PTO/S13/05 (04.04)
`Approved for use through 07/31/2006. OMB 0651-0032
`U.S. Patent and Trademark Office. U.S. DEPARTMENT OF COMMERCE
`Under the Paperwork Reduction Act of 1995 no persons are required to respond to a collection of information unless it displaysa valid OMB control number.
`562492000500
`Attorney Docket No.
`UTILITY
`Nicholas William ANDERSON
`PATENT APPLICATION
`nue POWER CONTROL IN A WIRELESS
`TRANSMITTAL
`COMMUNICATION SYSTEM
`(ONLY FOR NEW NONPROVISIONAL APPUCATIONS UNDER
`37 CFR 1.53(8))
`
`First Inventor
`
`APPLICATION ELEMENTS
`See MPEP chapter 600 concerning utility patent application contents.
`
`Express Mail Label No. EV 336627356 US
`Commissioner for Patents
`ADDRESS TO: P.O.
`Box 1450
`Alexandria, VA 22313-1450
`
`CD-ROM or CD-R in duplicate,
`large table or
`
`Computer Program (Appendix)
`
`Nucleotide and/or
`Amino Acid Sequence
`Submission
`
`(if applicable, all necessary)
`Readable Form (CRF)
`a.
`Computer
`
`7.
`8
`
`1
`
`27
`
`1. x Fee Transmittal
`Form (e.g., PTO/SB/17) (2 pages)
`
`(Submit an original and a duplicate for tee processing)
`2 n
` Applicant
`claims small entity status.
`CFR 1.27.
`See 37
`[Total Pages
`3. X Specification
`(preferred
`arrangement set forth bebw)
`- Descriptive
`title of the invention
`- Cross
`Reference to Related Applications
`- Statement
`Regarding Fed sponsored R & D
`- Reference
`to sequence listing, a table,
`or a computer
`program listing appendix
`of the Invention
`- Background
`- Brief
`Summary of the Invention
`- Brief
`Description of the Drawings (if Bled)
`- Detailed
`Description
`- Claim(s)
`- Abstract
`of the Disclosure
`4. x Drawing(s)
`(35 U.S.C. 113)
`5. Oath or Declaration
`a.
`Newly
`executed (original or copy)
`Copy
`from a prior application (37 CFR 1.63(d))
`(for continuation/divisional
`b q
`with Box 18 completed)
`I. q
`DELETION OF INVENTOR(S)
`
`SIGNED STATEMENT ATTACHED DELETING
`INVENTOR(S).
`NAMED IN THE PRIOR APPLICATION,
`SEE 37 CFR 1.63(D)(2) AND 1.33(B).
`
`[Total Sheets
`
`[Total Sheets
`
`4
`
`1
`]
`
`b.
`
`
`Sequence Listing Specification on:
`I. q
`CD-ROM or CD-R (2
`copies); or
`
`
`
`II.
`
`Paper
`
`verifying Identity
`c. ri Statements
`of above copies
`
`ACCOMPANYING APPLICATION PARTS
`
`Papers (cover sheet & document(s))
`Assignment
`3.73(b) Statement
`Power of
`37 CFR
`is an assignee)
` Attorney
`(when there
`Translation Document
`(if applicable)
`English
`Disclosure
`El Copies of IDS
`q
`Information
`(IDSYPTO-1449
`Citations
`Statement
`Amendment
`Preliminary
`Receipt Postcard (MPEP
`503)
`Return
`be specifically itemized)
`(Should
`Copy of Priority Document(s)
`Certified
`primly is claimed)
`(ff foreign
`
`ication Request under 35 U.S.C. 122 (bX2XBX1).
`Nonpub
` Applicant
`
`must attach form PTO/SB/35 or its equivalent
`Other
`
`x
`
`9.
`
`10.
`
`11.
`
`12.
`
`13.
`
`14.
`
`15.
`
`16.
`
`17.
`
`APPLICATION, check appropriate box, and supp y the requisite information below and in the first sentence of the
`
`6. X Application
`Data Sheet See 37 CFR 1.76 (2 sheets)
`18. If a CONTINUING
`
`
`specification following the title, or in an Application Data Sheet under 37 CFR 1.78:
`of prior application No.:
`Continuation
`a Divisional
`n Continuation-in-part (CIP)
`
`
`Prior application information: Examiner
`Art Unit:
`For CONTINUATION
`OR DIVISIONAL APPS only; The entire disclosure of the prior application, from which an oath or declaration Is supplied
`under Box 5b, Is considered
`a part of the disclosure of the accompanying continuation or divisional application and is hereby Incorporated by
`
`reference. The Incorporation can only be relied upon when a portion has been Inadvertently omitted from the submitted application parts.
`19. CORRESPONDENCE ADDRESS
`OR
`address below q Correspondence
`25226
`
`
`
`X Customer Number
`
`
`
`Name
`
`Address
`
`City
`Country
`Name (Print/Type) B
`
`Signature
`
`.
`
`yrnan
`
`State
`Telephone
`
`Zip Code
`Fax
`
`Registration No. (Altomey/Agen )
`
`7 77.1.7 ,.............-"---
`
`48,049
`Date August 12, 2004
`
`I hereby certify that this correspondence is being deposited with the U.S. Postal Service as Express Mail, Airtill No. EV 336627356 US,
`in an envelope addressed to: Commissioner for Patents, P.O. Box 1450, Alexandria, VA 22313-1450, on the date shown below.
`
`Dated: August 12, 2004
`
`Signature:
`
`(Tia B. Zimmerman)
`
`pa-909812 v1
`
`NAC1002
`Page 1
`
`

