Wireless communications approach

Details Wireless communications approach Wireless communications approach

1999-03-26

2001-11-20

Bost, Dwayne (Department: 2681)

Telecommunications

Transmitter and receiver at separate stations

Plural transmitters or receivers

C455S410000, C455S411000

Reexamination Certificate

active

06321095

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to wireless communications, and more specifically, to an approach for providing direct, wireless communications between mobile stations.
BACKGROUND OF THE INVENTION
Wireless communication systems provide several important advantages over conventional telephone systems. First, wireless communication users can communicate in locations where conventional telephone service is not available, for example in remote or particularly rugged locations. Second, wireless communications users have much more mobility because they don't have to connect to a fixed network of telephone lines. These and other favorable characteristics make wireless communications ideally suited for search and rescue, law enforcement and a myriad of other uses, including everyday use. Two of the most common approaches for providing wireless communications are two-way radios and cellular telephone systems.
In their most simplistic form, two-way radios are portable frequency-modulated (FM) transceivers that allow users to both transmit and receive FM signals directly to and from other users. Two-way radios are relatively simple, are inexpensive to manufacture, are easily miniaturized and provide relatively robust performance and mobility over reasonable distances. Examples of two-way radios include citizen band (CB) radios and “walkie talkies” such as Motorola Corporation's TalkAbout® radios.
Despite the benefits of two-way radios, they have several drawbacks. First, two-way radios typically support only half-duplex operation, meaning that only one user can talk at a time. A user must push a “talk” button to talk to another user and if both users push their “talk” buttons at the same time, then the users cannot hear each other. The reason for this is that all participants transmit data on the same channel. Two-way radios also require that users agree upon and select a particular channel to use for a conversation. If the channel being used is lost or cannot be used because of excessive interference, then the users must transfer to a different channel which can be difficult to do unless an alternate channel has been previously agree upon. Another problem with two-way radios is that communications are generally not private. Anyone with a compatible radio can eavesdrop on a conversation simply by tuning their radio to the channel on which the conversation is being held. Finally, two-way radios do not provide the call services available with digital systems such as call waiting, caller identification and messaging.
Cellular telephone systems are based upon a network of base stations that provide a coverage area in which users can communicate. Users communicate indirectly with other users through the base stations. Digital cellular telephone systems generally provide superior voice quality and are more secure than analog cellular telephone systems and two-way radios. Furthermore, digital cellular telephone systems provide a wide variety of call services such as call waiting, call forwarding and voice mail, that are not available on analog cellular telephone systems and two-way radios.
Notwithstanding the advantages that digital cellular telephone systems provide over analog cellular telephone systems and two-way radios, they also have some drawbacks. One drawback is that users can only communicate within the coverage area of the cellular network. Cellular telephone system coverage is typically provided only in metropolitan areas and is not available in remote areas where it is less economically feasible to install the necessary infrastructure. Another problem with cellular telephone systems is that users must pay for “air time” to connect to public service telephone networks (PSTNs).
Based on the need for wireless communications and the limitations in the prior approaches, an approach for providing wireless communications that does not suffer from the limitations of the prior approaches is highly desirable.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a method provides wireless communications between mobile stations. A first portion of a radio frequency (RF) band is selected to carry communications between the first mobile station and a second mobile station. A first request signal is transmitted on a first sub-portion of the first portion of the RF band directly to the second mobile station to request communications between the first mobile station and the second mobile station. In response to receiving the first request signal, a first acknowledge signal is transmitted on a second sub-portion of the first portion of the RF band directly to the first mobile station to acknowledge the first request signal. Finally, in response to receiving the first acknowledge signal from the second mobile station, a direct communication link is established between the first mobile station and the second mobile station on the first portion of the RF band.
According to another aspect of the invention, a method provides direct, wireless communications between mobile stations using a frequency division multiple access/time division multiple access communication protocol. First, a first mobile station selects a particular circuit from a plurality of circuits in a radio frequency (RF) band to carry communications between the first mobile station and a second mobile station, wherein the particular circuit comprises a plurality of slots. The first mobile station transmits a first request signal on a first slot from the plurality of slots directly to the second mobile station to request communications between the first mobile station and the second mobile station. The second mobile station transmits, in response to receiving the first request signal, a first acknowledge signal on a second slot from the plurality of slots directly to the first mobile station to acknowledge the first request signal. Finally, the first mobile station selects and assigns, in response to receiving the first acknowledge signal from the second mobile station, a slot (either the first slot or another slot) from the plurality of slots for carrying communication data from the first mobile station to the second mobile station, and a fourth slot from the plurality of slots for carrying communication data from the second mobile station to the first mobile station.
According to another aspect of the invention, a mobile station provides direct, wireless communications with another mobile station on a portion of a radio frequency (RF) band. The mobile station includes a transmitter configured to transmit communication signals on a first sub-portion of the portion of the RF band directly to another mobile station, a receiver configured to receive communication signals directly from the other mobile station on a second sub-portion of the RF band and processing logic configured to select the first sub-portion and the second sub-portion from a plurality of sub-portions of the portion of the RF band. The transmitter and receiver may transmit signals and receive signals, respectively, on any available portions of the RF band.
According to another aspect of the invention, a wireless communication system includes a first mobile station and a second mobile station. The first mobile station is configured to select a first available portion of a radio frequency (RF) band to carry communications between the first mobile station and the second mobile station, transmit a first request signal on a first sub-portion of the first portion of the RF band directly to the second mobile station to request communications between the first mobile station and the second mobile station, and establish, in response to receiving a first acknowledge signal from the second mobile station, a direct communication link between the first mobile station and the second mobile station on the first portion of the RF band. The second mobile station is configured to transmit, in response to receiving the first request signal from the first mobile station, a first acknowledge signal on a second sub-portion of the first portion of the

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