1. Field of Invention
This application relates to transmission of data, and in particular to an encoding scheme to efficiently transfer data with low latency.
2. Description of the Related Arts
In 2003, the FCC-licensed for use 13 GHz of spectrum in the 70 GHz and 80 GHz bands, also known as the E-band millimeter wave Radio Frequency (RF) spectrum. Ten bands in this spectrum were made commercially available for a broad range of fixed wireless applications operating at gigabit data transfer rates. Applications include point-to-point local wireless networks and broadband internet access. Communication of data through E-band signals potentially serves as a cheap alternative to more costly fiber solutions, particularly in urban areas due to the cost of laying fiber. E-band RF data transfer is a particularly cost effective solution for filling the gap for short-haul wireless connectivity in the so-called “last mile” between network service providers and customers. E-band RF data transfer can also offer data rates that overlap with lower the end of rates available with fiber-based solutions.
When digital data is transmitted, it is desirable for the transmitted signal to be DC-balanced and have bounded disparity. In a DC balanced signal, the total number of one bits transmitted is ideally equal to the total number of zero bits transmitted (or close to it), and bounded discrepancy refers the difference between the number of one and zero bits transmitted in any given segment of transmitted data. For example, in one common implementation developed by IBM™, each 8-bit chunk of data is encoded into a 10-bit symbol. The 10-bit symbols used are selected such that no more than five consecutive bits have the same value (to provide DC balancing) and the difference between the number of ones and zeroes in any given 10-bit symbol (the disparity of that symbol) is no more than two (i.e., no symbol has more than six ones or zeros).
In addition to transmitting the digital data, some communications systems also transmit control information relating to the operation of the data link. Typically, such control information is transmitted by replacing some potential data segments in the transmitted signal with control segments, or by inserting control segments between data segments. For example, typical control segments are used to indicate the start of a frame, the end of a frame, a link idle state, and the like. As the control characters are embedded into the data stream in place of data symbols, they reduce the bandwidth available for the transmission of data.
The Figures (FIGS.) and the following description relate to exemplary embodiments by way of illustration only. It should be noted that from the following discussion, alternative embodiments of the structures and methods disclosed herein will be readily recognized as viable alternatives that may be employed without departing from the principles of what is claimed. Reference will now be made in detail to several embodiments, examples of which are illustrated in the accompanying figures. It is noted that wherever practicable similar or like reference numbers may be used in the figures and may indicate similar or like functionality. The figures depict embodiments of the disclosed system (or method) for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles described herein.