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A spectral content of a baseband waveform is varied and a measure of the baseband waveform whose spectral content has been varied is used by a transmitter in order to convey information. According to embodiments of inventive concepts, a set of frequencies that is used to provide spectral content to

A spectral content of a baseband waveform is varied and a measure of the baseband waveform whose spectral content has been varied is used by a transmitter in order to convey information. According to embodiments of inventive concepts, a set of frequencies that is used to provide spectral content to the baseband waveform is varied. In some embodiments, the spectral content comprises non-contiguous first and second frequency intervals wherein a third frequency interval that is between the first and second frequency intervals remains substantially devoid of providing spectral content in order to reduce or avoid interference. In other embodiments, the spectral content that is varied comprises a bandwidth that is varied. The inventive concepts are relevant to 4G LTE carrier aggregation systems/methods and/or other aspects of 4G LTE. Various transmitter/receiver embodiments are disclosed including direct synthesis transmitter/receiver embodiments.

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1. A communications method comprising: mapping by a transmitter information into a baseband waveform; andvarying a spectral content of the baseband waveform, without resorting to chipping, by using for said mapping first and second waveform elements that differ therebetween in bandwidth. 2. The comm

1. A communications method comprising: mapping by a transmitter information into a baseband waveform; andvarying a spectral content of the baseband waveform, without resorting to chipping, by using for said mapping first and second waveform elements that differ therebetween in bandwidth. 2. The communications method according to claim 1, wherein over a first time interval the baseband waveform comprises a first discrete-time waveform comprising a first spectral content; wherein over a second time interval the baseband waveform comprises a second discrete-time waveform comprising a second spectral content that differs from the first spectral content; wherein the first and second time intervals are adjacent one another; and wherein the first and second discrete-time waveforms are used to transmit respective first and second information over said first and second time intervals, respectively. 3. The communications method according to claim 1, wherein said mapping is preceded by: processing a bit sequence to obtain the information. 4. The communications method according to claim 1, wherein said varying is followed by: further processing the baseband waveform, the spectral content Of which was varied; andwirelessly transmitting the information using the baseband waveform that was further processed. 5. The communications method according to claim 1, wherein said first and second waveform elements that differ therebetween in bandwidth comprise respective first and second spectral contents that partially overlap therebetween. 6. The communications method according to claim 5, wherein the first and second waveform elements are used over adjacent transmit/receive intervals. 7. The communications method according to claim 1, wherein said first and second waveform elements that differ therebetween in bandwidth comprise respective first and second spectral contents that are devoid of overlap therebetween. 8. The communications method according to claim 7, wherein the first and second waveform elements are used over adjacent transmit/receive intervals. 9. The communications method according to claim 1, wherein said first and second waveform elements are separated therebetween by a range of frequencies that is devoid of the information that was mapped into the baseband waveform. 10. The communications method according to claim 1, further comprising: distributing a frequency content of the baseband waveform over first and second frequency intervals that are separated therebetween by a third frequency interval; andrefraining from distributing the frequency content over the third frequency interval. 11. The communications method according to claim 1, wherein the baseband waveform comprises a sequence of discrete-time waveforms; wherein a first waveform of the sequence of discrete-time waveforms comprises a first duration; and wherein a second waveform of the sequence of discrete-time waveforms comprises a second duration that differs from the first duration. 12. The communications method according to claim 1, wherein over a first time interval the baseband waveform comprises a first discrete-time waveform comprising a first spectral content; wherein over a second time interval the baseband waveform comprises a second discrete-time waveform comprising a second spectral content that differs from the first spectral content; wherein the first and second time intervals are adjacent transmit/receive intervals; and wherein the first and second discrete-time waveforms are used to transmit respective first and second information over said first and second time intervals, respectively. 13. The communications method according to claim 1, wherein the transmitter comprises a mobile transmitter that is stationary relative to the Earth. 14. The communications method according to claim 1, wherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; wherein the transmitter comprises a mobile transmitter that is stationary relative to the Earth; and wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission of the mobile transmitter while the mobile transmitter remains stationary relative to the Earth. 15. The communications method according to claim 1, wherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform, and further comprises: excluding certain frequency intervals responsive to an interference concern, and varying said bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission of the transmitter and subject to said excluding certain frequency intervals responsive to an interference concern. 16. The communications method according to claim 1, wherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said mapping by a transmitter information into a baseband waveform comprises:evaluating a frequency content;forming a desired spectrum shape responsive to the frequency content and responsive to an interference concern; andusing a time-domain representation of the desired spectrum shape to modulate the single carrier frequency. 