Transmission of data (including binary data and multi-component symbols and vectors) is a generally well understood and developed area of art. FSK comprises one particularly well understood form of data representation. Generally speaking, with FSK, a carrier signal is modulated with a signal having an amplitude that varies (or “shifts”) as a function of the data elements being represented. For example, a logical “1” can be represented by a series of pulses having a first amplitude and a logical “0” can be represented by a series of pulses having a second and different amplitude (in most FSK systems, this timevarying amplitude variation comprises the parameter that controls the timevarying frequency of a voltage controlled oscillator). When using FSK modulation in a wireless context, it is known that the resultant transmission will not be evenly distributed with respect to power over the frequency domain. Rather, increased power will exist that reflects “tones” that correspond to the frequencies that represent the data.
For many applications, such an uneven frequency domain profile does not result in any particular problems. There are situations, however, where such phenomena is troublesome. For example, when used to support relatively high speed data transmissions (such as 10 to 20 Mbps or higher) in the U-NII mid band (5.25 to 5.35 GHz) or the U-NII upper band (5.725 to 5.825 GHz), such distorted spectral profiles in turn typically require reduced transmission power in order to otherwise comply with regulations regarding allowed power at such bands. Such reduction, in turn, leads to a reduced effective transmission range.
Because of such problems, system operators must often either install a significantly large number of transmitters to ensure adequate coverage over a given service area or use an alternative data transmission technology that itself presents other concerns and issues (for example, orthogonal frequency division multiplexing is often considered for such use at such bands, but itself constitutes a somewhat non-robust approach that is also relatively expensive).
A desire therefore exists to use FSK for such purposes, but the reduced range of present solutions have tended to move many users to other approaches and/or to accept the burden and costs of installing and maintaining a large number of FSK transmitters for a given area of overall coverage.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are typically not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.