WO2006097805A1 - Regulation des flux avec attribution de priorite dynamique pour appels de transferts intercellulaires - Google Patents

Regulation des flux avec attribution de priorite dynamique pour appels de transferts intercellulaires Download PDF

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Publication number
WO2006097805A1
WO2006097805A1 PCT/IB2006/000451 IB2006000451W WO2006097805A1 WO 2006097805 A1 WO2006097805 A1 WO 2006097805A1 IB 2006000451 W IB2006000451 W IB 2006000451W WO 2006097805 A1 WO2006097805 A1 WO 2006097805A1
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WIPO (PCT)
Prior art keywords
priority
handover
scheduling
flow control
user
Prior art date
Application number
PCT/IB2006/000451
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English (en)
Inventor
Jeroen Wigard
Klaus Ingemann Pedersen
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Nokia Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US11/134,378 external-priority patent/US20060209686A1/en
Application filed by Nokia Corporation filed Critical Nokia Corporation
Publication of WO2006097805A1 publication Critical patent/WO2006097805A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/70—Admission control; Resource allocation
    • H04L47/76—Admission control; Resource allocation using dynamic resource allocation, e.g. in-call renegotiation requested by the user or requested by the network in response to changing network conditions
    • H04L47/765—Admission control; Resource allocation using dynamic resource allocation, e.g. in-call renegotiation requested by the user or requested by the network in response to changing network conditions triggered by the end-points
    • H04L47/767—Admission control; Resource allocation using dynamic resource allocation, e.g. in-call renegotiation requested by the user or requested by the network in response to changing network conditions triggered by the end-points after changing the attachment point, e.g. after hand-off
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/10—Flow control; Congestion control
    • H04L47/15—Flow control; Congestion control in relation to multipoint traffic
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/10—Flow control; Congestion control
    • H04L47/24—Traffic characterised by specific attributes, e.g. priority or QoS
    • H04L47/2458—Modification of priorities while in transit
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/70—Admission control; Resource allocation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/70—Admission control; Resource allocation
    • H04L47/82—Miscellaneous aspects
    • H04L47/821—Prioritising resource allocation or reservation requests
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/70—Admission control; Resource allocation
    • H04L47/82—Miscellaneous aspects
    • H04L47/824—Applicable to portable or mobile terminals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/0226—Traffic management, e.g. flow control or congestion control based on location or mobility
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/10—Flow control between communication endpoints
    • H04W28/14—Flow control between communication endpoints using intermediate storage
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/56—Allocation or scheduling criteria for wireless resources based on priority criteria
    • H04W72/566—Allocation or scheduling criteria for wireless resources based on priority criteria of the information or information source or recipient
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/10—Flow control between communication endpoints
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements

Definitions

  • the present invention relates to a flow control method and apparatus for scheduling high-speed packet data in time-shared channels.
  • UTRANs UMTS Terrestrial Radio Access Networks
  • 3GPPP specification TS 25.308 emerging standards for next-generation DS-CDMA (Direct Sequence Code Division Multiple Access) systems are currently extended to cope with higher data rates.
  • DS-CDMA Direct Sequence Code Division Multiple Access
  • HDR High Data Rate
  • HSDPA High Speed Downlink Packet Access
  • rate control and time- division scheduling algorithms are used in forwarding packet data transmission to utilize the radio resource effectively and support the high transmission rate.
  • Employing an efficient packet scheduling algorithm is an essential technique in order to improve the total system throughput as well as the peak throughput of each access user. Although always scheduling the user with the highest link quality may maximise capacity, it can result in a performance too unfair among the us- ers.
  • the proportional fair scheduling method assigns transmission packets based on criteria such as a ratio between an instantaneous signal-to-interference power ratio (SIR) and a long-term average SIR value of each user.
  • SIR signal-to-interference power ratio
  • Another well-known proportional fair scheduling algorithm is the so-called proportional fair throughput (PFT) algorithm which provides a trade-off between throughput maximisation and fairness among users within a cell.
  • PFT proportional fair throughput
  • the PFT algorithm selects the user to be scheduled during the next transmission time interval (TTI) according to a priority metric, which can be expressed as:
  • R n Rn/Tn for a user numbered n, where R n denotes the throughput which can be offered to user n during the next TTI where this user is scheduled, and T n denotes the mean or average throughput delivered to this user within a predetermined time period. It is noted that the value R n is typically time-variant as it depends on the SIR value of this user.
  • HSDPA is based on techniques such as adaptive modulation and Hybrid Automatic Repeat Request (HARQ) to achieve high throughput, reduced delay and high peak rates. It relies on a new type of transport channel, i.e. the High Speed Downlink Shared Channel (HS-DSCH), which is terminated in the Node B.
  • the Node B is the UMTS equivalent to base station in other cellular networks.
  • the priority metric P n is calculated for all users sharing the time-multiplexed channel, e.g. the Downlink Shared Channel (DSCH) or the High Speed Downlink Shared Channel (HS-DSCH) as described in the 3GPP (third generation Partnership Project) specification TS 25.308 V5.4.0.
  • the user with the largest calculated or determined priority metric is selected to be scheduled during the next TTI. Hence, if the user n has not been scheduled for a long period of time, the monitored average throughput T n will decrease and consequently cause an increase of the priority P n of said user.
  • the new functionalities of HARQ and HS-DSCH scheduling are included in the MAC layer. In UTRAN, these functions are included in a new entity called MAC-hs 10 located in the Node B. However, the other Layer 2 functionalities, like RLC (Radio Link Control), MAC-d and MAC-c/sh, are located in the RNC (Radio Network Controller).
  • RLC Radio Link Control
  • MAC-d MAC-d
  • MAC-c/sh Radio Network Controller
  • a flow control function is used in order to transfer data from the RNC to the Node-B.
  • the flow control part at the Node-B monitors the queues in the Node-B and requests data from the RNC.
  • the flow control part in the RNC can fulfil the request or it can send less than the amount of data requested.
  • One reason for sending less may be that the lub capacity is less than the total requested data by the Node-B (the Node-B is not aware of the available capacity on the lub).
  • HSDPA uses hard handover, so when a handover is triggered, the connection be- tween the 'old' Node-B is released and a connection to the target Node-B is set up. This can lead to a gap in the transmission, since data from the RNC has to be put in the target Node-B in order to be able to transmit it to the user. Thus, during the HSDPA handover, a period with an empty user buffer may occur, which leads to worse user experience and lower cell throughput.
  • transport resources are often the bottleneck in the system (instead of for instance the air interface resources).
  • a flow control apparatus for schedul- ing data packets in a multiplexed high-speed channel comprising:
  • priority determination means for determining a scheduling priority for a user based on a predetermined scheduling algorithm
  • dynamic priority change means for dynamically increasing said determined scheduling priority in response to the detection of a handover state of said user.
  • the highest or one but highest priority may be reserved for hand- over calls, and the scheduling priority can then be increased to said reserved priority.
  • the handover state of a user could be detected for example by using an RRC signalling.
  • the dynamic priority increase may be performed before the first data packet has arrived at a handover target device. Then, a slow response due to slow signalling of the handover state does not affect the benefits of the proposed solution.
  • a connection to a handover target cell can be set up and flow control can be started in the target cell prior to an activation time of the handover.
  • Fig. 1 shows a schematic functional block diagram of a MAC-hs unit with a packet scheduler which can be used in connection which the preferred embodiment
  • Fig. 2 shows a schematic functional block diagram of a flow control scheme according to the preferred embodiment. DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • MAC Medium Access Control
  • the transport channel HS-DSCH is controlled by a MAC-hs 10.
  • each shared control channel HS-SCCH
  • UE user equipment
  • Data received on the HS-DSCH is mapped to the MAC-hs 10.
  • the MAC-hs 10 is configured by a Radio Resource Control (RRC) function to set the parame- ters according to the allowed transport format combinations for the HS-DSCH.
  • RRC Radio Resource Control
  • ADS Associated downlink signalling
  • associated Dedicated Physical Channel carries information for supporting the HS-DSCH and associated uplink signalling (AUS) carries feedback information.
  • AUS uplink signalling
  • the AUS it may be distinguished between the associated DPCH and the HS-DPCCH (High Speed Dedi- cated Physical Control Channel) which is the channel carrying the acknowledgements for packet data units (PDUs) received on the HS-DSCH. If a HS-DSCH is assigned to the concerned UE 1 PDUs to be transmitted are transferred to the MAC-hs 10 via respective Iu interfaces to provide the required scheduling function for the common HS-DSCH.
  • the MAC-hs 10 is responsible for handling the data transmitted on the HS-DSCH. Furthermore, it is responsible for the management of physical resources allocated to the HS-DSCH. To achieve this, the MAC-hs 10 receives configuration parameters via messages of the Node B Application Part (NBAP).
