Multiplex communications – Communication over free space – Repeater
Reexamination Certificate
1999-01-15
2004-12-28
Chin, Wellington (Department: 2664)
Multiplex communications
Communication over free space
Repeater
C370S230000, C370S320000
Reexamination Certificate
active
06836469
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to communication systems. More specifically, the present invention relates to a medium access control (MAC) protocol for use in a multi-channel communication system based on, for example, Code Division Multiple Access (CDMA), Wavelength Division Multiple Access (WDMA), Frequencies Division Multiple Access (FDMA) or other multiple-channel systems.
2. Description of Related Art
In a typical wireless communication system, messages are transmitted asynchronously via data packets between a base station (BS) and a plurality of mobile stations (MS). Each of the data packets includes an information portion containing a coded message and a header description portion containing codes indicating the terminals destined to receive the message. The wireless communication system may be a single-channel system, based on, for example, TDMA in which the data packets are transmitted serially and successively in the same channel in the time domain (i.e., they are transmitted in different time-slots in the same channel), or a multi-channel system, such as CDMA, FDMA, or WDMA, in which the data packets are transmitted either serially in the same channel or concurrently in different channels.
FIG. 1
illustrates a conventional single-channel wireless communication system. The system has an uplink channel
12
and a downlink channel
14
which carry data packets between mobile stations
16
1
-
16
3
and base station
18
.
FIG. 2
shows a conventional multi-channel wireless communication system
20
having a plurality of uplink channels
22
1
-
22
3
and downlink channels
24
1
-
24
3
. Uplink channels
22
1
-
22
3
are used to transmit data packets from mobile stations
26
1
-
26
3
to a base station
28
. Downlink channels
24
1
-
24
3
transmit data packets form base station
28
to mobile stations
26
1
-
26
3
. The systems shown in
FIGS. 1 and 2
are contentional systems in which the respective mobile stations share one or more common channels in a manner that can lead to conflicts.
The following references provide background information relating to wireless communication systems and are hereby incorporated by reference in their entireties:
(1) D. Bertsekas, and R. Gallager, “Data Networks”, 2
nd
edition, Prentice-Hall Inc.
(2) A. Tanenbaum, “Computer Networks”, 3
rd
edition, Prentice-Hall Inc., 1996;
(3) ETSI, “Radio Equipment and Systems (RES); High Performance Radio Local Area Network (HIPERLAN); Functional Specification,” Version 1.1 25/01/1995;
(4) G. A. Halls, “HIPERLAN: The High Performance Radio Local Area Network Standard,” Electronic and Communication Engineering Journal, pp. 289-296;
(5) Raychaudhuri, . . . et al., “Multiservices Medium Access Control Protocal for Wireless ATM System”, U.S. Pat. No. 5,638,371, June 1997;
(6) D. Raychaudhuri, and N. D. Wilson, “ATM-Based Transport Architecture for Multiservices Wireless Personal Communication Networks,” IEEE Journal on Selected Area in Communications, Vol. 12, No. 8, October 1994, pp. 1401-1414;
(7) W. Yue, “The Effect of Capture on Performance of Multichannel Slotted ALOHA Systems”, IEEE Transactions on Communications, Vol. 39, No. 6, Jun. 1991, pp. 818-822;
(8) Z. Liu, and M. El Zarki, “Performance Analysis of DS-CDMA with Slotted ALOHA Random Access for Packet PCNs”, ACM/Baltzer Wireless Networks, Vol. 1, No. 1, February 1995, pp. 1-16;
(9) Chen et al., “Method of Controlling the Operation of a Packet Switched CDMA Telecommunication Network”, U.S. Pat. No. 5,394,391, February 1995;
(10) Umeda et al., “Random Access Communication Method by CDMA and Mobile Station Equipment Using the Same”, U.S. Pat. No. 5,581,547, December 1996;
(11) Raychaudhuri et al., “Stabilization of Random Access Packet CDMA Networks”, U.S. Pat. No. 4,841,527, June 1989;
(12) I. M. I. Habbab, M. Kavehrad, and C. W. Sundberg, Protocols for Very High-speed Optical Fiber Local Area Networks Using a Passive Star Topology”, IEEE Journal of Lightwave Technology, Vol. LT-5, No.
