Modularly clustered radiotelephone system

• US 5,852,604 A
• Filed: 05/20/1996
• Issued: 12/22/1998
• Est. Priority Date: 09/30/1993
• Status: Expired due to Term

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Cooley, David M., Lemmo, Mark A., Kaewell, John D., Regensburg, Michael W., Kurtz, Scott D., DiGiovanni, Joseph J., Johns, Eric, Vessal, David
• Primary Examiner(s): Jung, Min
• Application Number:
  US08/650,491
• Time in Patent Office: 946 Days
• Field of Search: 370/324, 370/503, 370/507, 375/222, 375/356
• US Class Current: 370/324
• CPC Class Codes: H04B 1/1615 Switching on; Switching off, e.g. remotely battery saving circuits associated with selective call operation H04W52/00; details of power consumption reduction in a PLL, H03L7/0802, H03L7/14, H03L2207/08, H03L2207/18; muting amplifiers by gain control see H03G3/34
• CPC Class Codes: H04B 7/2643 using time-division multiple access [TDMA] H04B7/2615, H04B7/2618 take precedence
• CPC Class Codes: H04B 7/2656 for structure of frame, burst
• CPC Class Codes: H04J 3/0685 Clock or time synchronisation in a node; Intranode synchronisation
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/56 based on priority criteria
• CPC Class Codes: H04W 74/0891 for synchronized access
• CPC Class Codes: H04W 84/14 WLL [Wireless Local Loop]; RLL [Radio Local Loop]
• CPC Class Codes: H04W 88/00 Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
• CPC Class Codes: H04W 88/021 adapted for Wireless Local Loop operation
• CPC Class Codes: H04W 88/08 Access point devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A power-conserving time division multiple access (TDMA) radio telephone system is disclosed in which a cluster of subscriber stations, remote from a base station, employs a common pool of frequency-agile modems each of which digitally synthesizes, on a timeSlot-by-timeSlot basis, the different channel-identifying intermediate frequencies needed to support communications between several of the subscriber stations and the base station. Power conservation is facilitated inter alia by controlling the assignment of modems to calls, maintaining unassigned modems in a powered-down state and by controlling the number of calls using the same time slot. Delay in assigning a powered-down modem to a call is eliminated by making available to all modems the highest quality synchronization information obtained by any of the active modems.

Claims

1. A method of minimizing synchronization delay in a radiotelephone system between a modular subscriber cluster communicating with a common base station, the modular subscriber cluster receiving repetitive time slots from the base station and having a plurality of frequency-agile modems, the method comprising the steps of:

synchronizing a selected one of the modems to a selected time slot of the received time slots;

generating a frame sync signal from said selected modem; and

distributing said frame sync signal to remaining ones of the plurality of modems.

2. The method according to claim 1 wherein said synchronizing step further comprises the steps of:

receiving a plurality of channel-identifying frequencies from the common base station, each of said channels containing a synchronization time slot;

instructing the plurality of modems to search said channels for said synchronization time slot;

locating within one of said channels said synchronization time slot by one of the plurality of modems; and

assigning said one of the plurality of modems as said selected modem.

3. The method according to claim 1 wherein said distributing step further comprises the steps of:

sourcing said frame sync signal over a common bus coupled to all of the plurality of modems; and

aligning each of the plurality of modems start frame with said frame sync signal.

4. The method according to claim 2 further comprising the steps of:

determining synchronization parameters for each active modem from the plurality of modems;

ascertaining reliability from said synchronization parameters;

identifying from said synchronization parameters the modem with the highest reliability; and

designating said modem with the highest reliability as said selected modem.