U.S. patent application number 12/116937 was filed with the patent office on 2008-11-13 for method and apparatus of improving reset of evolved media access control protocol entity in a wireless communications system.
Invention is credited to Li-Chih Tseng.
Application Number | 20080279194 12/116937 |
Document ID | / |
Family ID | 39541254 |
Filed Date | 2008-11-13 |
United States Patent
Application |
20080279194 |
Kind Code |
A1 |
Tseng; Li-Chih |
November 13, 2008 |
Method and Apparatus of Improving Reset of Evolved Media Access
Control Protocol Entity in a Wireless Communications System
Abstract
A method of improving reset of an evolved media access control
(MAC-ehs) protocol entity for a user equipment of a wireless
communications system is disclosed. The MAC-ehs entity includes a
plurality of reordering queues and a plurality of reassembly
entities. The method includes receiving a reset request for
resetting the MAC-ehs entity, delivering all reordering packet data
units (PDUs) stored in the plurality of reordering queues to the
corresponding reassembly entities for performing a reassembly
process to deliver complete upper layer PDUs to an upper layer
entity, and discarding all PDU segments still existing in the
plurality of reassembly entities.
Inventors: |
Tseng; Li-Chih; (Taipei
City, TW) |
Correspondence
Address: |
NORTH AMERICA INTELLECTUAL PROPERTY CORPORATION
P.O. BOX 506
MERRIFIELD
VA
22116
US
|
Family ID: |
39541254 |
Appl. No.: |
12/116937 |
Filed: |
May 7, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60916546 |
May 7, 2007 |
|
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Current U.S.
Class: |
370/394 |
Current CPC
Class: |
H04L 1/0091 20130101;
H04L 69/324 20130101; H04L 1/1835 20130101 |
Class at
Publication: |
370/394 |
International
Class: |
H04L 12/56 20060101
H04L012/56 |
Claims
1. A method for improving reset of an evolved media access control,
named MAC-ehs hereinafter, protocol entity in a user equipment of a
wireless communications system, the MAC-ehs protocol entity
comprising a plurality of reordering queues and a plurality of
reassembly protocol entities, the method comprising: receiving a
reset request for resetting the MAC-ehs protocol entity; delivering
all reordering Packet Data Units, named PDUs hereinafter, stored in
the plurality of reordering queues to the plurality of reassembly
protocol entities for reassembly and delivering complete upper
layer PDUs to an upper layer protocol entity; and discarding all
PDU segments still existing in the plurality of reassembly
entities.
2. The method of claim 1, wherein the reset request is generated by
an upper layer protocol entity.
3. The method of claim 1, wherein each reordering PDU stored in the
plurality of reordering queues is carried in a MAC-ehs PDU, and
comprises at least one PDU or PDU segment.
4. The method of claim 3, wherein the MAC-ehs PDU is received by
the MAC-ehs protocol entity.
5. The method of claim 3, wherein the at least one PDU comprises a
MAC-ehs serving data unit, named MAC-ehs SDU, MAC-d PDU or MAC-c
PDU.
6. The method of claim 1, wherein the wireless communications
system is an Evolved High Speed Packet Access system.
7. A communications device used in a wireless communications system
for improving reset of an evolved media control access, named
MAC-ehs hereinafter, protocol entity, the MAC-ehs protocol entity
comprising a plurality of reordering queues and a plurality of
reassembly protocol entities, the communications device comprising:
a control circuit for realizing functions of the communications
device; a central processing unit coupled to the control circuit
for executing a program code to operate the control circuit; and a
memory coupled to the central processing unit for storing the
program code; wherein the program code comprises: receiving a reset
request for resetting the MAC-ehs protocol entity; delivering all
reordering Packet Data Units, named PDUs hereinafter, stored in the
plurality of reordering queues to the plurality of reassembly
protocol entities for reassembly and delivering complete upper
layer PDUs to an upper layer protocol entity; and discarding all
PDU segments still existing in the plurality of reassembly
entities.
8. The communications device claim 7, wherein the reset request is
generated by an upper layer protocol entity.
9. The communications device of claim 7, wherein each reordering
PDU stored in the plurality of reordering queues is carried in a
MAC-ehs PDU, and comprises at least one PDU or PDU segment.
10. The communications device of claim 9, wherein the MAC-ehs PDU
is received by the MAC-ehs protocol entity.
