WO2005034382A1 - Method for power ramping in a telecommunication system - Google Patents

Method for power ramping in a telecommunication system Download PDF

Info

Publication number
WO2005034382A1
WO2005034382A1 PCT/SE2004/001394 SE2004001394W WO2005034382A1 WO 2005034382 A1 WO2005034382 A1 WO 2005034382A1 SE 2004001394 W SE2004001394 W SE 2004001394W WO 2005034382 A1 WO2005034382 A1 WO 2005034382A1
Authority
WO
WIPO (PCT)
Prior art keywords
rach
power
preamble
initial
transmission
Prior art date
Application number
PCT/SE2004/001394
Other languages
French (fr)
Inventor
Johan Torsner
Stefan Parkvall
Original Assignee
Telefonaktiebolaget Lm Ericsson (Publ)
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
Application filed by Telefonaktiebolaget Lm Ericsson (Publ) filed Critical Telefonaktiebolaget Lm Ericsson (Publ)
Publication of WO2005034382A1 publication Critical patent/WO2005034382A1/en

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/38—TPC being performed in particular situations
    • H04W52/50—TPC being performed in particular situations at the moment of starting communication in a multiple access environment

Definitions

  • the present invention relates to a method for power ramping on the random access channel (RACH) in a mobile 3 rd generation telecommunication system.
  • RACH random access channel
  • Figure 1 shows the power ramping procedure on the random access channel (RACH) as disclosed in current 3GPP- specifications .
  • the initial power value P ⁇ rut is calculated from information that is broadcasted by the UMTS Radio Access Network (UTRAN) in its system information and calculated from the measured received power.
  • UTRAN UMTS Radio Access Network
  • UTRAN UMTS Radio Access Network
  • the information that is broadcasted in the system information and used to calculate the initial preamble power can only be broadcasted rather infrequently due to the limited resources on the broadcast channel. Typically the needed information can be broadcasted every 160-320ms. However, this also means that the received information may be quite old when the preamble ramping process actually starts.
  • the specified procedure in 3GPP also includes a back-off mechanism if a maximum number of preambles have been reached without having received any acknowledgement from the Node-B. Also other parameters than mentioned above can be configured by UTRAN, namely the step size Pstep, and been reached without having received any acknowledgement from the Node-B.
  • UTRAN namely the step size Pstep, and the time interval between preambles .
  • the power ramping procedure and the calculated preamble initial power is specified in technical specification documents 3GPP TS25.214: "Physical layer procedures (FDD)", 3GPP TS25.321: “Medium Access Control (MAC) protocol specification”, and 3GPP TS25.331: “Radio Resource Control (RRC) protocol specification” all issued by the 3 rd Generation Partnership Project.
  • FDD Physical layer procedures
  • MAC Medium Access Control
  • RRC Radio Resource Control
  • FIG 1 shows an overview of the current RACH-preamble structure according to the state of the art.
  • WCDMA Wideband Code Division Multiple Access
  • a large amount of data is transmitted on dedicated channels whereas small amounts of data are transmitted on common/shared transport channels.
  • resources must first be negotiated between a user equipment (UE) and the UTRAN. Also this negotiation is performed on common channels.
  • UE user equipment
  • an initial signalling must first be performed on common channels before a dedicated channel can be used.
  • Uplink transmissions on the random access channel do not use closed loop power control. Instead, a probing process is used where the user equipment transmits preambles with gradually increasing power values until the Node-B can detect the preamble and will send an acknowledgement on the AICH. This procedure is known as power ramping. When the user equipment receives the acknowledgement from the Node-B the power ramping procedure is aborted and the actual message is transmitted with the same power as the last transmitted preamble. Thus, a suitable transmission power for the RACH message can be found without closed loop power control .
  • the method according to the present invention aims to solve the problem that the preamble ramping process on the random access channel can take a considerable time and, as a consequence, cause significant delays in RRC signalling and user data transmission on RACH.
  • the problem is particularly evident when the transmitted data does not fit into one TTI . In this case, the data need to be segmented into several TTI : s and the preamble ramping process need to be applied for each TTI.
  • the solution according to the present invention suggests to base the calculation of the initial preamble power value on the last performed RACH transmission instead of calculating the initial preamble power from the information that is broadcasted in the system information.
  • the transmission power of the latest RACH transmission is a better estimate of the needed power than provided by the current calculations according to the state of the art and, consequently, a smaller margin can be used when calculating the initial preamble power.
  • This results in fewer preamble rampings until the pre.amble is detected in the Node-B, i.e. a lower delay is required for the ramping process.
  • the back-off from the latest performed RACH transmission is increased over time in order to consider that the radio conditions may have changed since the latest RACH transmission occurred. This can be achieved, e.g., with a simple linear filter.
  • the example below illustrates one conceivable approach to calculate the preamble power P ⁇ n ⁇ t (1) that is used at a frame i:
  • P( ⁇ ) denotes the transmission power of the latest RACH transmission
  • P ( i) is the calculated preamble power if a RACH transmission takes places in frame i
  • Pini ( Re i 5 ) is the preamble power that is calculated according to the current specifications.
  • (O ⁇ l) denotes a filter coefficient.
  • This method will lead to a back-off that is increasing over time until the calculated preamble power equals the power according to the one defined in the current specifications.
  • the UTRAN can control how aggressive this back-off shall be.
  • a simpler alternative of the method described above would be to apply a fixed back-off from the power that was used for the latest RACH transmission if the subsequent RACH transmission takes place within a given time.
  • the back-off and the time during which the aggressive setting is allowed to be used is configured by the UTRAN. If no transmission is done within said configured time the current method according to the state of the art as defined in Release 5 of the 3GPP-specifications is used.
  • a more aggressive RACH setting could be achieved by changing the power step size Pstep in the ramping process, either alone or in conjunction with adjusting the initial power value. If a larger power step size is used, the ramping procedure will be faster; however, this is possibly at the cost of increased interference in the system. A larger power step size could be used during the aggressive period, and the user equipment returns to the normal setting once the backoff time has expired.
  • Another embodiment of the present invention takes the traffic priorities into account for the process.
  • High priority traffic for instance, could employ a more aggressive ramping scheme as outlined above, while low priority traffic always uses the "normal" set of ramping parameters .
  • Still another embodiment of the present invention is to use a similar approach also for the first RACH transmission.
  • the current solution would be extended with a time varying back-off, e.g. with a linear filter as described above.
  • the result would be that the back-off is small when the information in the calculation is recent and gradually increasing when the information gets older.
  • the method allows a more aggressive power ramping scheme where the initial preamble power can be set higher than with the current solution and still avoiding excessive interference. This results in a faster power ramping cycle which can significantly reduce the delay for RACH transmissions.
  • a reduced delay on RACH improves the performance both for control signaling and user data.