`

`FEE TRANSMITTAL
`•
`for FY 2004
`
`Effective 10/01/2003. Patent fees am subject to annual revision.
`
`Application Number
`Filing Date
`First Named Inventor
`Examiner Name
`
`PTO/SW17 (10-03)
`Approved for use through 7/31/2006. OMB 0651-0032
`U.S. Patent and Trademark Office; U.S. DEPARTMENT OF COMMERCE
`Under the Paperwork Reduction Act of 1995, no persons are required to respond to a collection of information unless it displays a veld OMB control number.
`Complete If Known
`Not Yet Assigned
`Concurrently Herewith
`Nicholas William Anderson
`Not Yet Assigned
`Not Yet Assigned
`Art Unit
`562492000500
`Attorney Docket No.
`FEE CALCULATION (continued)
`None 3. ADDITIONAL FEES
`
`q Applicant claims small entity status. See 37 CFR 1.27
`TOTAL AMOUNT OF PAYMENT I
`($) 942.00
`METHOD OF PAYMENT (check all that apply)
`Money
`Cmd
`Card t
`Order
`
`Check
`
`Other
`
`Deposit Account
`
`X
`Deposit
`Account
`Number
`
`03-1952
`
`Deposit
`Account
`Name
`
`The Director is authorized to: (check all that
`
`Morrison & Foerster LLP
`
`apply)
`
`Large Entity Small Entity
`Fee
`Fee
`Fee
`Fee
`Code
`(8)
`Code
`(8)
`
`Fee Description
`
`Fee Paid
`
`1051
`
`130 2051
`
`1052
`
`50
`
`2052
`
`65 Surcharge - late filing fee or oath
`25 Surcharge - late provisional filing fee or cover
`sheet.
`
`Charge fee(s) indicated below
`
`X
`
`Credit any overpayments
`
`1053
`
`130 1053
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`130 Non-English specification
`
`X
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`X
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`Charge any additional fee(s) or any underpayment of fee(s)
`
`Charge fee(s) indicated below, except for the filing fee
`
`
`
`to the above-identified deposit account.
`FEE CALCULATION
`
`1. BASIC FILING FEE
`Large Entity
`Small Entity
`Fee
`Fee
`Fee
`Fee
`Code
`(8) Code
`(8)
`1001
`770
`2001
`385
`1002
`340
`2002
`170
`1003
`530
`2003
`265
`1004
`770
`2004
`385
`1005
`160
`2005
`80
`
`Fee Description
`
`Fee Paid
`
`770.00
`
`Utility filing fee
`Design filing fee
`Plant filing fee
`Reissue filing fee
`Provisional filing fee
`
`SUBTOTAL (1)
`
`($)
`
`770.00
`
`2. EXTRA CLAIM FEES FOR UTILITY AND REISSUE
`Extra
`Fee from
`Fee Paid
`Claims
`below
`0
`18.00
`0.00
`
`x
`
`=
`
`13
`5
`
`-20" =
`-3..=
`
`1812 2,520 1812 2,520 For tiling a request for ex parte reexamination
`920* Requesting publication of SIR prior to
`1804
`920r 1804
`Examiner action
`1805 1,840' 1805 um. Requesting publication of SIR after
`Examiner action
`1251
`110 2251
`55 Extension for reply within first month
`1252
`420
`2252
