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Redwood City Police <br /> Department System Description <br /> l� (R.DLAP)radio channel protocol format, and encapsulating them <br /> in the robust Highspeed Data Link Control (�IDLC) fraznes for <br /> delivery to the base site. Similarly, the RNC receives the MDD to <br /> host messages,strips away the HDLC layers, converts the data to <br /> TCP/IP over Ethernet, and delivers the transmission to the message <br /> switch forrouting to the appropriate CAD or Records host. <br /> Radio Link Control <br /> One way the RNC maximizes the efficiency of the radio channels <br /> while ensuring reliable delivery is by breaking long dispatch and <br /> inquiry data into optimum sized packets for over the air <br /> transmission. Similazly, once a segmented message is received <br /> from an NIDD,it is the RNC that recombines the inbound packets <br /> for complete message transfer to the host computers. <br /> � This process of packetization allows for an RF protocol that is fast <br /> and resistant to enviranmentai noise. In order to maintain the <br /> proper order of group data packets, the RNC assigns and verifies <br /> sequencing values for each transnussion. Thus,both inbound and <br /> �� - <br /> outbound messages are checked for cantent and completeness. <br /> In the cases of heavy RF fades,the RNC can retransmit a message <br /> to the MDD or instruct the MDD to attempt sending its inbound <br /> message again. In such instances the ei�ciency of the RF channel <br /> is ma�m;�ed as the packetizing and sequencing of inessages <br /> allows the RNC to require retransmission of only the faded <br /> sections of a long dispatch or inquiry. <br /> Roaming Management <br /> The RNC is responsible for managing the roaming mobile devices <br /> among the backbone site within its controL Upon MDD powering <br /> up,the unit examines the system backbone channels and selects <br /> one as the best for communication with the host The RNC is then <br /> alerted of the unit's activity and the site it hss selected for <br /> registration. Additionally, as the MDD's travel about the coverage <br /> area,they constantly monitor base signals and select the best site <br /> for communications with the host Each time the radio chooses a <br /> new site, the RNC updates the registration tables. This constantly <br /> maintained database allows messages to reach a MDD without <br /> requiring the resources of the other backbone site in the system. <br /> �� <br /> �MOTOROLA ' 2 - 3 <br /> . _ ._ ___. _ <br />