17. The communications method according to claim 1, wherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said mapping by a transmitter information into a baseband waveform comprises: forming by the transmitter a sequence of information symbols {Ik} responsive to an information bit sequence; andmapping by the transmitter the sequence of information symbols {Ik} onto a waveform sequence {Uk};wherein a Fourier transform of the waveform sequence {Uk} comprises a plurality of frequencies each one of which comprises a non-zero amplitude that depends upon an information symbol of said sequence of information symbols {Ik} but is not the information symbol. 18. The communications method according to claim 1, wherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; wherein the transmitter comprises a mobile transmitter that is stationary relative to the Earth;wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission of the mobile transmitter while the mobile transmitter remains stationary relative to the Earth;wherein said varying a spectral content of the baseband waveform further comprises:excluding certain frequency intervals responsive to an interference concern, and varying said bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission of the transmitter and subject to said excluding certain frequency intervals responsive to an interference concern;wherein said mapping by a transmitter information into a baseband waveform comprises:evaluating a frequency content;forming a desired spectrum shape responsive to the frequency content and responsive to an interference concern; andusing a time-domain representation of the desired spectrum shape to modulate the single carrier frequency; andwherein said mapping by a transmitter information into a baseband waveform further comprises:forming by the transmitter a sequence of information symbols {Ik} responsive to an information bit sequence; andmapping by the transmitter the sequence of information symbols {Ik} onto a waveform sequence {Uk};wherein a Fourier transform of the waveform sequence {Uk} comprises a plurality of frequencies each one of which comprises a non-zero amplitude that depends upon an information symbol of said sequence of information symbols {Ik} but is not the information symbol. 19. The communications method according to claim 1, wherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform over two successive signaling intervals that are adjacent therebetween. 20. The communications method according to claim 1, further comprising: varying said spectral content of the baseband waveform, without resorting to chipping, by using for said mapping said first and second waveform elements further differing therebetween in frequency range while avoiding certain frequency intervals from being included in said spectral content responsive to an interference concern;transmitting by said transmitter said first and second waveform elements that differ therebetween in bandwidth and differ therebetween in frequency range over respective first and second transmit/receive time intervals that are adjacent therebetween; andtransmitting by said transmitter cyclostationary waveforms;wherein said transmitter is a transmitter of a cellular telecommunications system wherein covertness is not a primary concern;wherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; andwherein said information that is mapped into said baseband waveform comprises a bit sequence that is operated upon by said transmitter to thereby form an information symbol sequence which is then mapped by said transmitter into said baseband waveform. 21. The communications method according to claim 20, wherein said first and second waveform elements that differ therebetween in bandwidth and differ therebetween in frequency range vary and are orthogonal therebetween over a first time span; and vary and are non-orthogonal therebetween over a second time span. 22. The communications method according to claim 1, further comprising: generating by said transmitter cyclostationary waveforms; andtransmitting by said transmitter cyclostationary waveforms;wherein said mapping by a transmitter information into a baseband waveform comprises:mapping by the transmitter an input bit sequence {b} into an information symbol sequence {Ik} and mapping by the transmitter the information symbol sequence {Ik} into a discrete-time, cyclostationary, baseband waveform sequence {Uk(nT)}; wherein k denotes values of discrete time; k=1, 2, . . . ; wherein for each value of k, n takes on a plurality of integer values corresponding to a respective plurality of values of the discrete-time, cyclostationary, baseband waveform Uk(nT); T>0; andwherein said mapping by the transmitter the information symbol sequence {Ik} into a discrete-time, cyclostationary, baseband waveform sequence {Uk(nT)}, comprises:using first and second discrete-time, cyclostationary, baseband waveform elements, over respective first and second successive and adjacent values of k; said first and second discrete-time, cyclostationary, baseband waveform elements differing therebetween in respective first and second frequency ranges that provide respective first and second frequency contents thereto and further differing therebetween in respective first and second bandwidths thereof; andtransmitting by said transmitter said discrete-time, cyclostationary, baseband waveform sequence {Uk(nT)} following further processing thereof by the transmitter;wherein said transmitter is a transmitter of a cellular telecommunications system wherein covertness is not a primary concern; andwherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency. 23. The communications method according to claim 22, wherein said first and second discrete-time, cyclostationary, baseband waveform elements differing therebetween in respective first and second frequency ranges that provide respective first and second frequency contents thereto and further differing therebetween in respective first and second bandwidths thereof, are orthogonal therebetween. 24. The communications method according to claim 23, wherein a time duration that is associated with said discrete-time, cyclostationary, baseband waveform Uk(nT) varies over different values of k. 25. The communications method according to claim 22, wherein said first and second discrete-time, cyclostationary, baseband waveform elements differing therebetween in respective first and second frequency ranges that provide respective first and second frequency contents thereto and further differing therebetween in respective first and second bandwidths thereof, are non-orthogonal therebetween. 