WO2008032032A1 - Appareil et procédé de communication - Google Patents

Appareil et procédé de communication Download PDF

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Publication number
WO2008032032A1
WO2008032032A1 PCT/GB2007/003410 GB2007003410W WO2008032032A1 WO 2008032032 A1 WO2008032032 A1 WO 2008032032A1 GB 2007003410 W GB2007003410 W GB 2007003410W WO 2008032032 A1 WO2008032032 A1 WO 2008032032A1
Authority
WO
WIPO (PCT)
Prior art keywords
communication link
measurements
data rate
link
quality
Prior art date
Application number
PCT/GB2007/003410
Other languages
English (en)
Inventor
Alexander Weir
Original Assignee
Iti Scotland Limited
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 Iti Scotland Limited filed Critical Iti Scotland Limited
Publication of WO2008032032A1 publication Critical patent/WO2008032032A1/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
    • H04L47/10—Flow control; Congestion control
    • H04L47/24—Traffic characterised by specific attributes, e.g. priority or QoS
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
    • 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
    • H04L47/25—Flow control; Congestion control with rate being modified by the source upon detecting a change of network conditions
    • 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
    • H04W28/0231—Traffic management, e.g. flow control or congestion control based on communication conditions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/16—Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
    • H04W28/18—Negotiating wireless communication parameters
    • H04W28/22—Negotiating communication rate

