Title of Invention

AN IMPROVED CONGESTION CONTROL IN A WIRELESS MOBILE SYSTEM

Abstract The invention refers to a method for improved congestion control in a wireless mobile system where a high speed packet data access (HSDPA) between a node and a number of mobile stations (MS) have been established by dedicating a high speed physical downlink shared channel (HS-PDSCH) to all mobile stations (MS) and one associated dedicated channel (A-DPCH) per each mobile station (MS). The method comprises the steps of; -in case of congestion, detecting the amount of download data still to be downloaded by each of the mobile stations (MS) and, -based on the amount of download data still to be downloaded, releasing the associated dedicated channel (A-DPCH) for one or more first mobile stations (MS) having an amount of data above a predetermined threshold level.
Full Text TECHNICAL FIELD
The invention refers to a method for improved congestion control in a wireless
mobile system and a control device arranged to carry out the method. The method is
used in a wireless mobile system where a high speed packet data access has been
established between a node and a number of mobile stations by dedicating a high
speed physical downlink shared channel to all mobile stations and one associated
dedicated channel per each mobile station.
BACKGROUND ART
Abbreviations:
3GPP-3rd Generation Partnership Project (standards body)
A-DPCH-Associated Dedicated Physical Channel
DL-DownLink
FDD-Frequency Division Duplex
GGSN-Gateway GPRS Support Node
GPRS-General Packet Radio System
GSM-Global System for Mobile Communications
HSDPA-High Speed Downlink Packet Access
HS-PDSCH High Speed Physical Downlink Shared CHannel
LLC-Logical Link Control
MAC- Medium Access Code
MS-Mobile station
PDP-Packet Data Protocol
RLC- Radio Link Control
RNC-Radio Network Controller
SGSN-Serving GPRS Support Node
SNDCP-Sub Network Dependent Convergence Protocol
TCP-Transport
TDD-Time Division Duplex
UL-UpLink
UMTS-Universal Mobile Telecommunications System
UTRAN- UMTS Terrestrial Radio Access Network

WCDMA- Wide band Code Division Multiple Access
The 3rd Generation Partnership Project (3GPP) specification is a standard for the
third generation mobile telephony system. The system supports different user data
rates for different users. The transmission power used for a certain user is
determined by interference level in a certain cell, user data rate, channel quality and
requested quality of the data transmission in the cell.
Control channels and traffic channels are referred to as logical channels. These
logical channels are mapped onto physical channels.
A physical channel can be a radio broadcasting frequency, a pair of frequencies
(including duplex separation) in an analog mobile system or a time slot on a pair of
frequencies in a digital mobile system.
A physical channel may, for example, be a time slot on a particular frequency
channel in a TDMA system and may also be said to be a carrier of a logical channel,
such as a traffic channel (sometimes abbreviated TCH), or several logical channels,
such as various control channels in a multi frame structure.
In digital systems based on TDMA the mapping process means that a time slot and a
frequency are allocated to the traffic burst.
The traffic channels convey voice or data (such as Internet traffic) between the
mobile and base station. The channels are allocated on a per call basis. Ordinarily, a
time slot is used for one call only (full rate), but an alternative with two calls per time
slot (half rate) has also been specified.
All the present mobile systems are based on multiple access, which means that all
users have simultaneous access to the medium. This requires a number of rules to
prevent situations in which mobiles "all talk at the same time". The medium, which is
a common resource, must satisfy the needs of all users.
Traffic channels are assigned through control-channel signalling.

Each cell in a cellular system can be regarded as an individual medium because a
mobile leaving the cell loses contact with that cell's base station. However, all
mobiles in the cell utilise the same radio resource, namely, that portion of the
frequency spectrum which has been assigned to the cell.
One technique for channel multiplexing using multiple access is CDMA (Code
division multiple access). CDMA systems are capable of transmitting and receiving
over the entire frequency band and a "third dimension" is used to separate traffic
channels, namely coding.
A typical feature of the CDMA technique is that all mobiles in the network are
assigned a unique code: a chip sequence. When a mobile wishes to transmit a bit
stream, it replaces every bit with its code (for ones) or with the code's ones
complement (for zeros). The result is that a number of air interface bits (referred to
as a "chip"), depending on the spreading factor used, are transmitted for every
payload bit. Provided that the same modulation methods are used as those used in
TDMA, the required bandwidth will be correspondingly larger. Instead of using some
tens of kHz for a voice channel, the chip will be modulated over approximately 3.84
MHz. That is why this technique is also referred to as a spread-spectrum technique.
The mobile telephone system may, for example, be a WCDMA system which has a
downlink transport channel called High Speed Downlink Shared Channel (HS-
DSCH) mapped onto a set of physical channels called High Speed Physical
Downlink Shared CHannels (HS-PDSCH). The HS-DSCH provides enhanced
support for interactive, background, and, to some extent streaming radio-access-
bearer (RAB) services in the downlink direction.
In a HSDPA supporting WCDMA system (e.g. according to 3GPP release 5) every
user that is given access to a HS-PDSCH (High Speed Physical Downlink Shared
Channel) channel must also have an associated dedicated Physical Channel A-
DPCH used, for example, for communicating control information.
A typical action in case of overload (congestion) consists of the Radio Network
Controller RNC releasing certain channels to reduce the load on the particular
resource that is in shortage, for example DL Power, UL interference, DL Codes, etc.