26. The communications method according to claim 25, wherein a time duration that is associated with said discrete-time, cyclostationary, baseband waveform Uk(nT) varies over different values of k. 27. A communications method comprising: processing by a receiver a waveform that comprises a variable spectral content and is devoid of chipping, by using by the receiver first and second waveform elements that differ therebetween in bandwidth; andmapping the waveform that was processed into an information sequence. 28. The communications method according to claim 27, wherein said processing by a receiver a waveform is preceded by wirelessly receiving at the receiver a measure of the waveform and wherein said processing by a receiver a waveform further comprises: using by the receiver a Fourier transform operation;synchronizing by the receiver said first and second waveform elements that differ therebetween in bandwidth with said variable spectral content; anddetecting an information content of said variable spectral content by using said first and second waveform elements that differ therebetween in bandwidth. 29. The communications method according to claim 28, wherein said synchronizing by the receiver is preceded by wirelessly receiving at the receiver synchronization information. 30. The communications method according to claim 29, wherein said processing by a receiver a waveform further comprises; using the synchronization information that is wirelessly received at the receiver in said using first and second waveform elements that differ therebetween in bandwidth. 31. The communication method according to claim 27, wherein said mapping is followed by: generating a bit sequence from said information sequence. 32. The communications method according to claim 27, wherein the receiver comprises a mobile receiver that is stationary relative to the Earth. 33. The communications method according to claim 27, wherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; and wherein said using by the receiver first and second waveform elements that differ therebetween in bandwidth comprises:excluding certain frequency intervals from said first and second waveform elements, and using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 34. A communications method comprising: mapping information that is to be transmitted into a baseband waveform;varying a spectral content of the baseband waveform, without resorting to chipping, by using for said mapping first and second waveform elements that differ therebetween in spectral content;processing a waveform that comprises a variable spectral content and is devoid of chipping by using first and second waveform elements that differ therebetween in bandwidth; andmapping the waveform that was processed into a received information sequence. 35. The communications method according to claim 34, wherein over a first time interval the baseband waveform comprises a first discrete-time waveform comprising a first spectral content; wherein over a second time interval the baseband waveform comprises a second discrete-time waveform comprising a second spectral content that differs from the first spectral content; wherein the first and second time intervals are adjacent one another; and wherein the first and second discrete-time waveforms are used to transmit respective first and second information over said first and second time intervals, respectively. 36. The communications method according to claim 34, wherein said mapping information that is to be transmitted into a baseband waveform is preceded by: processing a bit sequence to obtain the information that is to be transmitted. 37. The communications method according to claim 34, wherein said varying is followed by: further processing the baseband waveform, the spectral content of which was varied; andwirelessly transmitting said information that is to be transmitted using the baseband waveform that was further processed. 38. The communications method according to claim 34, wherein said first and second waveform elements that differ therebetween in spectral content further differ therebetween in bandwidth. 39. The communications method according to claim 38, wherein the first and second waveform elements that differ therebetween in spectral content and further differ therebetween in bandwidth are used over adjacent transmit/receive intervals. 40. The communications method according to claim 34, wherein said first and second waveform elements that differ therebetween in spectral content differ therebetween in a frequency range that is being used to provide said spectral content. 41. The communications method according to claim 40, wherein the first and second waveform elements that differ therebetween in spectral content and differ therebetween in said frequency range that is being used to provide said spectral content are used over adjacent transmit/receive intervals. 42. The communications method according to claim 34, wherein said first and second waveform elements that differ therebetween in spectral content are separated therebetween by a range of frequencies that is devoid of the information that was mapped into the baseband waveform. 43. The communications method according to claim 34, further comprising: distributing a frequency content of the baseband waveform over first and second frequency intervals that are separated therebetween by a third frequency interval; andrefraining from distributing the frequency content over the third frequency interval. 44. The communications method according to claim 34, wherein the baseband waveform comprises a sequence of discrete-time waveforms; wherein a first waveform of the sequence of discrete-time waveforms comprises a first duration; and wherein a second waveform of the sequence of discrete-time waveforms comprises a second duration that differs from the first duration. 45. The communications method according to claim 34, wherein over a first time interval the baseband waveform comprises a first discrete-time waveform comprising a first spectral content; wherein over a second time interval the baseband waveform comprises a second discrete-time waveform comprising a second spectral content that differs from the first spectral content; wherein the first and second time intervals are adjacent transmit/receive intervals; and wherein the first and second discrete-time waveforms are used to transmit respective first and second information over said first and second time intervals, respectively. 