COM 0089.000 2008-2010 - Laserfiche WebLink

Home

rv ~>F`V! Hawaii Preliminary Technical Assessmen! lCTAP-H UHA-PREASSESS-001-RO' 3. Site Selection One of the major concerns we had with the Macro Corp. plan is the reliance on so many un- developed sites. The requirement to build out seven (7) new sites on County owned land plus an additional nine (9) new sites on land that needs to be procured is unprecedented in other county-level system design reviews pertormed by ICTAP. Additional effort should be made to look into other potential sites that are presently used for radio commuhications and grade them according to the ease of County use, i.e. County owned sites, state owned site, other government owned (Federal or local) sites, public utility owned sites and commercial (two way radio and cellular) sites. This process is a give and take process that may cause an RF site to be placed on an existing tower that may not be in the optimum location but will satisfy the needs when the system is evaluated as a whole. We understand that anytime that a system is changed out from a conventional VHF system to a 700/800 MHz simulcast system there is a need to add additional sites. The goal is to do so in the most cost effective manner. The costs to develop new sites and the recurring costs for leases can make the best designed radio system too expensive to field or maintain. Coverage requirements should also be considered. The coverage, as laid out by the Macro Conceptual Design Analysis & Recommendation Report, is portable coverage with 6 dB of in-building attenuation island wide. For a county that has vast areas of rural, farming, and open land this is a very aggressive coverage requirement. Furthermore, 6 dB is insuffcient for true in-building attenuation calculations even for residential structures. An alternative approach is to develop service areas and specify coverage levels for the service areas. An example for the County of Hawaii would be to develop a service area that covers the Hilo area and a second that incorporates the Kailua-Kona area including the hotels. These service areas could then have a more aggressive coverage requirement of 95 (or higher) percent reliability to portables on the hip with 12 to 16 d6 of in-building attenuation. The remaining island could have a coverage requirement of 95 percent to mobiles. This is a more common approach to large areas like county wide systems and ensures adequate radio coverage where a majority of the calls originate. 4. Microwave System The main concern that we have with the microwave design is at the planned Police Department and Fire Dispatch (PDFD) Center in Hilo. The first concern is that this is the single most important site in the whole plan. It is the primary control site for the proposed 700 MHz trunking system, the proposed 700 MHz HPD system and the VHF fire alert paging system. In spite of the critical need to communicate to and from this site, the PDFD Center is not placed on the microwave ring. Instead it is a spur off of the ring causing a single point of failure for the entire communications system of the County. To make the system even less reliable, an 18 GHz microwave system is planned to tie this site to the ring. We strongly recommend that 18 GHz technology is not used in the Hilo area due to it's susceptibility to fading caused by weather. We do not recommend 18 GHz and above technology in any mission critical public safety environment even in very dry locations. 18 GHz would be suitable for alternate path redundancy. We would recommend that the system be re-designed to allow this site to be placed on the ring or at the very least have two (2) spurs from this site to the microwave system to allow for system redundancy. The neM concern is the bandwidth of the PDFD Center microwave. It is planned to be a 28 T1 (45 Mbs) radio tying to a 3-DS3 (45 Mbs x 3) ring. The concern here is as the new site becomes the key to operations around the island, that this bandwidth will be insufficient and a choke point for data getting on and off the ring. The connectivity to the ring should be equal to the ring capacity. The Conceptual Design Analysis & Recommendation Report states the following (page 3-11): October 2008 13