11. The communications device of claim 9, wherein the at least one
PDU comprises a MAC-ehs serving data unit, named MAC-ehs SDU, MAC-d
PDU or MAC-c PDU.
12. The communications device of claim 7, wherein the wireless
communications system is an Evolved High Speed Packet Access
system.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60916546, filed on May 7, 2007 and entitled "Method
and Apparatus for allocating HARQ configuration and concatenation
and delivery of MAC PDUs", the contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method and apparatus for
improving reset of an evolved media access control, named MAC-ehs
hereinafter, protocol entity in a user equipment of a wireless
communications system, and more particularly to a method and
apparatus for resetting the MAC-ehs protocol entity by correctly
discarding previously stored packet data unit segments in a user
equipment in a wireless communications system.
[0004] 2. Description of the Prior Art
[0005] The third generation (3G) mobile telecommunications system
has adopted a Wideband Code Division Multiple Access (WCDMA)
wireless air interface access method for a cellular network. WCDMA
provides high frequency spectrum utilization, universal coverage,
and high quality, high-speed multimedia data transmission. The
WCDMA method also meets all kinds of QoS requirements
simultaneously, providing diverse, flexible, two-way transmission
services and better communication quality to reduce transmission
interruption rates.
[0006] In the prior art, lengths of all Protocol Data Units (PDUs)
outputted from a Radio Link Control (RLC) layer are the same.
However, this decreases bandwidth utility rate and data processing
efficiency, especially for high data rate applications, such as
High Speed Downlink Package Access (HSDPA) and High Speed Uplink
Package Access (HSUPA) in the 3G mobile telecommunications system.
Thus, targeting high data rate applications, the 3rd Generation
Partnership Project (3GPP) makes some modifications for RLC and
Media Access Control (MAC) layers, which primarily includes
adopting flexible RLC PDU sizes and providing PDU
segmentation/reassembly in the MAC layer, to enhance bandwidth
utility rate and data processing efficiency, thereby making high
data rate enabled by physical layer features such as Multi-input
Multi-output (MIMO) and high order modulations possible.
[0007] In such a situation, the 3GPP newly introduces a MAC-ehs
protocol entity in the MAC layer, which allows the support of
flexible RLC PDU sizes as well as MAC segmentation/reassembly.
Furthermore, unlike MAC-hs for HSDPA, MAC-ehs allows multiplexing
of data from several priority queues within one transmission time
interval (TTI) of 2 ms. Detailed operations of the MAC-ehs entity
can be found in the MAC protocol specification formulated by the
3GPP, and are not narrated herein.
[0008] Please refer to FIG. 1, which illustrates a schematic
diagram of a MAC-ehs PDU. The MAC-ehs PDU consists of a plurality
of reordering PDUs R_PDU.sub.n and a corresponding MAC-ehs header.
Each reordering PDU consists of at least one consecutive MAC-ehs
Serving Data Unit (SDUs) or segments of MAC-ehs SDUs belonging to
the same priority queue, or reordering queue. A MAC-ehs SDU, i.e.
an upper layer PDU, is either a MAC-c PDU or a MAC-d PDU. For each
reordering PDU, the MAC-ehs header carries a Logical channel
identifier (LCH-ID) field LCH-ID.sub.n, a Length field L.sub.n, a
Transmission Sequence Number (TSN) field TSN.sub.n, a Segmentation
Indication (SI) field SI.sub.n, and a header extension field
F.sub.n. The LCH-ID field LCH-ID.sub.n indicates a priority queue
for each reordering PDU, wherein the mapping between the logic
channel and the priority/reordering queue is provided by upper
layers. The Length field L.sub.n indicates data length of each
reordering PDU. The TSN field TSN.sub.n indicates a TSN of each
reordering PDU for reordering purpose. The SI field SI.sub.n
indicates whether MAC-ehs SDUs included in each reordering PDU are
segmented and segmentation type of the reordering PDU for
reassembly. The header extension field F.sub.n then indicates
whether there exists a next reordering PDU in the following.
[0009] Thus, when a MAC-ehs PDU is received by the UE, each
reordering PDU is firstly assigned to a corresponding reordering
queue for reordering according to the LCH-ID field LCH-ID.sub.n and
the TSN field TSN.sub.n. In each reordering queue, if the latest
received reordering PDU is determined to be consecutive to a
previously stored segment of a MAC-ehs SDU, the reordering PDU
shall be further concatenated with the previously stored segment of
the MAC-ehs SDU according to the SI field SI.sub.n, so that
complete MAC-ehs SDUs can be delivered to upper layers.