46. The communications method according to claim 34, wherein said processing a waveform comprises: synchronizing said first and second waveform elements that differ therebetween in bandwidth with said variable spectral content; anddetecting said variable spectral content by using said first and second waveform elements that differ therebetween in bandwidth. 47. The communications method according to claim 34, wherein said processing a waveform comprises: using a Fourier transform operation. 48. The communications method according to claim 34, wherein said processing a waveform is preceded by: wirelessly receiving said waveform. 49. The communication method according to claim 34, wherein said mapping the waveform is followed by: generating a bit sequence from said received information sequence. 50. The communications method according to claim 34, wherein said mapping information, varying a spectral content, processing a waveform, and mapping the waveform are performed by a transceiver comprising a transmitter and a receiver; wherein the transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; said transceiver comprising a mobile transceiver that is stationary relative to the Earth; and wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission of the mobile transceiver while the mobile transceiver remains stationary relative to the Earth; andwherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:excluding certain frequency intervals from said first and second waveform elements, and using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 51. The communications method according to claim 34, wherein said mapping information, varying a spectral content, processing a waveform, and mapping the waveform are performed by a transceiver; wherein the transceiver comprises a transmitter and a receiver; wherein the transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform, and further comprises: excluding certain frequency intervals responsive to an interference concern, and varying said bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission of the transceiver and subject to said excluding certain frequency intervals responsive to an interference concern;wherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:excluding certain frequency intervals from said first and second waveform elements, and using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 52. The communications method according to claim 34, wherein said mapping information, varying a spectral content, processing a waveform, and mapping the waveform are performed by a transceiver comprising a transmitter and a receiver; and wherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said mapping information that is to be transmitted into a baseband waveform comprises:evaluating a frequency content;forming a desired spectrum shape responsive to the frequency content and responsive to an interference concern; andusing a time-domain representation of the desired spectrum shape to modulate the single carrier frequency;wherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:excluding certain frequency intervals from said first and second waveform elements, and using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 53. The communications method according to claim 34, wherein said mapping information, varying a spectral content, processing a waveform, and mapping the waveform are performed by a transceiver comprising a transmitter and a receiver; wherein the transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said mapping information that is to be transmitted into a baseband waveform comprises: forming by the transmitter a sequence of information symbols {Ik} responsive to an information bit sequence; andmapping by the transmitter the sequence of information symbols {Ik} onto a waveform sequence {Uk};wherein a Fourier transform of the waveform sequence {Uk} comprises a plurality of frequencies each one of which comprises a non-zero amplitude that depends upon an information symbol of said sequence of information symbols {Ik} but is not the information symbol;wherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:excluding certain frequency intervals from said first and second waveform, elements, and using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 54. The communications method according to claim 34, wherein said mapping information, varying a spectral content, processing a waveform, and mapping the waveform are performed by a transceiver comprising a transmitter and a receiver; wherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency;wherein the transceiver comprises a mobile transceiver that is stationary relative to the Earth;wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission of the mobile transceiver while the mobile transceiver remains stationary relative to the Earth;wherein said varying a spectral content of the baseband waveform further comprises:excluding certain frequency intervals responsive to an interference concern, and varying said bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission of the transceiver and subject to said excluding certain frequency intervals responsive to an interference concern;wherein said mapping information that is to be transmitted into a baseband waveform comprises:evaluating a frequency content;forming a desired spectrum shape responsive to the frequency content and responsive to an interference concern; andusing a time-domain representation of the desired spectrum shape to modulate the single carrier frequency;wherein said mapping information that is to be transmitted into a baseband waveform further comprises:forming by the transmitter a sequence of information symbols {Ik} responsive to an information bit sequence; andmapping by the transmitter the sequence of information symbols {Ik} onto a waveform sequence {Uk};wherein a Fourier transform of the waveform sequence {Uk} comprises a plurality of frequencies each one of which comprises a non-zero amplitude that depends upon an information symbol of said sequence of information symbols {Ik} but is not the information symbol;wherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:excluding certain frequency intervals from said first and second waveform elements, and using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 55. The communications method according to claim 34, wherein said mapping information, varying a spectral content, processing a waveform, and mapping the waveform are performed by a transceiver comprising a transmitter and a receiver; wherein the transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform over two successive signaling intervals that are adjacent therebetween; andwherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 56. A communications system comprising: a processor that is configured to perform operations comprising:mapping information into a baseband waveform; andvarying a spectral content of the baseband waveform, without resorting to chipping, by using for said mapping first and second waveform elements that differ therebetween in bandwidth. 