Data transmitting method in a CDMA system

Details Data transmitting method in a CDMA system Data transmitting method in a CDMA system

2000-12-29

2004-10-12

Olms, Douglas (Department: 2661)

Multiplex communications

Communication over free space

Having a plurality of contiguous regions served by...

C370S342000, C370S441000, C370S479000, C370S320000, C370S468000

Reexamination Certificate

active

06804219

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a Code Division Multiple Access (CDMA) mobile communication system, and in particular, to a packet data communication method.
2. Description of the Related Art
Conventional CDMA mobile communication systems, which primarily provide voice service, have evolved into IMT-2000 standard systems. In addition to voice service, IMT-2000 systems can provide high quality voice service, moving picture service, and Internet browsing.
Communication links between a mobile station (MS) and a base station (BS) in a CDMA mobile communication system are a forward link directed from the base station to the mobile station and a reverse link directed from the mobile station to the base station.
In the CDMA mobile communication system, packet data communication is characterized in that data is bursty and an idle state without transmission data occurs frequently. It has been proposed for the future mobile communication system that channels should be connected only when data is transmitted in a packet data communication service. Considering limited radio resources, base station capacity, and power consumption in a mobile station, a base station must release channels for used in data communication with another mobile station for a non-data transmission period and rapidly reconnect them when data transmission resumes.
Channels are generally classified into physical channels and logical channels. A logical channel is established on a physical channel and a plurality of logical channels may be set up on one physical channel. If the physical channel is released, the logical channel is automatically released. To establish a logical channel, a physical channel is not always established. When a physical channel required for establishing an intended logical channel was established for a different logical channel, all that has to be done is to assign the intended logical channel to the physical channel.
Physical channels are grouped into dedicated channels and common channels according to their characteristics. The dedicated channels are dedicated to communication between a base station and a specific mobile station, like a fundamental channel (FCH), a dedicated control channel (DCCH), and a supplemental channel (SCH). The FCH transmits a voice signal, a data signal, and a signaling signal. The DCCH transmits a data signal and a control signal, supporting a discontinuous transmission mode where data transmission occurs only if transmission data is generated from a higher layer, which makes the DCCH suitable as a control channel for providing packet service efficiently. The SCH transmits a large amount of data. The FCH can be used compatibly based on TIA/EIA-95-B.
Common channels are so named because they are shared by a plurality of mobile stations. Common channels on the forward link are a paging channel, a broadcast channel, a forward common control channel. An access channel, an enhanced access channel, and a reverse common control channel are common channels on the reverse link. The paging channel and the access channel may be used compatibly based on IS-95-B.
Logical channels established on the dedicated physical channels include a dedicated signaling channel (DSCH) and a dedicated traffic channel (DTCH). The DSCH can be assigned on the FCH and the DCCH to exchange control signals between a base station and a mobile station, whereas the DTCH can be established on the FCH, DCCH, and SCH to exchange user data between them.
As common logical channels assigned on the common physical channels, there are a common control channel (CSCH) for transmitting a control signal and a common traffic channel (CTCH) for transmitting user data. The common logical channels are assigned to the forward common channels on the forward link and to the reverse common channels on the reverse link.
FIG. 1
is a conventional state transition diagram for data transmission.
Referring to
FIG. 1
, when power is applied, a packet null state
110
is entered and a data service-related request is awaited. If a packet data service request is received, the packet null state
110
is transited to an initialization state
120
.
Control channels needed for data transmission are established on the forward and reverse links in the initialization state
120
. An FCH or a DCCH as a dedicated physical channel is established and a DSCH as a logical channel is established on the FCH or DCCH, in turn. Once the DSCH is established, a mobile station and a base station can carry on a negotiation procedure to negotiate about standards related with an intended service. The standards are termed a service option. Upon completion of the negotiation about a service option, a data service object establishes a DTCH for transmission of user data and transits to an active state
140
. If the initialization fails, the packet null state
110
is transited to.
In the active state
140
, data is transmitted on the DTCH. If the data service object transits to the active state
140
after setting the service option and as a result, the DTCH is available, the base station and the mobile station perform initialization procedures of RLP (Radio Link Protocol) and PPP (Point-to-Point Protocol). If data transmission is discontinued for a predetermined time T_Active in the active state
140
, the DTCH is released and a control hold state
130
is entered. If it is anticipated from an estimate of the amount of oncoming transmission data that a non-data transmission period will last longer, the active state
140
may be transited directly to a suspended state
150
or a dormant state
160
without interposing the control hold state
130
.
In the control hold state
130
, information about the service option, the RLP, and the PPP are preserved between the mobile station and the base station and the DSCH is still connected. The data service object establishes the DTCH when data transmission resumes within a predetermined time T_Hold and then returns to the active state
140
. On the contrary, if transmission data is not generated with T
13
Hold, the DSCH is released and the suspended state
150
is entered. If it is anticipated from an estimate of the amount of oncoming transmission data that a non-data transmission period will last longer, the control hold state
130
may be transited directly to the dormant state
160
without interposing the suspended state
150
.
In the suspended state
150
, the FCH or the DCCH is released. As a result, the logical channels, the DSCH and the DTCH are released. CSCHs established on a paging channel and an access channel are used for communication between the mobile station and the base station. The information about the service option, the RLP, and the PPP are still preserved between the base station and the mobile station in this state. If user data to be transmitted is generated within a predetermined time T_Suspended, the DSCH and the DTCH are established simultaneously and the suspended state
150
is transited to the active state
140
. If no transmission data is generated within T_Suspended, the dormant state
160
is entered.
In the dormant state
160
, only the PPP is connected for data service and the other call-related information is all released. If data transmission is to occur within a predetermined time T_Dormant, the active state
140
is transited to. Otherwise, the PPP information is released and the packet null state
110
is entered.
FIG. 2
is a state transition diagram for packet data transmission within the active state.
The active state
200
refers to a state where a DTCH is assigned. As described above, the DTCH may be assigned on an FCH, DCCH, or SCH. Since the SCH is shared in time division by a plurality of mobile stations, it is assigned only when necessary even in the active state. Therefore, the active state
200
is divided into a low rate transmission substate
220
and a high rate transmission substate
210
according to whether the SCH is established or not.
In the low rate transmission substate
220
, the FCH or

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