Landscapes

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

Abstract

The present invention aims to solve the problem that the preamble ramping process on a random access channel (RACH) of a 3rd generation telecommunication network can take a considerable time and, as a consequence, cause significant delays in RRC signalling and user data transmission on RACH. The present invention suggests to base the calculation of the initial preamble power value on the last performed RACH transmission instead of calculating the initial preamble power from the information that is broadcasted in the system information. This results in fewer preamble rampings until the preamble is detected in the Node-B.

Description

METHOD FOR POWER RAMPING IN A TELECOMMUNICATION SYSTEM
FIELD OF THE INVENTION
The present invention relates to a method for power ramping on the random access channel (RACH) in a mobile 3rd generation telecommunication system.
BACKGROUND OF THE INVENTION
Figure 1 shows the power ramping procedure on the random access channel (RACH) as disclosed in current 3GPP- specifications . The initial power value Pιrut is calculated from information that is broadcasted by the UMTS Radio Access Network (UTRAN) in its system information and calculated from the measured received power. At each transmission on the RACH a new preamble ramping procedure is started, where the value of Pιnιt is recalculated. This implies that, if all parameters in the system information as well as the measured received power remain constant, the value of Pιnιt will be the same for each RACH access.
The information that is broadcasted in the system information and used to calculate the initial preamble power can only be broadcasted rather infrequently due to the limited resources on the broadcast channel. Typically the needed information can be broadcasted every 160-320ms. However, this also means that the received information may be quite old when the preamble ramping process actually starts. The specified procedure in 3GPP also includes a back-off mechanism if a maximum number of preambles have been reached without having received any acknowledgement from the Node-B. Also other parameters than mentioned above can be configured by UTRAN, namely the step size Pstep, and been reached without having received any acknowledgement from the Node-B. Also other parameters than mentioned above can be configured by UTRAN, namely the step size Pstep, and the time interval between preambles . The power ramping procedure and the calculated preamble initial power is specified in technical specification documents 3GPP TS25.214: "Physical layer procedures (FDD)", 3GPP TS25.321: "Medium Access Control (MAC) protocol specification", and 3GPP TS25.331: "Radio Resource Control (RRC) protocol specification" all issued by the 3rd Generation Partnership Project.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows an overview of the current RACH-preamble structure according to the state of the art.
DETAILED DESCRIPTION OF THE INVENTION
In a Wideband Code Division Multiple Access (WCDMA) communication system different types of transport channels are specified for various purposes. Typically a large amount of data is transmitted on dedicated channels whereas small amounts of data are transmitted on common/shared transport channels. In order to be able to communicate on dedicated channels, resources must first be negotiated between a user equipment (UE) and the UTRAN. Also this negotiation is performed on common channels. Thus, even if the user data is transmitted mainly on dedicated channels, an initial signalling must first be performed on common channels before a dedicated channel can be used.
Uplink transmissions on the random access channel do not use closed loop power control. Instead, a probing process is used where the user equipment transmits preambles with gradually increasing power values until the Node-B can detect the preamble and will send an acknowledgement on the AICH. This procedure is known as power ramping. When the user equipment receives the acknowledgement from the Node-B the power ramping procedure is aborted and the actual message is transmitted with the same power as the last transmitted preamble. Thus, a suitable transmission power for the RACH message can be found without closed loop power control .