57. The communications system according to claim 56, wherein over a first time interval the baseband waveform comprises a first discrete-time waveform comprising a first spectral content; wherein over a second time interval the baseband waveform comprises a second discrete-time waveform comprising a second spectral content that differs from the first spectral content; wherein the first and second time intervals are adjacent one another; and wherein the first and second discrete-time waveforms are used to transmit respective first and second information over said first and second time intervals, respectively. 58. The communications system according to claim 56, wherein said processor is further configured to process a bit sequence in order to obtain the information. 59. The communications system according to claim 56, wherein said processor is configured to further process the baseband waveform, the spectral content of which was varied, following said varying; and wherein the communication system further comprises a transmitter that is configured to perform operations comprising wirelessly transmitting the information using the baseband waveform that was further processed. 60. The communications system according to claim 56, wherein said first and second waveform elements that differ therebetween in bandwidth comprise respective first and second spectral contents that partially overlap therebetween. 61. The communications system according to claim 56, wherein the first and second waveform elements are used over adjacent transmit/receive intervals. 62. The communications system according to claim 56, wherein said first and second waveform elements that differ therebetween in bandwidth comprise respective first and second spectral contents that are devoid of overlap therebetween. 63. The communications system according to claim 62, wherein the first and second waveform elements are used over adjacent transmit/receive intervals. 64. The communications system according to claim 56, wherein said first and second waveform elements are separated therebetween by a range of frequencies that is devoid of the information that was mapped into the baseband waveform. 65. The communications system according to claim 56, wherein the operations further comprise: distributing a frequency content of the baseband waveform over first and second frequency intervals that are separated therebetween by a third frequency interval; andrefraining from distributing the frequency content over the third frequency interval. 66. The communications system according to claim 56, wherein the baseband waveform comprises a sequence of discrete-time waveforms; wherein a first waveform of the sequence of discrete-time waveforms comprises a first duration; and wherein a second waveform of the sequence of discrete-time waveforms comprises a second duration that differs from the first duration. 67. The communications system according to claim 56, wherein over a first time interval the baseband waveform comprises a first discrete-time waveform comprising a first spectral content; wherein over a second time interval the baseband waveform comprises a second discrete-time waveform comprising a second spectral content that differs from the first spectral content; wherein the first and second time intervals are adjacent transmit/receive intervals; and wherein the first and second discrete-time waveforms are used to transmit respective first and second information over said first and second time intervals, respectively. 68. The communications system according to claim 56, wherein said processor is part of a mobile transmitter that is stationary relative to the Earth; wherein said mobile transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission by the mobile transmitter while the mobile transmitter remains stationary relative to the Earth. 69. The communications system according to claim 56, wherein said processor is part of a transmitter; wherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform, and further comprises: excluding certain frequency intervals responsive to an interference concern, and varying said bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission by the transmitter while subject to said excluding certain frequency intervals responsive to an interference concern. 70. The communications system according to claim 56, wherein said processor is part of a transmitter; wherein the transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said mapping information into a baseband waveform comprises: evaluating a frequency content;forming a desired spectrum shape responsive to the frequency content and responsive to an interference concern; andusing a time-domain representation of the desired spectrum shape to modulate the single carrier frequency. 71. The communications system according to claim 56, wherein said processor is part of a transmitter; wherein the transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said mapping information into a baseband waveform comprises: forming a sequence of information symbols {Ik} responsive to an information bit sequence; andmapping the sequence of information symbols {Ik} onto a waveform sequence {Uk};wherein a Fourier transform of the waveform sequence {Uk} comprises a plurality of frequencies each one of which comprises a non-zero amplitude that depends upon an information symbol of said sequence of information symbols {Ik} but is not the information symbol. 