Title of Invention

A METHOD FOR REDUCING POWER CONSUMPTION OF A SUBSCRIBER STATION

Abstract 370/CHENP/2004 ABSTRACT A METHOD FOR REDUCING POWER CONSUMPTION OF A SUBSCRIBER STATION" A method and system for Utilization of an Outer Decoder in a Broadcast Services Communication System is described. An outer decoder and an itmer decoder encode a block of information to be transmitted, to improve protection by adding redundancy. The redundancy permits decoding of the information from less than a complete encoded block of information. Consequently, the receiving station determines when sufficient amount of information for successful decoding has been received, and utilizes the time remaining before the next block of information arrives to perform other activities, e.g. hard handoff on a broadcast channel, inter-frequency, hard handoff, and other activities. Alternatively, the receiving station can cease reception, thus decrease power consumption. Furthermore, part of the information block may be utilized for transmission of signaling information. (Figure 1)
Full Text

BACKGROUND
Field
[1001] The present invention relates to broadcast communications,
othenwise known as point-to-multipoint communications, in a wireline or a
wireless communication system. More particularly, the present invention relates
to a system and method for utilization of an outer decoder in such a broadcast
communication system.
Background
[1002] Communication systems have been developed to allow transmission
of information signals from an origination station to a physically distinct
destination station. In transmitting information signal from the ongination station
over a communication channel, the information signal is first converted into a
form suitable for efficient transmission over the communication channel.
Conversion, or modulation, of the information signal involves varying a
parameter of a carrier wave in accordance with the information signal in such a
way that the spectrum of the resulting modulated carrier is confined within the
communication channel bandwidth. At the destination station the original
information signal is replicated from the modulated carrier wave received over
the communication channel. Such a replication is generally achieved by using
an inverse of the modulation process employed by the origination station.
[1003] Modulation also facilitates multiple-access, i.e., simultaneous
transmission and/or reception, of several signals over a common
communication channel. Multiple-access communication systems often include
a plurality of subscnber units requiring intermittent service of relatively short
duration rather than continuous access to the common communication channel.
Several multiple-access techniques are known in the art, such as time division
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multiple-access (TDMA), frequency division multiple-access (FDMA), and
amplitude modulation multiple-access (AM). Another type of a multiple-access
technique is a code division multiple-access (CDMA) spread spectrum system.
that conforms to the "TIA/EIA/IS-95 Mobile Station-Base Station Compatibility
Standard for Dual-Mode Wide-Band Spread Spectrum Cellular System,"
hereinafter referred to as the IS-95 standard. The use of CDMA techniques in a
multiple-access communication system is disclosed in U.S. Patent No.
4,901,307, entitled "SPREAD SPECTRUM MULTIPLE-ACCESS
COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL
REPEATERS," and U.S. Patent No. 5,103.459, entitled "SYSTEM AND
METHOD FOR GENERATING WAVEFORMS IN A CDMA CELLULAR
TELEPHONE SYSTEM," both assigned to the assignee of the present
invention.
[1004] A multiple-access communication system may be a wireless or wire-
line and may carry voice and/or data. An example of a communication system
carrying both voice and data is a system in accordance with the IS-95 standard,
which specifies transmitting voice and data over the communication channel. A
method for transmitting data in code channel frames of fixed size is described in
detail in U.S. Patent No. 5,504,773, entitled "METHOD AND APPARATUS FOR
THE FORMATTING OF DATA FOR TRANSMISSION", assigned to the
assignee of the present invention. In accordance with the IS-95 standard, the
data or voice is partitioned into code channel frames that are 20 milliseconds
wide with data rates as high as 14.4 Kbps. Additional examples of a
communication systems carrying both voice and data comprise communication
systems conforming to the "3rd Generation Partnership Project" (3GPP),
embodied in a set of documents including Document Nos. 3G TS 25.211, 3G
TS 25.212, 3G TS 25.213, and 3G TS 25.214 (the W-CDMA standard), or "TR-
45.5 Physical Layer Standard for cdma2000 Spread Spectrum Systems" (the
IS-2000 standard).
[1005] An example of a data only communication system is a high data rate
(HDR) communication system that conforms to the TIA/EIA/IS-856 industry
standard, hereinafter referred to as the IS-856 standard. This HDR system is
3

based on a communication system disclosed in co-pending application serial
number 08/963,386, entitled "METHOD AND APPARATUS FOR HIGH RATE
PACKET DATA TRANSMISSION," filed November 3,1997, and assigned to the
assignee of the present invention. The HDR communication system defines a
set of data rates, ranging from 38.4 kbps to 2.4 Mbps, at which an access point
(AP) may send data to a subscriber station (access terminal, AT). Because the
AP is analogous to a base station, the terminology with respect to cells and
sectors is the same as with respect to voice systems.
[1006] In a multiple-access communication system, communications
between users are conducted through one or more base stations. A first user
on one subscriber station communicates to a second user on a second
subscriber station by transmitting data on a reverse link to a base station. The
base station receives the data and can route the data to another base station.
The data is transmitted on a forward link of the same base station, or the other
base station, to the second subscriber station. The forward link refers to
transmission from a base station to a subscriber station and the reverse link
refers to transmission from a subscriber station to a base station. Likewise, the
communication can be conducted between a first user on one subscriber station
and a second user on a landline station. A base station receives the data from
the user on a reverse link, and routes the data through a public switched
telephone network (PSTN) to the second user. In many communication
systems, e.g., 18-95, W-CDMA, IS-2000, the fonward link and the reverse link
are allocated separate frequencies.
[1007] The above described wireless communication service is an example
of a point-to-point communication service. In contrast, broadcast sen/ices
provide point-to-multipoint communication sen/ice. The basic model of a
broadcast system consists of a broadcast net of users served by one or more
central stations, which transmit information with a certain contents, e.g., news,
movies, sports events and the like to the users. Each broadcast net user's
subscriber station monitors a common broadcast forward link signal. Because
the central station fixedly determines the content, the users are generally not
communicating back. Examples of common usage of broadcast services

communication systems are TV broadcast, radio broadcast, and the like. Such
communication systems are generally highly specialized purpose-build
communication systems. With the recent, advancements in wireless cellular,
telephone systems there has been an interest of utilizing the existing
infrastructure of the - mainly point-to-point cellular telephone systems for
broadcast services. (As used herein, the term "cellular" systems encompasses
communication systems utilizing both cellular and PCS frequencies.)
[1008] The information signal to be exchanged among the terminals in a
communication system is often organized into a plurality of packets. For the
purposes of this description, a packet is a group of bytes, including data
(payload) and control elements, arranged into a specific format. The control
elements comprise, e.g., a preamble and a quality metric. The quality metric
comprises, e.g., cyclical redundancy check (CRC), parity bit(s), and other types
of metric known to one skilled in the art. The packets are usually formatted into
a message in accordance with a communication channel structure. The
message, appropriately modulated, traveling between the origination terminal
and the destination terminal, is affected by characteristics of the communication
channel, e.g., signal-to-noise ratio, fading, time variance, and other such
characteristics. Such characteristics affect the modulated signal differently in
different communication channels. Consequently, transmission of a modulated
signal over a wireless communication channel requires different considerations
than transmission of a modulated signal over a wire-like communication
channel, e.g., a coaxial cable or an optical cable. In addition to selecting
modulation appropriate for a particular communication channel, other methods
for protecting the information signal have, been devised. Such methods
comprise, e.g., encoding, symbol repetition, interleaving, and other methods
know to one of ordinary skill in the art. However, these methods increase
overhead. Therefore, an engineering compromise between reliability of
message delivery and the amount of overhead must be made. Even with the
above-discussed protection of information, the conditions of the communication
channel can degrade to the point at which the destination station possibly
cannot decode (erases) some of the packets comprising the message. In data-
5"

