Frequency Translating Zone Enhancer (FTZE)
A DCI Zone Enhancer creates a positive CDMA business case. One zone enhancer can extend a CDMA sector up to 40 km into marginal coverage areas and small towns, at a cost of less than half of a full BTS.
The FTZE was developed in conjunction with Sask Tel Mobility. Sask Tel Mobility is presently using 20 Zone Enhancer units in small towns in Saskatchewan to further extend their coverage. The product is in operation and is well-proven.
The Zone Enhancer is Industry Canada certified for linearity and spurious signals. Our measured RHo factor is typically .96, which is well above the CDMA standard of .92.
The DCI unit taps into the antenna line at a BTS, translates the frequency and then beams the signal to a small town, where the signal is re-translated and transmitted. A cellular provider can use either an underutlilized sector, or have a sector dedicated to a town.
In Saskatchewan, Canada, the link frequency is on unused PCS channels at 1900 MHz, but other link frequencies could be used.
The overall system gain, including link antennas, is usually -13 dB, which was chosen to minimize the loss of sensitivity at the BTS because of injected noise. If a cellular provider uses a dedicated sector, this gain can be increased.
Operating Frequencies and Power
The FTZE is designed to operate on a single 1.23 MHz wide CDMA channel. The current model transmits on 881.52 MHz and uses 1986.52 MHz and 1906.52 Mhz as link frequencies. It injects the signal back into the BTS RX at 836.52 MHz. The frequencies can be built to accommodate any channel in the CDMA Band.
The overall gain in both forward and reverse directions is -13 dB, which is chosen to minimize the added noise to the BTS RX. The forward signal is sampled from the BTS TX line which has a maximum level of +43 dBm, and is retransmitted in the remote town at a level of +30 dBm (1 watt). A return signal of -70 dBm at the remote antenna is injected into the BTS RX line at -83 dBm. The injection of noise at this level reduces the sensitivity of the BTS RX by about 1 dB. This effect is further reduced if RX diversity is in use.
The linearity of the complete system, both forward and reverse, is designed to exceed the CDMA Rho standard of .92 (typically .96 or better), as well as the Industry Canada specifications for intermod products and linearity.