It is possible that also A-DPCHs will be released, especially if all
interactive/background traffic is carried on HS-PDSCH and there's a need to make
more DL Codes available to handle a sharp increase in conversational traffic
(speech, video, ...) or if it turns out that A-DPCHs consume a significant amount of
power.
Current congestion control randomly selects the A-DPCHs to be released for certain
mobile stations and thereby inhibiting the downlink information flow in the HS-
PDSCH for the thereby randomly chosen mobile station. This can lead to a situation
where a user that is almost done with a download is thrown out of the system at the
expense of a user that has just got into the system. As an end user, this can be very
annoying, especially if the application gives some kind of indication of the progress
of the download (one case could be that the end user can see that the down load is
95% completed and then interrupted).
Therefore, there is a need for an improved congestion control in a HSDPA based
system or the like, with enhanced data transmission flow control giving more pleased
users.
DISCLOSURE OF INVENTION
The invention intends to remedy the above problems by a method for improved
congestion control and a control device arranged for carrying out the method.
The method is used in a wireless mobile system where a high speed packet data
access HSDPA has been established between a node and a number of mobile
stations MS by dedicating a high speed physical downlink shared channel HS-
PDSCH to all mobile stations MS and one associated dedicated channel A-DPCH
per each mobile station MS. The above HSDPA setup may be performed by the
node.
The method comprises the steps of:
-in case of congestion, a control device detecting the amount of download data still
to be downloaded by each of the mobile stations MS and,

-based on the amount of download data still to be downloaded, the control device
releasing the associated dedicated channel A-DPCH for one or more first mobile
stations MS having an amount of data above a predetermined threshold level.
The advantage of the invention lies in that the mobile stations that are almost
finished downloading, are allowed to finish downloading, instead of as in prior art
being randomly thrown out regardless of status.
In one embodiment of the invention, the threshold level is an amount of download
data to be downloaded by one or several second mobile stations MS using the same
high speed physical downlink shared channel HS-PDSCH as the first mobile
station(s). In this embodiment the threshold is set by comparing all mobile stations
and to release the A-DPCH for one or several user units having more data to be
downloaded than at least another mobile station. The comparison may give a
hierarchy with the mobile station having the most data to be downloaded at the top
and the mobile station with the least data at the bottom. The threshold may here be a
floating value that is always set at the mobile station having the second most data to
download, i.e. mobile station No two in the hierarchy. The advantage here is that the
mobile station having the most still to download will be thrown out in a first round,
and during the next round the next in order is thrown out if more recourses have to
be liberated, while all the other mobile stations may continue downloading and the
mobile stations having the least to download is thus given a chance to finish
downloading. The threshold level may also be set at a level indicating a specific
mobile station in the hierarchy and all the mobile stations above that mobile station in
the hierarchy may be subject to the release of the associated the A-DPCH.
In one embodiment of the invention, the threshold level is a preset value, for
example, all mobile stations having downloaded more than a certain percentage of
an intended amount may continue and the other mobile stations may be subject to
the release of the associated the A-DPCH .
The wireless mobile system may be a WCDMA based system wherein the node
being an RNC. However, the invention is applicable on all systems using a downlink
shared channel and an associated dedicated channel that always consumes an
amount of the total system recourse, for example for control information. As referred