  • NBAP Node B Application Part
  • the MAC-hs 10 comprises four different functional entities.
  • a flow control unit 102 provides a flow control function intended to limit layer 2 signalling latency and reduce discarded and transmitted data as a result of HS-DSCH congestion.
  • Flow control is provided independently per priority class for each MAC flow.
  • a packet scheduling unit 104 is provided which manages HS- DSCH resources between HARQ entities and data flows according to their priority class. Based on status reports from associated uplink signalling, e.g. HS-DPCCH signalling, either new transmission or retransmission is determined. Further, the priority class identifiers and transmission sequence numbers are set for each new data block being served.
  • a new transmission can be initiated on a HARQ process at any time.
  • the transmission sequence number is unique to each priority class within a HS-DSCH 1 and is incremented for each new data block. It is not permitted to schedule new transmissions within the same TTI, along with retransmission originating from the HARQ layer.
  • a subsequent HARQ unit 106 comprises HARQ entities, wherein each HARQ en- tity handles the HARQ functionality for one user.
  • One HARQ entity is capable of supporting multiple instances of stop and wait HARQ protocols. In particular, one HARQ process may be provided per TTI.
  • Transport Format Resource Combination (TFRC) selection unit 108 is provided for selecting an appropriate transport format and resource combination for the data to be transmitted on the HS-DSCH.
  • TFRC Transport Format Resource Combination
  • Fig. 2 shows a schematic functional block diagram of the proposed flow control functionality or mechanism implemented at an RNC 20.
  • the RNC 20 comprises a MAC-d unit 202 in which a priority class is set individually for each MAC-d flow which is a flow of MAC-d PDUs which belong to logical channels which are MAC-d multiplexed.
  • a priority class is set individually for each MAC-d flow which is a flow of MAC-d PDUs which belong to logical channels which are MAC-d multiplexed.
  • One HS-DSCH can transport several priority classes.
  • the priority class is modified to dynamically increase the allocated priority for handover calls, i.e. during a handover situation. This can be achieved by providing a timer unit 204 to which an information HO indicating a handover call is supplied, e.g. from respective determination functions (not shown) provided from the MAC-d 202 or another RNC function or external network function.
  • the timer unit 204 generates a temporary control signal during which a dynamical priority allocation function 206 increases the allocated priority class of the concerned MAC-d flow to a reserved higher priority class dedicated to handover calls.
  • a dynamical priority allocation function 206 can be implemented as discrete hardware units or as software routines based on a which a processing unit is controlled.
  • the timer unit 204 and the dynamical priority allocation function 206 may be implemented as integrated functions of the MAC-d unit 202.
  • the MAC-d flows with their allocated priority classes are forwarded over the lur/lub interface to the MAC-hs unit 100 of a Node B 10 of a handover target cell.
  • the data of handover users (users in a handover situation) are most likely to be passed from the RNC 20 to the target Node B 10.
  • a priority selection function at the target Node B 10 is arranged to select one of a plurality of priority buffers to which respective priority classes are allocated. Data packets supplied to the same priority buffer have the same allocated priority class. As long as a buffer with a higher priority class stores a data packet, data packets in priority buffers of lower priority classes are not forwarded towards the common HS-DSCH.
  • the highest or at least a high priority in the flow control mechanism of the MAC-d unit 202 is thus reserved for handover users, such that: in case of congestion, the data of these users is quickly passed from the RNC 20 to the Node-B 10. Also in case of non congestion this principle can be used, such that the data of the handover users is sent first or alt least at reduced delay to the Node-B 10.
  • the implementation can be done by using dynamic priorities changed is response to a con- trol signal supplied from the dynamic priority allocation function 206.
  • the highest or one but highest priority is reserved for handover calls.
  • this data is treated as high priority data, i.e. the data gets served before other lower piority data.
  • the reserved priority is set to the original lower priority.
  • the priority change operation can be based on RRC signalling and may thus be rather slow. This however does not affect the benefits of the dynamic priority.
  • the change of the priority can be slowly dynamic, as long as the change of the priority is done before the first data packet arrives at the new or target Node-B 10. This can be achieved, since the RNC 20 has knowledge about this situation.
  • the RNC 20 may define the activation time for the exact change from the source cell to the target cell. Before the activation time, the connection to the target cell is then setup already. So, the flow control in the target cell can start before the activation time. Then, some data can already exist in MAC-hs buffer of the Node B 10 of the target cell when the data transmission is started in the target cell (i.e. at the activation time).
  • This additional mechanism can be combined with other above dynamic priority mechanism.
  • the proposed flow control scheme provides a possibility to improve HSDPA performance. HSDPA UEs in handover state will have highest priority for flow control and packet scheduling operations over a certain time period. Thereby, flow control and packet scheduling delays during handovers can be prevented or at least reduced, which in turn improves QoS and system performance.
  • a flow control method and apparatus for scheduling data packets in a high-speed time-shared channel is suggested, wherein a scheduling priority is dy- namically increased for a predetermined time period for users in a handover state.
  • the present invention is not restricted to the above HSDPA-related flow control mechanism with dynamic priority setting for handover calls.
  • the present invention can be applied to any flow control or scheduling mechanism in order to improve data throughput for handover calls.
  • the present invention can be applied to any DSCH or HSDPA scheduling algorithm or other scheduling algorithms in all kinds of data packet connections.
  • the timer unit 204 and the dynamical priority allocation function 206 may be implemented within the Node B 10 or any other base station device, so that at least the throughput at the target cell can be increased in response to a determined handover situation. The preferred embodiments may thus vary within the scope of the attached claims.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

