Multiplex communications – Communication over free space – Combining or distributing information via time channels
Reexamination Certificate
1999-09-03
2004-01-20
Chin, Vivian (Department: 2682)
Multiplex communications
Communication over free space
Combining or distributing information via time channels
C370S337000, C370S347000, C370S442000
Reexamination Certificate
active
06680929
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a base station and a terminal configuring a wireless network, and a communication method. This invention relates to the base station, terminal, and communication method suitable for a multiple access protocol for maximizing a utilization of a frequency band and realizing a maximum throughput and a minimum delay, for example.
2. Description of the Related Art
The multiple access protocol in a wireless network is expected to maximize the utilization of the frequency band and realize the maximum throughput and the minimum delay (“Mobile Wireless Computing: Challenge in Data Management” by T. Imielinski and B. R. Badrinacth, Commun. ACM, vol. 37, pp. 18-28, October 1994 (related art 1)).
Several studies have been made on the multiple access protocol for broadcast channels, e.g., a wireless network, communication satellite, etc. (“Data Networks” by D. Bertsekas and R. Gallager, Second Edition, Prentice-Hall, 1992 (related art 2)), (“Multiaccess Protocols in Packet Communication Systems” by F. A. Tobagi, IEEE Trans Commun. Vol. COM-28, pp. 468-488, April 1980 (related art 3)), (“The ALOHA System—Another Alternative for Computer Communications” by N. Abramson in 1970 Fall Joint Comput. Conf. AFIPS Conf. Proc. Vol. 37. Montvale, N.J.: AFIPS Press, pp. 281-285, 1970 (related art 4)), (“Packet Switching in Radio Channels: Part I—Carrier Sense Multiple-Access Modes and their Throughput-Delay Characteristics” by L. Kleinrock and F. A. Tobagi, IEEE Trans. Commun., vol. COM-23, pp. 1400-1416, December 1975 (related art 5)), (“Packet Switching in Radio Channels: Part II—the Hidden Terminal Problem in Carrier Sense Multiple-Access and the Busy-Tone Solution” by F. A. Tobagi and L. Kleinrock, IEEE Trans. Commun., vol. COM 23, pp. 1417-1433, December 1975 (related art 6)), (“Tree Algorithms for Packet Broadcast Channels” by J. I. Capetanakits, IEEE Trans. Information Theory, vol. IT-25, September 1979 (related art 7)).
Among recent studies on the multiple access method using a wireless channel, as a distributed control method, FAMA for confirming an acquisition of a transmission right between a sender terminal and a receiver terminal for preventing a drop in a throughput due to a hidden terminal is proposed by Fullmer, etc. in addition to CSMA/CD (Carrier Sense Multiple Access/Collision Detection) (“Floor Acquisition Multiple Access (FAMA) for Packet-Radio Networks” by C. L. Fullmer and J. J. Garcia-Luna-Aceves, Proc. ACM SIGCOM 95, Cambridge, Mass., Aug. 30-Sep. 1, 1995 (related art 8)). FAMA-PJ (Floor Acquisition Multiple Access with Pauses and Jamming), an improved version of the FAMA, in which jamming is provided for preventing a propagation delay and a collision due to a transmission timing in the CSMA/CD, is proposed (“FAMA-PJ: A Channel Access Protocol for Wireless LANs” by C. L. Fullmer and J. J. Garcia-Luna-Aceves, Proc. ACM MOBICOM 95, pp. 76-85, 1995 (related art 9)).
