In CDMA no frequency reuse is required. Therefore, every cell can have the same 120 channels: number of annels/cell (in CDMA). In cellular, because the frequency reuse factor is applied on FDMA and TDMa schemes but not on CDMA, therefore, cellular CDMA has a greater spectrum efficiency than cellular FDMA or TDMA [ Lee, May 1991] New Microcell System The conventional microcell system [Lee, Nov. 1991, 1993] reduces the transmit power and makes a cell less than 1 km in radius. The concept of using cell splitting is to increase capacity. Furthermore, the new microcell system needs to find a way to make a conventional microcell to be intelligent. The conventional microcell does not have the intelligence to know where the mobile or portable units are located within the cell. Therefore, the cell site has to cover the signal strength over the whole cell or whole sector. The more unnecessary signal power transmitted, the more interference will be caused in the system and less capacity will be achieved. In this new intelligent microcell system, each cell is an intelligent cell. In a new microcell, there are three or more zones. The cell will know which zone a particular mobile unit is in. Then a small amount of power will be needed to deliver in that zone. The cochannel interference reduction factor(CiRF) now will be measured from two cochannel zones instead of two cochannel cells. Then the two cochannel cells can be located much closer. In this new microcell system, the frequency reuse factor K becomes K=3. As compared to the conventional microcell K= 7, the new microcell system has a capacity increase of 2. 33(= 7/3)times. These two techniques can be used in buildings and outside buildings. Defining Terms CDMA: A multiple access scheme by using code sequences as traffic channels in a comom radio channel. Cell splitting: A method of increasing capacity by reducing the size of the cell. Cochannel interference reduction factor(CIRF): A key factor used to design a cellular system to avoid the cochannel interference FDMA: A multiple access scheme by dividing an allocated spectrum into different radio channels. Frequency reuse factor(K): A number based on frequency reuse to determine how many channels per cell. GSM(Global System Mobile): European digital cellular standard using TDMA. Handoff: A frequency channel will be changed to a new frequency channel as the vehicle moves from one IDEN (Integrated Dispatch and Enhanced Network): A cellular-like system. Mobile cellular systems: A high-capacity system operating at 800-900 MHz using a frequency reuse scheme vehicle and portable telephone communications PHS(Personal Handy Phone System): A TDD system deployed in Japan. SMR(Specialized Mobile Radio): A trunked system for dispatch TDMA: A multiple access scheme by dividing a radio channel into many time slots where each slot carries a Related Topic 69.2 Radio References W. C. Y. Lee, Mobile Cellular Telecommunication Systems, New York: McGraw Hill, 1989 W. C. Y Lee," Overview of cellular CDMA, IEEE Trans. on Veh. Tech, vol. 40, PP. 290-302, May 1991 w. C.Y. Lee,"Microcell architecture--Smaller cells for greater performance, " IEEE Commun. Magazine, vol 29, PP.19-23,Nov.1991 W. C.Y. Lee, Mobile Communications Design Fundamentals, 2nd ed, New York: Wiley, 1993. c2000 by CRC Press LLC© 2000 by CRC Press LLC In CDMA no frequency reuse is required. Therefore, every cell can have the same 120 channels: number of channels/cell (in CDMA). In cellular, because the frequency reuse factor is applied on FDMA and TDMA schemes but not on CDMA, therefore, cellular CDMA has a greater spectrum efficiency than cellular FDMA or TDMA [Lee, May 1991]. New Microcell System The conventional microcell system [Lee, Nov. 1991, 1993] reduces the transmit power and makes a cell less than 1 km in radius. The concept of using cell splitting is to increase capacity. Furthermore, the new microcell system needs to find a way to make a conventional microcell to be intelligent. The conventional microcell does not have the intelligence to know where the mobile or portable units are located within the cell. Therefore, the cell site has to cover the signal strength over the whole cell or whole sector. The more unnecessary signal power transmitted, the more interference will be caused in the system and less capacity will be achieved. In this new intelligent microcell system, each cell is an intelligent cell. In a new microcell, there are three or more zones. The cell will know which zone a particular mobile unit is in. Then a small amount of power will be needed to deliver in that zone. The cochannel interference reduction factor (CIRF) now will be measured from two cochannel zones instead of two cochannel cells. Then the two cochannel cells can be located much closer. In this new microcell system, the frequency reuse factor K becomes K = 3. As compared to the conventional microcell K = 7, the new microcell system has a capacity increase of 2.33 (= 7/3) times. These two techniques can be used in buildings and outside buildings. Defining Terms CDMA: A multiple access scheme by using code sequences as traffic channels in a comom radio channel. Cell splitting: A method of increasing capacity by reducing the size of the cell. Cochannel interference reduction factor (CIRF): A key factor used to design a cellular system to avoid the cochannel interference. FDMA: A multiple access scheme by dividing an allocated spectrum into different radio channels. Frequency reuse factor (K): A number based on frequency reuse to determine how many channels per cell. GSM (Global System Mobile): European digital cellular standard using TDMA. Handoff: A frequency channel will be changed to a new frequency channel as the vehicle moves from one cell to another cell without the user’s intervention. IDEN (Integrated Dispatch and Enhanced Network): A cellular-like system. Mobile cellular systems: A high-capacity system operating at 800–900 MHz using a frequency reuse scheme for vehicle and portable telephone communications. PHS (Personal Handy Phone System): A TDD system deployed in Japan. SMR (Specialized Mobile Radio): A trunked system for dispatch. TDMA: A multiple access scheme by dividing a radio channel into many time slots where each slot carries a traffic channel. Related Topic 69.2 Radio References W. C. Y. Lee, Mobile Cellular Telecommunication Systems, New York: McGraw Hill, 1989. W. C. Y. Lee, “Overview of cellular CDMA,” IEEE Trans. on Veh. Tech., vol. 40, pp. 290–302, May 1991. W. C. Y. Lee, “Microcell architecture—Smaller cells for greater performance,” IEEE Commun. Magazine, vol. 29, pp. 19–23, Nov. 1991. W. C. Y. Lee, Mobile Communications Design Fundamentals, 2nd ed., New York: Wiley, 1993