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Q. What is different about Adapt4's radio?
A. Adapt4 cognitive radios are software radios based our proprietary Spectral Reuse Technology. They Cohabitate a range of RF Channels with primary licensed users with minimal impact on other users.
Q. What is frequency hopping?
A. There are at least two types of frequency hopping: Adapt4's patent-pending form and a traditional form. Traditional frequency hopping is a form of spread spectrum (FH-SS) in which a radio continuously hops from one frequency to another at high speed, using the entire bandwidth in the band (whether the frequency is in use by another station or not). In theory, this is "invisible" to many other analog or digital modulation types since it appears for a very short time period. However each FH-SS radio raises the noise floor a bit until the band is degraded for all radios, regardless of modulation type.
Adapt4's patent-pending form of frequency hopping uses a smaller set of frequencies at any given instant and only uses frequencies that are not in use. Thus, Adapt4's radio is "cognitive" (of other users in the band). The radio does this by constantly scanning the entire band (480 channels) to look for and avoid interference from other users (including other secondary or primary licensees). Should a frequency in use by the XG1 suddenly become interfered with, the radio will instantly select a free channel from its constantly updated Free Channel List. Each of the radio's 1 to 45 channels is individually managed in this way so that small segments of bandwidth throughout the entire band can be used. And to minimize further the possibility of extended interference, the radio will constantly change its frequency even without interference to minimize its profile in the band. In other words, Versaband has the advantages of frequency hopping spread spectrum without the disadvantages. It should be noted that FH-SS radios are not permitted in licensed bands as secondary users.
Q. What is a cognitive radio?
A. Cognitive Radio is a broad term, but in general, a cognitive radio is one that can change the way it operates based on the characteristics of the band in which it is operating or the behavior of the users in the network, etc. Perhaps an early, minimal example is a dial modem that "trains" or lowers its bandwidth depending on line noise. In the case of Adapt4's XG1 cognitive radio, cognitive refers to its ability to avoid interference to or from other users on the network. [See "What is frequency hopping," above] The radio does this by constantly scanning the entire band (480 channels) to look for and avoid interference from other users (including other secondary or primary licensees). Should a frequency in use by the XG1 suddenly become interfered with, the radio will instantly select a free channel from its constantly updated Free Channel List. Each of the radio's 1 to 45 channels is individually managed in this way so that segments of bandwidth throughout the entire band can be used. And to minimize further the possibility of extended interference, the radio will constantly change its frequency even without interference to minimize its profile in the band. In other words, Versaband has the advantages of frequency hopping spread spectrum without the disadvantages.
Q. What is a software-defined radio?
A. A software defined radio is one in which its characteristics (especially its modulation and demodulation type) are defined in easily-changeable software within a Digital Signal Processor. Adapt4's XG1 cognitive radio is software-defined, since its modulation and demodulation firmware can be downloaded over the air, as well as its radio control software, management software, and configuration.
Q. What is a Primary License? A Secondary License?
A. The FCC auctions or grants portions of some radio bands, such as the 217-220 MHz band for “primary users.” These users have the right to use the band without interference. However, this is not an exclusive license. The FCC may issue “secondary” licenses for these bands. Secondary users may use spectrum in the band as long as they do not interfere with the primary user (who may use the band infrequently).
A secondary user with a fixed-frequency radio will have to visit a site and change the frequency (or change out the radio) if a primary user begins using the frequency. However, an Adapt4 radio will automatically detect the use of the frequency by the primary user and move to another set of unused frequencies, without the need of human intervention and without loss of data. Adapt4's patent-pending radio gives secondary users the advantage of a licensed band, without the headaches and cost of occasional reconfiguration of the network.