Definitions

  • This invention relates to a communication apparatus and method, and in particular to an apparatus and method in an ultra-wideband communication system, which allows an optimal data rate for a link between devices to be efficiently selected.
  • Ultra-wideband is a radio technology that transmits digital data across a very wide frequency range, 3.1 to 10.6 GHz. By spreading the RF energy across a large bandwidth the transmitted signal is virtually undetectable by traditional frequency selective RF technologies. However, the low transmission power limits the communication distances to typically less than 10 to 15 meters.
  • UWB Ultra-wideband
  • Figure 1 shows the arrangement of frequency bands in a Multi Band Orthogonal Frequency Division Multiplexing (MB-OFDM) system for ultra-wideband communication.
  • the MB-OFDM system comprises fourteen sub-bands of 528 MHz each, and uses frequency hopping every 312 ns between sub-bands as an access method.
  • Within each sub-band OFDM and QPSK or DCM coding is employed to
  • UWB0007 transmit data. It is noted that the sub-band around 5GHz, currently 5.1-5.8 GHz, is left blank to avoid interference with existing narrowband systems, for example 802.11a WLAN systems, security agency communication systems, or the aviation industry.
  • the fourteen sub-bands are organised into five band groups, four band groups having three 528MHz sub-bands, and one band group having two 528MHz sub-bands.
  • the first band group comprises sub-band 1 , sub-band 2 and sub- band 3.
  • An example UWB system will employ frequency hopping between sub-bands of a band group, such that a first data symbol is transmitted in a first 312.5 ns duration time interval in a first frequency sub-band of a band group, a second data symbol is transmitted in a second 312.5 ns duration time interval in a second frequency sub-band of a band group, and a third data symbol is transmitted in a third 312.5 ns duration time interval in a third frequency sub-band of the band group. Therefore, during each time interval a data symbol is transmitted in a respective sub-band having a bandwidth of 528 MHz, for example sub-band 2 having a 528 MHz baseband signal centred at 3960 MHz.
  • ultra-wideband mean that it is being deployed for applications in the field of data communications.
  • applications that focus on cable replacement in the following environments:
  • PCs and peripherals i.e. external devices such as hard disc drives, CD writers, printers, scanner, etc. home entertainment, such as televisions and devices that connect by wireless means, wireless speakers, etc. communication between handheld devices and PCs, for example mobile phones and PDAs, digital cameras and MP3 players, etc.
  • Communication signals are transmitted in an ultra-wideband communications system between transmitter and receiver stations in the form of data packets.
  • Each data packet includes a header portion, a data portion (or “payload"), and an error check portion, typically based on a cyclic redundancy check (CRC).
  • the payload relates to the data to be sent from a transmitter to a receiver.
  • one or more devices periodically transmit a beacon frame.
  • the main purpose of the beacon frame is to
  • UWB0007 provide for a timing structure on the medium, i.e. the division of time into so-called superframes, and to allow the devices of the network to synchronize with a beacon group.
  • QoS Quality of Service
  • the flow specification is applied to a reservation algorithm which will determine the optimal reservation scheme and data rate for the logical link, taking account of any existing reservations and any constraints they may exhibit. It is important to balance these requirements to satisfy the required quality of service.
  • a conventional method of obtaining an appropriate data rate is to check the channel quality through creation of an initial control channel.
  • the link quality of this control channel is monitored, and the determined link quality metrics are used to set the data rate of the logical channel.
  • this method has the disadvantage of requiring initial monitoring and maintenance of the link quality metric information.
  • a method of determining a data rate for a new communication link between a first device and a second device comprising the step of using measurements of a previous communication link between the first device and the second device to determine the data rate for the new communication link.
  • a method of determining a data rate for a communication link between a first device and a second device comprises the step of using measurements of a first communication link between the first device and the second device to determine the data rate for a second communication link between the first device and the second device.
  • the present invention uses link quality metrics gathered from previous links with a remote device to determine the current optimal data rate.
  • the historical metrics give the device a higher likelihood of selecting a data rate for the current link that is better matched to the capabilities of the remote device, and the link quality that is likely to be achieved.
  • Application of this technique will derive the optimal data rate more quickly and without prior signalling, providing efficiency improvements in comparison to traditional techniques.
  • a device for use in a communication network the device being adapted to establish a communication link with a second device, the device comprising means for determining a data rate at which to transmit data to the second device, the means being adapted to determine the data rate at which to transmit data using measurements of a previous communication link with said second device.
  • Figure 1 shows the multi-band OFDM alliance (MBOA) approved frequency spectrum of a MB-OFDM system
  • Figure 2 is a flow chart of a method according to the present invention.
  • Figure 2 is a flow chart illustrating the steps in a method according to the present invention.
  • the method takes place in a first device forming part of a wireless communication network, such as an ultra-wideband network.
  • the first device is establishing a communication link with a second device in the network.
  • One or more of the devices may be fixed nodes of the network or mobile devices.
  • a request to create a new asynchronous or isochronous wireless link is received by a first device from a second device.
  • This request may include quality of service (QoS) parameters or a quality of service threshold which set the quality of the wireless link that is required.
  • QoS quality of service
  • Steps 102-108 indicate the method used to determine a data rate for a new link in accordance with the invention.
  • the first device determines whether there are any historical link quality metrics from a previous wireless link with the second device. That is, the first device determines if there are any measurements of a first, earlier, link between the first device and the second device.
  • the historical link quality metrics can include data rate or rates used in the link, the bit error rate, signal-to-noise ratio, re-send rates, CRC errors, or any other well-known link quality metric.