72. The communications system according to claim 56, wherein said processor is part of a mobile transmitter that is stationary relative to the Earth; wherein said mobile transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission by the mobile transmitter while the mobile transmitter remains stationary relative to the Earth;wherein said varying a spectral content of the baseband waveform further comprises:excluding certain frequency intervals responsive to an interference concern, and varying said bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission by the transmitter while subject to said excluding certain frequency intervals responsive to an interference concern;wherein said mapping information into a baseband waveform comprises:evaluating a frequency content;forming a desired spectrum shape responsive to the frequency content and responsive to an interference concern; andusing a time-domain representation of the desired spectrum shape to modulate the single carrier frequency;wherein said mapping information into a baseband waveform further comprises:forming a sequence of information symbols {Ik} responsive to an information bit sequence; andmapping the sequence of information symbols {Ik} onto a waveform sequence {Uk};wherein a Fourier transform of the waveform sequence {Uk} comprises a plurality of frequencies each one of which comprises a non-zero amplitude that depends upon an information symbol of said sequence of information symbols {Ik} but is not the information symbol. 73. The communications system according to claim 56, wherein said processor is part of a transmitter that is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform over two successive signaling intervals that are adjacent therebetween. 74. The communications system according to claim 56, wherein said processor is part a transmitter and is further configured to perform operations comprising: varying said spectral content of the baseband waveform, without resorting to chipping, by using for said mapping said first and second waveform elements further differing therebetween in frequency range while excluding certain frequency intervals from being included in said spectral content responsive to an interference concern; andproviding to said transmitter, and transmitting by said transmitter, said first and second waveform elements that differ therebetween in bandwidth and differ therebetween in frequency range over respective first and second transmit/receive time intervals that are adjacent therebetween;wherein said transmitter is configured to transmit cyclostationary waveforms and is a transmitter of a cellular telecommunications system wherein covertness is not a primary concern;wherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; andwherein said information that is mapped into said baseband waveform comprises a bit sequence that is operated upon by said processor to thereby form an information symbol sequence which is then mapped by said processor into said baseband waveform. 75. The communications system according to claim 74, wherein said first and second waveform elements that differ therebetween in bandwidth and differ therebetween in frequency range vary and are orthogonal therebetween over a first time span; and vary and are non-orthogonal therebetween over a second time span. 76. The communications system according to claim 56, further comprising: a transmitter that is connected to said processor;wherein the processor is configured to perform further operations comprising:generating discrete-time, cyclostationary, baseband waveforms;wherein said mapping information into a baseband waveform comprises:mapping by the processor an input bit sequence {b} into an information symbol sequence {Ik} and mapping by the processor the information symbol sequence {Ik} into a discrete-time, cyclostationary, baseband waveform sequence {Uk(nT)}; wherein k denotes values of discrete time; k=1, 2, . . . ; wherein for each value of k, n takes on a plurality of integer values corresponding to a respective plurality of values of the discrete-time, cyclostationary, baseband waveform Uk(nT); T>0; andwherein said mapping by the processor the information symbol sequence {Ik} into a discrete-time, cyclostationary, baseband waveform sequence {Uk(nT)}, comprises:using first and second discrete-time, cyclostationary, baseband waveform elements, over respective first and second successive and adjacent values of k; said first and second discrete-time, cyclostationary, baseband waveform elements differing therebetween in respective first and second frequency ranges that provide respective first and second frequency contents thereto and further differing therebetween in respective first and second bandwidths thereof;providing by the processor said discrete-time, cyclostationary, baseband waveform sequence {Uk(nT)} to said transmitter for further processing and transmission thereof; andtransmitting by said transmitter said discrete-time, cyclostationary, baseband waveform sequence {Uk(nT)} following said further processing thereof;wherein said transmitter is a transmitter of a cellular telecommunications system wherein covertness is not a primary concern; andwherein said transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency. 77. The communications system according to claim 76, wherein said first and second discrete-time, cyclostationary, baseband waveform elements differing therebetween in respective first and second frequency ranges that provide respective first and second frequency contents thereto and further differing therebetween in respective first and second bandwidths thereof, are orthogonal therebetween. 78. The communications system according to claim 77, wherein a time duration that is associated with said discrete-time, cyclostationary, baseband waveform Uk(nT) varies over different values of k. 79. The communications system according to claim 76, wherein said first and second discrete-time, cyclostationary, baseband waveform elements differing therebetween in respective first and second frequency ranges that provide respective first and second frequency contents thereto and further differing therebetween in respective first and second bandwidths thereof, are non-orthogonal therebetween. 80. The communications system according to claim 79, wherein a time duration that is associated with said discrete-time, cyclostationary, baseband waveform Uk(nT) varies over different values of k. 81. A communications system comprising: a processor that is configured to perform operations comprising:processing a waveform that comprises a variable spectral content and is devoid of chipping by using first and second waveform elements that differ therebetween in bandwidth; andmapping the waveform that was processed into an information sequence. 