`210 Extension for reply within second month
`1253
`950
`2253
`475 Extension for reply within third month
`
`1254 1,480 2254
`
`740 Extension for reply within fourth month
`
`1255 2,010 2255 1,005 Extension for reply within fifth month
`1401
`330
`2401
`165 Notice of Appeal
`1402
`330
`2402
`165 Filing a brief in support of an appeal
`1403
`290
`2403
`145 Request for oral hearing
`1451 1,510 1451 1,510 Petition to institute a public use proceeding
`1452
`110 2452
`55 Petition to revive- unavoidable
`1453 1,330 2453
`665 Petition to revive - unintentional
`1501 1,330 2501
`665 Utility issue fee (or reissue)
`
`1502
`
`480
`
`2502
`
`240 Design issue fee
`
`2503
`640
`130 1460
`
`Total Claims
`Independent
`Claims
`Multiple Dependent
`
`2
`
`x
`
`86.00
`
`=
`
`172.00
`
`290.00 =
`
`0.00
`
`Large Entity Small Entity
`Fee
`Fee
`Fee
`Fee
`Code
`(8)
`Code
`(8)
`1202
`18
`2202
`9 Claims in excess of 20
`1201
`86
`2201
`43 Independent claims in excess of 3
`
`Fee Description
`
`1203
`1204
`
`290
`86
`
`2203
`2204
`
`1205
`
`18
`
`2205
`
`145 Multiple dependent claim, if not paid
`43 ** Reissue independent claims
`over original patent
`** Reissue daims in excess of 20
`and over original patent
`
`9
`
`SUBTOTAL (2) (8)
`172.00
`"or number previously paid, if greater, For Reissues, see above
`
`1503
`1460
`
`1807
`
`50
`
`1807
`
`1806
`
`180
`
`1806
`
`8021
`
`40
`
`8021
`
`1809
`
`770 2809
`
`1810
`
`770 2810
`
`1801
`
`770 2801
`
`1802
`
`900
`
`1802
`
`Other fee (specify)
`
`320 Plant issue fee
`130 Petitions to the Commissioner
`
`50 Processing fee under 37 CFR 1.17(c1)
`180 Submission of Information Disclosure Stint
`40 Recording each patent assignment per
`property (times number of properties)
`385 Filing a submission after final rejection
`(37 CFR 1.129(a))
`385 For each additional Invention to be
`examined (37CFR 1.129(b))
`385 Request for Continued Examination (RCE)
`Request for expedited examination
`of a design application
`
`900
`
`*Reduced by Basic Filing Fee Paid
`
`SUBTOTAL (3)
`
`(8)
`
`0.00
`
`SUBMITTED BY
`Name (Print/Type) Brya
`
`. Wyman
`
`Signature
`
`R istration Na
`y/Agent)
`
`148,049
`
`(Complete (if applicable))
`- -
`Telephone (650) 813-5779
`August 12, 2004
`
`Date
`
`pa-909815 v1
`
`NAC1002
`Page 2
`
`

`

`IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
`
`APPLICATION FOR U.S. LETTERS PATENT
`
`Title:
`
`POWER CONTROL IN A WIRELESS COMMUNICATION SYSTEM
`
`Inventor:
`
`Nicholas William ANDERSON
`
`56249-20005.00
`
`Bryan H. Wyman - 48,049
`MORRISON & FOERSTER LLP
`755 Page Mill Road
`Palo Alto, California 94304
`(650) 813-5779
`
`NAC1002
`Page 3
`
`

