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WO2002032006A2 - Regulation de la puissance d'un canal rf - Google Patents

Regulation de la puissance d'un canal rf Download PDF

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Publication number
WO2002032006A2
WO2002032006A2 PCT/EP2001/011473 EP0111473W WO0232006A2 WO 2002032006 A2 WO2002032006 A2 WO 2002032006A2 EP 0111473 W EP0111473 W EP 0111473W WO 0232006 A2 WO0232006 A2 WO 0232006A2
Authority
WO
WIPO (PCT)
Prior art keywords
channel
signal levels
operable
measured
pattern
Prior art date
Application number
PCT/EP2001/011473
Other languages
English (en)
Other versions
WO2002032006A3 (fr
Inventor
David Smith
Original Assignee
Telefonaktiebolaget L M 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 L M Ericsson (Publ) filed Critical Telefonaktiebolaget L M Ericsson (Publ)
Priority to AU2002223587A priority Critical patent/AU2002223587A1/en
Publication of WO2002032006A2 publication Critical patent/WO2002032006A2/fr
Publication of WO2002032006A3 publication Critical patent/WO2002032006A3/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. Transmission Power Control [TPC] or power classes
    • H04W52/04—Transmission power control [TPC]
    • H04W52/18—TPC being performed according to specific parameters
    • H04W52/24—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/713—Spread spectrum techniques using frequency hopping
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. Transmission Power Control [TPC] or power classes
    • H04W52/04—Transmission power control [TPC]
    • H04W52/18—TPC being performed according to specific parameters
    • H04W52/22—TPC being performed according to specific parameters taking into account previous information or commands
    • H04W52/223—TPC being performed according to specific parameters taking into account previous information or commands predicting future states of the transmission

Definitions

  • the present invention relates to RF channel power control in communications systems.
  • the required power value is applied for a period of time which is many times the length of the frame, and indeed the hopping sequence.
  • the Hopping sequence is a cyclic pattern comprising 4 carrier frequencies, each frequency will be used 26 times per SACCH period.
  • a transmit power level set to give the required nominal carrier/interference ratio C/l on the most disturbed burst (s) on the channels results in unnecessary high C for all other bursts on the chanel .
  • C nominal carrier/interference ratio
  • a higher value of C represents a higher value of I presented to other channels. If the carrier C value is unnecessarily high, the interference I it presents to other channels is correspondingly unnecessarily high.
  • a principle feature of hopping is to decorrelate interference . This means that the interference level found on the channel varies burst by burst .
  • a method of controlling output power of an RF channel in a frequency hopping RF system having plurality of carriers comprising: measuring signal levels in the channel over a predetermined time period; identifying a pattern in the measured signal level; predicting future signal levels on the basis of the identified pattern; and controlling the RF output power level on the basis of the predicted signal levels.
  • the preferred embodiment of the invention can be described in the context of a cyclic hopping channel of a cellular radio system constructed according to the GSM standard. It will be readily apparent, however, that the techniques described are also applicable to other systems.
  • the channel is analysed in order to identify a pattern in burst by burst received signal . This pattern can then be extrapolated to predict the approximate transmit power for future bursts to come, per hopping channel.
  • the preferred embodiment of the present invention analyses the characteristics of the channel burst by burst, rather than looking at some aggregate characteristics reported per SACCH period or similar cycle that is substantially slower than the hopping mechanism, said analysis identifying any recurring pattern in the signal characteristics that is due to the effect of the hopping sequence of the channel on the channel's C, arid the interaction between the hopping channel and (independently) hopping interference sources. Further, the embodiment then extrapolates this pattern to predict the likely characteristics of subsequent bursts, and derives from this power control values than can be optimised to the propagation characteristics of each frequency in the hopping sequence individually, rather than having to respond simply to a mean or worst case value.
  • burst by burst signal level on a channel is monitored for long enough to identify a recurring pattern using, for example, a "bounded comb" or Kalman filter.
  • a simple comb implementation that can be described in a straightforward manner is to look at the signal strength on each n't burst, where n is the number of carriers in the hopping sequence, and separately look at the strength of each (n+l)'th etc i.e. if the hopping sequence is AB C DA B C D A B C D A B....
  • a simple implementation might assume that the next burst to use A will have very similar signal strength to the last burst on A, and this will be found to be true within a reasonable confidence and accuracy tolerance.
  • An enhanced embodiment might filter a rolling set of the last j bursts per frequency, improving confidence, however j should not be too large otherwise transient response to fading dips will be compromised.
  • Another enhanced implementation might predict that A (next) will be of signal strength A (current) -A(last) ) , that is to say assuming that any recent trend in the rate of change in the signal strength will continue, and again such a strategy will (statistically) be correct more often that it is wrong, and will be a quantitatively "less wrong" more often than "more wrong", i.e. represents a net improvement.
  • such a comb filter can be "seeded" since the length of the hopping sequence is known.
  • the modulo of the signal pattern may not be known (since interference often comes from several surrounding cells, which may have different hopping sequences) . Nevertheless, the pattern can be found by (as one simple implementation) an "exhaustive search" , i.e. trial and error use of combs of all lengths from 2 to x, with some metric assigned to evaluate the correlation of the bursts dropping through the comb. The comb length that gives the best correlation is then used, and the others abandoned. More algorithmic solutions include the use of hashing algorithms and variations of the SW implementations of Viterbi and Fast Fourier Transform algorithms etc (
  • a preferred embodiment is to monitor the channel continuously, a repeating pattern being identified, thereafter this pattern is tracked.
  • the GSM air interface is synchronised to a very stable clock, the pattern of the interplay between interfering hopping sequences is extremely stable, even though the signal levels vary over time due to fading etc ..
  • the level of signal on a given frequency will vary due to fading, but typically this will occur at a rate orders of magnitude slower than the hopping sequence repetition rate, and is thus easy to track.
  • interfering cells have equal length (equal number of ARFCN in the HFS) , such that the pattern will be the same length in frames. Note that the interfering cells do not have to be synchronised - the alignment does not matter, as it will be stable.
  • the interfering cycles will "walk" across each other and are only guaranteed to recur every x frames, where x is the lowest common multiple of the respective lengths of the HFS's concerned.
  • x is the lowest common multiple of the respective lengths of the HFS's concerned.
  • a cyclic hopping sequence of 3 ARFCN' s walking across a sequence with 4 ARFCN' s will repeat regularly an interference pattern which is 12 frames long. It might be reasonably expected that even a simple and na ⁇ ve algorithm to lock to this in ⁇ 200mS. (a "naive" algorithm being an algorithm that does not have any hints to guide it) .
  • a seeded algorithm (given a priori knowledge, for example the length of the sequences, "x" which is known in the BSC) might typically lock in ⁇ . ⁇ 100mS, in theory after just "x" frames .
  • the sequence is tracked and held, adapting dynamically to changes due to, for example, fading variations in the interfering propagation multipath and DTX (discontinuous transmission) on interfering channels.
  • a frame can be destroyed if more than a few bits are lost.
  • FER frame error rate
  • the interference level is not necessarily constant throughout a burst.
  • the system can lock to and intelligently power control against decorrelated channels eg HR sharing the same hopping sequences. For example. If the algorithm can predict when bursts on the two orthogonal hopping sequences will not collide, interference can be predicted to be low and low power can be used, whereas high power can be used when they will collide.

