Multiplex communications – Communication over free space – Combining or distributing information via code word channels...
Reexamination Certificate
2000-12-06
2001-07-10
Wellington, Chin (Department: 2664)
Multiplex communications
Communication over free space
Combining or distributing information via code word channels...
C370S342000, C370S347000, C370S441000
Reexamination Certificate
active
06259689
ABSTRACT:
BACKGROUND OF THE INVENTION
Reservation ALOHA channels have been discussed and analyzed in the literature since the first reservation ALOHA channel was proposed. In a reservation ALOHA channel the random access ALOHA channel is used to transmit a packet which reserves capacity either in a separate channel or in fixed time locations in the ALOHA channel itself. However all reservations made in a reservation ALOHA channel are made for capacity which is used as a separate dedicated data channel.
SPREAD ALOHA Multiple Access (SAMA) systems are distinguished from Code Division or Time Division Multiple Access (CDMA or TDMA) systems, which assign separate spreading codes or times to individual users. In a SAMA system multiple users with remote transmitter units (RTUS) employ identical spreading codes in random access modes. SAMA systems are described in U.S. Pat. Nos. 5,537,397 and 5,745,485, the disclosures of which are incorporated herein by reference.
Needs exist for reservations systems for SAMA users and for improved reservations systems which do not require separate dedicated channels.
SUMMARY OF THE INVENTION
The present invention addresses those needs with a new random access SPREAD ALOHA Multiple Access (SAMA) reservation system. In the new invention reservations for specific chip phase are transmitted in a random access mode. A user reserves and uses a specific chip phase. Alternatively, reservation may be made by beginning a transmission with a certain chip phase and continuing to use that chip phase. The SAMA hub broadcasts a list of reserved chip phases or broadcasts a list of free chip phases to ensure that other transmitters do not use the reserved chip phase. Alternately, the hub requires a transmitter to adjust chip phases of its transmitters.
In a SPREAD ALOHA Multiple Access (SAMA) channel it is possible to use distinct chip phases to label portions of a common SAMA channel and to reserve specific phases by means of a random access packet in the same SAMA channel. That is the basis of this invention.
In the new SAMA reservation channel protocol, reservations consisting of the specification of a given chip phase are transmitted in a random access mode in a common SAMA channel. After a given user has reserved a given chip phase, that chip phase can be used on a reserved basis by that user to guarantee a certain quality of service. In an alternate realization of the invention the reservation can be made by a user who simply initiates transmissions with a given chip phase and continues to use that chip phase if the user's first packet (the packet making the reservation) is received correctly.
In both cases the hub station of the SAMA network broadcasts a list of the reserved chip phases (or alternatively of the free chip phases) to all users to ensure that no transmitter, other than the one making the reservation, transmits at an occupied chip phase.
This kind of reservation in a SAMA channel can provide the confirmed reservations required to transmit long files or digitized compressed voice signals within a SPREAD ALOHA network. This latter capability was not feasible in conventional ALOHA networks or even in those with a separate channel or fixed time location reservation capability, since the burst data rate of conventional ALOHA was not consistent with the requirements of several voice channels.
A SPREAD ALOHA Multiple Access (SAMA) System transmits packets of data bytes as chips in particular phases on a multiple access channel using identical spreading codes and interposing the data packets from distinct individual sources. A new reservation channel protocol reserves chip phases for transmitting long files or digitized compressed voice signals in the data packets. A hub station broadcasts lists of chip phases to users of the channel, insuring that no transmitter other than the transmitter making the reservation transmits data packets in chips at an occupied chip phase.
In one embodiment, the hub station broadcasts a list of reserved chip phases. In another embodiment, the hub station broadcasts a list of free chip phases.
A new method of using a Spread ALOHA Multiple Access (SAMA) channel uses a reservation protocol for transmitting long data files or digitized compressed voice signals from a transmitter to a hub. Chip phases are reserved by transmitting chips representative of bits in long spread bit data packets or by requesting reserved chip phases for use in the transmitting of the long data packets. In one embodiment, reserving the chip phases occurs by beginning the transmitting of chips. The hub station broadcasts a list of reserved or available chip phases.
These and further and other objects and features of the invention are apparent in the disclosure, which includes the above and ongoing written specification, with the claims and the drawings.
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Tjahjono Danurahardjo
Wethington Carin
Aloha Networks, Inc.
Creighton Wray James
Narasimhan Meera P.
Tran Maikhanh
Wellington Chin
LandOfFree
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