only communications systems, the cure is to re-transmit the non-decoded
packets using an Automatic Retransmission reQuest (ARQ) made by the
destination station to the origination station. However, as discussed, the
subscribers do not communicate back to the base station. Furthermore, even iif
the subscribers were allowed to communicate ARQ, this communication might
overload the communication system. Consequently, other means of information
protection are desirable.
[1009] Based on the foregoing, there is a need in the art for a method and a
system and method for utilization of an outer decoder in such a broadcast
communication system.
SUMMARY
[1010] Embodiments disclosed herein address the above stated needs by
providing a method and a system executing the method to utilize an outer
decoder. The use of the outer decoder further facilitates reducing power
consumption of a subscriber station by determining a number of frames that
must be received correctly; and terminating reception of the frames when said
determined number of frames was received correctly.
[1011] In another aspect of the invention, the use of the outer decoder
further facilitates improved method for hard handoff on a common broadcast
channel by receiving at a subscriber station frames transmitted on the common
broadcast channel from a first sector; determining at the subscriber station a
need for handoff; identifying at the subscriber station at least one sector
belonging to a soft handoff group different from a soft handoff group including
the first sector; determining a number of frames from a current buffer that must
be received correctly; terminating reception of the frames when said determined
number of frames were received correctly; and beginning reception of frames
from the identified at least one sector.
[1012] In another aspect of the invention, the use of the outer decoder
further facilitates improved method for inter-frequency hard handoff by receiving
at a subscriber station service on a channel from a sector in the origination

system; determining at the subscriber station a need for handoff; identifying at
the subscriber station a destination system; determining a number of frames
from a current buffer that must be received correctly; terminating reception of
the frames when said determined number of frames were received correctly;
tuning to a frequency of the destination system; and receiving sen/ice on a
channel from at least one sector if the at least one sector of the destination
system is acquired at the subscriber station.
[1013] In another aspect of the invention, the use of the outer decoder
further facilitates utilizing a common broadcast channel for signaling by
replacing part of a content of a parity portion of a transmitting buffer with a
signaling information; and transmitting a content of the transmitting buffer at a
determined time on the common broadcast channel.
BRIEF DESCRIPTION OF THE DRAWINGS
[1014] FIG, 1 illustrates conceptual block diagram of a High-Speed
Broadcast Service communication system;
[1015] FIG. 2 illustrates a concept of physical and logical channels for the
HSBS;
[1016] FIG. 3 illustrates a prior art encoding;
[1017] FIG. 4 illustrates physical layer processing in accordance with one
embodiment of the invention;
[1018] FIG. 5 illustrates a transmit buffer;
[1019] FIG. 6 illustrates concept of soft-handoff groups in a broadcast
communication system; and
[1020] FIG. 7 illustrates timing diagram for hard handoff.
V

DETAILED DESCRIPTION
Definitions
[1021] The word "exemplary" is used herein to mean "serving as an
example, instance, or illustration." Any embodiment described herein as
"exemplary" is not necessarily to be construed as preferred or advantageous
over other embodiments.
[1022] The terms point-to-point communication is used herein to mean a
communication between two subscriber stations over a dedicated
communication channel.
[1023] The terms broadcast communication or point-to-multipoint
communication are used herein to mean a communication wherein a plurality of
subscriber stations are receiving communication from one source.
[1024] The term packet is used herein to mean a group of bits, including data
(payload) and control elements, arranged into a specific format. The control
elements comprise, e.g., a preamble, a quality metric, and others known to one
skilled in the art. Quality metric comprises, e.g., a cyclical redundancy check
(CRC), a parity bit, and others known to one skilled in the art.
[1025] The term access network is used herein to mean a collection of base
stations (BS) and one or more base stations' controllers. The access network
transports data packets between multiple subscriber stations. The access
network may be further connected to additional networks outside the access
network, such as a corporate intranet or the Internet, and may transport data
packets between each access terminal and such outside networks.
[1026] The term base station is used herein to mean the hardware with
which subscriber stations communicate. Cell refers to the hardware or a
geographic coverage area, depending on the context in which the term is used.
A sector is a partition of a cell. Because a sector has the attributes of a cell, the
teachings described in terms of cells are readily extended to sectors.
[1027] The term subscriber station is used herein to mean the hardware with
which an access network communicates. A subscriber station may be mobile or
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stationary. A subscriber station may be any data device that communicates
through a wireless channel or through a wired channel, for example using fiber
optic or coaxial cables. A subscriber station may further be any of a number of.
types of devices including but not limited to PC card, compact flash, external or
internal modem, or wireless or wireline phone. A subscriber station that is in the
process of establishing an active traffic channel connection with a base station
is said to be in a connection setup state. A subscriber station that has
established an active traffic channel connection with a base station is called an
active subscriber station, and is said to be in a traffic state. ■
[1028] The term physical channel is used herein to mean a communication
route over which a signal propagates described in terms of modulation
characteristics and coding.
[1029] The term logical channel is used herein to mean a communication
route within the protocol layers of either the base station or the subscriber
station.
[1030] The term communication channel/link is used herein to mean a
physical channel or a logical channel in accordance with the context.
[1031] The term reverse channel/link is used herein to mean a
communication channel/link through which the subscriber station sends signals
to the base station.
[1032] A fonward channel/link is used herein to mean a communication
channel/link through which a base station sends signals to a subscriber station.
[1033] The term soft hand-off is used herein to mean a communication
between a subscriber station and two or more sectors, wherein each sector
belongs to a different cell. The reverse link communication is received by both
sectors, and the fonA/ard link communication is simultaneously carried on the
two or more sectors' fonA/ard links.
[1034] The term softer hand-off is used herein to mean a communication
between a subscriber station and two or more sectors, wherein each sector
belongs to the same cell. The reverse link communication is received by both
sectors, and the fonA/ard link communication is simultaneously carried on one of
the two or more sectors' forward links.

[1035] The term erasure is used herein to mean failure to recognize a
message.
[1036] The term dedicated channel is used herein to mean a channel
modulated by information specific to an individual subscriber station.
[1037] The term common channel is used herein to mean a channel
modulated by information shared among all subscriber stations.
Description
[1038] As discussed, a basic model of a broadcast system comprises a
broadcast net of users, served by one or more central stations, which transmit
information with a certain contents, e.g., news, movies, sports events and the
like to the users. Each broadcast net user's subscriber station monitors a
common broadcast fonA/ard link signal. FIG. 1 illustrates conceptual block
diagram of a communication system 100, capable of performing High-Speed
Broadcast Service (HSBS) in accordance with embodiments of the present
invention.
[1039] The broadcast content originates at a content sen/er (CS) 102. The
content server may be located within the carrier network (not shown) or outside
Internet (IP) 104. The content is delivered in a form of packets to a'broadcast
packet data-sen/ing node (BPDSN) 106. The term BPSDN is used because
although the BPDSN may be physically co-located or be identical to the regular
PDSN (not shown), the BPSDN may be logically different from a regular PDSN.
The BPDSN 106 delivers the packets according to the packet's destination to a
packet control function (PCF) 108. The PCF is a control entity controlling
function of base stations 110 for the HSBS as a base station controller is for
regular voice and data services. To illustrate the connection of the high level
concept of the HSBS with the physical access network, FIG. 1 shows a PCF
physically co-located or even identical, but logically different from a base station
controller (BSC). One of ordinary skills in the art understands that this is for a
pedagogical purposes only. The BSC/PCF 108 provides the packets to base
stations 114.
)0

[1040] The communication system 100 enables High-Speed Broadcast
Sen/ice (HSBS) by introducing a forward broadcast shared channel (F-BSCH)
112 capable of high data rates that can be received by a large number of,
subscriber stations 114. The term forward broadcast shared channel is used
herein to mean a single fonward link physical channel that carries broadcast
traffic. A single F-BSCH can carry one or more HSBS channels multiplexed in a
TDM fashion within the single F-BSCH. The term HSBS channel is used herein
to mean a single logical HSBS broadcast session defined by the session's
broadcast content. Each session is defined by a broadcast content that may
change with time; for example, 7am - News, Sam - Weather, 9am - Movies, etc.
FIG. 2 illustrates the discussed concept of physical and logical channels for the
HSBS.
[1041] As illustrated in FIG. 2, an HSBS is provided on two F-BSCHs 202,
each of which is transmitted on a separate frequency fx, fy. Thus, for example,
in the above-mentioned cdma2000 communication system such a physical
channel can comprise e.g., a forward supplemental channel (F-SCH), fonA/ard
broadcast control channel (F-BCCH), forward common control channel (F-
CCCH), other common and dedicated channels and the channel's combination.
The use of common and dedicated channels for information broadcast is
disclosed in a provisional U.S. Patent Application Serial No. 60/279,970, entitled
"METHOD AND APPARATUS FOR GROUP CALLS USING DEDICATED AND
COMMON CHANNELS IN WIRELESS NETWORKS", filed March 28, 2001, and
assigned to the assignee of the present invention. One of ordinary skills in the
art understands that other communication systems utilize channels performing
similar function, therefore, the teaching is applicable to other communication
systems. The F-BSCHs 202 carry the broadcast traffic, which may comprise
one or more broadcast sessions. The F-BSCHs 2Q2b carries one HSBS
channel 204c; two HSBS channels 204a, 204b are multiplexed onto the F-
BCCH 202a. The content of an HSBS channel is formatted into packets
comprising a payload 206'and a header 208.
[1042] One of ordinary skill in the art recognizes that the HSBS broadcast
service deployment as illustrated in FIG. 2 is for pedagogical purposes only.
/I

Therefore, in a given sector, the HSBS broadcast service can be deployed in
several manners in accordance with features supported by an implementation of
a particular communication system. The implementation features include, e.g.,
the number of HSBS sessions supported, number of frequency assignments,
number of broadcast physical channels supported, and other implementation
features known to one skilled in the art, Thus, for example, more than two
frequencies, and F-BSCHs may be deployed in a sector. Furthermore, more
than tNO HSBS channels may be multiplexed onto one F-BSCH. Furthermore,
a single HSBS channel can be multiplexed onto more than one broadcast
channel within a sector, on different frequencies to serve the subscribers
residing in those frequencies.
[1043] As discussed, communications systems often transmit information in
frames or blocks, which are protected by encoding against adverse condition
affecting a communication channel. Examples of such systems comprise
cdma2000, WCDMA, UMTS. As illustrated in FIG. 3, the bit stream of
information to be transmitted 302, originating at higher layers, is provided to an
(inner) encoder 304 on a physical layer. The encoder accepts a block of bits of
a length S. This block of S bits typically includes some overhead, e.g., tail bits
for the inner encoder, a cyclic redundancy check (CRC) to assist the inner
decoder at the receiving side ascertain success or failure of decoding help the
inner decoder, and other overhead information known to one of ordinary skills in
the art. The encoder then encodes the S bits with a selected code resulting in
an encoded block of length P = S + R, where R denotes the number of
redundant bits. One of ordinary skills in the art understands that although the
embodiments are explained in terms of layering model, this is for pedagogical
purposes, and the various illustrative logical blocks, modules, circuits, and
algorithm steps described in connection with the physical layer are implemented
as electronic hardware, computer software, or combinations of both. Thus, for
example, the inner encoder 304 may be implemented or performed with a
general purpose processor, a digital signal processor (DSP), an application
specific integrated circuit (ASIC), a field programmable gate array (FPGA) or
other programmable logic device, discrete gate or transistor logic, discrete

hardware components, or any combination thereof designed to perform the
functions described herein. A general purpose processor may be a
microprocessor, but in the alternative, the processor may be any conventional.
processor, controller, microcontroller, or state machine. A processor may also
be implemented as a combination of computing devices, e.g., a combination of
a DSP and a microprocessor, a plurality of microprocessors, one or more
microprocessors in conjunction with a DSP core, or any other such
configuration.
[1044] In accordance with one embodiment of the present invention, as
illustrated in FIG. 4, the bit stream of information to be transmitted 402 is first
encoded by an outer decoder 406 and the encoded stream is then provided into
the inner encoder (not shown), residing on the physical layer 408. The bit
stream of information to be transmitted 402, originating at higher layers, is
provided to a transmit buffer 404. The transmit buffer is illustrated in more detail
in FIG. 5. Referring to FIG. 5, the bits fill the systematic portion 504(1) of the
transmit buffer 404 (of FIG. 4) row by row from left to right. The systematic
portion 504(1) comprises k rows 508 of length L. In one embodiment, as shown
in FIG. 5, the length L of the buffer coincides with the length of a radio frame
without the overhead (e.g., CRC to help the inner decoder and the tail bits for
the inner encoder). Referring back to FIG. 4, once the systematic portion
504(4) (of FIG. 5) is full, the outer block encoder 406 is activated to perform
column-wise encoding of the bits in the systematic portion 504(1) (of FIG. 5) to
generate (n-k) additional rows 510 (of FIG. 5) of parity bits. This column-wise
operation is performed column by column for binary outer code, i.e., m = 1. For
non-binary code, i.e., m > 1, every m adjacent columns in a row are treated as a
m-bit symbol. The m-bit symbols along the top k rows are read by the outer
encoder to produce n-k m-bit symbols that fill the corresponding lower n-k rows
of these columns.
[1045] In another embodiment, the length L of the buffer is equal to the
number of bits the inner coded frames carries divided by m, the dimension of
the outer encoder code. In this embodiment, the first m rows from the TX buff,er
are sent in the first inner coded frame, the second m rows of bits are sent in the
)3

second inner-coded frame, until the entire buffer is transmitted. Referring back
to FIG. 4, once the systematic portion 504(4) (of FIG. 5) is full, the outer block
encoder 406 is activated to perform column-wise encoding of the bits in the
systematic portion 504(1) (of FIG. 5) to generate m(n-k) additional rows 510 (of
FIG. 5) of parity bits. This column-wise operation is performed column by
column for binary outer code, i.e., m = 1. For non-binary code, i.e., m > 1, every
m-rows of a column form a m-bit symbol. The k symbols from the top k m rows
in the column are read by the outer encoder to produce (n - k) m-bit symbols
that fill the corresponding lower m(n-k) rows of this column.
[1046] In one embodiment the outer encoder comprises a systematic Reed-
Solomon (R-S). The content of the transmit buffer 404 is then provided to a
physical layer 408. On the physical layer 408, the individual frames are
encoded by an inner encoder (not shown), which results in encoded frames.
The structure of the inner decoder may be, e.g., the structure of FIG. 3. The
systematic rows and the parity rows of the buffer may be intedaced during
transmission to reduce the chance of large number of systematic rows erased
when the total number of inner code erasure exceeds the outer code's
correcting capability. The frames are further processed in accordance with a
selected modulation scheme. In one embodiment, the processing is performed
in accordance with the IS-2000 standard. The processed frames are then
transmitted over a communication channel 410.
[1047] The transmitted frames are received at the destination station and
provided to a physical layer 412. On the physical layer 412, the individual
frames are demodulated and provided to an inner decoder (not shown). In one
embodiment, the inner decoder decodes each frame, and if the decoding is
successful, outputs a correctly decoded frame; or if the decoding is
unsuccessful, declares an erasure. The success or failure of decoding must be
determined with a high accuracy. In one embodiment, this is achieved by
including a long (for example, 16-bit) cyclic redundancy check (ORG) in the
frame after outer encoding and before inner encoding. However, one of
ordinary skills in the art recognizes that other mechanisms for frame quality
indication may be used. The included ORG obtained from the decoded frame is
1^

compared with a CRC calculated from the bits of the decoded frame, and if the
two CRCs are identical, the decoding is declared successful. Further
processing at the physical layer proceeds in accordance with the result of the
inner decoder decision.
[1048] The correctly decoded frames are provided to the appropriate rows of
a of a receive buffer 414. if all the systematic /(frames are correctly decoded by
the inner decoder, the systematic frames from the systematic portion 414(1) of
the receive buffer 414 are passed to upper layer (not shown) for further
processing without outer decoding.
[1049] If the inner decoder cannot decode the frame, the decoder declares
an erasure, and provides an outer block decoder 416 with an indication that the
frame is missing. The process continues until there are as many parity frames
received correctly and passed to a parity portion 414(2) of a receive buffer 414,
as there are erased systematic frames. The receiver stops the reception of any
remaining frames and the outer decoder (not shown) is activated to recover the
erased systematic frames. The recovered systematic frames are passed to the
upper layer.
[1050] If the total number of correctly received frames in the receive buffer
414 is less than k, in accordance with one embodiment the outer decoder is not
activated since there is no guarantee that the decoding would be successful.
The correctly received systematic frames together with identification of the
missing bits are passed to the higher layers. In another embodiment, the
receiver uses decoded bits from the inner decoder (which are unreliable as
indicated by the failed CRC checks) to recover bits for the systematic bits. In
accordance with one embodiment, the receiver decode the unreliable bits from
the inner decoder and finds the most likely codeword. In the another
embodiment, the receiver uses measurement of the signal quality of the erased
frames in the buffer to choose enough erroneously received frames with the
highest signal to noise ratio to form a sub buffer with k rows. The receiver then
performs bit flipping (changing a bit value of 0 to a bit value 1 and vice versa at
one column at a time) and checks whether the bit flipping resulted in a
codeword. In one embodiment, the bit flipping is first performed on the least

reliable bits and continues with bits in the order of the bits' increasing reliability.
The reliability of a bit may be determined in accordance with inner decoding
melrics, e.g., a signal to noise and interference ratio during the frame, like the
Yamamoto metric, the re-encoded symbol error rate, re-encoded energy metric,
and other metrics known to one of ordinary skills in the art, or the metrics'
combinations. If a codeword was not found, the bit flipping continues through all
the remaining columns for all the unreliable rows. If a codeword was not found,
the bit flipping continues with increased number of bits flipped (that is, changing
2 bits at a time, then 3 bits, until the maximum number of bits), until either a
codeword is found or all combinations are exhausted. In another embodiment,
the CRC from the unreliable rows are used to check the overall success of the
decoding in this situation. The frames are passed to the higher layers only if the
CRC from all rows match; othenwise, only bits from reliable rows are passed to
the higher layers.
[1051] To improve reliability of decoding, in another embodiment, the
demodulation and inner decoding are performed for more than k correctly
received frames in a buffer. In accordance in yet another embodiment the
demodulation and inner decoding are performed for all frames in the buffer. In
both embodiments, the outer decoding is performed on the k (or km) rows with
the highest quality. The quality may be determined in accordance with inner
decoding metrics, e.g., a signal to noise and interference ratio during the frame,
like the Yamamoto metric, the re-encoded symbol error rate, re-encoded energy
metric, and other metrics known to one of ordinary skills in the art, or the
metrics' combinations. Use of quality metrics for quality estimation is disclosed
in detail in U.S. Patent No. 5,751,725 entitled "METHOD AND APPARATUS
FOR DETERMINING THE RATE OF RECEIVED DATA IN A VARIABLE RATE
COMMUNICATIONS SYSTEM" and U.S. Patent No. 5,774,496 entitled
"METHOD AND APPARATUS FOR DETERMINING DATA RATE OF
TRANSMITTED VARIABLE RATE DATA IN A COMMUNICATIONS
RECEIVER" and both are assigned to the assignee of the present invention.
;^

Battery Power Savings
[1052] An important requirement for a subscriber station is low battery power,
consumption. The above-described encoding method ensures that less than n
correctly received frames are sufficient for decoding the systematic information
per one transmitting buffer. Consequently, it is not necessary for the subscriber
station to receive all n frames to decode the transmitted information. If the
subscriber station determines the amount of redundancy, for example from an
encoding rate of the frames, the subscriber station may determine a number of
frames that must be received correctly, i.e., be declared correctly decoded by
the inner decoder for the outer decoder to decode correctly. The subscriber
station may determine the encoding rate by several methods known to one of
ordinary skills in the art. Thus, for example, there can be only one fixed
encoding rate. If more than one rate is used, the subscriber station can use a
blind rate determination, or the possible data rates are provided to the
subscriber station by the origination station. Furthermore, the information about
the amount of redundancy may be provided to the subscriber station.
[1053] Once the subscriber station accumulates the determined number of
frames correctly decoded by the inner decoder into the receive buffer, 414 (both
the systematic portion 414(1) and the parity portion 414(2)), the subscriber
station may terminate reception and inner decoding of additional frames.
Therefore, a battery power savings is accomplished. Because the subscriber
station knows a number of frames in the transmit buffer 404 and the number of
frames it received, the subscriber station may determine time when the
subscriber station needs to start reception and inner decoding of the frames
comprising new systematic information.
[1054] Because the HSBS is provided in addition to traditional
communication system services, e.g., voice, short message system, data, and
other sen/ices known to one of ordinary skills in the art, the subscriber station is
required to be able to receive such traditional services while engaged in an
HSBS. Thus, the subscriber station needs to be able to receive signaling
messages. The signaling in broadcast sen/ices is disclosed in detail in a co-
17

pending application serial number 09/933,978, entitled "METHOD AND
SYSTEM FOR SIGNALING IN BROADCAST COMMUNICATION SYSTEM,"
filed August 20, 2001, and assigned to the assignee of the present invention.
The signaling activities include, e.g., paging message reception, answer to
paging message, overhead messages containing the system configuration
reception, search for the neighboring systems on the same or different
frequencies, and other signaling known to one of ordinary skills in the art. As
discussed above, the subscriber station may discontinue reception activities
after accumulating enough frames in the buffer, thus may miss signaling
information.
[1055] Consequently, in one embodiment, the signaling activities the
subscriber station receiving the broadcast channel has to perform are carried
out during the most likely time the subscriber station is receiving the broadcast
channel. The most likely time the subscriber station receiving the broadcast
channel is usually when the portion of the buffer where systematic rows are
transmitted over the air. Alternatively, a subscriber station is obligated to
received the broadcast channel at a pre-defined time. Therefore, the subscriber
station must ascertain that the subscriber station does not terminate reception
of the frames before the time, during which the subscriber station is obligated to
receive the broadcast channel.
Hard Handoff on a Common Broadcast Forward Link
[1056] To enhance the Common Broadcast Forward Link performance, soft
and softer handoffs are desirable in overlapped coverage areas of different
sectors. The method and system for providing a communication with a
subscriber station through more than one base station during the soft hand-off
process are disclosed in a co-pending application serial number 09/933,607,
entitled "METHOD AND SYSTEM FOR A HANDOFF IN A BROADCAST
COMMUNICATION SYSTEM," filed on August 20, 2001, and assigned to the
assignee of the present invention.

[1057] Although the described soft and softer handoff method is desirable
because the subscriber station does not experience a discontinuity in
transmitted information, such methods cannot be always utilized in a broadcast,
communication system. A subscriber station may soft combine only
synchronous transmissions; consequently, the subscriber station may perform a
soft and softer handoff only between base stations that belong to the same soft
handoff (SHO) group. As used herein a SHO group means a group of all Base
Stations transmitting the Common Broadcast FonA/ard Link simultaneously and
synchronously. FIG. 6 illustrates two SHOs, one comprising BSi, BS2, and BS3,
the other comprises BS4, BS5, BSe, and BS7. Consequently, if the subscriber
station crosses boundaries from a coverage area of SHO Group 1 602 to a
coverage area of SHO Group 2 604, a hard handoff is required.
[1058] The use of the above-described encoding method increases the
probability that the subscriber station either does not experience a discontinuity
in transmitted information or minimize such discontinuity if the discontinuity
occurs.
[1059] FIG. 7 illustrates unsynchronized transmission between SHO Group 1
602 and SHO Group 2 604 (from FIG. 6), where the transmission from the Base
Stations of SHO Group 1 602 is delayed relative to the transmission from the
Base Stations of SHO Group 2 604. The subscriber station (not shown) is
monitoring transmission from a base station of SHO Group 1 602. At time to the
subscriber station determines that a hard handoff to a different SHO Group is
indicated. The handoff is indicated, e.g., when a quality metric of received
transmission falls below a threshold. The subscriber station then determines
whether a soft handoff is possible. In accordance with one embodiment, the
subscriber station determines a configuration of neighbor sectors in accordance
with a value of an HSBS neighbor configuration indicator
(NGHBR_CONFIG_HSBS) transmitted by the current base station. Such a
method is described in detail in the above-cited co-pending application serial
number 09/933.607 entitled "METHOD AND SYSTEM FOR A HANDOFF IN A
BROADCAST COMMUNICATION SYSTEM," filed August 20, 2001, and
assigned to the assignee of the present invention. The subscriber station
1^

continues to accumulate frames of Buffer 1 702(1) until time ti, when the
subscriber station has accumulated enough good frames in Buffer 1 702(1) for
decoding. This includes packets Po 704(2), Pi (which was transmitted in part
Pi.i 704(4) in Buffer 0 702(0) and part P1.2 706(2) in Buffer 1 702(1) ), and P3
706(4). The symbol P denotes a systematic part of a buffer; the symbol R
denotes the redundant part. The subscriber station initiates hard handoff and
acquires transmission a base station of SHO Group 2 604 in time Xz. The
interval At = t^~t^ depends on the type of handoff the subscriber station
performs, e.g., inter-frequency hard handoff, same frequency handoff, design of
the subscriber station and base station, and other criteria known to one of
ordinaiy skills in the art. Different methods of performing handoff are discussed
in the above-cited co-pending application serial number 09/933,607, entitled
"METHOD AND SYSTEM FOR A HANDOFF IN A BROADCAST
COMMUNICATION SYSTEM," filed August 20, 2001 and assigned to the
assignee of the present invention. Thus at time Iz the subscriber station begins
receiving frames 712 transmitted by a base station of SHO Group 2 604.
Because of the correcting capability of the encoding in accordance with an
embodiment of this invention, the received frames may be enough to correctly
decode packets P2 716(2), P3 716(4) of Buffer 1 716(4). The subscriber station
discards any duplicate packets. One of ordinary skills in the art recognizes that
the above-disclosed principles apply in the scenario, in which the transmission
from the base stations of SHO Group 1 602 is advanced relative to the
transmission from the base stations of SHO Group 2 604
Inter-frequency Hard Handoff
[1060] If a subscriber station travels outside the boundary of the
communication system, with which it is currently communicating, it is desirable
to maintain the communication link by transferring the call to a neighboring
system, if one exists. The neighboring system may use any wireless technology,
examples of which are CDMA, NAMPS, AMPS, TDMA or FDMA. If the
neighboring system uses CDMA on the same frequency band as the current

system, an inter-system soft handoff can be performed. In situations where
inter-system soft handoff is not available, the communication link is transferred
through a hard handoff where the current connection is broken before a new
one is made. Examples of typical hard handoff situations include: (1) the
situation in which a subscriber station is traveling from region serviced by a
CDMA system to a region serviced by a system employing an alternate
technology and (2) the situation in which a call is transferred between two
CDMA systems which use different frequency bands (inter-frequency hard
handoff).
[1061] inter-frequency hard handoffs can also occur between base stations
of the same CDMA system. For example, a region of high demand such as a
downtown area may require a greater number of frequencies to sen/ice demand
than the suburban region surrounding it. It may not be cost effective to deploy
all available frequencies throughout the system. A call originating on a
frequency deployed only in the high congestion area must be handed off as the
user travels to a less congested area. Another example is that of a microwave
or other service operating on a frequency within the system's boundaries. As
users travel into an area suffering from interference from the other service, their
call may need to be handed off to a different frequency.
[1062] A method for performing hard handoff attempt with greater probability
of success is disclosed in the U.S. Patent. No. 5,999,816, entitled "METHOD
AND APPARATUS FOR PERFORMING MOBILE ASSISTED HARD HANDOFF
BETV/EEN COMMUNICATION SYSTEMS", assigned to the assignee of the
present invention. In the 5,999,816 patent, subscriber stations tune temporarily
to the frequency of the hard handoff destination system and search for available
pilot signals on that frequency, for inclusion of the associated base stations in
the active set. If the search is successful, and at least one of the associated
base stations satisfies the criteria to be included in the active set, the subscriber
station acquires the base station. In the event that the hard handoff attempt is
unsuccessful, the subscriber station return to the original system with
information, which the original system uses to assist in the performance of
future handoff attempts. Alternatively, with no handoff attempt made, the
2_)

subscriber station searches the destination system. After the searching task is
completed, the subscriber station will retune to the original frequency to resume
current communications. While tuned to an alternate frequency, any frames of
data generated by the subscriber station or transmitted by the base station will
be corrupted. Typically, the base station will provide only a subset of the
possible offsets for the subscriber station to search. Even so, the duration of
the handoff attempt or search can be so long as to potentially corrupt a number
of frames of data.
[1063] Consequently, an improved method for performing hard handoff
attempt with greater probability of success is disclosed in the U.S. Patent No.
6,134,440 entitled "METHOD AND APPARATUS FOR PERFORMING MOBILE
STATION ASSISTED HARD HANDOFF USING OFF LINE SEARCHING", and
assigned to the assignee of the present invention. In the U.S. Patent No.
6,134,440, after having been directed to search for pilot signals in an alternate
frequency band, the subscriber station tunes to that alternate frequency and
samples the incoming data, storing those samples in memory. During the time
that the subscriber station is tuned to the alternate frequency, all data being
transmitted to the subscriber station on the forward link is lost. Similarly, any
reverse link data transmitted by the subscriber station would be transmitted on
the alternate frequency. Therefore, such reverse link data would not be
received at the origination base station. When a sufficient number of samples
have been stored, the subscriber station retunes to the origination frequency.
At this time, the fonward link data is again received by the subscriber station,
and reverse link data can be successfully transmitted to the origination base
station. After retuning to the origination frequency, a searcher in the subscriber
station will subsequently be employed to search for pilot signal offsets utilizing
the stored data collected from the alternate frequency. In accordance with the
present invention, due to the relatively short period of time required to sample
and store information on the alternative frequency, the active communication
link is not broken. Neither is the active communication link affected by the
subsequent off-line search. Because less time is required to sample the data
on the alternate frequency than is required to actively search for pilot signals in'

real time, and because the communication link is corrupted by the hard handoff
process only while the subscriber station is tuned to the alternate frequency, the
interruption the forward and reverse links on the originating system are
minimized. In fact, the error correction coding employed in modern
communication systems may eliminate all errors introduced by sampling the
alternate frequency, if the sampling time is small enough.
[1064] Using the above-described encoding method improves the searching
method disclosed in both above-described co-applications. Because the
subscriber station does not need to accumulate all n frames from the transmitter
buffer 404, for recovering all the systematic information, once the subscriber
station accumulates the determined number of frames correctly decoded by the
inner decoder into the receive buffer 414 of FIG. 4 (both the systematic portion
414(1) and the parity portion 414(2)), the subscriber station may terminate
reception of additional frames. Because the subscriber station knows a number
of frames in the transmit buffer 404 and the number of frames it received, the
subscriber station may determine time when it needs to start reception and
inner decoding of frames comprising new systematic information. The
subscriber station then may use the time between terminating the reception of
additional frames and the time of restarting reception and inner decoding of
frames to perform handoff/search in accordance to the concepts disclosed in
the U.S. Patent Nos. 5,999,816 and 6,134,440.
[1065] Consequently, once the subscriber station accumulates the
determined number of frames correctly decoded by the inner decoder and the
time when the subscriber station needs to start reception and inner decoding,
the subscriber station terminates reception of additional frames. The subscriber
station then tunes to a frequency of the destination system. The information
pertaining to the destination system may be obtained, e.g., from the origination
system. If the subscriber station tuned to the destination system to perform a
handoff, the subscriber station attempts to acquire at least one sector of the
destination system, if at least one sector of the destination system is acquired
as measured e.g., by a minimum pilot signal strength of the at least one sector
of the destination system, the handoff is deemed to be successful and the
25

subscriber station remains on the destination system and begins to receive a
service on a channel from the acquired sector. OthenA/ise, the subscriber
station begins receiving signals at the frequency of the destination system and
storing the signals. The subscriber station performs the storing for a time
required or until the time the subscriber station needs to re-tune back to the
sector in the origination system. The subscriber station then concurrently
receives frames and analyzes the stored signals to identify sector(s) in a
destination system to handoff. The subscriber station then may repeat the
described method or to handoff to sector(s) identified by the analysis.
[1066] One of ordinary skills in the art recognizes, that the embodiments of
the present invention are equally applicable to a hard handoff on a common
broadcast channel and handoff on a traffic channel, as long as the encoding-
decoding of the present invention is utilized by the particular channel.
Paging
[1067] As illustrated in FIG. 6, all subscriber stations in an SHO Group are
either monitoring the common broadcast fonward link, engaged in a
communication with other subscriber stations, or monitoring a paging channel.
The paging channel, which the subscriber station are monitoring, is' known to
the communication system. The paging channel is assigned to the subscribers
monitoring the paging channel and engaged in a communication with other
subscriber stations in accordance with methods utilized by current
communications systems, e.g., IS-2000, WCDMA, UMTS.
Additionally/alternatively, the paging channel to the subscribers is assigned in
accordance with methods disclosed in co-pending application serial number
09/933,978, entitled "METHOD AND SYSTEM FOR SIGNALING IN
BROADCAST COMMUNICATION SYSTEM," filed August 20, 2001, and
assigned to the assignee of the present invention. Consequently, it is possible
to page any subscriber.
[1068] In accordance with one, the common broadcast channel is utilized for
paging the subscriber station monitoring the common broadcast forward link.

As explained in reference to FIG. 4, HSBS channels, organized into packets,
are multiplexed on the F-BSCH. Therefore, a subscriber station receiving an
HSBS channel must be able to discern packets carrying signaling messages,
e.g., a paging message from packets carrying the HSBS channel content. In
accordance with one embodiment, a BSRJD of certain value, e.g., '000' may be
resen/ed to indicate that the content of a packet or packets carry signaling
(paging) information. A disadvantage of this approach is that because the
content of the packet or packets is synchronized in an SHO group, all
subscriber stations in the SHO group receive the same paging information,
whether it is meant for them or not. Because the payload per packet is finite, It
may take several packets carrying paging information to page all subscribers in
the SHO group. This results in delay of the HSBS channel content, which may
be undesirable in certain applications.
[1069] Consequently, in accordance with another embodiment, a content of
a packet or packets of an HSBS channel transmitted by the sectors in an SHO
group is unsynchronized in pre-defined periodic inten/als. Consequently, the
content of the packet or packets can be different in each sector, therefore,
allowing paging subscriber stations on a per sector basis. Because the periodic
intervals are pre-defined, the subscriber stations know that the-.packet or
packets transmitted in that inten/al carry signaling information.
[1070] Referring back to FIG. 5, in accordance with one embodiment,
several pre-determined rows in the parity portion 506 of the transmitting buffer
502 are replaced with the paging information. When a subscriber station
encounters a packet that the subscriber station knows carries paging
information, the subscriber station interprets the pre-determined rows as
signaling information. Because several pre-determined rows in the parity
portion 506 were replaced, the information bits are unprotected, and may be
erased. However, because the paging information is carried in a few packets,
the base station may increase power for the time during which the packets
carrying both signaling information and HSBS content are transmitted to
compensate for the loss of protection due to encoding.
2^

[1071] Alternatively, the outer encoder can encode the information rows with
lesser redundancy for packet carrying both HSBS content and paging
information than the redundancy for packets carrying HSBS content information.
Therefore, less than (n - k) rows of the parity portion 506 of the transmitting
buffer 502 are filled with the parity information. The rows unused by the parity
bits may be used for the paging information. Although the protection of the
packet carrying both HSBS content and paging information is less than of the
packet carrying HSBS content information, the encoding rate may be designed
to be satisfactory under normal channel conditions. Furthermore, the base
station may increase power for the time during which the packets carrying both
signaling information and HSBS content are transmitted to compensate for the
loss of protection due to lesser encoding.
[1072] in accordance with another embodiment, there is no need to pre-
define periodic inten/als for the transmission of paging information. A packet
carrying HSBS content information is encoded with one encoding rate and a
packet carrying paging information is encoded with another rate. The
subscriber station attempts to decode a received packet in accordance with a
first rate hypothesis. If the decoding is successful, the packet is processed in
accordance with the relationship between the rate hypothesis and the packet
content. If the decoding is unsuccessful, the subscriber station attempts to
decode the received packet in accordance with a second rate hypothesis. If the
decoding is successful, the packet is processed in accordance with the
relationship between the rate hypothesis and packet content. Othenwise, an
erasure is declared.
[1073] One skilled in the art will appreciate that although the flowchart
diagrams are drawn in sequential order for comprehension, certain steps can be
carried out in parallel in an actual implementation. Furthermore, unless indicate
othenA/ise, method steps can me interchanged without departing form the scope
of the invention.
[1074] Those of skill in the art would understand that information and signals
may be represented using any of a variety of different technologies and
techniques. For example, data, instructions, commands, information, signals,'
^6

bits, symbols, and chips that may be referenced throughout the above
description may be represented by voltages, currents, electromagnetic waves,
magnetic fields or particles, optical fields or particles, or any combination
thereof,
[1075] Those of skill would further appreciate that the various illustrative
logical blocks, modules, circuits, and algorithm steps described in connection
with the embodiments disclosed herein may be implemented as electronic
hardware, computer software, or combinations of both. To clearly illustrate this
interchangeability of hardware and software, various illustrative components,
blocks, modules, circuits, and steps have been described above generally in
terms of their functionality. Whether such functionality is implemented as
hardware or software depends upon the particular application and design
constraints imposed on the overall system. Skilled artisans may implement the
described functionality in varying ways for each particular application, but such
implementation decisions should not be interpreted as causing a departure from
the scope of the present invention.
[1076] The various illustrative logical blocks, modules, and circuits described
in connection with the embodiments disclosed herein may be implemented or
performed with a general purpose processor, a digital signal processor (DSP),
an application specific integrated circuit (ASIC), a field programmable gate array
(FPGA) or other programmable logic device, discrete gate or transistor logic,
discrete hardware components, or any combination thereof designed to perform
the functions described herein. A general purpose processor may be a
microprocessor, but in the alternative, the processor may be any conventional
processor, controller, microcontroller, or state machine. A processor may also
be implemented as a combination of computing devices, e.g., a combination of
a DSP and a microprocessor, a plurality of microprocessors, one or more
microprocessors in conjunction with a DSP core, or any other such
configuration.
[1077] The steps of a method or algorithm described in connection with the
embodiments disclosed herein may be embodied directly in hardware, in a
software module executed by a processor, or in a combination of the two. A
a7

software module may reside in RAM memory, flash memory, ROM memory,
EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a
CD-ROM, or any other form of storage medium known in the art. An exemplary
storage medium is coupled to the processor such the processor can read
information from, and write information to, the storage medium. In the
alternative, the storage medium may be integral to the processor. The
processor and the storage medium may reside in an ASIC. The ASIC may
reside in a user terminal. In the alternative, the processor and the storage
medium may reside as discrete components in a user terminal.
[1078] The previous description of the disclosed embodiments is provided to
enable any person skilled in the art to make or use the present invention.
Various modifications to these embodiments will be readily apparent to those
skilled in the art, and the generic principles defined herein may be applied to
other embodiments without departing from the spirit or scope of the invention.
Thus, the present invention is not intended to be limited to the embodiments
shown herein but is to be accorded the widest scope consistent with the
principles and novel features disclosed herein.
[1079] A portion of the disclosure of this patent document contains material
which is subject to copyright protection. The copyright owner has no objection
to the facsimile reproduction by anyone of the patent document or the patent
disclosure, as it appears in the Patent and Trademark Office patent file or
records, but otherwise resep\/es all copyright rights whatsoever.
s^


WE CLAIM:
1. A method for reducing power consumption of a subscriber station, comprising:
determining a number of frames that must be received correctly; and
terminating reception of the frames when said determined number of frames was
received correctly.
2. The method as claimed in claim 1 wherein said determining a number of frames that
must be received correctly comprises:
determining an amount of redundancy; and
determining the number of frames that must be received correctly in accordance
with said determined amount of redundancy.
3. The method as claimed in claim 2 wherein said determining an amount of redundancy
comprises:
providing the amount of redundancy independently of the received frames.
4. The method as claimed in claim 2 wherein said determining an amount of redundancy
comprises:
determining an encoding rate of received frames; and
determining the amount of redundancy in accordance with the encoding rate.
5. The method as claimed in claim 2 wherein said determining the number of frames that
must be received correctly in accordance with said determined mount of redundancy
comprises:
determining a minimum number of frames that must be received.
6. The method as claimed in claim 5, comprising:
increasing said determined minimum number of frames that must be received
correctly by a first number.
29

7. The method as claimed in claim 4 wherein said determining an encoding rate of
received frames comprises:
determining an encoding rate of received frames in accordance with the received
frames.
8. The method as claimed in claim 4 wherein said determining an encoding rate of
received frames comprises:
providing an encoding rate of received frames independently of the received
frames.
9. The method as claimed in claim 1 wherein said terminating reception of the frames
when said determined number of frames was received correctly comprises:
terminating reception of the frames when said determined number of frames was
received correctly and a time during which the subscriber station is obligated to receive
the frames expired.
10. A method for performing hard handoff on a common broadcast channel comprising:
receiving at a subscriber station frames transmitted on the common broadcast
channel from a first sector;
determining at the subscriber station a need for handoff;
identifying at the subscriber station at least one sector belonging to a soft handoff
group different from a soft handoff group including the first sector;
determining a number of frames from a current buffer that must be received
correctly;
terminating reception of the frames when said determined number of frames were
received correctly; and
beginning reception of frames fr^om the identified at least one sector.
30

11. The method as claimed in claim 10 wherein said determining a number of frames
that must be received correctly comprises:
determining an amount of redundancy; and determine number of frames that must
be received correctly in accordance with said determined amount of redundancy.
12. The method as claimed in claim 11 wherein said determining an amount of
redundancy comprises:
providing the amount of redundancy independently of the received frames.
13. The method as claimed in claim 11 wherein said determining an amount of
redundancy comprises:
determining an encoding rate of received frames; and
determining the amount of redundancy in accordance with the encoding rate.
14. The method as claimed in claim 10 wherein said determining number of frames that
must be received correctly in accordance with said determined amount of redundancy
comprises:
determining a minimum number of frames that must be received correctly.
15. The method as claimed in claim 14, comprising:
increasing said determining minimum number of frames that must be received
correctly by a first number.
16. The method as claimed in claim 13 wherein said determining an encoding rate of
received frames comprises:
determining an encoding rate of received frames in accordance with the received
frames.
31

17. The method as claimed in claim 13 wherein said determining an encoding rate of
received frames comprises:
providing an encoding rate of received frames independently of the received
frames.
18. The method as claimed in claim 10 wherein said terminating reception of the frames
when said determined number of frames were received correctly comprises:
terminating reception of the frames when said determined number of frames were
received correctly and a time during which the subscriber station is obligated to receive
the frames expired.
19. The method as claimed in claim 10, comprising:
determining whether at least some decoded packets received from the at least one
sector are identical to at least some decoded packets received from the first sector; and
discarding the identical packets.
20. A method for a handoff from an area covered by an origination system into an area
covered by a destination system comprising:
receiving at a subscriber station service on a charmel from a sector in the
origination system;
determining at the subscriber station a need for handoff;
identifying at the subscriber station a destination system;
determining a number of frames from a current buffer that must be received
correctly;
terminating reception of the frames when said determined number of frames were
received correctly;
tuning to a frequency of the destination system; and
receiving service on a channel from at least one sector if the at least one sector of
the destination system is acquired at the subscriber station.
32

21. The method as claimed in claim 20, comprising:
determining a time to restart receiving at a subscriber station service on the
channel from the sector in the origination system.
22. The method as claimed in claim 20, comprising:
storing signals received at the frequency of the destination system;
retuning to the origination frequency;
at the subscriber station concurrently:
receiving service on the charmel from the sector in the origination system;
and
analyzing the stored signals to identify a sector in a destination system that
can provide service;
if no sector of the destination system is acquired at the subscriber station.
23. The method as claimed in claim 22 wherein said retuning to the origination
frequency comprises:
retuning to the origination frequency before the time to restart receiving service
on a channel from a sector in the origination system.
24. The method as claimed in claim 22, comprising:
performing hard handoff if the sector in a destination system is identified.
25. A method for utilizing a common broadcast channel for signaling, comprising:
replacing part of a content of a parity portion of a transmitting buffer with a
signaling information; and
transmitting a content of the transmitting buffer at a determined time on the
common broadcast channel.
33

26. The method as claimed in claim 25, comprising:
increasing power for transmission of the common broadcast channel during the
determined time.
27. A method for utilizing a common broadcast channel for signaling, comprising:
encoding a content of a systematic portion of a transmitting buffer with a first
code to provide parity bits into a first part of a parity portion of the transmitting buffer;
adding signaling information into a second part of the parity portion of the
transmitting buffer, the second part being different from the first part;
transmitting a content of the transmitting buffer at a determined time on the
common broadcast channel.
28. The method as claimed in claim 25, comprising:
encoding a content in the systematic portion of the transmitting buffer with a
second code to provide parity bits into the parity portion of the transmitting buffer; and
transmitting a content of the transmitting buffer at other than the determined time
on the common broadcast channel.
29. The method as claimed in claim 27, comprising:
increasing power for transmission of the common broadcast channel during the
determined time.
30. A method for receiving signals generated utilizing a common broadcast channel for
signaling as recited in one of claims 27-29, comprising:
providing frames received on the common broadcast channel to a receiving
buffer;
decoding the receiving buffer with a first code if the frames were received in error
during a determined time; and
34

decoding the receiving buffer with a second code if the frames were received in
error otherwise.
31. The method as claimed in on of claims 27-29, comprising:
encoding a packet containing channel content information with a first code;
encoding a packet containing charmel content information and signaling
information with a second code; and
transmitting said encoded packets.
32. The method as claimed in claim 30, comprising:
decoding a received packet in accordance with a first rate hypothesis; and
decoding the received packet in accordance with a second rate hypothesis if said
decoding the received packet in accordance with a first rate hypothesis was unsuccessful.

35

Documents:

0370-chenp-2004 abstract-duplicate.pdf

0370-chenp-2004 abstract.pdf

0370-chenp-2004 claims-duplicate.pdf

0370-chenp-2004 description (complete)-duplicate.pdf

0370-chenp-2004 form-18.pdf

0370-chenp-2004 pct search report.pdf

0370-chenp-2004 pct.pdf

0370-chenp-2004 petition.tif

0370-chenp-2004-claims.pdf

0370-chenp-2004-correspondnece-others.pdf

0370-chenp-2004-correspondnece-po.pdf

0370-chenp-2004-description(complete).pdf

0370-chenp-2004-drawings.pdf

0370-chenp-2004-form 1.pdf

0370-chenp-2004-form 26.pdf

0370-chenp-2004-form 3.pdf

0370-chenp-2004-form 5.pdf

0370-chenp-2004-pct.pdf

370-chenp-2004.tif


Patent Number 232323
Indian Patent Application Number 370/CHENP/2004
PG Journal Number 13/2009
Publication Date 27-Mar-2009
Grant Date 16-Mar-2009
Date of Filing 23-Feb-2004
Name of Patentee QUALCOMM INCORPORATED
Applicant Address 5775 Morehouse Drive, San Diego, California 92121-1714,
Inventors:
# Inventor's Name Inventor's Address
1 CHEN, Tao 5 Harvest Run Drive, San Diego, California 92130,
2 WOLF, Jack, K 8529 Prestwick Drive, La Jolla, CA 92037,
3 ODENWALDER, Joseph, P 18176 Lago Vista, Rancho Santa Fe, CA 92067-8981,
4 TIEDEMANN, Edward, G., Jr 656 Barretts Mill Road, Concord, MA 01742,
5 BUTLER, Brian, K 2171 Via Nina, La Jolla, CA 92037,
6 WEI, Yongbin 12140 Brickellia Street, San Diego, CA 92129,
PCT International Classification Number H04H 1/00
PCT International Application Number PCT/US02/26037
PCT International Filing date 2002-08-15
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 09/933,912 2001-08-20 U.S.A.