CA2351164A1 - Method and apparatus for supplemental channel soft hand off in cdma systems - Google Patents

Method and apparatus for supplemental channel soft hand off in cdma systems Download PDF

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Publication number
CA2351164A1
CA2351164A1 CA002351164A CA2351164A CA2351164A1 CA 2351164 A1 CA2351164 A1 CA 2351164A1 CA 002351164 A CA002351164 A CA 002351164A CA 2351164 A CA2351164 A CA 2351164A CA 2351164 A1 CA2351164 A1 CA 2351164A1
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Canada
Prior art keywords
active
mobile station
strength measurement
time
supplemental channel
Prior art date
Legal status (The legal status 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 status listed.)
Abandoned
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CA002351164A
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French (fr)
Inventor
David Paranchych
Geng Wu
Ashvin Chheda
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Nortel Networks Ltd
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Nortel Networks Ltd
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Publication of CA2351164A1 publication Critical patent/CA2351164A1/en
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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W36/00Hand-off or reselection arrangements
    • H04W36/0005Control or signalling for completing the hand-off
    • H04W36/0083Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/0085Hand-off measurements
    • H04W36/0088Scheduling hand-off measurements
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W36/00Hand-off or reselection arrangements
    • H04W36/16Performing reselection for specific purposes
    • H04W36/18Performing reselection for specific purposes for allowing seamless reselection, e.g. soft reselection
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W36/00Hand-off or reselection arrangements
    • H04W36/24Reselection being triggered by specific parameters
    • H04W36/30Reselection being triggered by specific parameters by measured or perceived connection quality data

Abstract

The present system and method of use comprises a system that efficiently determines the optimal set of base transceiver sets that are to transmit data over supplemental channels to a mobile station. More specifically, the invention includes having the mobile station transmit periodic signal strength measurement message to the BTSs to rank the pilot signal strengths being received from the plurality of base station transceiver systems. Whenever the number of fundamental channel sectors that are active exceeds the maximum number of active supplemental channel sectors, periodic pilot strength measurement messages are transmitted by the mobile station. However, to improve resource usage, the periodic pilot strength measurement messages are not transmitted as often as required to insure that the active supplemental channel sectors are the ones from which the strongest signals are received by the mobile station.
Rather, a combination of periodic pilot strength measurement messages and calculated reverse link signal strength over spectral noise density values are used to determine which BTSs should be used for the active set of supplemental channel sectors.