to in the prior art description, HS-PDSCH and A-DPCH refers to a WCDMA system,
but the present invention may be applicable in, for example, CDMA 2000 1x, EVDO
(Evolution Data Only) and EVDV (Evolution Data/Voice), where the HS-PDSCH is
denoted F-PDCH (Forward link Packet Data CHannel) and the corresponding A-
DPCH is denoted F-FCH (Forward link Fundamental CHannel). CDMA 2000 refers
to the 3GPP2 and the EVDO and EVDV corresponds to the HSDPA system in the
3GPP3 based WCDMA system. The invention may also be used in any other FDMA
and/or a TDMA based system with a similar channel configuration as the WCDMA or
CDMA 2000.
In one embodiment the threshold level is a preset value of not yet acknowledged
data in an RLC in the RNC. The not yet acknowledged data may be detected by
looking in the RLC buffers, where it would be possible to find users with low amounts
of not yet acknowledged data. The threshold may then be defined in bytes. The most
straightforward way to use this information would be to define the threshold such that
mobile stations with less remaining data than this threshold are protected at least in
a first round of releasing A-DPCHs.
If there's a proxy in the RNC, information from this proxy could be passed over an
RNC internal interface to a radio resource management function in a control device
taking the decision on which A-DPCH to be released. The radio resource
management function is preferably a part of the RNC.
It would of course also be possible to combine this criterion with other criteria such
as detection of power usage of the individual Radio Link. The not yet acknowledged
data may also be used for the above described comparison between different mobile
stations.
The basic idea of the invention is thus to find/detect users that have very little data
waiting for transmission and the benefits is an improved end user experience for
wireless data services in a WCDMA or another similar system using a HSDPA
supporting network or a network similar to HSDPA.

In principle the same mechanisms can be considered also for interactive or
background traffic on dedicated channels as well, but the gain is assumed to be
lower.
The invention refers also to a control device for improved congestion control in a
wireless mobile system where a high speed packet data access (HSDPA) between a
node and a number of mobile stations (MS) have been established by a high speed
physical downlink shared channel (HS-PDSCH) being dedicated to all mobile
stations (MS) and one associated dedicated channel (A-DPCH) being dedicated per
each mobile station (MS),
-in case of congestion, the control device being arranged to detect the amount of
download data still to be downloaded by each of the mobile stations (MS) and,
-the control device being arranged to, based on the amount of download data still to
be downloaded, release the associated dedicated channel (A-DPCH) for one or
more first mobile stations (MS) having an amount of data above the predetermined
threshold level.
All the above stated advantages with the method is also valid for the control device.
The control device is preferably a part of the RNC and may be arranged to carry out
all the above stated method steps.
BRIEF DESCRIPTION OF/DRAWINGS
The invention will below be described in more details in connection to a number of
drawings, where;
Figure 1 schematically shows a TCP/IP based network in a GPRS standard
according to one embodiment of the present invention;
Figure 2 schematically shows different stacked protocols of the GGSN over the Gn
interface to the SGSN and the SGSN over the lu interface to the MS, and where;
Figure 3 shows a diagram over a buffer versus time.

EMBODIMENTS OF THE INVENTION
Figure 1 schematically shows a TCP/IP based network in a GPRS standard
according to one embodiment of the present invention. The network comprises a
landline based network a wireless radio network. The land line based network
comprises a host in the form of a SERVER and a GGSN and a SGSN. The radio
network comprises an RNC, a Node B and a client in the form of an MS, all based on
WCDMA, see also figure 2. The interface between the GGSN and the SGSN is
called Gn, and the interface between the SGSN and the RNC is called lu. The
interface between the MS and the Node-B in the second radio network is called Uv.
The interface between the GGSN and the SERVER is called Gj.
When discussing figure 1, cross-references are made to figure 2. Figure 2
schematically shows different stacked protocols of the GGSN over the Gn interface
to the SGSN and the SGSN over the lu interface to the MS. In figure 3, UTRAN
refers to the RNC and the Node-B in figure 1.
The GGSN refers to a gateway GPRS support node acting as an interface between
the GPRS backbone network and the external packet data networks (radio network
and the IP network). It converts the GPRS packets coming from the SGSN into the
appropriate packet data protocol (PDP) format (e.g. IP) and sends them out on the
corresponding packet data network. In the other direction, PDP addresses of
incoming data packets are converted to the GSM address of the destination user.
The readdressed packets are sent to the responsible SGSN. For this purpose, the
GGSN stores the current SGSN address of the user and his or her profile in its
location register. The GGSN also performs authentication and charging functions
towards external systems, whereas SGSN may perform authentication.
The function of the SGSN is as a router in the interface between the wireless
network and the land line based network and has been explained above.
WCDMA technology is used for UTRAN air interface. UMTS WCDMA is a Direct
Sequence CDMA system where user data is multiplied with quasi-random bits
derived from WCDMA Spreading codes. In UMTS, in addition to channelisation,

