Wireless communication systems that use pilot information are well known in the art. Pilot information generally serves to facilitate an assessment of the wireless channel by a receiving party. By providing pilot information having known characteristics, a receiver can utilize its knowledge of the differences (such as amplitude and phase differences) between the pilot information as it should have been received and the pilot information as it was received to ascertain and compensate for alterations that were occasioned by the channel to thereby promote a more accurate recovery of other information as was also received by the receiver via that channel. Pilot information can also be used to effect other purposes as well.
Unfortunately, there are a variety of trade-offs that are ordinarily accepted when combining pilot information with a user payload. Such trade-offs, in various ways, usually impact the usable bandwidth or user payload throughput capacity of the channel. For example, in a code division multiplexed wireless communication system that makes use of orthogonal variable spreading factor codes to permit differentiation of a number of data channels, a control channel that includes pilot information will also have, or share, such a code. Within the context of such a system, this means that some portion of overall available power must be allocated for the control channel/pilot information. When less power than is necessary at any given moment is used to support the pilot information, however, user information throughput capacity is negatively impacted.
Conversely, of course, the opposite can also occur. More power may be accorded the pilot information than is necessary to overcome the present vagaries of the channel. As a result, less power is available for the user payload and this again can lead to a diminution of the receiver's ability to properly decode the user payload.
One prior art approach relies upon a simulated study of a channel for a given set of conditions (such as, for example, a given data rate and service overhead for the data payload). Running the simulation develops a set of corresponding gain factors to be used with the data/control channel. By providing these results in a look-up table, the gain factor as corresponds to a given data rate and service can then be recovered and used during ordinary operations. One significant drawback of this approach is that this technique does nothing to assist a wireless communication unit that must use, for whatever reason, a data rate that is not represented in the look-up table. Since new data rates are a common and frequent occurrence, this constitutes a considerable obstacle to effective use.
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.