  • step 103 If there are no historical link quality metrics from a previous link available, then the process moves to step 103, in which a conventional technique is used to determine the link quality metrics for the new or second wireless link. These conventionally determined link metrics are then applied later in steps 105 and 106 or 107 of the process to determine the appropriate data rate (frame coding) for the new link.
  • step 104 If there are historical link quality metrics available from a previous link, then the process moves to step 104, and these historical link metrics are retrieved from memory. These metrics are applied later in steps 105 and 106 or 107 of the process to determine the appropriate data rate for the new or second link.
  • step 103 or 104 the process moves to step 105, in which the channel access method is determined. If the channel access method is contention based, the process moves to step 106, where the appropriate access category and priority of the devices are applied. These, in combination with the link quality metrics determined or retrieved in steps 103 or 104 respectively, are then used to calculate the appropriate data rate for the new link.
  • step 107 the appropriate resource allocation and arbitration policy is determined. This, in combination with the link quality metrics determined or retrieved in steps 103 or 104 respectively, is then used to calculate the appropriate data rate of the new link.
  • step 105 can be omitted if the device or devices can only use one of a reservation or contention based access method. In this case, the method passes to the appropriate step 106 or 107 straight from step 103 or 104.
  • the data rate can be determined by one of selecting a minimum data rate, with the data rate being increased until the error rate becomes unacceptable; selecting a maximum data rate, with the data rate being decreased until an acceptable error rate is achieved; or selecting an intermediate data rate, with the data rate being adjusted up or down depending on the error rate.
  • selecting a minimum data rate with the data rate being increased until the error rate becomes unacceptable
  • selecting a maximum data rate with the data rate being decreased until an acceptable error rate is achieved
  • selecting an intermediate data rate with the data rate being adjusted up or down depending on the error rate.
  • Another approach may be to estimate link quality metrics based on logical channel QoS parameters or thresholds and the capabilities of the remote device.
  • the data rate can be determined by setting the data rate of the new link to match that of the previous link.
  • the historical link metrics also comprise measurements of the quality of the previous link or communication channel, a comparison can be performed between these measurements and current measurements of the channel, with the results of the comparison being used to adjust the previous data rate, if necessary. It will be appreciated that other methods of determining the data rate using the historical link metrics could be used in accordance with the invention.
  • step 108 the new link between the two devices is created based on the data rate and policies determined in either step 106 or 107.
  • the overall quality of the link is continuously or periodically monitored (step 109), for example on a frame by frame basis, after receipt of each superframe, or over a predetermined period of time.
  • This monitoring process involves determining the current link quality metrics, for example using one or more of the following: - the packet error rate (PER); the bit error rate and/or the rate at which packets need to be re-sent (i.e. monitoring re-sends); monitoring the signal-to-noise ratio SNR (using RSSI and LQI signals that are passed in each received frame).
  • PER packet error rate
  • SNR signal-to-noise ratio
  • link quality metrics could also be used, either alone or in combination. It is also noted that a frame must be received in full or in error before the link metrics can be updated.
  • link metrics are recorded and stored in a memory for use in determining an appropriate data rate for future links between the two devices, in accordance with the present invention.
  • the step of recording the metrics in step 109 allows step 102 for a subsequent wireless link (i.e. a third wireless link), to be answered positively.
  • the memory may comprise, for example, a non-volatile, flash or buffer memory.
  • the link metrics may be updated after the receipt of each frame, (i.e such that the link metrics from a previous frame become the historical link metrics). Alternatively, the link metrics can be updated after receipt of each superframe, or some other predetermined period.
  • an average data rate may be determined over a predetermined period of time, for example a communication session between the first and second devices, or part thereof.
  • the average data rate will be maintained during a communication session based on how the date rate is adjusted using the rate adaptation algorithm. The average data rate is then stored at the end of
  • step 110 After monitoring and recording the link quality in step 109, it is determined whether the link quality is acceptable to achieve the required QoS (step 110). The required QoS will have been included in the request to create a link, which was sent in step 101. If the link quality is acceptable, the process returns to step 109 and the link quality is monitored further.
  • step 111 it is determined whether it is possible for the data rate to be rolled back (i.e. it is determined whether the data rate is at its lowest possible value). If it is possible to roll the data rate back, the data rate is rolled back to the next lowest data rate in step 112, and monitoring of the link continues.
  • step 111 determines that the data rate cannot be rolled back further (i.e. it is at the lowest available data rate)
  • the quality of the channel is too poor to achieve the required QoS.
  • link quality metrics of the link indicate that the link does not achieve the required QoS, link failure is reported in step 113. At this point the decision to maintain or close the failing link should be taken by a higher protocol layer.
  • the present invention provides a method of allowing an optimal data rate between two devices to be determined quickly and efficiently.
  • the link metrics from the most recent links between the two devices are likely to provide an accurate estimate of the data rate the device can achieve in the given RF environment, in comparison to the published capabilities of the devices.
  • the historical data can be applied without the need to raise a test link to evaluate link quality.
  • the system may hunt backwards for even older historical data, or create a new test link to determine new link metrics.
  • the method is particularly suited in systems whereby the first and second devices are fixed, such that the physical link between the first and second devices is more likely to be the same as a previous physical link between the first and second devices.