82. The communications system according to claim 81, further comprising a receiver that is configured to wirelessly receive a measure of the waveform; and wherein said processor is further configured to perform a Fourier transform operation, synchronize said first and second waveform elements that differ therebetween in bandwidth with said variable spectral content and to detect an information content of said variable spectral content by using said first and second waveform elements that differ therebetween in bandwidth. 83. The communications system according to claim 82, wherein said receiver is further configured to wirelessly receive synchronization information. 84. The communications system according to claim 83, wherein said processor is further configured to use the synchronization information that is wirelessly received by the receiver in said using first and second waveform elements that differ therebetween in bandwidth. 85. The communication system according to claim 81, wherein said processor is further configured to generate a bit sequence from said information sequence. 86. The communications system according to claim 81, wherein said processor is part of a receiver; wherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:excluding certain frequency intervals from said first and second waveform elements, and using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 87. A communications system comprising: a processor that is configured to perform operations comprising:mapping information that is to be transmitted into a baseband waveform;varying a spectral content of the baseband waveform, without resorting to chipping, by using for said mapping first and second waveform elements that differ therebetween in spectral content;processing a waveform that comprises a variable spectral content and is devoid of chipping by using first and second waveform elements that differ therebetween in bandwidth; andmapping the waveform that was processed into a received information sequence. 88. The communications system according to claim 87, wherein over a first time interval the baseband waveform comprises a first discrete-time waveform comprising a first spectral content; wherein over a second time interval the baseband waveform comprises a second discrete-time waveform comprising a second spectral content that differs from the first spectral content; wherein the first and second time intervals are adjacent one another; and wherein the first and second discrete-time waveforms are used to transmit respective first and second information over said first and second time intervals, respectively. 89. The communications system according to claim 87, wherein said processor is further configured to process a bit sequence in order to obtain the information that is to be transmitted. 90. The communications system according to claim 87, wherein the processor is configured to further process the baseband waveform, the spectral content of which was varied, following said varying; and wherein the communication system further comprises a transmitter that is configured to perform operations comprising wirelessly transmitting said information that is to be transmitted using the baseband waveform that was further processed. 91. The communications system according to claim 87, wherein said first and second waveform elements that differ therebetween in spectral content further differ therebetween in bandwidth. 92. The communications system according to claim 91, wherein the first and second waveform elements that differ therebetween in spectral content and further differ therebetween in bandwidth are used over adjacent transmit/receive intervals. 93. The communications system according to claim 87, wherein said first and second waveform elements that differ therebetween in spectral content differ therebetween in a frequency range that is being used to provide said spectral content. 94. The communications system according to claim 93, wherein the first and second waveform elements that differ therebetween in spectral content and differ therebetween in said frequency range that is being used to provide said spectral content are used over adjacent transmit/receive intervals. 95. The communications system according to claim 87, wherein said first and second waveform elements that differ therebetween in spectral content are separated therebetween by a range of frequencies that is devoid of the information that was mapped into the baseband waveform. 96. The communications system according to claim 87, wherein the processor is further configured to distribute a frequency content of the baseband waveform over first and second frequency intervals that are separated therebetween by a third frequency interval; and to refrain from distributing the frequency content over the third frequency interval. 97. The communications system according to claim 87, wherein the baseband waveform comprises a sequence of discrete-time waveforms; wherein a first waveform of the sequence of discrete-time waveforms comprises a first duration; and wherein a second waveform of the sequence of discrete-time waveforms comprises a second duration that differs from the first duration. 98. The communications system according to claim 87, wherein over a first time interval the baseband waveform comprises a first discrete-time waveform comprising a first spectral content; wherein over a second time interval the baseband waveform comprises a second discrete-time waveform comprising a second spectral content that differs from the first spectral content; wherein the first and second time intervals are adjacent transmit/receive intervals; and wherein the first and second discrete-time waveforms are used to transmit respective first and second information over said first and second time intervals, respectively. 99. The communications system according to claim 87, wherein said processor is further configured to synchronize said first and second waveform elements that differ therebetween in bandwidth with said variable spectral content; and to detect an information content of said variable spectral content by using said first and second waveform elements that differ therebetween in bandwidth. 100. The communications system according to claim 87, wherein said processing a waveform comprises: using a Fourier transform operation. 101. The communications system according to claim 87, further comprising a receiver; wherein said processing a waveform is preceded by wirelessly receiving a measure of said waveform by the receiver. 102. The communications system according to claim 101, wherein the receiver comprises a wireless receiver. 