`

`POWER CONTROL IN A WIRELESS COMMUNICATION SYSTEM
`
`CROSS-REFERENCE TO RELATED APPLICATIONS
`
`[0001] Not applicable.
`
`1. Field of the Invention
`
`BACKGROUND OF THE INVENTION
`
`[0002] This invention relates to power control in a mobile radio system or wireless
`communication system, and more particularly, to controlling received power levels in a code
`
`division multiple access (CDMA) radio system.
`
`2. Description of the Prior Art
`
`[0003] Typically, radio signals transmitted with increased power result in fewer errors when
`
`received than signals transmitted with decreased power. Unfortunately, signals transmitted with
`
`excessive power may interfere with the reception of other signals sharing the radio link. Wireless
`
`communication systems employ power control schemes to maintain a target error rate of a signal
`
`received on a radio link.
`
`[0004]
`
`If a received signal includes a rate of errors far above a target error rate, the received
`
`signal may result in an undesirable effect on a delivered service. For example, excessive errors
`
`may lead to broken voice during voice calls, low throughput over data links, and glitches in
`
`displayed video signals. On the other hand, if the received signal includes a rate of errors well
`
`below the target error rate, the mobile radio system is not efficiently using its radio resources. A
`
`very low error rate may mean that a signal is transmitted with an excessive level of power and
`
`that user could be provided a higher data rate. Alternatively, if the power level of a signal is
`
`sufficiently reduced, additional users may be serviced. If data rates are increased, a user may
`
`receive a higher level of service. Therefore, if a target error rate for each user is met within a
`
`tolerance threshold, a radio resource may be more optimally used.
`
`1
`
`NAC1002
`Page 4
`
`

`

`[0005] A wireless communication system often employ one of either an open loop scheme or a
`
`closed loop scheme to control uplink transmit power of a mobile radio. Uplink typically refers to
`
`the radio link from a mobile radio to a base station, where as the downlink typically refers to the
`
`link from the base station to the mobile radio. A mobile radio is not necessarily mobile and may
`
`also be referred to as a mobile, a user, user equipment (UE), a terminal or terminal equipment. A
`
`base station may also be referred to as a Node-B.
`
`[0006] The error rate is related to a received signal to noise-plus-interference ratio (SNIR); a
`
`higher SNIR generally results in a lower error rate; and conversely, a lower SNIR generally
`
`results in a higher error rate. The exact relationship between SNIR and error rate, however, is
`
`often a function of several factors including radio channel type and the speed at which a mobile
`
`is travelling.
`
`[0007] A target error rate is often reached using a two stage process, which includes an outer
`
`loop and an inner loop. A first process may operate as an outer loop and may be tasked to adjust
`
`a target received SNIR (SNIR Target). This first process tracks changes in the relationship
`
`between SNIR and error rate. The outer loop sets an SNIR Target that is generally used several
`
`times by the inner loop. Periodically, the outer loop may adjust or update this SNIR Target used
`
`by the inner loop. For example, if an actual error rate exceeds a desired error rate, the outer loop
`
`may increase the value of the SNIR Target.
`
`[0008] A second process operates as an inner loop and tries to force the link to exhibit the
`
`SNIR Target determined by the outer loop. The inner loop may operate by closed loop or by
`
`open loop means.
`
`[0009] In the open loop method of the inner loop process, a UE uses an SNIR Target value that
`
`is derived by the network and signalled to the UE. The inner loop running in the UE attempts to
`
`maintain the SNIR Target. The UE uses the information signalled to it and monitors the received
`
`strength of signals it receives to determine a power level at which it will transmit.
`
`Advantageously, this open loop method compensates for fast channel fading by determining the
`
`path loss on a per frame bases and by adjusting the transmit power accordingly. Unfortunately,
`
`2
`
`NAC1002
`Page 5
`
`