Description

Sent By: Garlick 8~ Harrison; 214 902 8101; Jun-20-01 14:13; Page 5 Dcakot No. 11807RRUSOIU
TITTaE: D~T80D AND APPARATUS FOR SUPPL~NTAh CAANNEh SOFT
HAND OFF IN. CDM11 SYSTBiMS
BACICGROtJND
1. Fi~ld of the Invention The present invention relates generally to communications 3y~tems and particularly to channel selection.
in a code division multiple access communication system.
Description of Rslated Art Because the radio frequency (Rf) spectrum is limited, the government, more particularly, the rederal Communic;a~lorlS
Commission (FCC), governs the use of the radio frequency spectrum. This regulation inr.ludes deciding frequency band allocation among the various industries. Since the RF
spectrum is limited, only a small portion of the spectrum can ' be assigned to each industry. Accordingly, the assigned spectrums must be used efficiently in order to allow as many frequency users as possible to have access to the spectrum.
BQCause the numb~r and size of frequency bands are limited, multiple access modulation techniques are continuously being developed and improved to ~.mprove efficiency and capacity and to maximize use of the allocated RF spectrum. Examples of such modulation techniques include time division multiple access (TDMA), frequency division
2 Sent By: Liarlick 8~ Harrison; 214 902 8101; Jun-20-01 14:13; Page B
a Dookst No. ~~eo~~vsotv multiple access (FDMA), dnd code division multiple access ( C; UMA ) .
CDMA mc~di.yJ.ation employs a spread spectrum technique for the transmission of infornmi:ion. CDMA modulation techniques axe becoming popular because they enable more usP.rs t.o communicate at a given time. A spread spectrum system uses a ~twdulation technique~that distributes the transmitted signal over a wide frequency band. This frequency band i9 typically substantially wider than the minimum bandwidth required to 7.0 transmit the signal. The spread spectrum technique is accomplished by modulating each baseband data signal to be transmitted w~.th a unique wideband spreading code. Us~.ng this technique a signal having a bandwidth of only a few kilohertz can be spread over a bandwidth o~ more than a rnegahc~rtz. A form of frequency diversity is obtained by spreading the transmitted signal over a wide frequency range.
Since only 200-300 kHz of a signal is typically affected by a frequency selective fade (interference), the remaining spectrum of the transmitted signal is unaffected. A receiver that receives the spread spectrum signal, therefore, will be affected less by the fade condition.
In a CDMA telephone system, multip7,s~ ,signals are transmitted at the same frequency. A particular receiver then determ~.nCS which .signal is intended for that receiver by the unique spreading code in the signal. The signals at that
3 Sent By: Garlick & Harrison; 214 902 8101; Jun-20-01 14:13; Page 7 Dockst No. 11807RRUSO1L1' frequency without the particular spreading code intended for that particular receiver appear as noise to the receiver and are ignored.
Now generation CDMA communication networks are being formed to facilitate the transmission of large amounts of data on an as needed basis. Accordingly, a fundamental channel set is defined for trdt'ismitting vn going communications between the base station transceiver systems and t.he.mobile stations. Additionally, supplemental channels are being defined to transmit large amounts of data to a mobile station for use as needed. Because c:nMA systems typically include the tran:misaion of the communications signals from a plurality of base station transceiver systems to a given mobile station, sic~ntficdnt amounts of resources are consumed especially when a plui~alii:y of supplemental channels are being used by a plurality of base station transceiver systems to deliver large wo7.umes of data to the mobile station. In particular, because the supplemental channels are formed to be able to carry large amounts of data, there is a need for efficiently reserving capacity for supplemental channel data I:ransmission only from the base station transceiver systems that are transmitting the signals to the mobile station the most clearly. By reducing the number of base station transceiver systems that transmit data ovor a supplemental channel to a mobile station, resources in
4 _ Sent By:~Garlick 8 Harrison; 214 902 8101; Jun-20-01 14:13; Page 8 Doak~t No. 11807RR1J801V
other base station transceiver systems are not wasted and may be used for other purposes. Accordingly, there is a need for efficiently and effectively selecting tW base station transceiver systems that best transmit data over the supplemental channels.
5 Sent By:~Garlick & Harrison; 214 902 8101; Jun-20-01 14:14; Page 9 1 Dpokvt No. 118p7RRUSOlU
S~dARY OF TH$ INVENTION
The present: system and method of use comprises a system that solves the aforemantior~ed problems by eft~iciontly determining the optimal set of base station transceiver systems (HTSs) that are to transmit data over supplemental Channels to a mobile station. More specifically, the invention includes having the mobile station transmit periodic signal strength measurement message to the BTSs to rank the pilot signal strengths being received from the plurality of base station transceiver systems. Whenever the number of fundamental channels treat are active exceeds the maximum allowable number of active supplemental channels, the periodic pilot strength measurement message are transmitted by the mobile station. However, to improve resource usage, the periodic pilot strength measurement messages are not transmitted as often as required to insure that the active set of supplemenl.al channels are the ones receiving the strongest signals. Rather, a combination of periodic pilot strength measurement messages and calculated reverse link signal strength over spectral noise density values are used to determine which BT~Ss should be used for the actiire set of supplemental channels.
More specifically, if less than a specified amount of time has elapsed since the last pilot strength measurement message was received by a 8TS from a mobile station, then the
6 Sent By: Qarlick & Harrison; 214 902 8101; Jun-20-01 14:14; Page 10 Dock~t No, 11807RRUS01U
pilot strength measurement message is used to rank the supplcmer~tal channels and corresponding BTSs. If., however, more than a specified amount of time has elapsed, then a calculated reverse link signal to noise ratio (Eb/No) is used S to lank the BTSs and corresponding and supplemental rhannel,s.
Eb/No is the total measn red Eb/No across all multipath xnd all receive antennas per sector. In one embodiment of the in~rention, the list of active supplemental Channels is determined at the time in which a supplemental charnel is first required. Accordingly, system resources are optimized in a manner that effectively defines the supplemQntal channels whose signals are most likely to be received clearly by the mobile station.
.7 Sent By: Garlick 8 Harrison; 214 902 8101; Jun-20-01 14:14; Pege 11 Doakot No. 11807RRUSOlU
BRIEF DssCRipTZOar oa~ Tss D~warcs FIGURE 1 illustrates a typical CDMA rrransmitter system for use on the forward channel from a ba9e station transceiver system (BTS) to a CDMA mobile station.
FIGURE 2 is a function block diagram illustrating the operation of a pilot channel.
FTGURE 3 is a functional block diagram illustrating a mobile station in communication with a plurality of base stations.
rIGURE 4 is functional block diagram illustrating the operation of a mobile station with respect to a plurality ~f sectors defined by a given base station transceiver system.
FIGURE 5A is a timing diagram illustrating a difference in usage between a fundamental channel and a supplemental channel in modern CDMA networks.
FIGURE 5B is a table illustrating an example of channel allocations for a given mobile station in communication with a plurality of base stations.
FIGURE 6 is a state machine illustrating distributed logic for the transmission of pilot strength measurement messages that are to be transmitted by a u~obiJ,e station.
FIGURE 7 is a flow chart illustrating a method within a base station Controller for ranking p~,7.ots according to Sent By: (iarlick & Harrison; 214 902 8101; Jun-20-01 14:14; Page 12 Dockot No. 11807RitUS0lU
reverse link Eb/No according to one embodiment of the present invention.
FIGURE 8 is a flow chart illustrating a method performed by a base station controller whenever. a supplemental channel burst requ~:st is received according to one embodiment of the present invention.
FIGURE 9 is a flow chart illustrating a method wi.i:.hin a base station controller :for selecting the active set of supplemental channels duxing a burst according to one embodiment of the present invention.
FIGURE 10 is a functional block diagram of a communication network according to an embodiment of the present invention.

Sent By: Garlick ~ Harrison; 214 902 8101; Jun-20-01 14:14; Page 13 Docket No. 11807RRL1SOlU
DETAILED DESCRIDTIpN OF TFIE DRAWINGS
FZGUR~ 1 illustrates a typical CnMA transmitter system for use on the forward channel from a base station transceiver system (8TS) to a CDMA mobile station. An encoder 104 creates a digital baseband signal by encoding a digitized signal representing an analog voice or digital data service.
An encoder 104, accepts data bits in and produces code symbols on an output. For each clock cycle, a new data bit is shifted into a register of the encoder 104 and the data bil, previously received is output. The various inputs of an encoder are added (modulo 2) to produce two or more symbols out for each clock cycle. Since the new symbols ganera'l:ed for each clock cycle are derived from the values of the new bit being input in all current data bits occupying the shift register during a given interval, a certain level of predictability can be realized. The output symbols of the encoder 104, are then produced to a block interlever 106.
The block interlever 106 Serves to create a matrix of symbols wherein each matrix represents all of the information within a defined interval. ' For example, in one embodiment, 384 modulation symbols may be entered into an array at a rate of 19,200 symbols per second. The array is then rearranged to create an output array to decorrelate the data and to separate adjacent symbols in time.

Sent By: Garlick & Harrison; 214 902 8101; Jun-20-01 14:15; Page 14 Dockst No. 11807R~WSOl~T
One advantage of this process is that the effects of bursty errors may be diminished and information eliminated by the bursty ert~or may potentially be recovered. Moreover, in some embodiments, lower transmission rate data is xepeated.
Here, the lower rate repeated symbols axe also separated therefore increasing the survivability of symbols to signal bit errors. xn addition, for xeasons beyond this application, tho data array that is ou'Cput by the block interleaver 106 is slightly modified in that defined power control hits are inserted in place of various data symbols.
The power control bits are used for power control purposes to optimize network effectiveness. Each symbol that is output from the multiplexer, lOB is produced to a dc:-multiplexer 113, which passes the input bits alternately to an in-phase branch 115 and a quadrature branch 117. Each symbol that i~ output from the de-multiplexer 'l13 is exclusively vR.d with an assigned Walsh function. The Walsh function t.s what, in a CDMA context, creates the channels of communicatiotz. Stated simply, each symbol is added across a defined bit seguence Continuing to refer to FIGURE 1, a long PN code ge~~erator 11o generates long pseudo random number (PN!
sequences to generate user-specific sequences of symbols.
The Walah code spread symbols from the o~inJ~iner 112 are then spread ih quadrature. The symbols are input to two exclusive.

