In frequency range 30-1000 MHz, fixed and mobile systems may operate in point-to-point or point-to-multipoint communication methods; in simplex, semi-duplex or duplex operation using one frequency channel or two frequency channel transmission; in channel bandwidths of 50 kHz, 30 kHz, 25 kHz or 12.5 kHz. In order ensure quality of services, spectrum efficiency, as well as to suit to practical situation and specific characteristics of current spectrum uses, the channel bandwidth of 25 kHz is chosen and applied in this Plan. Interleaved channels may be used additionally, if necessary. Channel arrangement patterns with channel bandwidths of 12.5 kHz or 6.25 kHz are also allowed if these patterns are compatible with channel pattern of 25 kHz bandwidth in this Plan.

For one frequency channel transmission, channel pattern in a frequency band is illustrated in Figure 1 below:

Where:

 F1 is lowest frequency (lower boundary) of the frequency band (MHz)

 F2 is highest frequency (upper boundary) of the frequency band (MHz)

 fn is center frequency of the n^th frequency channel (MHz)

 X is frequency spacing between two adjacent channels (MHz)

Center frequency of the n^th frequency channel is expressed by the following relationship:

f_n = f₁ + (n-1) X,    n= 1,2,3,…

For tow frequency channel transmission, channel pattern in a frequency band is illustrated in Figure 2 below:

Where:

            P is duplex spacing (MHz)

            F₁ is lowest frequency (lower boundary) of the transmitting/receiving band (MHz)

            F₂ is highest frequency (upper boundary) of the transmitting/receiving band (MHz)

            F’₁ is lowest frequency (lower boundary) of the receiving/transmitting band (MHz)

            F’₂ is highest frequency (upper boundary) of the receiving/transmitting band (MHz)

            fn is center frequency of the n^th receiving/transmitting frequency channel (MHz)

            f’n is center frequency of the corresponding n^th transmitting/receiving frequency channel (MHz)

            X is frequency spacing between two adjacent channels (MHz)

            Y is receiving – transmitting gap (separation between innermost channels)

Center frequencies of the n^th transmitting and corresponding receiving channel are expressed by the following relationships:

f_n = f₁ + (n-1) X                   

f’_n = f’₁ + (n-1) X = f_n + P    where n = 1,2, 3,…