Abstract

La présente invention concerne un dispositif conçu pour être utilisé dans un réseau de communication, par exemple un réseau de communication à bande ultralarge, et qui permet d'établir une liaison de communication avec un second dispositif. Ledit dispositif comprend des moyens conçus pour déterminer un débit de données auquel transmettre les données au second dispositif à l'aide de mesures d'une liaison de communication précédente avec le second dispositif.
PCT/GB2007/003410 2006-09-15 2007-09-10 Appareil et procédé de communication WO2008032032A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0618241.4 2006-09-15
GB0618241A GB2441809A (en) 2006-09-15 2006-09-15 Setting a data rate in a data transmission link

Publications (1)

Publication Number Publication Date
WO2008032032A1 true WO2008032032A1 (fr) 2008-03-20

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Application Number Title Priority Date Filing Date
PCT/GB2007/003410 WO2008032032A1 (fr) 2006-09-15 2007-09-10 Appareil et procédé de communication

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GB (1) GB2441809A (fr)
TW (1) TW200814694A (fr)
WO (1) WO2008032032A1 (fr)

Citations (5)

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WO2002039650A2 (fr) * 2000-11-09 2002-05-16 Telefonaktiebolaget Lm Ericsson Dispositif et procede de tranfert de paquets de donnees
EP1211838A1 (fr) * 2000-11-29 2002-06-05 Lucent Technologies Inc. Adaptation du débit binaire dans un système de communication sans fil
EP1233564A1 (fr) * 2001-02-09 2002-08-21 Lucent Technologies Inc. Adaptation de débit dans un système de telecommunication sans fil
EP1628446A1 (fr) * 2004-08-18 2006-02-22 Infineon Technologies AG Procédé pour la transmission d'informations sur une liaison de communication et dispositif respectif de transmission et système de communication
US7088701B1 (en) * 2000-04-14 2006-08-08 Qualcomm, Inc. Method and apparatus for adaptive transmission control in a high data rate communication system

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FR2755562B1 (fr) * 1996-11-06 1998-12-24 Sagem Telecopieur a adaptation automatique de parametres de transmission
US6556553B1 (en) * 1999-04-12 2003-04-29 Intermec Ip Corp. Method for determining when a communication device should rate shift or roam in a wireless environment
GB2382271B (en) * 2001-11-19 2005-06-29 Hutchison Whampoa Three G Ip Bit rate allocation in mobile communications networks
US7336634B2 (en) * 2002-07-25 2008-02-26 Koninklijke Philips Electronics N.V. Method and system for generating and updating transmission rate for link adaptation in IEEE 802.11 WLAN
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WO2006012211A2 (fr) * 2004-06-24 2006-02-02 Meshnetworks, Inc. Systeme et procede pour le choix de debit adaptatif pour des reseaux sans fil
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Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7088701B1 (en) * 2000-04-14 2006-08-08 Qualcomm, Inc. Method and apparatus for adaptive transmission control in a high data rate communication system
WO2002039650A2 (fr) * 2000-11-09 2002-05-16 Telefonaktiebolaget Lm Ericsson Dispositif et procede de tranfert de paquets de donnees
EP1211838A1 (fr) * 2000-11-29 2002-06-05 Lucent Technologies Inc. Adaptation du débit binaire dans un système de communication sans fil
EP1233564A1 (fr) * 2001-02-09 2002-08-21 Lucent Technologies Inc. Adaptation de débit dans un système de telecommunication sans fil
EP1628446A1 (fr) * 2004-08-18 2006-02-22 Infineon Technologies AG Procédé pour la transmission d'informations sur une liaison de communication et dispositif respectif de transmission et système de communication

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Publication number Publication date
TW200814694A (en) 2008-03-16
GB2441809A (en) 2008-03-19
GB0618241D0 (en) 2006-10-25

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