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Shannon Score

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Shannon Score is a metric, named in honor of Claude Shannon, used to measure radio spectrum utilization efficiency of by one or more wireless networks operated by a wireless internet service provider. It was first introduced by Ubiquiti Networks to encourage efficient usage of unlicensed/lightly-licensed frequency bands and to quantify/compare efficiencies of different radio access technologies. The Shannon Score is clearly defined and easily computed for any wireless access protocol operating in any part of the radio spectrum.

Radio Spectrum Utilization Efficiency

Only a finite portion of the total electromagnetic spectrum supports radio communication, making it crucial to use this precious resource as efficiently as possible. With a more efficient technology, the same amount of spectrum can deliver greater capacity, either by delivering more bits per second of capacity to each user or by servicing more users.

The Federal Communication Commission (FCC) in USA, and regulatory agencies globally have facilitated unlicensed and lightly-licensed use of extremely valuable radio spectrum in order to promote economic productivity. These frequency bands, such as the 2.4 GHz and 5 GHz ISM Bands used by WiFi networks, are especially over utilized. Hence quantifying and improving spectrum utilization efficiency becomes especially important.

One important measure is spectral efficiency, which is the amount of data bandwidth that a specific technology can extract from a certain amount of radio spectrum. Spectral efficiency was originally represented in units of bits per seconds per hertz (bit/s/Hz). Since all modern wireless communication protocols occupy multiple megahertz of radio spectrum, an equivalent, yet more intuitive, unit is megabit per second per megahertz (Mbps/MHz). For example, a radio link utilizing 10 MHz of radio spectrum to transmit a data rate of 20 Mbps has a spectral efficiency of 2 Mbps/MHz or 2 bits/s/Hz.

Although the spectral efficiency measure is extremely useful, it typically characterizes the efficiency of only a single radio link and does not address another important measure of spectrum utilization efficiency, which is how readily the same spectrum is reused by multiple radio links . For example, in a Time Division Multiple Access (TDMA) network, the radio spectrum is time-shared amongst multiple radio links, such as in a point to multi-point network.

The Shannon Score addresses the above short-coming by measuring radio spectral utilization efficiency as a weighted average of individual radio link spectral efficiencies, weighted by the usage factor of each individual link.The Shannon Score can be useful in assessing historical gains in efficiency, evaluating the gains that might be achieved with new or improved technologies, in identifying opportunities for evolving to more efficient systems, or even to implementing a wholesale replacement technology.

Comparison of Shannon Scores

Examples of numerical Shannon Score values of some common communication systems can be found in the table below.

Wireless Standard/System	Year Launched	Bandwidth	Max Shannon Score
AMPS (1G Cellular)	1983	30 kHz	0.0015
GSM (2G Cellular)	1991	200 kHz	0.52
WCDMA (3G Cellular)	2001	5 MHz	0.077
LTE-Advance (4G Cellular)	2013	20 MHz	3.75
IEEE 802.11a/g	2003	20 MHz	2.75
IEEE 802.11n	2007	20/40 MHz	3.61
IEEE 802.11ac	2012	20/40/80 MHz	5.42

References

Rysavy, Peter (2014). "Challenges and Considerations in Defining Spectrum Efficiency", Proceedings of the IEEE, 102(3).

External links

link to airCRM website [TBD]