In order not to cause too high interference the initial preamble power cannot be too high. In addition, due to inaccuracies of measurements in the user equipment and the fact that the latest received system information can be several hundred milliseconds old, the parameters in the calculation must be set to achieve a rather conservative, i.e. sufficiently low, initial power. Therefore, the method according to the present invention aims to solve the problem that the preamble ramping process on the random access channel can take a considerable time and, as a consequence, cause significant delays in RRC signalling and user data transmission on RACH. The problem is particularly evident when the transmitted data does not fit into one TTI . In this case, the data need to be segmented into several TTI : s and the preamble ramping process need to be applied for each TTI.
The solution according to the present invention suggests to base the calculation of the initial preamble power value on the last performed RACH transmission instead of calculating the initial preamble power from the information that is broadcasted in the system information. The transmission power of the latest RACH transmission is a better estimate of the needed power than provided by the current calculations according to the state of the art and, consequently, a smaller margin can be used when calculating the initial preamble power. This in turn results in fewer preamble rampings until the pre.amble is detected in the Node-B, i.e. a lower delay is required for the ramping process. Hence, it is beneficial to set the power for an attempt to access the random access channel as a function of the latest, i.e. the previous, RACH transmission. In a preferred embodiment of the present invention the back-off from the latest performed RACH transmission is increased over time in order to consider that the radio conditions may have changed since the latest RACH transmission occurred. This can be achieved, e.g., with a simple linear filter. The example below illustrates one conceivable approach to calculate the preamble power Pιnιt(1) that is used at a frame i:
Pimt( = τaax(Pw ,Pinit(fΛIS) )
Figure imgf000006_0001
P(θ) denotes the transmission power of the latest RACH transmission, P(i) is the calculated preamble power if a RACH transmission takes places in frame i, and Pini (Rei5) is the preamble power that is calculated according to the current specifications. Finally, (O≤α≤l) denotes a filter coefficient.
This method will lead to a back-off that is increasing over time until the calculated preamble power equals the power according to the one defined in the current specifications. By configuring different values of the filter coefficient α, the UTRAN can control how aggressive this back-off shall be.
A simpler alternative of the method described above would be to apply a fixed back-off from the power that was used for the latest RACH transmission if the subsequent RACH transmission takes place within a given time. The back-off and the time during which the aggressive setting is allowed to be used is configured by the UTRAN. If no transmission is done within said configured time the current method according to the state of the art as defined in Release 5 of the 3GPP-specifications is used.
As an additional embodiment of the present invention, a more aggressive RACH setting could be achieved by changing the power step size Pstep in the ramping process, either alone or in conjunction with adjusting the initial power value. If a larger power step size is used, the ramping procedure will be faster; however, this is possibly at the cost of increased interference in the system. A larger power step size could be used during the aggressive period, and the user equipment returns to the normal setting once the backoff time has expired.
Another embodiment of the present invention takes the traffic priorities into account for the process. High priority traffic, for instance, could employ a more aggressive ramping scheme as outlined above, while low priority traffic always uses the "normal" set of ramping parameters .
Still another embodiment of the present invention is to use a similar approach also for the first RACH transmission. In this case the current solution would be extended with a time varying back-off, e.g. with a linear filter as described above. The result would be that the back-off is small when the information in the calculation is recent and gradually increasing when the information gets older. This would mean that UTRAN could apply a more aggressive setting of the initial power also for the first RACH transmission. The method allows a more aggressive power ramping scheme where the initial preamble power can be set higher than with the current solution and still avoiding excessive interference. This results in a faster power ramping cycle which can significantly reduce the delay for RACH transmissions. A reduced delay on RACH improves the performance both for control signaling and user data.