[0010] In the prior art, the UE is required by upper layers to
perform a MAC-ehs reset procedure for resetting the MAC-ehs
protocol entity in some situations. The MAC-ehs reset procedure
includes the following steps: Flushing soft buffers for all
configured Hybrid Automatic Repeat Request (HARQ) processes;
stopping all active reordering release timers and setting all
timers to their initial values; starting transmission sequence
numbers (TSNs) with value 0 for a next transmission of each
configured HARQ process; defining an initial range of a receiver
window; delivering all reordering PDUs in each reordering buffer to
a corresponding reassembly protocol entity; and flushing the
reordering buffer.
[0011] By the reassembly protocol entity, all reordering PDUs in
each reordering queue are reassembled with previously stored PDU
segments for further delivering complete PDUs to upper layers.
However, when the MAC-ehs reset procedure is performed, operation
of discarding PDU segments still existing in the reassembly entity
is not executed. In this situation, after resetting the MAC-ehs
protocol entity, later-received reordering PDUs may be incorrectly
concatenated with the stored PDU segments in the reassembly entity,
resulting in a data error of the UE.
SUMMARY OF THE INVENTION
[0012] It is therefore an objective of the present invention to
provide a method and apparatus for improving reset of a MAC-ehs
protocol entity in a user equipment of a wireless communications
system.
[0013] According to the present invention, a method for improving
reset of a MAC-ehs protocol entity in a user equipment of a
wireless communications system is disclosed. The MAC-ehs protocol
entity comprises a plurality of reordering queues and a plurality
of reassembly protocol entities. The method includes steps of
receiving a reset request for resetting the MAC-ehs protocol
entity; delivering all reordering Packet Data Units, named PDUs
hereinafter, stored in the plurality of reordering queues to the
plurality of reassembly protocol entities for reassembly and
delivering complete upper layer PDUs to a upper layer protocol
entity; and discarding all PDU segments still existing in the
plurality of reassembly entities.
[0014] According to the present invention, a communications device
used in a wireless communications system for improving reset of a
MAC-ehs protocol entity is further disclosed. The MAC-ehs protocol
entity comprises a plurality of reordering queues and a plurality
of reassembly protocol entities. The communications device includes
a control circuit for realizing functions of the communications
device; a processor installed in the control circuit, for executing
a program code to command the control circuit; and a memory
installed in the control circuit and coupled to the processor for
storing the program code. The program code includes steps of
receiving a reset request for resetting the MAC-ehs protocol
entity; delivering all reordering Packet Data Units, named PDUs
hereinafter, stored in the plurality of reordering queues to the
plurality of reassembly protocol entities for reassembly and
delivering complete upper layer PDUs to a upper layer protocol
entity; and discarding all PDU segments still existing in the
plurality of reassembly entities.
[0015] These and other objectives of the present invention will no
doubt become obvious to those of ordinary skill in the art after
reading the following detailed description of the preferred
embodiment that is illustrated in the various figures and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates a schematic diagram of a MAC-ehs PDU.
[0017] FIG. 2 is a functional block diagram of a communications
device.
[0018] FIG. 3 is a schematic diagram of the program code in FIG.
2.
[0019] FIG. 4 is a schematic diagram of a process according to an
embodiment of the present invention.
DETAILED DESCRIPTION
[0020] Please refer to FIG. 2, which is a functional block diagram
of a communications device 100. For the sake of brevity, FIG. 2
only shows an input device 102, an output device 104, a control
circuit 106, a central processing unit (CPU) 108, a memory 110, a
program code 112, and a transceiver 114 of the communications
device 100. In the communications device 100, the control circuit
106 executes the program code 112 in the memory 110 through the CPU
108, thereby controlling an operation of the communications device
100. The communications device 100 can receive signals input by a
user through the input device 102, such as a keyboard, and can
output images and sounds through the output device 104, such as a
monitor or speakers. The transceiver 114 is used to receive and
transmit wireless signals, delivering received signals to the
control circuit 106, and outputting signals generated by the
control circuit 106 wirelessly. From a perspective of a
communications protocol framework, the transceiver 114 can be seen
as a portion of Layer 1, and the control circuit 106 can be
utilized to realize functions of Layer 2 and Layer 3.