As a centralized control method, CARMA (Collision Avoidance and Resolution Multiple Access) for transmitting a control command of the FAMA using a stack algorithm (also called as a tree algorithm) is proposed by R. Garces, etc. (“Floor Acquisition Multiple Access with Collision Resolution” by R. Garces and J. J. Garcia-Luna-Aceves, Proc. ACM MOBICOM 96, pp. 187-197, 1996 (related art 10)). CARMA-NTG (Collision Avoidance and Resolution Multiple Access Protocol with Non-Persistent Trees and Transmission Groups), in which a node acquired a transmission right by the CARMA configures a transmission group, is also proposed by R. Garces, etc. (“Collision Avoidance and Resolution Multiple Access with Transmission Groups” by R. Garces and J. J. Garcia-Luna-Aceves, Proc. IEEE INFOCOM '97, pp. 134-142, 1997 (related art 11)).
Further, DQRUMA for making a reservation of a data transmission channel by an aloha method with a slot or the stack algorithm and, when the data transmission channel is obtained, maintaining the reservation using a piggyback request is proposed (“Distributed-Queuing Request Update Multiple Access (DQRUMA) for Wireless Packet (ATM) Networks” by M. J. Karol, Z. Liu, and K. Y Eng, Proc. of ICC '95, pp. 1224-1231, June, 1995 (Related art 12)).
Especially, the DQRUMA for reserving a data slot by the stack algorithm is an efficient protocol, which is stable even at a time with a high load.
The DQRUMA (related art 12); which is a basis of this invention; is outlined.
The DQRUMA is an efficient channel access protocol with a request-time-allocation type, which is designed for a packet in a fixed length.
FIG. 12
shows a configuration chart of time slots in the DQRUMA protocol.
In the DQRUMA, a transmission between terminals is relayed by a base station using a time slot
1201
. Each of time slots
1202
in an up-link, transmitted by the terminals and received by the base station, is divided into a request access channel
1204
and a data transmission channel
1206
. A piggyback request flag
1205
is used by a user, who has obtained a data transmission channel once, for adding a request information of a data transmission consecutively. Each of time slots
1203
in a down-link transmitted by the base station and received by the terminals is divided into a request access response channel
1207
, a data transmission permission channel
1208
, and a data transmission channel
1209
. In the base station, there is a request table with an entry for each of all the terminals in a cell. Each entry in the table includes a terminal identifier and a transmission request information (if the terminal still maintains transmission data). The DQRUMA protocol can be divided into a request access phase and a data transmission phase.
At first, explanations are made on the request access phase.
When the transmission data are generated, the terminal transmits a transmission request (of which content is the terminal identifier) to the base station using the request access channel
1204
in an up-link. The request access channel, i.e., a random access channel, is shared by all the terminals. Therefore, a collision can occur in the request access channel
1204
, and the aloha method with a slot or a binary-stack algorithm is used to prevent the collision. When the transmission request is received from the terminal normally, the base station sets a flag indicating that the terminal maintains transmitting data in the request table. The base station reports that the transmission request is accepted by broadcasting the received terminal identifier using the request access response channel
1207
in the down-link. When the acceptance of the request is reported, the terminal receives the data transmission permission channel
1208
in the down-link, while waiting for an allocation of the data transmission channel
1206
to the terminal.
Explanations are made on the data transmission phase.
The base station selects one of the terminals with the transmission request in the request table in accordance with a requested data transmission policy, e.g., a round robin, and permits the data transmission in a next time slot. This is reported by broadcasting the terminal identifier using the data transmission permission channel
1208
in the down-link. When the terminal transmits the data using the data transmission channel
1206
in the up-link, the terminal reports to the base station if any transmitting data are left by the piggyback request
1205
. The base station checks the piggyback request
1205
, and updates the entry in the request table.
When there is no transmission request in the request table, the base station reports that the data transmission channel
1206
in the next up-link is converted to a plurality of request access channels
1204
using the data transmission permission channel
1208
in the down-link. The data transmission channel
1209
in the next down-link is also converted to a plurality of request access response channels
1207
synchronously for responding to a plurality of request accesses.
In the DQRUMA protocol, the collision occurs only
Fukagawa Noritaka
Iida Noboru
Mizuno Tadanori
Ueno You
Watanabe Takashi
Chin Vivian
Persino Raymond B
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