Claims

1. A method in a telecommunication system comprising a random access channel (RACH) , c h a r a c t e r i s e d b y determining the RACH initial preamble power of a subsequent RACH transmission based on the power value of the latest RACH transmission.
2. The method according to claim 1, whereby the RACH initial preamble power is based on a priority value for the message to be transmitted.
3. The method according to claim 1 or 2 , whereby the power step size of the initial preamble procedure is variable.
4. The method according to claim 1 or 2 , whereby a fixed back-off value compared to the one of the latest RACH transmission is used during a given time.
5. The method according to claim 1 or 2 , whereby the backoff value is increased over time.
6. The method according to claim 5, whereby the back-off is increased by using a linear filter.
7. The method according to one of the preceding claims, whereby the initial preamble power for the first RACH transmission uses an offset that increases over time.
PCT/SE2004/001394 2003-10-06 2004-09-28 Method for power ramping in a telecommunication system WO2005034382A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0302655-6 2003-10-06
SE0302655A SE0302655D0 (en) 2003-10-06 2003-10-06 Method and arrangement in a telecommunication system

Publications (1)

Publication Number Publication Date
WO2005034382A1 true WO2005034382A1 (en) 2005-04-14

Family

ID=29398678

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2004/001394 WO2005034382A1 (en) 2003-10-06 2004-09-28 Method for power ramping in a telecommunication system

Country Status (2)

Country Link
SE (1) SE0302655D0 (en)
WO (1) WO2005034382A1 (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1742379A1 (en) * 2005-07-07 2007-01-10 Telefonaktiebolaget LM Ericsson (publ) Transmit power control in a random access scheme
EP1892845A1 (en) * 2006-08-21 2008-02-27 Nokia Siemens Networks Gmbh & Co. Kg Method and system for an efficient random access procedure in a mobile communications system
WO2010107354A1 (en) * 2009-03-17 2010-09-23 Telefonaktiebolaget L M Ericsson (Publ) High priority random access
EP1986343A3 (en) * 2007-04-27 2011-05-04 NEC Corporation Control method and device of uplink access transmission power in radio communications system
CN102986281A (en) * 2010-05-28 2013-03-20 高通股份有限公司 Apparatus and method for random access channel power prioritization
EP2086277A3 (en) * 2008-02-04 2017-06-21 LG Electronics Inc. Method of performing random access after applying back-off

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000021320A1 (en) * 1998-10-05 2000-04-13 Telefonaktiebolaget Lm Ericsson (Publ) Random access in a mobile telecommunications system
WO2000025443A1 (en) * 1998-10-28 2000-05-04 Koninklijke Philips Electronics N.V. Radio communication system
US6487420B1 (en) * 1999-10-15 2002-11-26 Telefonaktiebolaget Lm Ericsson (Publ) Adaptive rach power determination for mobile telecommunications user equipment unit
US20020183086A1 (en) * 2001-06-04 2002-12-05 Martin Hellmark Technique for improving open loop power control in spread spectrum telecommunications systems
GB2382746A (en) * 2001-11-20 2003-06-04 Ericsson Telefon Ab L M Establishing radio communication channels

