08-21-1996 - Laserfiche WebLink

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How Enhanced Specialized Mobile Radio (ESMR) Technology Works According to Government Affairs Notes - A Comparison of ESMR and Cellular, an ESMR system is "the coordinated operation of several contiguous SMR [Specialized Mobile Radio] systems operated with digital — rather than analog — technology and.a configuration of numerous low- power sites which employ significant frequency re-use throughout the ESMR system." First licensed in the 1970s, SMR towers were not allowed to reuse channels. Operating at 1000 watts of power and at high elevation sites, towers covered a 20 mile radius. ESMR systems, however, are permitted to reuse channels. Nextel's ESMR system muses channels by building transmitters at low elevation sites (generally shorter than 200 feet) and limiting the transmitters' power output to 100 watts of effective radiated power (ERP). By doing so, sites cover radii between two and eight miles. Operating on a system composed of cell sites, the ESMR technology functions similarly to the cellular technology. Like the cellular system, ESMR uses cell sites with radii between two and eight miles; operates by way of a main switching office that completes calls by transmitting them to a local telephone company; uses omni and sector cell configurations; employs whip and panel antennas on monopoles and buildings; reuses frequencies; and utilizes coverage and capacity sites. The main difference between ESMR and cellular systems is ESMR's use of digital technology, which allows it to make its sites more efficient than typical cellular sites. Because channels can accommodate six times as many callers, each site has increased capacity, which in turn, reduces the number of sites required to operate the system. How Personal Communications Services (PCS)Technology Works PCS also will function as a pattern of cell sites using digital technology. Incoming wireline calls will be transmitted by Iocal telephone company wires to a central control point. Similarly, incoming wireless calls will be routed through a PCS wireless switch to a local telephone system. Calls will be completed through microcells (antennas located on top of Iight poles or telephone poles), and macrocells (antennas mounted on the sides or tops of buildings). Microcells are expected to cover radii of 80 to 1200 feet and macrocells will cover approximately 1.2 milesJtwo kilometers). As the caller approaches the edge of the cell's boundary, the communication will be handed over from the original cell to the next. PCS providers are aiming to offer an alternative to the fixed telephone in a user's home by providing wireless coverage both within and outside of the home. Providers are in the process of developing a system referred to as "follow-me calling" or "the universal phone number," in which calls will be routed to people instead of to places regardless of location. PCS systems will utilize digital technology, and as a result, their cell sites will have higher calling capacities than analog cellular cell sites. However, due to the technology's higher frequencies on the electromagnetic spectrum (1,850 to 2,200 MHz versus 800 to 900 MHz), PCS cell sites will have smaller radii than cellular cell sites. As a result, some PCS providers estimate that they will • need two to three times as many transmission sites as cellular systems. 18