Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
2000-04-12
2004-06-08
Nguyen, Chau (Department: 2663)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S342000
Reexamination Certificate
active
06747963
ABSTRACT:
PRIORITY
This application claims priority to an application entitled “Apparatus and Method for Gated Transmission in CDMA Communication System” filed in the Korean Industrial Property Office on Apr. 12, 1999 and assigned Ser. No. 99-13610, filed on May 26, 1999, as well as Korean Application Ser. No. 99-19080, filed on Jul. 7, 1999, Korean Application Ser. No. 99-27355, filed on Jul. 8, 1999, and Korea Application Ser. No. 99-27398, the contents of all of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a CDMA mobile communication system, and in particular, to an apparatus and method for gated transmission which does not require a separate resynchronization process by assigning dedicated channels.
2. Description of the Related Art
A conventional CDMA (Code Division Multiple Access) mobile communication system primarily provides a voice service. However, the future CDMA mobile communication system will support the IMT-2000 standard, which can provide high-speed data service as well as voice service. More specifically, the IMT-2000 standard can provide high-quality voice service, moving picture service, an Internet search service, etc.
In a mobile communication system, data communication is typically characterized by bursts of data transmissions alternating with long non-transmission periods. The bursts of data are referred to as “packets” or “packages” of data. In the future mobile communication system, traffic data is transmitted over a dedicated traffic channel for a data transmission duration, and the dedicated traffic channel is maintained for a predetermined time even when the base station and the mobile station have no traffic data to transmit. The mobile communication system, after finishing transmitting traffic data over the dedicated traffic channel, maintains the downlink and uplink channels between the base station and the mobile station for a predetermined time even though there is no traffic data to transmit. This is done in order to minimize the time delay due to sync. reacquisition when there is traffic data to transmit.
The invention will be described with reference to a UTRA (UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access) mobile communication system. Such a mobile communication system requires many states according to channel assignment circumstances and state information existence
onexistence in order to provide a packet data service as well as a voice service. For example, a state transition diagram for a cell connected state, a user data active substate and a control-only substate are well defined in 3GPP RAN TS S2 series S2.03, 99. 04.
FIG. 1A
shows state transition in the cell connected state of the mobile communication system. Referring to
FIG. 1A
, the cell connected state includes a paging channel (PCH) state, a random access channel (RACH)/downlink shared channel (DSCH) state, a RACH/forward link access channel (FACH) state, and a dedicated channel (DCH)DCH/DCH, DCH/DCH+DSCH, DCH/DSCH+DSCH Ctrl (Control Channel) state.
FIG. 1B
shows a user data active substate and a control-only substate of the DCH/DCH, DCH/DCH+DSCH, DCH/DSCH+DSCH Ctrl state. It should be noted that the novel gated transmission device and method is applied when there is no traffic data for a predetermined time.
The existing CDMA mobile communication system, which mainly provides voice service, releases a channel after completion of data transmission and connects the channel again when there is further data to transmit. However, when providing packet data service as well as voice service, the conventional data transmission method has many delaying factors such as reconnection delay, thus making it difficult to provide high-quality service. Therefore, to provide packet data service as well as voice service, an improved data transmission method is required. For example, in many cases, data transmission is performed intermittently, such as for Internet access and file downloading. Therefore, there occurs a non-transmission period between transmissions of packet data. During this period, the conventional data transmission method releases or maintains the dedicated traffic (or data) channel. If the dedicated traffic channel is released, a long time is required in order to reconnect the channel, and, if the dedicated traffic channel is maintained, channel resources are wasted and reverse power is wasted. To solve such problems, a dedicated control channel is provided between the base station and the mobile station so that for the data transmission period, a control signal related to the dedicated traffic channel is exchanged and for the non-transmission period, the dedicated traffic channel is released and only the dedicated control channel is maintained. Such a state is referred to as the “control-only substate”.
A downlink (or forward link) for transmitting signals from the base station to the mobile station includes the following physical channels. A description of the physical channels which depart from the scope of the invention will be avoided for simplicity. The physical channels involved in the invention include a dedicated physical control channel (hereinafter, referred to as DPCCH) in which pilot symbols are included for sync acquisition and channel estimation, and a dedicated physical data channel (hereinafter, referred to as DPDCH) for exchanging traffic data with a specific mobile station. The downlink DPDCH includes the traffic data, and the downlink DPCCH includes, at each slot (or power control group), transport format combination indicator (hereinafter, referred to as TFCI) which is information about the format of transmission data, transmit power control (hereinafter, referred to as TPC) information which is a power control command, and control information such as the pilot symbols for providing a reference phase so that a receiver (the base station or the mobile station) can compensate the phase. The DPDCH and the DPCCH are time multiplexed within one power control group in the downlink, and the DPDCH and the DPCCH are separated from each other by orthogonal codes in the uplink.
For reference, the invention will be described with reference to the case where the frame length is 10 msec and each frame includes 16 power control groups, i.e., each power control group has a length of 0.625 msec. Alternatively, the invention will also be described with reference to another case where the frame length is 10 msec and each frame includes 15 power control groups, i.e., each power control group has a length of 0.667 msec. It will be assumed herein that the power control group (0.625 msec or 0.667 msec) has the same time period as the slot (0.625 msec or 0.667 msec). The power control group (or slot) is comprised of pilot symbol, traffic data, transmission data-related information TFCI, and power control information TPC in the downlink. The values stated above are given by way of example only.
FIG. 2A
shows a slot structure including the downlink DPDCH and DPCCH. In
FIG. 2A
, although the DPDCH is divided into traffic data
1
(DATA
1
) and traffic data
2
(DATA
2
), there is a case where the traffic data
1
does not exist and only the traffic data
2
exists according to the types of the traffic data. Table 1 below shows the symbols constituting the downlink DPDCH/DPCCH fields, wherein the number of TFCI, TPC and pilot bits in each slot can vary according to a data rate and a spreading factor.
Unlike the downlink DPDCH and DPCCH, uplink DPDCH and DPCCH for transmitting signals from the mobile station to the base station are separated by channel separation codes.
FIG. 2B
shows a slot structure including the uplink DPDCH and DPCCH. In
FIG. 2B
, the number of TFCI, FBI, TPC and pilot bits can vary according to the service being provided (which changes the type of the traffic data), or because of transmit antenna diversity, or because of a handover circumstance. The FBI (FeedBack Information) is information that the mobile station reques
Ahn Jae-Min
Lee Hyun-Woo
Park Chang-Soo
Dilworth & Barrese LLP
Ng Christine
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