Multiplex communications – Communication over free space – Using trunking
Reexamination Certificate
1999-07-13
2002-08-27
Urban, Edward F. (Department: 2685)
Multiplex communications
Communication over free space
Using trunking
C370S320000, C370S335000, C370S342000, C455S450000
Reexamination Certificate
active
06442152
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application entitled DEVICE AND METHOD FOR COMMUNICATING PACKET DATA IN MOBILE COMMUNICATION SYSTEM earlier filed in the Korean Industrial Property Office on Jul. 13, 1998, and there duly assigned Serial No. 98-28237 and also Korean Patent Application Serial No. 1998-29180.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device and method for communicating packet data in a mobile communication system, and more particularly, to a device and method used for rapidly assigning a dedicated channel for packet data service in a CDMA (Code Division Multiple Access) mobile communication system.
2. Description of the Related Art
In CDMA mobile communication systems, the IMT-2000 standard has evolved from the IS-95 standard. IS-95 supports voice service only, whereas IMT-2000 enables high-quality voice service, transmission of moving pictures, and internet browsing.
Data communication in the mobile communication system is characterized by a momentary active state and a long idle state. Accordingly, the next generation of mobile communication systems assign a dedicated channel in a data communication service only at the time when data is transmitted. That is, dedicated traffic and control channels are connected during data transmission and released after a predetermined time when no data is transmitted, due to limited radio resources, base station (BS) capacity, and mobile power consumption. Once the dedicated channels have been released, communication is made via common channels, thereby increasing use efficiency of the radio resources.
To do so, packet service is implemented in many state, depending on channel assignment and the presence or absence of state information.
FIG. 6
is a state transition diagram for packet service in a communication system. Referring to
FIG. 6
, the packet service is comprised of a packet null state, an initialization state, an active state, a control hold state, a suspended state, a dormant state, and a reconnect state. Packet service options are connected in the control hold state, active state, and suspended state.
Upon request for packet service in the packet null state, the initialization state is entered where a connection attempt for packet service is performed, and transition to the control hold state occurs if a dedicated control channel is established. The dedicated control channel is needed to transmit a layer
3
(L
3
) message and a medium access control (MAC) message. Then, upon entering the active state, forward and reverse dedicated control channels and traffic channels are maintained with RLP (Radio Link Protocol) frames being communicated on these channels. If a relatively short inactive time period is set, the suspended state is entered to efficiently use radio resources and conserve mobile station (MS) power. In the suspended state, the dedicated control and traffic channels are released but can be re-assigned in a relatively short time because both the BS and the MS retain status information including RLP initialization, traffic channel assignment, and encryption variables. If there is no data exchanged for a predetermined time, the suspended state transitions to the dormant state. In the dormant state, only a PPP (Point-to-Point Protocol) connection is maintained and if transmit data is generated, a reconnect state is entered. If the dedicated control channel is established, the reconnect state transitions to the control hold state. While the MS and the BS are in a common channel state, such as the suspended, dormant, and reconnect states, the MS monitors a paging channel and a common control channel on a forward link, and the BS monitors an access channel and a common control channel on a reverse link. There may be a plurality of paging channels and access channels. Each paging channel is distinguished by a different Walsh code and each access channel is distinguished by a different long code.
In
FIG. 6
, after the active state transitions to the suspended state through the control hold state in the absence of data for a predetermined time during a data communication, messages are exchanged on common channels. Upon generation of a control message for resuming data transmission, the BS attempts to connect to the MS on a paging channel and then the MS transmits a response message on an access channel. However, this common channel message transmission is susceptible to message contention if other MSs use the same access channel, resulting in a reception failure in the BS. If each MS fails to receive an acknowledgement from the BS within a predetermined time, it perceives the occurrence of message contention and resumes a message transmission after a randomized time delay. If repeated attempts to access the access channel for predetermined times fail, the procedure starts again. Information is transmitted on the access channel in access channel slots.
In the mechanism of transmitting an access channel message, the entire process of sending one message and receiving (or failing to receive) an acknowledgement for that message is called an access attempt. Each transmission in the access attempt is called an access probe. Each access probe consists of an access channel preamble and an access channel message capsule. When a message contention occurs, an access probe is re-transmitted with a power level set at a specified amount higher than the previous access probe's power level after a randomized time delay.
In the case of the MSs initiation of data communication, the same message transmission procedure is performed without the paging step of the BS. If an access channel message is too long to be sent at one time, it is divided into appropriate segments prior to transmission and the above procedure for each segment.
After exchanging the common channel messages, the BS assigns a dedicated code channel and sends a traffic channel assignment message on the dedicated channel. When the BS responds to the message, user data is sent on a dedicated traffic channel.
The procedure of assigning the dedicated channel is implemented in the same manner during transitions from the suspended state to the active state and from the dormant state to the active state. Transition from the suspended state to the active state requires service option negotiation associated with radio resources assignment and RLP initialization because only PPP information is reserved and no radio resources-related information exists in the dormant state.
FIG. 1
describes a conventional data service resuming procedure for a call initiated by a BS in a dormant state. A BS
112
sends a forward control message for resuming a data service to a corresponding addressed MS
114
on a paging channel (F-PCH) being a forward common channel (step
120
). Then, the MS
114
sends a response message for the control message on a reverse access channel (R-ACH) (step
122
). On the reverse access channel, a preamble precedes an access channel message to facilitate acquisition of a reverse physical channel in the BS
112
(step
126
).
The entire process of sending one message and receiving (or failing to receive) an acknowledgement for that message is called an access attempt. Each transmission in the access attempt is called an access probe. Each access probe is comprised of a preamble and a message capsule. Upon contention of access probes, the mobile station transmits an access probe at a progressively higher power level than the previous access probe after a randomized delay. Here, transmission of the preamble is transmitted on a reverse pilot channel to synchronize timing between the BS and the MS which had a communication interrupted.
Reverse access channels share a long code. In a long code sharing scheme, an MS uses a Hash function to determine a long code among all available long codes (access channel long codes) in its initialization state, so that all MSs fairly share the long codes for access
Ahn Jae-Min
Kim Doo-Gyun
Kim Young-Ky
Park Jin-Soo
Park Su-Won
Dilworth & Barrese LLP
Samsung Electronics Co,. Ltd.
Urban Edward F.
Zewdu Meless
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