Portable cellular telephone using spread spectrum communication with mobile transceiver

A portable cellular telephone system including a stationary transceiver for radio communication with a plurality of mobile transceivers within a geographic cell, a mobile transceiver within said geographic cell and having sufficient power to communicate with said stationary transceiver, and a portable transceiver of limited size for personal transport and use. The portable transceiver communicates with the mobile transceiver by spread spectrum techniques, and the mobile transceiver communicates with the stationary transceiver by frequency modulated radio transmission or by digital radio transmission.

BACKGROUND OF THE INVENTION 
This invention relates generally to cellular telephone systems, and more 
particularly the invention relates to a portable cellular telephone with 
increased transmission power and interference immunity while retaining a 
small compact size. 
Cellular radio telephone systems have become commonplace in most 
metropolitan areas in the United States. Car phones include transceivers 
for communicating by FM radio with a stationary transmitter and receiver 
within the geographic area (cell) in which the car is located. The 
stationary transceiver provides a link between the mobile car phone and 
the local public telephone system. 
Hand-held portable cellular telephones are available which can be carried 
by an individual for communication with the local telephone system via the 
stationary transceiver. Batteries are provided in the hand set, thus power 
is limited to a few hundred milliwatts. A transportable cellular telephone 
with three watts of power is also available. Typically the transceiver and 
batteries are housed in a hand-held satchel to which a telephone handset 
is connected by a cord. 
The present invention is directed to providing a portable cellular 
telephone which can be accommodated in a handset without the requirement 
for a separate satchel for the transceiver and power package but with 
increased transmission quality and higher transmission power. 
SUMMARY OF THE INVENTION 
In accordance with the invention a hand-held portable cellular telephone is 
provided which interfaces with a transceiver in an automobile, for 
example, for communicating with a stationary cell transceiver and a local 
public telephone system. So long as the hand-held telephone is within an 
operable range including the automobile transceiver, the hand-held unit 
can utilize the automobile transceiver in communicating in the local 
public telephone system and thus can function with much less power 
requirements than the conventional transportable cellular telephone, thus 
obviating the need for the satchel. 
In accordance with a feature of the invention, the hand-held unit and the 
automobile unit communicate using spread spectrum transmission in which 
the requisite transmission power is spread over carrier frequencies across 
a frequency band, thereby using the Instrumentation, Scientific and 
Medical (ISM) frequency bands allocated by the Federal Communications 
Commission (FCC) for unlicensed use by spread spectrum systems. 
The invention and objects and features thereof will be more readily 
apparent from the following detailed description and appended claims when 
taken with the drawing.

DESCRIPTION OF SPECIFIC EMBODIMENTS 
Referring now to the drawing, FIG. 1 is a schematic diagram of the 
conventional cellular telephone system. A mobile transceiver in an 
automobile 10, a transportable transceiver 12 carried by an individual 3, 
and a portable hand-held transceiver 13 carried by an individual, 
communicate directly with a stationary transceiver 14 located in the area 
or cell in which the mobile and portable units are located. Transceiver 14 
then interfaces with a local public telephone system 16. 
The power requirement for communicating directly with the stationary 
transceiver 14 anywhere in a physical cell is readily accommodated in the 
automobile 10. The transceiver for the transportable unit 12 is of such 
size that it must be housed in a satchel which is transported by an 
individual with the handset connected to the satchel by a cord. Such a 
system is bulky and awkward in operation. The limited power of the 
portable, hand-held unit 13 severely affects transmission quality and 
performance range. 
In accordance with the present invention the power requirements of the 
portable unit 13 are reduced by having the portable unit communicate 
through the transceiver of the mobile unit 10 with the stationary 
transceiver 14 as shown in FIG. 2. This requires that the portable unit is 
within a reasonable distance (e.g., one mile) of the mobile unit 10 which 
might by located, for example, at a golf course parking lot with the 
portable unit being carried by a golfer. 
In accordance with the invention the communication between the mobile unit 
10 and the portable unit 13 including an audio transducer 18 is spectrally 
accommodated by using spread spectrum transmission as illustrated in FIG. 
3. The Federal Communications Commission (FCC) has allocated 
Instrumentation, Scientific and Medical (ISM) frequency bands in the U.S. 
for unlicensed use by spread spectrum systems. Accordingly, by 
communicating in an ISM band, communication between the mobile unit and 
the portable unit is readily accommodated. The spread spectrum signaling 
permits many users with reduced interference in the same geographic area 
or cell. The FCC specifications for the ISM bands include a maximum 
transmitter power of 1 watt. This accommodates a reasonable transmission 
range of 1 mile between the portable unit and the mobile unit. 
The mobile unit 10 has a spread spectrum transceiver B for communicating 
with the portable unit 13 and an FM transceiver A for communicating with 
the stationary transceiver 14 over an FM frequency band. Alternatively, 
transceiver A can be a digital radio transceiver should cellular telephone 
convert from FM to digital communications. 
There has been described a cellular telephone system including a portable 
hand-held transceiver which communicates in the system through a mobile 
transceiver to increase transmission quality, range, and performance. 
While the invention has been described with reference to specific 
embodiments, the description is illustrative of the invention and is not 
to be construed as limiting the invention. For example, the mobile 
transceiver can communicate with the stationary transceiver using digital 
transmission techniques. Thus, various modifications and applications may 
occur to those skilled in the art without departing from the true spirit 
and scope of the invention as defined by the appended claims.