`

`this open loop method is relatively slow at compensating for changes due to interfering signals
`
`from other transmitters.
`
`[0010]
`
`In the closed loop method of the inner loop process, a closed loop scheme operates to
`
`match an SNIR Target. A received SNIR measurement is made by the network on an uplink
`
`signal. The SNIR measurement is compared within the network to the SNIR Target value. The
`
`inner loop drives the system to match the SNIR Target by issuing transmit power control
`
`commands from the network to a UE. The commands instruct the UE to increase or decrease its
`
`transmitted power by a predetermined step dB amount. Unfortunately, such closed loop methods
`
`demand a very high command update rate to adequately compensate for fast channel fading
`
`because of the single-dB-step commands used. At slower update rates, fast channel fading is not
`
`tracked adequately since a large number of iterations and long delays are needed to compensate
`
`for a change in power that is substantially larger than the dB-step value.
`
`[0011] Both the closed loop scheme and the open loop scheme have their disadvantages.
`
`Therefore, an improved method and system are needed that better balances the conflicting goals
`
`of reducing errors in a received signal while also reducing interference imposed on signals
`
`received at other receivers. An improved method and system are also needed to better reduce the
`
`overall residual SNIR fluctuations experienced by each users signal at a receiver.
`
`BRIEF SUMMARY OF THE INVENTION
`
`[0012] Some embodiments provide a method of power control in a radio communications
`
`system, the method comprising: determining a path loss of a radio channel between a base station
`
`and a remote transceiver; receiving a transmit power control (TPC) command transmitted to the
`
`remote transceiver from the base station; and calculating a transmit power level for the remote
`
`transceiver based on the path loss and the TPC command.
`
`[0013] Some embodiments provide a method of power control in a radio communications
`
`system, the method comprising: receiving a signal at a second transceiver transmitted from a first
`
`transceiver; measuring a power level of the received signal; receiving a transmit power control
`
`(TPC) command at the second transceiver transmitted from the first transceiver; and calculating a
`
`3
`
`NAC1002
`Page 6
`
`

`

`transmit power level for the second transceiver based on the power level of the received signal
`
`and the TPC command.
`
`[0014] Some embodiments provide a method of uplink power control in a CDMA radio
`
`communications system, the method comprising: receiving an uplink signal; determining an error
`
`metric of the uplink signal; updating an SNIR target based on the error metric;measuring a
`
`received SNIR of the uplink signal; comparing the measured received SNIR with the SNIR
`
`target; assigning a first value to a step indicator if the measured received SNIR is greater than the
`
`SNIR target, and assigning a second value to a step indicator if the measured received SNIR is
`
`less than the SNIR target; transmitting a transmit power control (TPC) command instructing a
`
`transmitter to adjust an uplink transmit power level based on the step indicator; receiving the
`
`TPC command including the step indicator; accumulating the step indicator value; broadcasting a
`
`downlink signal including an indication of a downlink power level, wherein the signal is
`
`transmitted at the downlink power level; measuring the received power of the downlink signal;
`
`and setting a transmit power level base on the received power level, the indication of the
`
`downlink power level, and the accumulated step indicator value.
`
`[0015] Some embodiments provide a method comprising: measuring a power level of a
`
`received signal; receiving a transmit power control (TPC) command; and calculating a transmit
`
`power level based on the power level of the received signal and the TPC command.
`
`[0016] Some embodiments provide a radio comprising: a receiver including an output to
`
`provide a measured received power level; an accumulator having an input for accepting step
`
`increase and decrease instructions and an output providing a sum of past step instructions; a
`
`power level setting circuit coupled to the accumulator output and coupled to the receiver output,
`
`wherein the power level setting circuit sets a transmit power bases on the accumulator output and
`
`the measured received power level; and a transmitter, wherein the transmitter transmits a signal
`
`at the set transmit power.
`
`[0017] Other features and aspects of the invention will become apparent from the following
`
`detailed description, taken in conjunction with the accompanying drawings which illustrate, by
`
`4
`
`NAC1002
`Page 7
`
`

