Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-11-10
2001-12-04
Chang, Vivian (Department: 2682)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S450000, C455S515000, C370S343000
Reexamination Certificate
active
06327468
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates in general to the field of telecommunications, and in particular, to relocating a beacon in a wireless communications system such that mobile terminals know where to find it.
2. Description of Related Art
Wireless communication systems provide many benefits to both subscribers and network providers. Subscribers enjoy increased safety, convenience, and productivity while wireless network providers are able to provide telephone service with only incremental capital investments. Incremental capital investments are possible because some of today's modern wireless systems enable providers to easily add base stations, and thus capacity, as subscribers request additional service.
Some of these modern wireless systems operate in unlicensed portions of the electromagnetic spectrum. When operating a wireless system at shared unlicensed frequencies, certain Federal Communications Commission (FCC) regulations apply to system information broadcast channels. For example, FCC Rule 15.323 (c)(4) prohibits channels used exclusively for control and signaling information from transmitting continuously for more than 30 seconds. Beacon information is typically control or signaling information (or both) that is broadcast either exclusively or along with other information. Broadcast beacon channels, which aid in the operation of wireless systems, may therefore be subject to FCC Rule 15.323 (c)(4), depending on the content and intended intermittency of a given beacon channel.
Due to the randomness and uncertainty of the radio environment, complying with this FCC regulation and repeating the access criteria virtually guarantees that the same channel will not be consistently selected for the wireless beacon, nor will associated mobile terminals be able to predict the beacon channel selection process. Unfortunately, mobile terminals in wireless systems need to be able to receive system information broadcasts and must therefore locate the wireless beacon that is being broadcast from the associated base station.
Mobile terminals in conventional systems scan all of the available channels to locate the wireless beacon. Disadvantageously, when a mobile terminal must search the spectrum for its associated beacon every 30 seconds, considerable battery power is expended. In other words, the scanning causes battery life to suffer significantly, which reduces both the talktime and the standby time of the mobile terminal. This excessive power expenditure applies to all mobile terminals locked to a particular hopping beacon.
In summary, existing wireless systems have required that mobile terminals waste battery power in order for the system to comply with FCC regulations. It would be advantageous if mobile terminals could locate a channel-hopping beacon without the necessity of repeatedly scanning (e.g., every 30 seconds) all of the available channels.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus in a wireless communications system that enables a beacon to be leap-frogged. The system includes at least one radio fixed part (RFP) that is connected to a central control fixed part (CCFP) and is in radio communication with multiple portable parts (PP). The wireless communications system is adapted to operate in an unlicensed portion of the spectrum. Consequently, any channel that exclusively broadcasts control and signaling information must periodically change channels.
According to a first aspect of the present invention, an RFP is originally broadcasting system information with an old beacon on a first channel (a particular time slot and carrier pair). Prior to the expiration of a maximum continuous broadcast period, the RFP determines an appropriate second channel for a new beacon by performing access criteria. For example, the new beacon must be on a different carrier from the old beacon. Furthermore, the RFP must comply with the listening before talking and least interfered with channel protocols.
The RFP then begins broadcasting system information with the new beacon using the second channel. Prior to terminating the old beacon, the RFP informs associated PPs of the location (e.g., the carrier and time slot of the second channel) of the new beacon in a system information broadcast with the old beacon on the first channel. The old beacon is then terminated within the maximum continuous broadcast period to maintain compliance with FCC regulations. The beacon leapfrog-hopping is periodically repeated.
An object of the present invention is to provide a wireless communications system that comports with the FCC rules for unlicensed spectrum.
Another object of the present invention is to provide a wireless communications system that conserves battery power.
A further object of the present invention is to implement a method and apparatus in a wireless communications system that obviates the need for a terminal to constantly scan the entire allocated spectrum to locate a control and signaling information beacon.
Yet another object of the present invention is to implement a method and apparatus in a wireless communications system that enables terminals to know where to locate a control and signaling information beacon.
The above-described and other features of the present invention are explained in detail hereinafter with reference to the illustrative examples shown in the accompanying drawings. Those skilled in the art will appreciate that the described embodiments are provided for purposes of illustration and understanding and that numerous equivalent embodiments are contemplated herein.
REFERENCES:
patent: 4633509 (1986-12-01), Scheinert
patent: 5109527 (1992-04-01), Akerberg
patent: 5381443 (1995-01-01), Borth et al.
patent: 5570467 (1996-10-01), Sawyer
patent: 5606548 (1997-02-01), Vayrynen et al.
patent: 6032047 (2000-02-01), Cerwall et al.
patent: 6137772 (2000-10-01), Turcotte et al.
Federal Communications Commission(FCC)Rules, Part 15, Subpart D—Unlicensed Personal Communications Service Devices, Sections 15.301-15.323.
van Iersel Hans
van Puijenbroek Corné
Chang Vivian
Ericsson Inc.
Jenkens & Gilchrist a Professional Corporation
Nguyen Duc
LandOfFree
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