12
, December 1987, pp. 1782-1793;
(13) ETSI SMG2, “Concept group Alpha-Wideband Direct-Sequence CDMA, EVALUATION DOCUMENT (DRAFT 1.0), Part 1: System Description & Performance Evaluation”, UMTS Terrestrial Radio Access (UTRA), draft document, October 1997;
(14) Quick, Jr., “Random Access Communications Channel for Data Services”, U.S. Pat. No. 5,673,259, September 1997;
(15) Argyroudis et. al., “Wireless Remote Telemetry System”, U.S. Pat. No. 5,748,04, May 1998;
(16) TIA TR45.5, “The CDMA2000 ITU-R RTT Candidate Submission”, June 1998.
(17) ETSI standard GSM 03.64, version 5.2.0, “Digital Cellular telecommunications System (Phase
2
+): General Packet Radio Services (GPRS); Overall description of the GPRS radio interface, stage
2
”, January 1998;
(18) ETSI draft standard GSM 04.60, version 2.00, “Digital Cellular Telecommunications System (Phase
2
+): General Packet Radio Services (GPRS); Mobile Station (MS)-Base Station System (BSS) Interface; Radio Link Control/Medium access Control Protocol”, March 1998;
(19) A Polydoros, and J. Silvester, “Slotted Random Access Spread-Spectrum Networks: An Analytical Framework”, IEEE Journal on Selected Areas in Communication, Vol. SAC-5, No. 6 Jul. 1987, pp. 989-1002;
(20) D. Makrakis, and K. M. S. Murthy, “Spread Slotted ALOHA Techniques for Mobile and Personal Satellite Communication Systems”, IEEE Journal on Selected Areas in Communications, Vol. 10, No. 6, Aug. 1992, pp. 985-1002; and
(21) K Toshimitsu, T. Yamazato, M. Katayama, and A. Ogawa, “A Novel Spread Slotted ALOHA System with Channel Load Sensing Protocol”, IEEE Journal on Selected Areas in Communications, Vol. 12, No. 4, May 1994, pp. 665-672.
Channel conflicts in single-channel wireless communication systems are generally resolved through the implementation of protocols such as Slotted ALOHA, Carrier Sense Multiple Access (CSMA), Attempt and Defer, and Reservation, which are disclosed, e.g., in references [1] and [2]. In the Slotted ALOHA protocol, for example, all mobile stations wanting to send a data block are assumed to be synchronized in time-slots over the shared uplink channel. Any mobile station may choose, in a random manner, a time-slot to send its data block. If two or more mobile stations attempt to access the same time-slot, a collision occurs and all mobile stations in this attempt will back off and wait for a random number of time-slots before they make another attempt. The throughput is limited, i.e., less than 0.368.
In the CSMA scheme, the mobile station desiring to send a data block will attempt to sense an open channel prior to sending its data block. If a busy signal is detected, each mobile station with an attempt will wait until the channel is open. This is sometimes called “Listen Before Send.” The CSMA systems handles the occurrence of an access collision in the same way as the Slotted ALOHA protocol. However, the CSMA has improved performance relative to the Slotted ALOHA protocol, achieving a throughput of between 0.5 and 0.7.
In the Attempt and Defer protocol, as shown in
FIG. 3
, the data packet access process includes two phases, i.e., a contention resolution phase
30
and a data transmission phase
32
. In the contention resolution phase, all mobile stations
34
1
-
34
4
with attempts
36
1
-
36
4
become involved in a resolution process in which the occurrence of a collision is resolved by determining a successful mobile station that is permitted to transmit a data packet
38
in the data transmission phase
32
. Variances in the Attempt and Defer protocol, including Multi-Level Multi-Access or Binary Countdown as disclosed in reference [2] and the European wireless local network standard HiPERLAN as disclosed in references [3] and [4], also use bit sequences to compete for the access right, which results in at most one mobile station that successfully sends a data packet during the data transmission phase.
In the Reservation protocol illustrated in
FIG. 4
, there are three phases, i.e., request phase
40
Chin Wellington
Industrial Technology Research Institute
Schultz William
Stevens, Davis, Miller & Mosher,LLP
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