Sent By: (iarlick 8~ Harrison; 2i4 902 8101; Jun-20-01 14:15; Page 15 Doaket No. 11807RRi7S01U
OR combiners to generate a pair of short PN sequences. The first~combiner exclusively ORs the Welsh code spread symbols on t,t~e in~phase branch 115 with the end phase sequence while the second combiner exclusively ORs the Welsh codE spread symbols on the branch 117 with tale quadrature phase (I) and (Q) sequences . The I and Q~ sequences are then produced to a PN processor 11A. that, in turn, produces the fl.nal In Phase and Quadrature chip sequences for transmission, The resulting I and Q channel code spread sequences arcs uspc.9 to bi-phase modulate a quadrature pair of sinusoids by driving the power level of the pair of sinusoids. The sinusoidal output signals axe then processed for transm~.ssion by an antenna.
FIGURE 2 is a functional block diagram illustrating the operation of a pilot channel. The pilot channel is a reference channel that mobile 5t:ations use for acquisit~.on, timing, and as a phase reference for coherent demodulation.
The pilot Channel signal. is transmitted at all times by each base station on each active CDMA frequency. Each mobile station continuously tracks the pilot signal. Unlike long code sequences, pilot channel sequences are repeated many times every few seconds. For example, in one known system, the pilot sequence is repeated 75 tunes every two seconds.
Not only does this aid a mobile station in its initial acquisition when it powers up, but also ensures rapid 1~

Sent By: Garlick 8 Harrison; 214 902 8101; Jun-20-01 14:15; Page 16 Docket No. 11807RRU801U
detection of cells or base ststion transceiv~r systems that form good handoff candidates.
The Same PN sequence for the pilot channel is shared by all base stations. However, each base station transmits the pilot channel at, a unique phase offset value. Thus, the timing of the pilot channel provides txacking of a timing reference fur a given base station and phase reference. The phase separation provides for extremely high reuse within one CDMA channel., frequency. The encoded nature of the pilot signal facilitates acguisition by the mobile stations in addition to the short duration of the pilot PN sequence.
In one described embodiment, the pilot channel is sent unmodulated, and is orthogona7.ly spread with a Walsh function zero to ensure that it is easily r..ecoqnizad. Quadrature spreading and channel filtering occur exactly as discussed for all forward channel txaffic.
FIGURE 3 is a functional block diagram illustrating a mobile station in aommunicati~n with a plurality of base stations. More specifically, FIGURE 3 illustrates a mobile station 31.0 in conununication with, or at least receivi.ug the pilot signals from various base station transceiver systems coupled to towers 320, 330, and 340. AS mentioned above With respArt to FIGURE 2, each base station transmits a pilot channel at a unique phase offset value. Accordingly, as the mobile station receives the three different pilot channel i3 Sent By: . (3arlick 8~ Harrison; 214 902 8101 ; Jun-20-01 14:15; Page 17 Docket No. 11H07RRUSOlU
signals, it may identify the base station by the relative phase offsets.
In operation, mobile station 310 continuously evaluates the signal strength of the pilot channe3, signals that are continuously transmitted by each of the three 8TS lowers 320, 330, and 390 to determine which BTS should be used for carrying tha forward channel communications signals (from the BTS to LHe mobile s~tdl:ion). Additionally, the mobile station 310 evaluates the signal strength trends of the pilot channels to continuously create a list of candidate base stations in the event that a hand off is necessary from one base station to another.
Typically, a mobile station will iequest a handoff from one base station to another when it determines that the signal strength of the new base station is stronger ox will soon be stronger than that oL the current base stairion carrying the communication signals to the mobile station.
Thus, in the example of FIGURE 3, mobile stat~.on 310 communicates with one of the three BTSs while the other two are kept in its candidate list for handoff purposes.
FIGURE 4 is functional block diagram illustrating the operation of a mobile station with respect to a plurality of sectors defined by a given base station transcPi.ver .syst.em.
As may be seen from oxamining FIGURE 4, a mobile station A10 is in communication with a 13~1~s characterized by a cell area ~a Sent By: (iarlick 8~ Harrison; 214 902 8101; Jun-20-01 14:15; Page 18 Docket No. 11807RRL1601~1 420. In other words, the mobile station 41U is transmitting its reverse link communication signals through the BTS that has created the cell 420. FTGURE 4 further illustrates that a given BTS furtt'ier defines a plurality of Cell sectors 430, 990, and 950. As may be seen, mobile station 410 is within sector 440 of the cell 420. As is known by those skilled in the art, the plurality of cell sectors is often created by a plurality of corresponding directional antennas that transmit signals that propagate outwardly iri a range of directions characterized by an angle. In the example of FIGURE 4, three directional antennas each define a 120-degree range of direction (cell sectors).
Thus, similar to the concept of a plurality of cells, mobile station 410 communicates with the antennas that Create cell sector 490. As a mobile station transitions from one cell to another, a handoff from BTS to 8TS occurs tha'l: is known as a "soft handoff". The ridndoff is referred to as ~~joft" because there are no frequency changes that. occur due to the nature of CDMA modulation techniques. Similarly, as the mobile station tratlsitions into a different sector of the same cell, a "softer handoff" occurs as thra communication signals are relayed by the antenna that derines the new sector into which the mc:~b~.le station 910 is traveling . The ".softer halZdott" refers to a transition from one BTS sector to another sector served by the same BTS.
l~

Sent By: Garlick & Harrison; 214 902 8101; Jun-20-01 14:18; Page 19/28 Doak~t No. 11807RRUe0IU
FIGURE 5A is a timing diagram illustrating a difference in usage bel:ween a fundamental channel and a supplemental channel in modern CDMA networks. A fundamental channel is a channel that is routinely used to transmit data from a base station to a mobile station. A supplemental channel, on the other hand, is one that is rPgerved For transmitting large amounts of data in a temporary data burst from the base station to the mobile station on the forward link. Thus, as is illustrated in FIC;URF 5A, the amount of data transmitted over the fundamental channel, as shown generally at 510, is constant over time. With respect to the supplemental channel, however, the data pattern may be descrik~ed as bursty.
More specifically, and referring now l.o the portion of FIGURE 5A shown generally at 520, the supplemental channel is characterized by periods of no data, and by periods characterized by the transmission of large amounts of data relative to the fundamental channel. As may be Seen, in the chart portion shown generally at 520, three data bursts are shown beginni,pg at time periods 530, 540, and 550. Also as may be seen, the amount of data for the supplemental channel, shown at 560 is notably greater than the amount of data transmitt:.ed by the fundamental channel shown generally at 570.
..