`

`way of example, the features in accordance with embodiments of the invention. The summary is
`
`not intended to limit the scope of the invention, which is defined solely by the claims attached
`
`hereto.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0018] FIGURE 1 shows a block diagram of a wireless communication system.
`
`[0019] FIGURE 2 illustrates a wireless communication system using an open loop scheme.
`
`[0020] FIGURE 3 illustrates a wireless communication system using a closed loop scheme.
`
`[0021] FIGURE 4 illustrates a wireless communication system using elements of both open
`
`loop and closed loop schemes, in accordance with the present invention.
`
`[0022] FIGURES 5A, 5B and 5C each illustrate a simulated probability density function of the
`
`received SNIR in the network.
`
`DETAILED DESCRIPTION OF THE INVENTION
`
`[0023]
`
`In the following description, reference is made to the accompanying drawings which
`
`illustrate several embodiments of the present invention. It is understood that other embodiments
`
`may be utilized and mechanical, compositional, structural, electrical and operational changes
`
`may be made without departing from the spirit and scope of the present disclosure. The
`
`following detailed description is not to be taken in a limiting sense, and the scope of the
`
`embodiments of the present invention is defined by the claims of the issued patent.
`
`[0024] Some portions of the detailed description which follows are presented in terms of
`
`procedures, steps, logic blocks, processing, and other symbolic representations of operations on
`
`data bits that can be performed on computer memory. A procedure, computer executed step,
`
`logic block, process etc., are here conceived to be a self-consistent sequence of steps or
`
`instructions leading to a desired result. The steps are those utilizing physical manipulations of
`
`physical quantities. These quantities can take the form of electrical, magnetic, or radio signals
`
`capable of being stored, transferred, combined, compared, and otherwise manipulated in a
`5
`
`NAC1002
`Page 8
`
`

`

`computer system. These signals may be referred to at times as bits, values, elements, symbols,
`
`characters, terms, numbers, or the like. Each step may be performed by hardware, software,
`
`firmware, or combinations thereof.
`
`[0025] FIGURE 1 shows a block diagram of a wireless communication system. A network 100
`
`may include one or more base station controllers 120, such as a radio network controller (RNC),
`
`and one or more base stations 110, such as a Node-B, wherein each Node-B is connected to an
`
`RNC. The network 100 communicates with one or more users 140, 150 through a channel 160,
`
`also referred to as a radio link, created between a base station and a user.
`
`[0026] Two mechanisms are primarily responsible for changes in the SNIR of a signal
`
`travelling through a radio link.
`
`[0027] First, changes in the channel affect the SNIR. The instantaneous path loss between a
`
`base station and a user may vary as the user changes position or the user's environment changes.
`
`Rapid changes may occur as a result of a transmitted signal combining constructively and
`
`destructively as the signal travels along multiple paths from a base station and to the user.
`
`Additionally, slower changes may occur due to attenuation of the radio waves with increased
`
`distance between the base station and the user. Slower changes may also occur due to signal
`
`obstruction by buildings, vehicles and hills.
`
`[0028] Second, signals from other transmitters affect the SNIR. For example, signals intended
`
`for other mobile radios or other base stations may increase interference in the radio link and thus
`
`reduce a received signal's SNIR.
`
`[0029]
`
`In Time Division Duplex (TDD) systems, both uplink and downlink share the same
`
`carrier frequency. Due to this reciprocity in the links, path loss measurements made on the
`
`downlink by a mobile radio may be used estimate the path loss on the uplink. That is, a
`
`measured downlink path loss may be used to estimate the uplink path loss. The estimated uplink
`
`path loss will be less reliable with the passing of time but may be adequate within a frame period.
`
`Therefore, a mobile radio may determine a transmit power level for an uplink transition that
`
`6
`
`NAC1002
`Page 9
`
`