Landscapes

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

Abstract

L'invention concerne un procédé permettant de réguler la puissance de sortie d'un canal RF dans un système de saut de fréquence (SF) ayant plusieurs porteurs. Le procédé consiste à mesurer les niveaux de signaux dans les canaux pendant une durée prédéterminée, à identifier un motif dans le niveau du signal mesuré, à prédire des niveaux de signaux futurs, et à commander la puissance de sortie RF en fonction des niveaux de signaux prédits.
PCT/EP2001/011473 2000-10-09 2001-10-04 Regulation de la puissance d'un canal rf WO2002032006A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2002223587A AU2002223587A1 (en) 2000-10-09 2001-10-04 Rf channel power control

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0024680A GB2367981A (en) 2000-10-09 2000-10-09 Transmission power control in a frequency hopping RF system
GB0024680.1 2000-10-09

Publications (2)

Publication Number Publication Date
WO2002032006A2 true WO2002032006A2 (fr) 2002-04-18
WO2002032006A3 WO2002032006A3 (fr) 2002-07-18

Family

ID=9900918

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2001/011473 WO2002032006A2 (fr) 2000-10-09 2001-10-04 Regulation de la puissance d'un canal rf

Country Status (3)

Country Link
AU (1) AU2002223587A1 (fr)
GB (1) GB2367981A (fr)
WO (1) WO2002032006A2 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1734660A1 (fr) * 2005-06-15 2006-12-20 Matsushita Electric Industrial Co., Ltd. Commande de puissance de transmission dans un système utilisant des sauts de fréquence
WO2011054229A1 (fr) * 2009-11-03 2011-05-12 中兴通讯股份有限公司 Procédé et station de base de commande de puissance à boucle fermée dans un système à sauts de fréquence

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5459760A (en) * 1993-11-05 1995-10-17 Matsushita Electric Industrial Co., Ltd. Transmitting and receiving apparatus
FI105368B (fi) * 1997-05-16 2000-07-31 Nokia Networks Oy Tehonsäätö matkaviestinjärjestelmässä
US6115408A (en) * 1998-04-03 2000-09-05 Butterfly Vsli Ltd. Automatic transmission power level control method in a frequency hopping communication system
FR2784824B1 (fr) * 1998-10-16 2000-11-24 Mitsubishi Electric Inf Tech Procede de controle en boucle fermee de la puissance recue par un recepteur et transmise d'un emetteur d'un systeme de telecommunications

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1734660A1 (fr) * 2005-06-15 2006-12-20 Matsushita Electric Industrial Co., Ltd. Commande de puissance de transmission dans un système utilisant des sauts de fréquence
WO2011054229A1 (fr) * 2009-11-03 2011-05-12 中兴通讯股份有限公司 Procédé et station de base de commande de puissance à boucle fermée dans un système à sauts de fréquence

Also Published As

Publication number Publication date
AU2002223587A1 (en) 2002-04-22
GB0024680D0 (en) 2000-11-22
WO2002032006A3 (fr) 2002-07-18
GB2367981A (en) 2002-04-17

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