Sent By: (iarlick & Harrison; 214 902 8101; Jun-20-01 14:16; Page 20/28 ..
' aocxst rto, ziso~~vsola Tn current CDMA systems, the fundamental channels are lirnii:cd to car~t~y data ~ at one of two data rates, namely, 9 . 6 or 14.Q kilobits per second. The supplemental channel, however, i.s variable in rate. Zn some CDMA networks, the supplemental channel may be used to carry data in rates of 9.6. x9.2, 38.9, 76.8, and 153.6 kilobits per second. As may be seen therefore, at a maximum rate. thA ai,nr'1 a,.,e,..+~ ~, chatmel can carry almost eleven times mire data over a given period of time.
FIGURE 5H is a table illustrating an example of channel allocations for a given mobile station in communication with a plurality of base stations. As may be seen from referring to FIGURE 58, a given mobile station may have approximately up to six active channels being used as the fundamental channel for carrying ordinary dd~a communications. As may be seen in the column shown generally at 530, the mobile station is receiving data over a fundamental channel trorn g;X
different sectors, which tray be from up to six different base stations. Each of the sectors is represented by a letter A-F. The same mobile station may utili2e up to three sectors for receiving data during those periods in which transmission over a supplemental channel is Necessary.
Typically, the maximum number of sectors that may be used for a supplemental channel is limited to approximately two or three sectors for carxying data because the T '7 Sent By:~ Garlick 8~ Harrison; 214 902 8101; Jun-20-01 14:18; Page 21/2B
Docket No. 11807RRU$OlU
supplemental channels can consume much greater amounts of ' channel resources compared to the fundamental channels.
Thus, the maximum number of scsctors for use by supplemental channels is often referz~ed to as N,,~. While not shown specifically in FIGURE 58, supplemental channels are only allocated to a mobile station when there is a need to use a supplemental channel to transmit data in one embodiment of the present invention. Accordingly, while a mobile station is receiving data over a supplemental channel, it will decode the data from one sector, while also receiving it from one or two other sectors in the event that a soft or softer handoff is ns~cessary.
Referring again to FIGURE 4, mobi).e station 910 is shown within sectox 4~0 ~of the cell 420. ttowever, as may be seen, plurality of other BTSs is shown in FIGURE 4, each of which may be transmitting, to the mobile station 410 over a fundamental channel or a fundamerital~ channel and a supplemental channel. Because supplemental channels consume large amounts of resource relative to a fundamental channel in each sector, there is a need to minimize the number of sectors that are used to transmit data to a mobile station, such as mobile station 910 of FIGURE 4. Therefore, in the described embodiment, the active set of suppl~mental channels axe limited to a number N~, Which may be significantly lower than the number of fundamental channels, it is very important .. fg Sent By: (iarlick 8~ Harrison; 214 902 8101; Jun-20-01 14:18; Page 22/28 w a Doclelt No . iieo~~vsom to develop a system that selects the best (typically two or three) supplemental channels which truly are being received the most c~,early by the mobile set. Accordingly, there is a need for selecting the active supplemental channel set in a reliable way, The active sets are defined as the pilot signals associated with t~~e forward traffic channels that axe assigned to the mobile station. The candidate sets are the pilots not currently in the active set but being received by the mobile station with sufficient strength to indicate that the corresponding traffic channeJ.s can be successfully demodulated. The noighbor sets are those pilots that are not currently in the active or candidate sets but are likely handoff candidates.
I5 The pilot strength measurement message is used by the mobile station to direct the base station in the handoff process. Within this message, the mobile station reports the strength of the pilots associated with the forward traffic channels currently being demodulated (whether it would be likely to receive traffic from them , ns well as the pilots from the neighbor and remaining lists that are being received with sufficient strength so that traffic could be demodulated from them successfully if necessary. Ordinarily, a pilot stxength measurement message is sent under specified conditions.
I~

Sent By: (iarlick 8 Harrison; 214 902 8101; Jun-20-01 14:17; Page 23/28 Docket No, iieo~aRVSOitr For example, one condition is that a mobile station finds a sufficiently strong pilot in the nezghbor or remaining sets that is not associated with any of the Active Set and Candidate set pilots. Irrespective of wtlat event S triggered this message, the message will contain all Active and Candidate Set Pilots. Tn addition to these pilot, a "Keep" bit for each pilot is also Sent, which is the Mobile stations method of informing the Network which Pilots it wants t.o keep or add to the Active set and which pilots it wants to drop from the Active Set. Neighbor Set or Remaining set pilots, whose Strengths actually trigger the Pilot Strength MeasurErnent Message will first be put irvCo the Cand~.date set before the Message is generated and sent to the Network.
The basic algorithm for selecting , the active supplemental channel set is to limit the supplemental channols to those sectors whose pilot signal is the strongest. Eor example, the active supplemental channel set is limited to the three strongest pilot signals in the 24 described embodiment of the invention. Comparing this algo,~ithm to the active fundamental channel set, up to six strongest pilots may be used to select th~ active set of fundamental channels.
Because the number of sectors in the supplemental channel active set can be significantly lower thhn the number ..