`

`compensates for an estimated uplink path loss, thereby providing a received signal to a base
`
`station at an expected input power level.
`
`[0030] Downlink path loss measurements may be facilitated by a beacon channel, which is
`
`transmitted from a base station at a reference power level. A mobile radio is informed of the
`
`actual transmit power level being used by the base station for the beacon channel. In addition to
`
`knowing the actual transmit power level of a beacon channel, the mobile radio may measure a
`
`received signal power level. By measuring the received signal power level, the mobile radio can
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`compute a downlink path loss as the difference between the actual transmit power level and the
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`received signal power level. Thus, the mobile radio is able to estimate the uplink path loss in a
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`channel between the base station and the mobile radio and properly set its uplink transmit power
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`level.
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`[0031] The path loss calculation may be updated as often as a beacon signal is transmitted and
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`received. In a UTRA TDD system in compliance with the third generation partnership project
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`(3GPP) specifications, a beacon signal is transmitted either once or twice every 10 milliseconds
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`(ms). If an uplink transmission follows a beacon transmission within a relatively short period of
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`time, a mobile radio can compensate for the fast fluctuations (fast-fading) in a radio channel.
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`Such is the case for mobiles travelling at slow to moderate speeds if a beacon signal is
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`transmitted either once or twice every 10ms and the uplink transmissions occur in the intervening
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`period.
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`[0032] Additionally, a radio channel may be adversely affected by changes in interference
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`levels over time. These temporal interference changes may be accommodated by a base station
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`,measuring and communicating interference levels seen in each uplink timeslot. In a UTRA TDD
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`system, a table having values of the measured interference for each timeslot may be broadcast to
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`all users via a Broadcast Channel (BCH). The broadcasted information may be updated
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`approximately every 16 frames (160 ms) depending upon the system configuration. In other
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`embodiments, a mobile radio may receive this interference table as a signalled message directed
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`to the individual mobile radio.
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`[0033] The 3GPP specifications describe two separate schemes for power control of uplink
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`channels: an open loop scheme and a closed loop scheme. Foi example, in 3GPP 3.84
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`Megachips per second (Mcps) TDD systems, open loop power control is specified for all uplink
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`channels. In 3GPP 1.28 Mcps TDD systems, open loop power control is specified only for
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`physical random access channels (PRACH). Also defined by 3GPP is an implementation of a
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`closed loop power control scheme. For example, see 3GPP recommendations for UTRA TDD
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`systems operating at 1.28 Mcps for non-PRACH uplink channels.
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`[0034]
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`In a wireless communication system using an open loop scheme, a network and UE use
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`an outer loop to update and signal to the UE an SNIR Target value, thereby influencing the UE's
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`transmit power. The network updates the SNIR Target value to be signalled based upon an
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`observed error rate on the uplink. Once received, the mobile radio takes into account the
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`signalled SNIR Target value when deriving a transmit power level that it will apply to the next
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`uplink signal transmitted.
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`[0035]
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`In a 3GPP 3.84 Mcps system incorporating an open loop scheme, a network instructs
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`the UE with an SNIR Target value. The network also signals its beacon transmit power level and
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`may also provide a measure of uplink interference for each timeslot as measured by the network.
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`The UE receives an input signal that is typically a combination of attenuated versions of the
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`network signal, which passed through a radio channel, along with interfering signals from other
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`transmitters. The UE measures the received power level of the attenuated network signal and
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`determines a path loss of the radio channel. The UE also decodes the signalled SNIR Target
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`value from the network signal. The UE computes a transmit power level based on the SNIR
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`Target value, the determined path loss and, if available, the uplink interference measurements.
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`[0036] FIGURE 2 illustrates a wireless communication system using an open loop scheme. A
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`UE transmits 200 user data at a determined transmit power level. An uplink signal 202, which
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`includes user data 204, propagates through the radio link. The network receives an attenuated
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`version of the transmitted signal. The network measures 207 an uplink interference value and
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`determines 206 an error metric of the uplink signal. The network may use the measured uplink
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`interference value to update 208 an interference measurement table. The interference
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`measurement table may include average measured interference levels for each uplink timeslot.
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`[0037] The network also uses the error metric to update 210 an SNIR Target value. The
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`network transmits 212 SNIR Target in a signalling message on the downlink 214, which includes
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`the.SNlR Target 216. The UE receives and saves 220 the SNIR Target. The network also
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`broadcasts 222 a beacon signal on the downlink 224. The downlink 224 propagates the signal,
