selection of radiator feed points  214 ), in real-time, in accordance with a portion of each digital baseband value. In one implementation, the signal processor  120  varies the selection of transceivers  112  (and hence the location of active radiator feed points  214 ), in real-time, so that the instantaneous angular position of each modulated carrier, as each modulated carrier is transmitted by the electromagnetic radiator  200 , varies based on the baseband information. 
     For example, assuming that the location of each radiator feed point  214  on the surface of the electromagnetic radiator  200  can be specified by its polar co-ordinates (e.g. radius from a reference point on the surface of the electromagnetic radiator  200 , and angular position relative to a reference angular position on the surface of the electromagnetic radiator  200 ), the signal processor  120  may select the radiator feed point(s)  214  such that the instantaneous angular position of each electromagnetic (RF or laser) transmission from the surface of the electromagnetic radiator  200 , relative to a reference angular position on the surface of the electromagnetic radiator  200 , increases, in real-time, as a characteristic (e.g. amplitude, frequency, phase) of the baseband information increases, and the instantaneous angular position of each electromagnetic transmission from the surface of the electromagnetic radiator  200 , relative to a reference angular position on the surface of the electromagnetic radiator  200 , decreases, in real-time, as the characteristic of the baseband information decreases. At the same time, the signal processor  120  may also cause each selected transceiver  112  to increase the frequency and/or phase of each electromagnetic transmission, in real time, as the same or a different characteristic of the baseband information increases, and may cause each selected transceiver  112  to decrease the frequency and/or phase of each electromagnetic transmission, in real time, as the same or a different characteristic of the baseband information decreases. 
     Alternately, as shown in  FIG. 5 , the signal processor  120  may select the radiator feed point(s)  214  such that the instantaneous rate of change of the angular position of each electromagnetic (RF or laser) transmission from the surface of the electromagnetic radiator  200 , increases, in real-time, as a characteristic of the baseband information increases, and the instantaneous rate of change of the angular position of each electromagnetic transmission decreases, in real-time, as the characteristic of the baseband information decreases. The signal processor  120  may also simultaneously activate multiple radiator feed points  214 , and vary the instantaneous rate of change of the angular position of each transmission based on respective characteristics of the baseband information. Although not shown in  FIG. 5 , at the same time, the signal processor  120  may also cause each selected transceiver  112  to increase the frequency and/or phase of each transmission, in real time, as the same or a different characteristic of the baseband information increases, and may cause each selected transceiver  112  to decrease the frequency and/or phase of each electromagnetic transmission, in real time, as the same or a different characteristic of the baseband information decreases. 
     In another implementation, the signal processor  120  varies the selection of transceivers  112  (and hence the location of active radiator feed points  214 ), in real-time, so that the instantaneous radial position of each modulated carrier, as the modulated carrier is transmitted by the electromagnetic radiator  200 , relative to the centre of all such electromagnetic transmissions, varies based on the baseband information. 
     For example, assuming again that the location of each radiator feed point  214  on the surface of the electromagnetic radiator  200  can be specified by its polar co-ordinates (e.g. radius from a reference point on the surface of the electromagnetic radiator  200 , and angular position relative to a reference angular position on the surface of the electromagnetic radiator  200 ), the signal processor  120  may select the radiator feed point(s)  214  such that the instantaneous radial position of each electromagnetic (RF or laser) transmission from the surface of the electromagnetic radiator  200 , relative to the centre of all such electromagnetic transmissions, increases, in real-time, as a characteristic of the baseband information increases, and the instantaneous radial position of each electromagnetic transmission from the surface of the electromagnetic radiator  200 , relative to the centre of all such electromagnetic transmissions, decreases, in real-time, as the characteristic of the baseband information decreases. At the same time, the rate of change of the angular position of each electromagnetic transmission may remain constant. 
     As shown in  FIG. 6 , the signal processor  120  may simultaneously activate multiple radiator feed points  214 , and vary the instantaneous radial position of each electromagnetic transmission, relative to the centre of all such transmissions, based on respective characteristics of the baseband information. Preferably, the radiator feed points  214  are activated/deactivated in a sequence that produces two (or more) distinct simultaneous electromagnetic transmissions. Moreover, preferably the simultaneous electromagnetic transmissions do not interfere with one another, in the sense that a receiver that receives the two (or more) electromagnetic transmissions can correctly decode the information that is encoded in each electromagnetic transmission. The electromagnetic radiator  200  depicted in  FIG. 3  may be particularly advantageous for implementing this modulation scheme. 