Sent By: (iarlick & Harrison; 214 902 8101; Jun-20-01 14:17; Pege 24/28 Docket No. 11807RRUSO1U
of sectors in the fundamental channel active set, several ditTc~rent methodologies may be employed for selecting the strongest two or three pilot channels for the active supplemental channel set, For example, a base stdt.~oir controller may ask a mobile station to transmit a periodic pilot strength measurement message (PPSMM) to enable 'the cellular network to determine which sectors should be included as the supplemental channel active set for the mobile station. For example, it has been suggested that the periodic PSrlr~s be transmitted every second or once every two seconds so that the strongest two or three sectors may be frequently determined. This approach should bo reasonably effective at insuring that the strongest sectors axe being used for transmitting supplemental channel data 1:o the mobile station. One problem with this scheme is that it increases reverse link load and requires processing at the 8TS and the HSC. Thus, the amount of resource consumed to implemetzt this scheme is less than optimum. In other words, a scheltte that:
requires less processing by the BTS and HSC would be preferred.
Accordingly, a method of the present invention includes using a combination of reverse link signal strength to noiqe information (Eb/No) in addition to using periodic P~MM to determine wh~.oh supplemental channels should be part of the active supplemental channel set in one described embodiment Sent By: Oarlick & Harrison; 214 902 8101; Jun-20-01 14:17; Page 25/28 ' Doc7~et No. 11807RRUSOlU
of the present invention. Eb/Na is, more specifically, a measured energy per bit over spectral noise density.
FrGURE 6 is a state machine illustrating distributed logic for the transmission of pilot strength measurement messages that are to be transmitted by a mobile station. As discussed befoxe, a mobile station generates a pilot strength measurement message under a plurality of colldi Cic~ns including the detection of a new and strong pilot signal or the determination that a pilot signal asROCiated with a forward traffic channel has dropped below a specified threshold.
According to one embodiment of the present invention, however, the base station controller will request that the mobile transmits periodic pilot strength measurement messages under specified conditions. More specifically, the system contemplates two modal of oper$tion. The occasional pilot strength measurement messages are transmitted in an ordinary manner in a first mode of operation as illustrated at state 610. Whenever the active number of sectors carrying a fundamental channel exceeds the maximum number of active sectors that can be used tc~ carry a supplemental channel, however, the system transitions into a mode of transmitting periodic pilot strength measurement massage as reflected by state 620.
In the described embodiment of the invention, when the Sent By: Oarlick 8~ Harrison; 214 902 8101; Jun-20-D1 14:17; Page 28/28 ' Docket No. 11807RRT7S01U
system is in a state 620, the mobile station will generate a periodic pilot strength measurement message once every two seconds in one embodiment of the invention. It is understood, of course, that the period may be varied. For example, .in one embodiment, the period~,c pilot strength measurement messages are transmitted once every three seconds and in another embodiment, once every second.
The mobile station remains in a periodic pilot strength measurement message state G20 as long as the number of IO sectors in the fundamental channel active set exceeds the maximum number of sectors in the supplemental. channel active set. rf the size of the fundamental channel active sel: drops to equal the maximum size of the supplemental channel active set, then the system transitions back to state 610 wherein pilot strength measurement messages are only transmitted .occasionally according to ordinary operating guidelines described above.
In the described embodiment of the invention, the base station controller generates a signal to the mobile stat~.on to cause it to transition into tho periodic pilot strength measurement message transmission state 520. Once the mobile station receives the command to transition into state 620, it remains in that state until such time that the base statir~n controller generates a sa.gnal commanding it to transition to state 610 wherein pilot strength measurement messages are Sent By: Garlick 8~ Harrison; 214 902 8101; Jun-20-01 14:23; Page 2 Doak~E No. 11807RRUSOlU
only transmitted occasionally according to spec:ifi~:d r:onditions .
FIGURE 7 is a~ flow chart illustrating z~ method within a base station controlxer for r.anlcing' pilots according to reverse link Eb/No according to one embodiment of the present invention. FIGURE 6 had illustrated the various states of operation according to the number of sectors iri the fundamental channel active set in a relation to the number of sectors in the supplemental channel active set. As has been stated already, the number of sectors in the supplemental channel active set is typically limited in the described embodiment of the invent~.vn to two or three because of the back haul re.~ourc:es that are consumed in transmitting large amounts of data, through a plurality of active sectors from various base station transceiver systems. Thus, whenever the nu~~er of sectors in the fundamental charnel active set exceeded the number of active supplemental channel sectors, the system transitions into state 620 in which periodic pilot strength measurement messages are generated to insure that the active set of supplemental. channels is likely the strongest set of communications links.
FIGURE 7, therefore, illustrates a method within a base station controller that occurs while the system is in state 620 of FIGURE 6 . More specifically, ~ the systam c;otitinuously monitors to determine whether the number of active 2~