103. The communication system according to claim 87, wherein said processor is further configured to generate a bit sequence from said received information sequence. 104. The communications system according to claim 87, wherein said processor is part of a mobile transceiver that is stationary relative to the Earth; wherein the mobile transceiver comprises a transmitter and a receiver; wherein the transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission by the mobile transceiver while the mobile transceiver remains stationary relative to the Earth; wherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:excluding certain frequency intervals from said first and second waveform elements, and using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 105. The communications system according to claim 87, wherein said processor is part of a transceiver; wherein the transceiver comprises a transmitter and a receiver; wherein the transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform, and further comprises: excluding certain frequency intervals responsive to an interference concern, and varying said bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission by the transmitter and subject to said excluding certain frequency intervals responsive to an interference concern;wherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:excluding certain frequency intervals from said first and second waveform elements, and using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 106. The communications system according to claim 87, wherein said processor is part of a transceiver comprising a transmitter and a receiver; wherein the transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said mapping information that is to be transmitted into a baseband waveform comprises: evaluating a frequency content;forming a desired spectrum shape responsive to the frequency content and responsive to an interference concern; andusing a time-domain representation of the desired spectrum shape to modulate the single carrier frequency;wherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:excluding certain frequency intervals from said first and second waveform elements, and using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 107. The communications system according to claim 87, wherein said processor is part of a transceiver; wherein the transceiver comprises a transmitter and a receiver; wherein the transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said mapping information that is to be transmitted into a baseband waveform comprises: forming a sequence of information symbols {Ik} responsive to an information bit sequence; andmapping the sequence of information symbols {Ik} onto a waveform sequence {Uk};wherein a Fourier transform of the waveform sequence {Uk} comprises a plurality of frequencies each one of which comprises a non-zero amplitude that depends upon an information symbol of said sequence of information symbols {Ik} but is not the information symbol;wherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:excluding certain frequency intervals from said first and second waveform elements, and using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 108. The communications system according to claim 87, wherein said processor is part of a transceiver that comprises a transmitter and a receiver; wherein the transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency;wherein the transceiver comprises a mobile transceiver that is stationary relative to the Earth; andwherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission by the mobile transceiver while the mobile transceiver remains stationary relative to the Earth;wherein said varying a spectral content of the baseband waveform further comprises:excluding certain frequency intervals responsive to an interference concern, and varying said bandwidth of the baseband waveform over two successive signaling intervals, that are adjacent therebetween, responsive to a transmission by the transmitter and subject to said excluding certain frequency intervals responsive to an interference concern;wherein said mapping information that is to be transmitted into a baseband waveform comprises:evaluating a frequency content;forming a desired spectrum shape responsive to the frequency content and responsive to an interference concern; andusing a time-domain representation of the desired spectrum shape to modulate the single carrier frequency;wherein said mapping information that is to be transmitted into a baseband waveform further comprises:forming a sequence of information symbols {Ik} responsive to an information bit sequence; andmapping the sequence of information symbols {Ik} onto a waveform sequence {Uk};wherein a Fourier transform of the waveform sequence {Uk} comprises a plurality of frequencies each one of which comprises a non-zero amplitude that depends upon an information symbol of said sequence of information symbols {Ik} but is not the information symbol;wherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:excluding certain frequency intervals from said first and second waveform elements, and using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively. 109. The communications system according to claim 87, wherein said processor is part of a transceiver; wherein the transceiver comprises a transmitter and a receiver; wherein the transmitter is devoid of a plurality of modulators and comprises a single modulator modulating a single carrier frequency; and wherein said varying a spectral content of the baseband waveform comprises varying a bandwidth of the baseband waveform over two successive signaling intervals that are adjacent therebetween; wherein said waveform that comprises a variable spectral content and is devoid of chipping comprises a variable bandwidth that varies over first and second successive signaling intervals thereof that are adjacent therebetween; andwherein said using first and second waveform elements that differ therebetween in bandwidth comprises:using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween;wherein said using said first and second waveform elements that differ therebetween in bandwidth over said first and second successive signaling intervals, respectively, in order to receive said waveform that comprises the variable bandwidth over the first and second successive signaling intervals thereof that are adjacent therebetween comprises:forming first and second Fourier transforms over said first and second successive signaling intervals, respectively.