Codes are used for synchronisation and scrambling. WCDMA has two basic modes
of operation: Frequency Division Duplex (FDD) and Time Division Duplex (TDD).
The functions of the Node-B are:
• Air interface Transmission / Reception
• Modulation / Demodulation
• CDMA Physical Channel coding
• Micro Diversity
• Error Handing
• Closed loop power control
The functions of the RNC are:
• Radio Resource Control
• Admission Control
• Channel Allocation
• Power Control Settings
• Handover Control
• Macro Diversity
• Ciphering
• Segmentation / Reassembly
• Broadcast Signalling
• Open Loop Power Control
In the radio interface lu in the RNC for UMTS GPRS, concentration is performed in
the radio air interface lu, because the number of traffic channels is limited.
The invention refers to a method for congestion control where the dedicated channel
A-DPCH is released for some specific mobile stations. These mobile stations have
an amount of information to download above a set threshold level. In order to find

those mobile stations, a search for mobile stations below the threshold level reveals
mobile stations that shall not be released, at least not in a first round of sorting out.
By looking at RLC buffers in the RNC (See for example figure 2 and 3.), it is possible
to find mobile stations with low amounts of not yet acknowledged data, which is a
sign that the mobile stations have downloaded the main part of the information, and
that these mobile stations should be prioritised and not be thrown out by releasing
the mobile stations corresponding A-DPCH if there are other mobile stations having
a higher amount of not yet acknowledged data.
If there's a proxy in the RNC, information from this proxy could be passed over some
RNC internal interface to the radio resource management function. The proxy is
sometimes proposed as a means to hide the radio network from the application by
intermediate buffering of data.
Figure 3 shows a diagram over a buffer versus time in an RLC for a not yet
acknowledged data. The Amount of not yet acknowledged data is rising considerably
in the first part of the downloading process and then attenuates towards zero. In
figure 3 a threshold is set at a predetermined level. All the mobile stations MS having
not yet acknowledged data above the threshold is subject for being disrupted by
cancelling the corresponding A-DPCH for that user. As can be seen in figure 3, the
mobile stations just started to download is also below the threshold and will not be
thrown out. This is of course not a desired situation, but the not yet acknowledged
data is rising very fast so the mobile station will quickly be one of the mobile stations
above the threshold level and thus subject for releasing the corresponding A-DPCH.

WE CLAIM:
1. A method for improved congestion control in a wireless mobile system wherein a high
speed packet data access (HSDPA) is established between a node and a number of
mobile stations (MS) by dedicating a high speed physical downlink shared channel (HS-
PDSCH) to all mobile stations (MS) and one associated dedicated channel (A-DPCH)
per mobile station (MS), said method comprising the steps of: detecting with a control
device, in case of congestion, the amount of download data still to be downloaded by
each of the mobile stations; and, releasing by said control device, based on the amount
of download data still to be downloaded, the associated dedicated channel (A-DPCH) for
one or more first mobile stations having an amount of data above a predetermined
threshold level, wherein the threshold level is an amount of download data to be
downloaded by one or more second mobile stations using the same high speed physical
downlink shared channel (HS-PDSCH) as said one or more first mobile station.
2. A method as claimed in claim 1, wherein the threshold level being a preset value.
3. A method as claimed in claim 1, wherein the threshold level being a preset value of
not yet acknowledged data in a Radio Network Controller (RLC).
4.A method as claimed in any of the preceding claims, wherein the wireless mobile
system being a WCDMA based system wherein the node being an RNC comprising the
control device.
5. A control device for improved congestion control in a wireless mobile system wherein
a high speed packet data access (HSDPA) between a node and a number of mobile
stations (MS) is established by a high speed physical downlink shared channel (HS-
PDSCH) dedicated to all mobile stations (MS) and one associated dedicated channel (A-
DPCH) per mobile station, comprising: means operative, in case of congestion, to detect
the amount of download data still to be downloaded by each of the mobile stations; and,
means operative, as a function of the amount of download data still to be downloaded, to
release the associated dedicated channel (A-DPCH) for one or more first mobile stations
having an amount of data above a predetermined threshold level, wherein the threshold

level is an amount of download data to be downloaded by one or more second mobile
stations using the same high speed physical downlink shared channel (HS-PDSCH) as
said one or more first mobile station.
6. A control device as claimed in claim 5, wherein the threshold level being a preset
value.
7. A control device as claimed in claim 5, wherein the threshold level being a preset
value of not yet acknowledged data in an RLC.
8. A control device as claimed in any one of claims 5-7, wherein the wireless mobile
system being a WCDMA based system and the node being an RNC.