Cette invention concerne un procédé et un appareil de régulation des flux servant à ordonnancer les paquets de données dans un canal haute vitesse à temps partagé, dans lequel la priorité d'ordonnancement est accrue dynamiquement pour une période prédéterminée pour les utilisateurs se trouvant en état de transfert intercellulaire. Ainsi, les vides de transmission causés par des tampons vides dans le dispositif cible de transfert intercellulaire peuvent être évités. En outre, la capacité des cellules peut être augmentée en raison d'une meilleure diversité multi-utilisateur.
PCT/IB2006/000451 2005-03-15 2006-03-02 Regulation des flux avec attribution de priorite dynamique pour appels de transferts intercellulaires WO2006097805A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP05005650 2005-03-15
EP05005650.6 2005-03-15
US11/134,378 2005-05-23
US11/134,378 US20060209686A1 (en) 2005-03-15 2005-05-23 Flow control with dynamic priority allocation for handover calls

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WO2006097805A1 true WO2006097805A1 (fr) 2006-09-21

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008066429A1 (fr) * 2006-11-28 2008-06-05 Telefonaktiebolaget Lm Ericsson (Publ) Procédé permettant un meilleur traitement d'une congestion de trafic dans un système de télécommunication sans fil
CN102273255A (zh) * 2009-01-08 2011-12-07 株式会社Ntt都科摩 通信装置以及通信方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1432262A1 (fr) * 2002-12-20 2004-06-23 Matsushita Electric Industrial Co., Ltd. Conservation de contexte de protocole dans des systèmes de communication mobiles

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1432262A1 (fr) * 2002-12-20 2004-06-23 Matsushita Electric Industrial Co., Ltd. Conservation de contexte de protocole dans des systèmes de communication mobiles

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Universal Mobile Telecommunications System (UMTS); UTRA High Speed Downlink Packet Access (HSDPA); Overall description; Stage 2 (3GPP TS 25.308 version 6.3.0 Release 6); ETSI TS 125 308", ETSI STANDARDS, EUROPEAN TELECOMMUNICATIONS STANDARDS INSTITUTE, SOPHIA-ANTIPO, FR, vol. 3-R2, no. V630, December 2004 (2004-12-01), XP014027651, ISSN: 0000-0001 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008066429A1 (fr) * 2006-11-28 2008-06-05 Telefonaktiebolaget Lm Ericsson (Publ) Procédé permettant un meilleur traitement d'une congestion de trafic dans un système de télécommunication sans fil
CN102273255A (zh) * 2009-01-08 2011-12-07 株式会社Ntt都科摩 通信装置以及通信方法

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