- cept involves the concentration of interference to a small time-frequency element even at the expense of some system robustness. Base stations must be synchronized in the DECT system. A control channel carries information about access rights, base station capabilities, and paging messages. The DECT transmission rate is 1152 kbps. As a result of this and a relatively wide bandwidth, either equalization or antenna diversity is typically needed for using DECT in the more dispersive microcells. Japan has developed the personal handyphone system (PHS). Its frequency allocation is 77 channels, 300 kHz in width, in the band 1895-1918.1 MHz. The upper-half of the band, 1906.1-1918.1 MHz (40 frequencies), is used for public systems. The lower-half of the band, 1895-1906.1 MHz, is reserved for home/office operations. An operational channel is autonomously selected by measuring the field strength and selecting a channel on which it meets certain level requirements. In other words, fully dynamic channel assignment is used. The modulation is /4 DQPSK; average transmit power at the handset 18.10 WIRELESS LANS Table 18.1 Digital Cordless Telephone Interface Summary CT2 + Region Europe Canada Europe Japan United States Duplexing Frequency band (MHz) 864-868 944-948 1800-1900 1895-1918 1850-1910/1930-19902 Carrier spacing (kHz) 300/300 Number of carriers 16 pairs/10 MHz Bearer channels/carrier 8/pair Channel bit rate (kbps) Modulation /4 DQPSK /4 QPSK Speech coding 32 kbps 32 kbps 32 kbps 32 kbps Average handset transmit power (mW) Peak handset transmit power (mW) Frame duration (msec) aGeneral allocation to PCS; licensees may use PACS. Source: Ref. 18, Table 2. is 10 mW (80-mW peak power) and no greater than 500 mW (4-W peak power) for the cell site. The PHS frame duration is 5 msec. Its voice coding technique is 32-kbps ADPCM (Ref. 8). In the United States, digital PCS was based on the wireless access communication system (WACS), which has been modified to an industry standard called PACS (personal access communications servi