Sent By: Oarlick ~ Harrison; 214 902 8101; Jun-20-01 14:23; Page 3 Dookot No. 11807RRU901U
fundamental channel secto~;s is greater or less than or equal to the maximum number of active supplemental channel sectors (step 710) .
It should be understood that: the method of FTGURE 7 ' 5 illustrates a method that is continuously (periodicall.y) performed in a processor while monitoring ~y3tem conditions.
Thus, if the r~urnber of active fundamental channel sectors is not gxeater than the maximum number of active supplemental channel st~ctors, the method is terminated until its next execution. Such condition would exist as long as the system is operating within state 610 of FzGfIRE 6. Whenever the system transitions into state 62D, however, the first execution of the method in FTGURE 7 would lead to a result of yes at step 710, which cau9eg the remainder of the method to be executed.
More specifically, the next step includes initializing counters and registers as i.s common whenever a routine is first executed (step 720). Thereaf~.er, the reverse link Eb/No measurements that are determined by the active base station transceiver. systems are collected and transmitted to the base station controller. The base station controller, therefore, collects the revexse link Eb/No measurements (step 730) and ranks pilot signals according to the measured reverse link EL~/No (step 790). After a list of pilots is ranked in step 740, the base station control)c~r determines Sent By: (iarlick & Harrison; 214 902 8101; Jun-20-01 14:23; Page 4 Dookair No. 11807Ravsoiv whether a pilot strength measurement message has been received (step 750). If a pilot strenglrh measurement message hag hPPn received, then a counter is set equal to zero (step 760). If the pilot stxength measurement message has not been received then the counter of step 76U is incremented (step 770) .
Because the method of FIGURE 7 is processed repetitivel~r on a periodic basis, the counter incremented or set to zero in steps ?70 or 760, respectively serves to represent a period of time since the last pilot strength measurement message was received. The reason for this is that the method o~ FIGURE 7 is repeated on a frequent and relatively constant frequency. Thus the counter represents an approximate value of time that as elapsed.
In alternate embodiments of the present invention, rather than incrementing the counter, a base station controller merely evaluates the actual amount of time that has elapsed since the last pilot strength measurement message has been received. The amount of time or counter value will hc~ used i.n other methods described herein.
Either after step 770 or 760, Lhe k~dse sl:a~iou controller evaluates whether the number of active fundamental channel sectors is greater than the maximum number of active supplemental ctudririel sec:Lors (step 780) . If the answer is yes, then the system loops back to step 730 on the next 2fi -Sent By: Liarlick 8 Harrison; 214 902 8101; Jun-20-01 14:24; Page 5 Dook~t No. 1180~RRUSOlU
iteration or execution of the method herein. If the number of active fundamental channel sectors is no longer greater than the maximum number of active supplemental channel sectors, then the method includes proceeding to step 710 upon the next execution of the method. One reason that the method of FIGURE 7 is performed is to continuously maintain a list of pilots to determine the atrvngeat communication channels for the supplemental channel active set in the event that a supplemental channel burst request is reaeiVad.
FIGURE 8 is a flow chart illustrating a method peZformed by a base station contxollex whenever a supplemental channel burst request is received according to one embodiment of the prasenL invemLior~. Whertever~ a supplemental channel burst request is received (step 805),' the system initially evaluates whether the number of active fundamental channel sectors is greater than the maximum number of sectors in the supplemental channel active set (step 810).
If the number of active fundamental channel sectors is not greater than the maximum number of active supplemental channel sectors, then the actirre set of the supplemental.
channel is selected to equal the active set of t1-~e fundamental channel (step 820). If, however, the active number of fundamental channel sectors is grsatRx than the maximum number of active supplemental channel sectors, then the system evaluates whether the counter of steps 760 and 770 2~

Sent By: Darlick & Harrison; 214 902 8101; Jun-20-01 14:24; Page 8 Docket No. 11807RRUSO1V
of FIGURE 7 is below a defined threshold value (step 830).
If the counter is below the specified threshold, then the supplemental active set of sectors is chosen according to the last received pilot strength measurement message that was generated by th~ mobile station (sl:ep 84pj. This is true regardless of whether the pilot strength measurement message was generated by the mobile according to thc~ detection of a defined event as described herein or whether it was generated as a periodic pilot strength measurement message.
JO Zf the counter of steps 760 or 770 is nvt below ~h~s spec;;ified threshold, then the supplemental act~.ve set of sectors is chosen according to t:he reverse link Eb/No information (step 850). More specifically, the active set of supplemental channel sectors is chosen according to the pilots that were ranked ace~rding to xeverse link Eb/No in step 740 of FIGURE 7. As indical.ed in the discussion of FIGURE 7, the method of 830 includes evaluating a counter value. However, ~,f elapsed time is used as a measurement parameter instead of a counter value then step 830 involves evaluating whether the elapsed time is below a defined threshold. After each of the steps 820, 8~0, or 850 herein FIGURE 8, the next step ~f the method includes proceeding with the supplemental channel burst step 870. The method of FIGURE 8 is then ieped~ed the next time that a supplemental ~a Sent By: Garlick 8 Harrison; 214 902 8101; Jun-20-01 14:24; Pege 7 Docket No. 11807RRUSOlU
channel bur3t request is receivod in step 805.
FIGURE 9 is a flow chart illustrating a method within a base station controller for selecting the artiva Set of supplemental channel sectors during a burst according to one embodiment of the present invention. Referring now to FIGURE
9, the method includes determi.ni.ng, in a base station controller whether a burst is in progress (step 910). As before, the method herein is one that is continuously or periodically performed. If a burst is not in progress, the mel.lrcd of FIGURE 9 is terminated. If a burst is in progress, however, then the method includes determining whether a pilot strength measurement message ha: been received (step 920).
If a pilot strength measurement message has been received, then the active set of supplemental channel sectors is updated with new pilot strength information received within the plLot strength measurement message (step 930). After the supplemental channel active set is updated in 930, the timer Tpsmm is reoet to zero (step 935). If a pilot strength measurement message has not been received, however, then the method includes determining whether the counter of set 750 or 760 of FIGURE 7 has axceeded d Specified threshold (step 94U). As before, this threshold could also be evaluated against a lapsed time. If the threshold has been exceeded, the system determines whether the active set of supplemental channel sectors from the reverse link Eb/No information is 2~ _ Sent By: ~arlick & Harrison; 214 902 9101; Jun-20-01 14:24; Page 8 r Dockot No. 1180~RRUSO1L?
not equal to the current set of supplcmontal channels (step 950). If they are not equal, then the active set of supplemental channel sectors is selected to the pilots that were ranked according to the reverse link Eb/No information (step 960), zf the answer was no then the determination made in step 940 and 950 or if. the answers were yes to both of those and step 960 was performed, lieu l:he method includes determining whether the burst is continuing (step y70). If the burst. is continuing, then step 920 is .repeated. If the burst is not being c:vntinued, then the method is Germinated until the next iteration or execution of the method shown in FIGUTtE 9.
FIGURE 10 is a functional block diagram of a communication network according to an embodiment of the present invention. Referring now to FIGURE 10, a uel.wo.ck shown generally at lUUO includes a mobile switching center 1010 that is coupled to communicate with a base station controller 1020 which in turn is coupled to commuriic:ate with a plurality of base station transceiver systems 1030, 1040, and 1050. Each of the base station transceiver systems is coupled to a plurality of antennas 1035, 1045, and 1055, respectively. Each of the base station transceiver systems 1030, 10Q0, and 1050 communicate with mobile stations, by way of example, mobile station 1060 through the antennas 1035, 1045, and 1055, respectively.