     At the same time, the signal processor  120  may also cause each selected transceiver  112  to increase the frequency and/or phase of each electromagnetic transmission, in real time, as the same or a different characteristic of the baseband information increases, and may cause each selected transceiver  112  to decrease the frequency and/or phase of each electromagnetic transmission, in real time, as the same or a different characteristic of the baseband information decreases. 
     Alternately, the signal processor  120  may select the radiator feed point(s)  214  based on a combination of the foregoing controls. For example, as shown in  FIG. 7 , the signal processor  120  may select the radiator feed point(s)  214  such that the rate of change of the angular position of each electromagnetic transmission from the surface of the electromagnetic radiator  200 , increases, in real-time, as a characteristic of the baseband information increases, and the instantaneous radial position of each electromagnetic transmission from the surface of the electromagnetic radiator  200 , relative to the centre of all such transmissions, increases, in real-time, as another characteristic of the baseband information increases. Conversely, the rate of change of the angular position of each electromagnetic transmission from the surface of the electromagnetic radiator  200  may increase, in real-time, as a characteristic of the baseband information decrease, and the instantaneous radial distance of each electromagnetic transmission from the surface of the electromagnetic radiator  200 , relative to the centre of all such transmissions, may decrease, in real-time, as another characteristic of the baseband information increases. Again, the electromagnetic radiator  200  depicted in  FIG. 3  may be particularly advantageous for implementing this modulation scheme. 
     Although not shown in  FIG. 6 , at the same time, the signal processor  120  may also cause each selected transceiver  112  to increase the frequency and/or phase of each electromagnetic transmission, in real time, as the same or a different characteristic of the baseband information increases, and may cause each selected transceiver  112  to decrease the frequency and/or phase of each electromagnetic transmission, in real time, as the same or a different characteristic of the baseband information decreases. 
     In another implementation, the signal processor  120  varies the instantaneous number of transceivers  112  that are selected, in real-time, so that the diameter of the modulated carrier, as it is transmitted by the electromagnetic radiator  200 , varies based the baseband information. Simultaneously, the signal processor  120  may also cause each selected transceiver  112  to vary a different characteristic of each electromagnetic transmission, in real time, based the baseband information. 
     For example, the signal processor  120  may increase the instantaneous number of transceivers  112  (and hence the instantaneous number of radiator feed points  214 ) selected, in real-time, as a characteristic of the baseband information increases, and may decrease the instantaneous number of transceivers  112  (and hence the instantaneous number of radiator feed points  214 ) selected, in real-time, as the characteristic of the baseband information decreases. At the same time, the signal processor  120  may also cause each selected transceiver  112  to increase the frequency and/or phase of each electromagnetic transmission, in real time, as the same or a different characteristic of the baseband information increases, and may also cause each selected transceiver  112  to decrease the frequency and/or phase of each electromagnetic transmission, in real time, as the same or a different characteristic of the baseband information decreases. 
     When the communication subsystem  102  is in signal reception mode, each transceiver  112  receives a modulated carrier from the associated radiator feed point  214  of the electromagnetic radiator  200 , and uses the carrier generated by the local oscillator  114  to demodulate the modulated carrier and recover a portion of the information that was encoded in the modulated carrier. Each transceiver  112  performs analog to digital conversion on the recovered information, and forwards the recovered information to the signal processor  120  as a series of digital values. Based on the transceivers  112  (and hence antenna feed points  214 ) from which the signal processor  120  receives the digital values, the signal processor  120  recovers the remainder of the digital baseband information that was encoded in the modulated carrier. 
     As above, the instantaneous diameter of the modulated carrier may vary based on the baseband information, in which case the signal processor  120  may recover each digital baseband value, in real-time, from the instantaneous diameter of the modulated carrier as at the surface of the electromagnetic radiator  200 . Alternately, the instantaneous radial position of the modulated carrier may vary based on the baseband information, in which case the signal processor  120  may recover each digital baseband value, in real-time, from the instantaneous radial distance of the received modulated carrier relative to the centre of the reception at the surface of the electromagnetic radiator  200 . Alternately, or additionally, the instantaneous angular position of the modulated carrier may vary based on the baseband information, in which case the signal processor  120  may recover each digital baseband value, in real-time, from the instantaneous angular position of the received modulated carrier relative to a reference angular position at the surface of the electromagnetic radiator  200 . Depending on the wavelength selected, the foregoing methods of modulation may be advantageously implemented in short-range and/or line-of-sight wireless communications networks.