[0021] Please further refer to FIG. 3, which is a schematic diagram
of the program code 112 in FIG. 2. The program code 112 comprises
an application program layer 200, a layer 3 interface 202, a layer
2 interface 206, and a layer 1 interface 218. When transmitting
signals, the layer 3 interface 202 submits Service Data Units
(SDUs) 208 to the layer 2 interface 206 and the layer 2 interface
206 stores the SDUs 208 in a buffer 212. Then, the layer 2
interface 206 generates a plurality of PDUs 214 according to the
SDUs 208 stored in the buffer 212 and outputs the PDUs 214
generated to a destination through the layer 1 interface 218.
Conversely, when receiving a radio signal, the radio signal is
received through the layer 1 interface 218 and the layer 1
interface 218 outputs PDUs 214 to the layer 2 interface 206. The
layer interface 206 restores the PDUs 214 to SDUs 208 and stores
the SDUs 208 in the buffer 212. At last, the layer 2 interface 206
transmits the SDUs 208 stored in the buffer 212 to the layer 3
interface 202. Preferably, the communications device 100 is applied
in an Evolved High Speed Packed Access (Evolved HSPA) system, such
that the layer 2 interface 206 can be a MAC-ehs interface utilized
for handling MAC-ehs PDUs.
[0022] In some situations, the communications device 100 is
required to perform a MAC-ehs reset procedure for resetting the
MAC-ehs protocol entity according to a reset request generated by
upper layers. Thus, the embodiment of the present invention
provides a MAC-ehs reset program code 220 in the program code 112
utilized for correctly resetting the MAC-ehs protocol entity, so as
to avoid incorrect PDUs being generated and delivered to upper
layers. Please refer to FIG. 4, which illustrates a schematic
diagram of a process 30 according to an embodiment of the present
invention. The process 30 is utilized for improving reset of a
MAC-ehs protocol entity in a user equipment of a wireless
communications system, and can be compiled into the MAC-ehs reset
program code 220. The process 30 includes the following steps:
[0023] Step 300: Start.
[0024] Step 302: Receiving a reset request for resetting the
MAC-ehs protocol entity, wherein the MAC-ehs protocol entity
includes a plurality of reordering queues and a plurality of
reassembly protocol entities.
[0025] Step 304: Deliver all reordering PDUs stored in the
plurality of reordering queues to the plurality of reassembly
protocol entities for reassembly and for delivering complete upper
layer PDUs to an upper layer protocol entity.
[0026] Step 306: Discard all PDU segments still existing in the
plurality of reassembly entities.
[0027] Step 308: End.
[0028] According to the process 30, when the reset of the MAC-ehs
protocol entity is performed, all reordering PDUs stored in the
plurality of reordering queues shall be delivered to the plurality
of reassembly protocol entities for reassembly, so as to deliver
complete upper layer PDUs to an upper layer protocol entity, such
as to corresponding logic channels through a demultiplexing entity.
Finally, all PDU segments still existing in the plurality of
reassembly entities are discarded in the embodiment of the present
invention.
[0029] Therefore, after resetting the MAC-ehs protocol entity, no
previously stored PDU segments exist in the plurality of reassembly
protocol entities, so that occurrence of a data error generated by
incorrect concatenation can be avoided.
[0030] Certainly, in the embodiment of the present invention, the
process 30 can further includes steps of: flushing soft buffers for
all configured Hybrid Automatic Repeat Request (HARQ) processes,
stopping all active reordering release timers and setting all
timers to their initial values, starting transmission sequence
numbers (TSNs) with value 0 for a next transmission of each
configure HARQ process, defining an initial range of a receiver
window, delivering all reordering PDUs in each reordering buffer to
a corresponding reassembly protocol entity, and flushing the
reordering buffer, which are well known by those skilled in the art
and not narrated herein.
[0031] As mentioned above, when resetting the MAC-ehs protocol
entity, the embodiment of the present invention discards all stored
PDU segments in the reassembly entities, so as to avoid a data
error of the UE due to incorrect concatenation.
[0032] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention. Accordingly, the
above disclosure should be construed as limited only by the metes
and bounds of the appended claims.
* * * * *