Multiplex communications – Communication over free space – Combining or distributing information via code word channels...
Reexamination Certificate
2000-05-12
2004-05-18
Kizou, Hassan (Department: 2662)
Multiplex communications
Communication over free space
Combining or distributing information via code word channels...
C370S229000
Reexamination Certificate
active
06738368
ABSTRACT:
BACKGROUND
The invention generally relates to channels used by multiple users in a wireless code division multiple access spread spectrum system. More specifically, the invention relates to a system and method of prioritizing and controlling the flow of data for common and shared channels in a spread spectrum system.
FIG. 1
illustrates a simplified wireless spread spectrum code division multiple access (CDMA) communication system
18
. A node b
26
within the system
18
communicates with associated user equipment
20
-
24
(UE). The node b
26
has a single site controller (SC)
30
associated with either a single (shown in
FIG. 1
) or multiple base stations
28
. A Group of node bs
26
,
32
,
34
is connected to a radio network controller (RNC)
36
. To transfer communications between RNCs
36
-
40
, an interface between the RNCs (IUR)
42
is utilized. Each RNC
36
-
40
is connected to a mobile switching center (MSC)
44
which in turn is connected to the core network
46
.
To communicate within the system
18
, many types of communication channels are used, such as dedicated, shared and common. Dedicated channels transfer data between a node b
26
and a particular UE
20
-
24
. Common and shared channels are used by multiple UEs
20
-
24
or users. All of these channels carry a variety of data including traffic, control and signaling data.
Since shared and common channels carry data for different users, data is sent using protocol data units (PDUs) or packets. As shown in
FIG. 2
, to regulate the flow of data from differing sources
48
-
52
into a channel
56
, a controller
54
is used.
One common channel used for transmitting data to the UEs
20
-
24
is the forward access common channel (FACH)
58
. As shown in
FIG. 3
, the FACH
58
originates in a RNC
36
and is sent to a node b
28
-
34
for wireless transmission as a spread sprectrum signal to the UEs
20
-
24
. The FACH
58
carriers several data types from various sources, such as a common control channel (CCCH), dedicated control and traffic channel (DCCH and DTCH), and a downlink and uplink share channel (DSCH and USCH) control signaling. The FACH
58
also carries control signaling out of band, such as hybrid automatic repeat request (H-ARQ), and similar data transmitted via the IUR
62
from other RNCs
38
-
40
, such as CCCH, DCCH, DTCH and H-ARQ control data.
Various controllers are used by the RNC
36
to control the flow of data. A radio link controller (RLC)
64
handles the CCCH. The dedicated medium access controller (MAC-d)
66
handles the DCCH, the DTCH and some out of band H-ARQ control signaling. The shared medium access controller (MAC-sh)
68
handles the DSCH, USCH control signaling and out of band H-ARQ control signaling. Controlling the FACH
58
is the common medium access controller (MAC-c)
60
.
Due to the multiple sources of data
48
-
52
that can be transmitted over a common or shared channel, the channel controllers
54
queue the data prior to transmission. If a large backlog develops in the queue, data in the queue develops a latency. A large latency of certain data such as control data will result in the failure of a channel. To alleviate this problem, the prior art either flushed the queue to reduce congestion or rerouted the data. Flushing the queue results in the loss of data and requires retransmission which is undesirable. Rerouting data already queued creates a duplication of data within the system and does not resolve the existing congestion. According, it is desirable to reduce the latency of data for shared and common channels without the problems associated with the prior art.
SUMMARY
Packet data from a plurality of sources is received at a controller associated with the multiuser channel. Each packet of the packet data is prioritized based on in part the reroutability of a class of data types. Each packet is scheduled for transmission over the multiuser channel based on in part the prioritization. A backlog of packet data queued is tracked for transfer over the multiuser channel. Based on in part the tracked queue, the flow of data from each data source is limited.
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TS 25.321 V2.0.1 MAC Protocol Specification, TSG-RAN Working Group 2 (Radio Layer 2 and Radio Layer 3), Berlin, Germany, May 25-28, 1999.
Stephen E. Terry, FACH Scheduling, Prioritization and Queue Management, 3GPP TSG-RAN WG2 #4, Berlin, Germany, May 25-28, 1999.
InterDigital Technology Corporation
Kizou Hassan
Mills Donald L
Volpe and Koenig P.C.
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