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`which includes an indication of the beacon power level 226, over the radio link. The network
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`may also broadcast the interference measurements 228. The UE measures 230 the received
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`power level and saves 232 the interference measurements for later processing.
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`[0038] With the measured power level and the signalled beacon power level, the UE may
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`determine a path loss. The UE may use the saved received SNIR Target 216, the saved received
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`interference measurements 228 and the computed path loss to set 234 a transmit power level.
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`This transmit power level may be used by transmitter 200 to set the power level of transmitted
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`user data 204 on the uplink 202.
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`[0039] The 3GPP specifications also define a closed loop scheme. For example, a 3GPP
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`1.28 Mcps system employs a closed loop scheme using an outer loop and an inner loop. The
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`closed loop TPC scheme is the primary power control mechanism used for all non-PRACH
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`channels in a 1.28 Mcps TDD system. The closed loop TPC scheme is not currently employed
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`for the uplink of 3.84 Mcps TDD systems.
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`[0040] The outer loop determines an SNIR Target value and the inner loop uses the SNIR
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`Target value. The outer loop includes network components that determine an error metric, such
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`as a bit error rate, a block error rate or a CRC error count, on uplink traffic from UEs. This error
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`metric is used to set and update an SNIR Target value. An inner loop includes network
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`components that use the SNIR Target value computed and set by the outer loop. The network
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`measures a received SNIR value of the uplink signal.
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`[0041] Next, a comparator determines whether the measured SNIR value is greater than or less
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`than the SNIR Target value. If the measured SNIR value is greater than the SNIR Target value,
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`the network signals a transmit power control (TPC) command on the downlink instructing the
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`UE to reduce its current transmitter power by a step value (e.g., 1 dB). On the other hand, if the
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`measured SNIR value is less than the SNIR Target value, the network signals a TPC command
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`instructing the UE to increase its current transmitter power by the step dB value.
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`[0042]
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`In a system employing only a closed loop power control scheme, several TPC
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`commands may be necessary to properly bring the UE's transmitted power in line with the SNIR
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`Target value. For example, if a path loss increases from one frame to the next by 15 dB, the
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`system will take 15 TPC commands to compensate for the 15 dB fade. A UE accumulates the
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`increase and decrease TPC commands to determine a proper uplink transmit power level. By
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`increasing and decrease uplink power levels of each UE, a network attempts to control the power
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`level of each UE such that the ratio of the received uplink energy level per transmitted bit to the
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`spectral density of the noise and interference signals is a constant value. This TPC command
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`adjustment process is performed for each UE in a cell. The constant value, however, may be
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`non-uniform among the UEs depending upon the configuration of the system.
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`[0043]
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`In a closed loop TPC scheme, the inner loop SNIR is maintained via a closed loop
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`method using binary feedback. The feedback indicates either power up or power down. Every
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`time a TPC command is received an integrator in the UE is used within the inner loop to update
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`the UE transmit power by a step amount +/-A dB. The TPC commands themselves are derived
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`by the network and are signalled to the UE via a downlink channel. When calculating the proper
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`TPC command to send, the network measures the received SNIR and compares this measured
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`value to an SNIR Target value. If the SNIR is too low, an up command is sent. If the SNIR is
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`too high, a down command is sent. The target SNIR value is updated by the outer loop based
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`upon the observed error performance of the link. In this way, both the inner and outer feedback
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`loops are closed by the TPC signalling.
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`[0044] FIGURE 3 illustrates a wireless communication system using a closed loop scheme.
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`The closed loop scheme includes an outer loop in which a UE transmits 300 user data over the
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`radio link in an uplink signal 302 that contain the user data 304. The network determines 306 an
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`error metric of the received uplink signal. Using the error metric, the network computes and
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`updates 308 an SNIR Target value.
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`[0045] The closed loop scheme also includes an inner loop in which the network measures 310
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`the received SNIR of the uplink signal 302. The network compares 312 the measured SNIR with
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`the SNIR Target determined in the outer loop. The inner loop generates and transmits 314 a TPC
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`command based on the comparison 312. A downlink signal 316 carries the TPC command 318
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`over the radio link. The UE accumulates 320 the TPC commands and uses the accumulated TPC
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`commands to set 322 a transmit power for future uplink transmissions 300.
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`[0046] A mobile radio s