Sent By: Oarlick 8 Harrison; 214 902 8101; Jun-20-01 14:24; Page 9 Docket No. 11g07RRU901U
' More specifically, each of the base station transceiver systems 1030, 1040, and 1050 creates a wireless communication link 1070, 1080, and 1090 respect9.vely with mobile station 1060.
Each base station controller includes a processing unit 1052 and a memory 1054. Memory 1054 includes computer instructions that define the operational logic of the bass station controller. Processing unit 1052 rpcc~ives the computer instruca~.ons stored in memory 1054 by way of an internal bus 1055. Thus, processing unit 1052 receives the computer instructions over bus 1056 and executes them to perform the method and processes of the present .invention.
While the described embodiment includes a processing unit that executes the computer instructions stored within memory 1054, an alternative design of the present invention includes the use of ASIC processors that are formed specifically to execute the defined logic. Accordingly, i.n the alternat~ embodiment of the invdntion, the ASIC processor itself will include circuit modules that perform the logic defined by the inventive processes herein. It is undcxstood, therefore, that in the discussion hefiein relating to processing unit and mQmory, execution ~f, the inventive methods may alternately be performed by a module. Similarly, in the d~.scussion relating to a module that executes the specified logic may also be alternately implemented in the Sent By: Garlick ~ Harrison; 214 902 8101; Jun-20-01 14:25; Page 10 Docket No. meo~~ursmv scheme including processing units, memory, and internal buses.
Each of the base transceiver sets, by way of example, base station transceiver system 1050, includes a module that determines the reverse link Eb/N~ for the communication s~.gnals transmitted by mobile station 1060 to antenna 1055.
Thus, BTS 1050 determines the reverse link Eb/No and transmits the same to base station controller 1020. ~As described herein, base station transceiver system 1050 may implement the module 1052 either in hardware, or in software stored as computer instructions within an internal memory that is executed by an internal pr.o~PSSor.
In operation, the mobile station 1060 transcni~s the pilot strongth measurement message 1095 over communication link 1090 to antenna 1055 which then conducts the same to HTS
1050. DTS 1050 then transmits Lire pilot strength measurement message to BSC 102U. Additionally, module 1052 of BTS 1050 calculates the reverse link Eb/No and transmits the same in a message 1054 to B3C 1020.
2U While the invention is susceptible to various modifications and a7.ternative forms, specific ernbvdiments thereof have been ,shown by way of example in the drawings and detailed description. It should be understood, however, that the drawings and detailed description thereto az;e not intended to limit the invention to the particular form Sent By: (iarlick & Harrison; 214 902 8101; Jun-20-01 14:25; Page 11 Dock~t No. 11807RRU801U
disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the claims. Fo.r example, the circuitry described herein may be foriued of electrical or optical components or a combination thereof. Additionally, the logic of the above described invention may be formed in haxdw»r.s ~r defined by computer instructions stored in memory and executed by a processor. As may be seen, the described embodiments may be modified in many different ways without depart~.ng from the scope or teachings of the invention.

Claims (16)

Claims:
1. A base station controller, comprising:
circuitry to prompt the base station controller to transmit a signal to a mobile station to cause the mobile station to transmit pilot strength measurement messages only when defined conditions are detected: and circuitry to prompt the base station controller to transmit a signal to the mobile station to cause it to generate pilot strength measurement messages on a periodic basis.
2. The base station controller of claim 1 wherein the base station controller transmits a signal to the mobile station to prompt it to transmit periodic pilot strength measurement messages whenever an active number of fundamental channels is greater than a maximum number of active supplemental channel sectors.
3. The base station controller of claim 1 wherein the base station controller transmits a signal to the mobile station to cause it to transmit pilot strength measurement messages only upon detecting conditions whenever the active number of fundamental channel sectors is equal to or less than the maximum number of active supplemental channel sectors.
3~
4. A method for selecting an active set of supplemental channel sectors in a code division multiple access system, comprising:
determining an approximate amount of time since a pilot strength measurement message was received from a mobile station;
determining a signal strength over noise value; and selecting an active set of supplemental channel sectors based upon one of the determined signal strength over noise value or the list of strongest pilots as indicated from the pilot strength measurement message.
5. The method of claim 4 wherein the set of active supplemental channel sectors is determined by evaluating the signal strength over noise value whenever a specified amount of time has elapsed since the last pilot strength measurement message was received.
6. The method of claim 4 wherein the set of active supplemental channel sectors is determined by evaluating the pilot signal strength whenever the amount of time that has elapsed since the last pilot strength measurement message was received is below a specified amount of time.
7. The method of claim 4 wherein the step of selecting includes evaluating a threshold value of time that is approximately equal to two seconds.
8. The method of claim 4 wherein the approximate amount of time is determined by evaluating the actual amount of time that has elapsed.
9. The method of claim 4 wherein the approximate amount of time is determined by evaluating a counter value that is incremented each time the determination is made since the last pilot signal strength measurement message was received.
10. Circuitry for selecting a set of active supplemental channel sectors, comprising:
a memory for storing computer instructions;
a bus coupled to the memory;
a processor coupled to the bus to receive and execute computer instructions stored within the memory; and wherein the computer instructions define logic to prompt the processor to select the active set of supplemental channel sectors according the approximate amount of time that has elapsed since a last pilot signal strength measurement message was received from a mobile station.
11. The circuitry of claim 10 wherein the logic of the computer instructions utilizes a counter that is incremented each time the processor determines the active set of supplemental channel sectors.
12. The circuitry of claim 11 wherein the counter is reset each time a pilot signal strength measurement message is received.
13. The circuitry of claim 12 wherein the counter value represents an approximate amount of time since the last pilot signal strength measurement message was received.
14. The circuitry of claim 10 wherein the approximate amount of time is determined by evaluating the amount of time that has elapsed.
15. The circuitry of claim 10 wherein the approximate amount of time is defined as a threshold value and is equal to two seconds.
16. The circuitry of claim 10 wherein the active supplemental set of channel sectors is determined at a time when a supplemental channel is needed to carry data.
CA002351164A 2000-06-22 2001-06-21 Method and apparatus for supplemental channel soft hand off in cdma systems Abandoned CA2351164A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8472965B2 (en) 2009-03-17 2013-06-25 Qualcomm Incorporated Mobility in multi-carrier high speed packet access