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000021320A1 (en) * 1998-10-05 2000-04-13 Telefonaktiebolaget Lm Ericsson (Publ) Random access in a mobile telecommunications system
WO2000025443A1 (en) * 1998-10-28 2000-05-04 Koninklijke Philips Electronics N.V. Radio communication system
US6487420B1 (en) * 1999-10-15 2002-11-26 Telefonaktiebolaget Lm Ericsson (Publ) Adaptive rach power determination for mobile telecommunications user equipment unit
US20020183086A1 (en) * 2001-06-04 2002-12-05 Martin Hellmark Technique for improving open loop power control in spread spectrum telecommunications systems
GB2382746A (en) * 2001-11-20 2003-06-04 Ericsson Telefon Ab L M Establishing radio communication channels

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1742379A1 (en) * 2005-07-07 2007-01-10 Telefonaktiebolaget LM Ericsson (publ) Transmit power control in a random access scheme
WO2007006701A1 (en) * 2005-07-07 2007-01-18 Telefonaktiebolaget L M Ericsson (Publ) Transmit power control in a random access scheme
US8554153B2 (en) 2005-07-07 2013-10-08 Telefonaktiebolaget L M Ericsson (Publ) Transmit power control in a random access scheme
EP1892845A1 (en) * 2006-08-21 2008-02-27 Nokia Siemens Networks Gmbh & Co. Kg Method and system for an efficient random access procedure in a mobile communications system
EP1986343A3 (en) * 2007-04-27 2011-05-04 NEC Corporation Control method and device of uplink access transmission power in radio communications system
US8046020B2 (en) 2007-04-27 2011-10-25 Nec Corporation Control method and device of uplink access transmission power in radio communications system
EP2086277A3 (en) * 2008-02-04 2017-06-21 LG Electronics Inc. Method of performing random access after applying back-off
WO2010107354A1 (en) * 2009-03-17 2010-09-23 Telefonaktiebolaget L M Ericsson (Publ) High priority random access
CN102986281A (en) * 2010-05-28 2013-03-20 高通股份有限公司 Apparatus and method for random access channel power prioritization
US10536910B2 (en) 2010-05-28 2020-01-14 Qualcomm Incorporated Apparatus and method for random access channel power prioritization
US11212757B2 (en) 2010-05-28 2021-12-28 Qualcomm Incorporated Apparatus and method for random access channel power prioritization

Also Published As

Publication number Publication date
SE0302655D0 (en) 2003-10-06

Similar Documents

Publication Publication Date Title
US7197314B2 (en) Communication system
EP1916863B1 (en) Efficient and reliable random access procedure in a mobile communication system
EP2263341B1 (en) Method and apparatus for performing random access procedures
EP3709543B1 (en) Radio communication system, communication device, radio communicaton network system and method therefor
KR101496397B1 (en) Method and apparatus for radio link synchronization and power control in cell_fach and idle mode
EP2802184B1 (en) Physical random access channel access method, base station and user equipment
JP7071781B2 (en) Methods and equipment in cellular communication systems
EP3879886B1 (en) Communication method and communication apparatus
EP1564905A2 (en) An apparatus and a method for distributing a transmission power in a cellular communications network
US20220078786A1 (en) Methods and arrangements in a wireless communications system
US20110310857A1 (en) Random access procedure
WO2008090528A1 (en) Collision detection for random access procedure
EP2243328A2 (en) Random access channel frequency allocation
EP1860797A1 (en) Transmission power control method, mobile station, fixed station, and communication system
WO2005034382A1 (en) Method for power ramping in a telecommunication system
KR20010050524A (en) Wireless network with a plurality of persistency probabilities for accessing a rach channel
CN103687009A (en) Resource selection method for random access and terminal device
KR101417058B1 (en) Method and apparatus for the configuration of reception/transmission timing for enhanced uplink service in cell_fach state in mobile communication system

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): BW GH GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase