IEEE 802.22.2-2012 pdf download IEEE Recommended Practice for Information Technology- Telecommunications and information exchange between systems Wireless Regional Area Networks (WRAN)- Specific requirements Part 22.2: Installation and Deployment of IEEE 802.22mM Systems
51.11 Point-to-point propagation model
A point-to-point propagation model determines the signal power loss between a point where a transmittermight be located and a point where a receiver might be located considering all obstructions andatmospheric effects on the propagation path. The power loss determination between two points representsthe performance of a link.
A point-to-point propagation model can be extended to an area by subdividing the area to be analyzed witla rectangular grid where each intersection point becomespoint to be considered for propagationprediction. Typically, in a unidirectional transmission system, a transmitter is positioned at a unique pointwhile it is assumed that a receiver is located at each intersection in the grid. Over the entire area to beanalyzed, each intersection point is independent and its propagation link is quantified by its power lossrom the point where the transmitter is located. In a bidirectional transmission system, the propagation patlis usually reciprocal but it may not be because of factors such as the use of different frequencies in the twodirections, local level of man-ade noise, effect of antenna diversity, etc. In such case, the power losswhen the transmitter is located at the intersection point and the receiver at the single point (i.e, theupsfream) would also need to be calculated.
The point-to-point propagation model is more precise than empirical point-to-multipoint propagationmodels based on field test measurements. The estimations and approximations inherent to empirical point-to-multipoint propagation models decrease processing time but increase the likelihood of inaccuratepropagation predictions. Popular empirical point-t-multipoint propagation models are outdated andprocessing power is more readily available to perform more complex point-to-point propagation modelingA system planner should invest in any additional processing resources to gain as much precision as possibleso that the planned service operates efficiently and without harmful interference.
51.1.2 Desired-to-undesired protection ratios
D/U’s for the various channel relationships considered should be selected from a scientific technicallyreputable reference (e.g., ATSC B1]) that provides results from analysis examining the specificmodulations used by both the desired and undesired signals as well as agreed upon typical transmitter ancreceiver characteristics for the equipment involved.
D/U’s express the desired field strength above any undesired field strength in dB that is required in order tcavoid harmful interference and to allow acceptable reception of an RF service. The desired field strength isthat which is produced by the transmitter providing the desired RF service while the undesired fieldstrength is that which is produced by a potentially interfering signal. The D/U is measured at the antennaterminals of a receiver
D/U’s should be selected depending on the channel relationship between the desired and undesired signalsFor example, D/U’s are usually defined for co-channel and adiacent channel relationships. D/U’s are alscoften defined for channel relationships that can extend out to -l5 channels of separation between thedesired and undesired signals (e.g., ATSC JBlJ). D/U’s are specified to account for any interferencemechanism, including co-channel interference, leakage from out-of-band interfering signals at the receiver.out-of-band emission at the interfering transmitters, and higher-order inter-modulation interference causedby the presence of high power interfering signals at the receiver.
D/U’s may vary depending on the modulation used for the desired signal and the modulation used for theundesired signal. The D/U’s should be determined through compatibility testing in a laboratory using the