Families Citing this family (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1142227A2 (en) * 1998-12-23 2001-10-10 Nokia Wireless Routers, Inc. A unified routing scheme for ad-hoc internetworking
WO2001041479A1 (en) * 1999-11-24 2001-06-07 Fujitsu Limited Base station control station device, radio terminal device and radio communication system
US20020068566A1 (en) * 2000-12-04 2002-06-06 Jonas Ohlsson Preliminary performance of handover function in telecommunications system
KR100373343B1 (en) * 2001-03-05 2003-02-25 주식회사 하이닉스반도체 Softer Handoff Method for Supplemental Channel in Time Division Multiplexing
US8160020B2 (en) 2001-06-25 2012-04-17 Airvana Network Solutions, Inc. Radio network control
US8195187B2 (en) 2001-06-25 2012-06-05 Airvana Network Solutions, Inc. Radio network control
KR100480799B1 (en) * 2002-09-04 2005-04-07 엘지전자 주식회사 Method for Reverse Supplemental Channel Handoff in CDMA Mobile Communication System
US7787419B2 (en) * 2002-09-17 2010-08-31 Broadcom Corporation System and method for providing a mesh network using a plurality of wireless access points (WAPs)
US7783312B2 (en) * 2003-01-23 2010-08-24 Qualcomm Incorporated Data throughput improvement in IS2000 networks via effective F-SCH reduced active set pilot switching
KR100547805B1 (en) * 2003-08-30 2006-01-31 삼성전자주식회사 Reverse Link Coupling Apparatus and Method in Mobile Communication System Supporting Softener Handoff
US20060009206A1 (en) * 2004-07-06 2006-01-12 Gandhi Asif D Method of adding a sector to an active set
US7917624B2 (en) * 2004-11-18 2011-03-29 Sanjay M. Gidwani Wireless network having control plane segregation
US7933247B2 (en) * 2004-11-18 2011-04-26 Sanjay M. Gidwani Real-time scalable wireless switching network
US7787416B2 (en) * 2004-11-18 2010-08-31 Gidwani Sanjay M Wireless network having real-time channel allocation
US20060229025A1 (en) * 2005-03-30 2006-10-12 Lucent Technologies Inc. Method for extracting optimal reverse link capacity by scaling reverse link Eb/No setpoint based on aggregate channel load and condition
US8099504B2 (en) * 2005-06-24 2012-01-17 Airvana Network Solutions, Inc. Preserving sessions in a wireless network
TW200721861A (en) * 2005-09-09 2007-06-01 Nokia Corp Use of measurement pilot for radio measurement in a wireless network
US7751835B2 (en) 2005-10-04 2010-07-06 Airvana, Inc. Non-circular paging areas
US8145221B2 (en) 2005-12-16 2012-03-27 Airvana Network Solutions, Inc. Radio network communication
US8619702B2 (en) 2005-12-16 2013-12-31 Ericsson Evdo Inc. Radio network control
US8094630B2 (en) 2005-12-16 2012-01-10 Airvana Network Solutions, Inc. Radio frequency dragging prevention
US8085696B2 (en) 2006-07-14 2011-12-27 Airvana Networks Solutions, Inc. Dynamic modification of route update protocols
US9131486B2 (en) * 2006-12-01 2015-09-08 Qualcomm Incorporated Control signal transmission for wireless communication systems
US8379578B2 (en) * 2006-12-01 2013-02-19 Qualcomm Incorporated Control signal transmission for wireless communication systems
US8843638B2 (en) 2007-12-13 2014-09-23 Ericsson Evdo Inc. Handing off active connections
US8472992B1 (en) 2010-05-18 2013-06-25 Sprint Spectrum L.P. Power control setpoint based on virtual termination target
US8396512B1 (en) 2010-06-14 2013-03-12 Sprint Spectrum L.P. Enhanced virtual termination target mechanism
US8705385B1 (en) * 2010-06-17 2014-04-22 Sprint Spectrum L.P. Dynamic virtual termination target based on RF conditions
US8472382B1 (en) 2010-11-10 2013-06-25 Sprint Spectrum L.P. Adaptive virtual termination target
WO2013183649A1 (en) * 2012-06-08 2013-12-12 日本電気株式会社 Communication apparatus, communication system, communication method, and program
CN108169734A (en) * 2017-12-07 2018-06-15 国网山东省电力公司烟台供电公司 A kind of method of locating terminal and system based under fiber mode

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6418148B1 (en) * 1995-10-05 2002-07-09 Lucent Technologies Inc. Burst-level resource allocation in cellular systems
KR100196447B1 (en) * 1996-12-20 1999-06-15 서정욱 Active set maintenance method in cdma system by controlling handoff area
US5987326A (en) * 1997-02-11 1999-11-16 Qualcomm Incorporated Transmit power reduction for a high speed CDMA link in soft handoff
KR100265855B1 (en) * 1997-07-10 2000-09-15 정선종 Method for processing handoff call in wireless communication system
US6377809B1 (en) * 1997-09-16 2002-04-23 Qualcomm Incorporated Channel structure for communication systems
KR100291476B1 (en) * 1998-05-25 2001-07-12 윤종용 A method and a system for controlling a pilot measurement request order in cellular system
KR100277058B1 (en) * 1998-06-15 2001-01-15 윤종용 A method for deciding the starting time of inter-frequency hard handoff and a method for initiating of hard handoff in mobile telecommunication system
KR100262229B1 (en) * 1998-06-22 2000-07-15 김영환 Handoff method of cdma mobile communication system
US6018662A (en) * 1998-09-08 2000-01-25 Nortel Networks Corporation Method for performing progressive soft handoff in CDMA systems
KR100313914B1 (en) * 1998-10-09 2001-12-20 서평원 Packet Data Transmission Rate Control Method in Mobile Communication System
US6516196B1 (en) * 1999-04-08 2003-02-04 Lucent Technologies Inc. Intelligent burst control functions for wireless communications systems

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8472965B2 (en) 2009-03-17 2013-06-25 Qualcomm Incorporated Mobility in multi-carrier high speed packet access

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