The invention refers to a method for improved congestion control in a wireless
mobile system where a high speed packet data access (HSDPA) between a node
and a number of mobile stations (MS) have been established by dedicating a high
speed physical downlink shared channel (HS-PDSCH) to all mobile stations (MS)
and one associated dedicated channel (A-DPCH) per each mobile station (MS). The
method comprises the steps of;
-in case of congestion, detecting the amount of download data still to be downloaded
by each of the mobile stations (MS) and,
-based on the amount of download data still to be downloaded, releasing the
associated dedicated channel (A-DPCH) for one or more first mobile stations (MS)
having an amount of data above a predetermined threshold level.

Documents:

02069-kolnp-2007-abstract.pdf

02069-kolnp-2007-claims.pdf

02069-kolnp-2007-correspondence others 1.1.pdf

02069-kolnp-2007-correspondence others.pdf

02069-kolnp-2007-description complete.pdf

02069-kolnp-2007-drawings.pdf

02069-kolnp-2007-form 1.pdf

02069-kolnp-2007-form 2.pdf

02069-kolnp-2007-form 3.pdf

02069-kolnp-2007-form 5.pdf

02069-kolnp-2007-gpa.pdf

02069-kolnp-2007-international exm report.pdf

02069-kolnp-2007-international publication.pdf

02069-kolnp-2007-international search report.pdf

02069-kolnp-2007-pct request form.pdf

2069-KOLNP-2007-(15-09-2011)-CORRESPONDENCE.pdf

2069-KOLNP-2007-(15-09-2011)-PA.pdf

2069-KOLNP-2007-ABSTRACT 1.1.pdf

2069-KOLNP-2007-AMANDED CLAIMS.pdf

2069-KOLNP-2007-CANCELLED PAGES 1.1.pdf

2069-KOLNP-2007-CORRESPONDENCE 1.1.pdf

2069-KOLNP-2007-CORRESPONDENCE 1.2.pdf

2069-KOLNP-2007-Correspondence 1.4.pdf

2069-KOLNP-2007-CORRESPONDENCE 1.5.pdf

2069-KOLNP-2007-CORRESPONDENCE-1.3.pdf

2069-KOLNP-2007-CORRESPONDENCE.pdf

2069-KOLNP-2007-DESCRIPTION (COMPLETE) 1.1.pdf

2069-KOLNP-2007-DRAWINGS 1.1.pdf

2069-KOLNP-2007-EXAMINATION REPORT.pdf

2069-KOLNP-2007-FORM 1.1.1.pdf

2069-KOLNP-2007-FORM 18.pdf

2069-KOLNP-2007-FORM 2.1.1.pdf

2069-KOLNP-2007-FORM 3 1.3.pdf

2069-KOLNP-2007-FORM 3.1.1.pdf

2069-KOLNP-2007-FORM 3.1.2.pdf

2069-KOLNP-2007-FORM 3.pdf

2069-KOLNP-2007-FORM 5.1.1.pdf

2069-KOLNP-2007-FORM 5.pdf

2069-KOLNP-2007-FORM-27-1.pdf

2069-KOLNP-2007-FORM-27.pdf

2069-KOLNP-2007-GPA.pdf

2069-KOLNP-2007-GRANTED-ABSTRACT.pdf

2069-KOLNP-2007-GRANTED-CLAIMS.pdf

2069-KOLNP-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

2069-KOLNP-2007-GRANTED-DRAWINGS.pdf

2069-KOLNP-2007-GRANTED-FORM 1.pdf

2069-KOLNP-2007-GRANTED-FORM 2.pdf

2069-KOLNP-2007-GRANTED-SPECIFICATION.pdf

2069-KOLNP-2007-OTHERS 1.1.pdf

2069-KOLNP-2007-OTHERS.pdf

2069-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf

2069-KOLNP-2007-REPLY TO EXAMINATION REPORT1.1.pdf

abstract-02069-kolnp-2007.jpg


Patent Number 249809
Indian Patent Application Number 2069/KOLNP/2007
PG Journal Number 46/2011
Publication Date 18-Nov-2011
Grant Date 14-Nov-2011
Date of Filing 07-Jun-2007
Name of Patentee TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Applicant Address SE-164 83 STOCKHOLM
Inventors:
# Inventor's Name Inventor's Address
1 ANDERSSON, ANDREAS TALLBANEVÄGEN 15, S-438 35 LANDVETTER
PCT International Classification Number H04Q 7/38
PCT International Application Number PCT/SE2004/001629
PCT International Filing date 2004-11-10
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA