Motorola Corporation

Keith A Chanroo

Walter L Davis

Zaffer S Merchant

Xiaojun Li

Francis R Steel, Deceased

A selective call system (100) has a plurality of base sites (120-124) for communicating with a plurality of selective call receivers (108) with acknowledge-back capability. A base site transmitter (210) transmits signals encoded with a stored location identifier (132), a base site receiver (241) receives acknowledge-back signals in response to the transmitted signals and a controller (206) determines when a selective call receiver (108) is authorized to receive location specific information (134). The base site transmitter (210) downloads the location specific information (134) to the selective call receiver (108) in response to verifying that the selective call receiver (108) is authorized. The selective call receiver (108) the signals having the location identifier (132) and the downloaded location specific information (134). A decoder/controller (306) compares the location identifier (132) received with the stored location identifier (132) of selective call receiver (108) to determine when the selective call receiver (108) has roamed to the new service area and stores the new location identifier (132). An acknowledge-back transmitter (334) transmits the new location identifier (132) to a home service area for enabling paging information to be routed from the home service area to the selective call receiver (108) at the new service area.

Method and apparatus for downloading location specific information to

A selective call base station (100) for receiving a signal comprising a plurality of communication signals has an Analog-to-Digital (A/D) converter (220) for digitizing the signal. A memory (204) for storing the signal as a plurality of digitized bits (502-518), and a Digital Signal Processor (DSP) (218) for converting each of the plurality of digitized bits (502-518) into a frequency domain signal (FIG. 6) that has a plurality of frequency samples. The memory (204) stores the plurality of frequency samples corresponding to each of the plurality of digitized bits (502-518). A decoder (206, 218) decodes the plurality of communication signals from the plurality of frequency samples. The decoder (206, 218) further includes a generator (718) for generating a window (902) for measuring energy of at least one frequency sample of the plurality of digitized bits (502-518) in each of the plurality of communication signals. A determinator (728) determines the at least one frequency sample of each of the plurality of communication signals having a maximum energy.

Communication system for communicating with a plurality of selective

A three dimensional cellular communication system comprising a plurality of cells arranged in a multi-level environment to reduce interference and improve frequency reuse in both horizontal and vertical directions by offsetting cells stacked on different levels of the multi-level environment.

Three dimensional cellular communication system with coordinate offset

A received phases modulated signal includes a plurality of information bits preceeded by three preamble bits. At periodic time intervals, approximately equal to one bit period, the receiver samples the signal and determines the phase angle of each bit at the sampling time. For the preamble bits, the receiver computes the phase error between the first and second preamble bits (A.sub.y -A.sub.x) and the phase error between the second and third preamble bits (A.sub.z -A.sub.y). An overall phase error (PE) is computed by taking the average of these two phase errors. To demodulate a DPSK signal, the average phase error (PE) is added to the phase angle (A.sub.i) of the present information bit. This adjusted phase angle (A.sub.i ') is then compared to the phase angle of the previous bit (A.sub.i -1) to demodulate the signal. To demodulate a PSK signal, the average phase error (PE) multiplied by D is added to the phase angle of the present information bit. This adjusted phase angle (A.sub.i ') is compared to the phase angle (A.sub.r) of a reference bit to demodulate the signal. D is the 'distance'; i.e., the number of bits between the present information bit and reference bit.

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Coral Springs, FL, United States of America

Keith A Chanroo