A METHOD OF COOPERATIVELY RELAYING DATA IN CELLULAR

NETWORKS FOR A BROADCAST MULTICAST SERVICES

TECHNICAL FIELD

The present invention relates to a method of relaying data, and more particularly, to

a method of cooperatively relaying data in cellular networks for Broadcast Multicast

Services (BCMCS). Although the present invention is suitable for a wide scope of

applications, it is particularly suitable for relaying data in cellular networks.

BACKGROUND ART

A ^' Broadcast Multicast Service (BCMCS) provides the ability to transmit the same

information stream to multiple users simultaneously. More specifically, the BCMCS is

intended to provide flexible and efficient mechanism to send common or same information

to multiple users. The motivation for this service is to achieve the most efficient use of air

interface and network resources when sending the same information to multiple users. The

type of information transmitted can be any type of data (e.g., video, text, multimedia,

streaming media). The BCMCS is delivered via the most efficient transmission technique

based on the density of the BCMCS users, information (media type) being transmitted, and

available wireless resources.

Transmission territory for each BCMCS program can be independently defined.

Here, the BCMCS program refers to a logical content transmitted using the BCMCS

capabilities. Moreover, the BCMCS program is composed of one or more internet protocol

flows. In operation, the programs can be transmitted in time sequence on a given channel.

The BCMCS programs can be transmitted to all or selected regions of the network. These

regions constitute the transmission territory which refers to an area of wireless network

coverage where transmission of a BCMCS program can occur. The transmission territory

can be defined by a set of cells/sectors that can transmit a BCMCS program. In addition, the

BCMCS programs can be received by all users or can be restricted to a subset of users via

encryption.

In the BCMCS, retransmission and acknowledgement are not required since the type

of transmission is "one way" and/or "one to many."

The BCMCS subscription is normally associated with the program (e.g., ABC, TNT,

ESPN), not the content (media type such as music, video, etc.). That is, by selecting the

program, the user selects the type of content the user wishes to receive.

The BCMCS in cellular networks typically incur coverage holes and limited

capacity (channels) per carrier. This can arise due to channel propagation impairments (e.g.,

severe shadowing), large cell sizes (e.g., with site-to-site distances greater than 2 km) due to

high cost of base terminal station (BTS) deployments, limited bandwidth, and interference

from adjacent cells transmitting different BCMCS content. Consequently, BCMCS

coverage becomes limited along with broadcast multicast system capacity.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention is directed to a method of cooperatively relaying

data in cellular networks for a Broadcast Multicast Services (BCMCS) that substantially

obviates one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a method of receiving subpackets in

a mobile communication system using at least one frequency carrier.

Another object of the present invention is to provide a method of receiving

subpackets in a mobile communication system using a single frequency carrier.

A further object of the present invention is to provide a method of transmitting

subpackets in a mobile communication system using at least one frequency carrier.

Yet, another object of the present invention is to provide a method of transmitting

subpackets in a mobile communication system using a single frequency carrier.

Additional advantages, objects, and features of the invention will be set forth in part

in the description which follows and in part will become apparent to those having ordinary

skill in the art upon examination of the following or may be learned from practice of the

invention. The objectives and other advantages of the invention may be realized and

attained by the structure particularly pointed out in the written description and claims hereof

as well as the appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of

the invention, as embodied and broadly described herein, a method of receiving subpackets

in a mobile communication system using at least one frequency carriers includes receiving a

first broadcast subpacket from a base station (BS) at a first time slot on a first frequency

carrier and receiving at least one subsequent broadcast subpacket from the BS via at least

one relay station (RS) at a second time slot on a second frequency carrier, wherein

information of the first broadcast subpacket and the subsequent broadcast subpacket are the

same.

In another aspect of the present invention, a method of receiving subpackets in a

mobile communication system using a single frequency carrier includes receiving a first

broadcast subpacket from a base station (BS) at a first time slot and receiving at least one

subsequent broadcast subpacket from the BS via at least one relay station (RS) and the BS

at a second time slot, wherein information of the first broadcast subpacket and the

subsequent broadcast subpacket are same and wherein the at least one subsequent broadcast

subpacket is received on the single frequency carrier.

In a further aspect of the present invention, a method of transmitting subpackets in a

mobile communication system using at least one frequency carriers transmitting a first

broadcast subpacket to a mobile station (MS) at a first time slot on a first frequency carrier

and transmitting at least one subsequent broadcast subpacket to the MS via at least one relay

station (RS) at a second time slot on a second frequency carrier, wherein information of the

first broadcast subpacket and the subsequent broadcast subpacket are the same.

Yet, in another aspect of the present invention, a method of transmitting subpackets

in a mobile communication system using a single frequency carrier transmitting a first

broadcast subpacket to a mobile station (MS) at a first time slot and transmitting at least one

subsequent broadcast subpacket to the MS via at least one relay station (RS) and the MS at

a second time slot, wherein information of the first broadcast subpacket and the subsequent

broadcast subpacket are same and wherein the at least one subsequent broadcast subpacket

is transmitted on the single frequency carrier.

It is to be understood that both the foregoing general description and the following

detailed description of the present invention are exemplary and explanatory and are

intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding

of the invention and are incorporated in and constitute a part of this application, illustrate

embodiment(s) of the invention and together with the description serve to explain the

principle of the invention. In the drawings;

FIG. 1 illustrates a plurality of modules that are respectively one hop apart;

FIG. 2 is a diagram illustrating an example of a relay station (RS) in a multi-hop

system;

FIG. 3 illustrates a scheme for a relayed BCMCS according to an embodiment of the

present invention;

FIG. 4 illustrates an example of a transmitting end having multiple antennas;

FIG. 5 is an example of a receiving end having multiple antennas;

FIG. 6 illustrates a scheme for a relayed BCMCS according to another embodiment

of the present invention;

FIG. 7 illustrates a scheme for a relayed BCMCS according another embodiment of

the present invention; and

FIG. 8 illustrates a scheme for a relayed BCMCS according to another embodiment

of the present invention.

BEST MODE FOR CARRYING OUT THE EWENTION

Reference will now be made in detail to the preferred embodiments of the present

invention, examples of which are illustrated in the accompanying drawings. Wherever

possible, the same reference numbers will be used throughout the drawings to refer to the

same or like parts.

In a wireless mobile communication system that supports the BCMCS, multimedia

data such as audio and video is transmitted at a high data rate to mobile stations located in

the broadcast area. In order to perform BCMCS, a packet data channel of a physical (PHY)

layer has to be able to support high data rate. In the current wireless mobile communication

system, the BCMCS data is transmitted on the existing packet data channel of the PHY

layer.

With respect to the BCMCS, the broadcast contents generated from the BTS and/or

contents delivered from other BTS are transmitted to a plurality of mobile stations in the

BTS cell/sector. Before the contents using the BCMCS can be transmitted, the BTS and the

MS share a same protocol.

Although the BCMCS data is transmitted on the packet data channel, since the

BCMCS uses a transmission scheme where a BTS transmits to a plurality of mobile stations,

there is no independent received signal quality feedback from each MS. For example, even

if there is error in the received subpacket, the MS does not need to send an acknowledgment

(ACK) or a negative ACK (NACK) signals to the BTS.

Furthermore, the BTS performing the BCMCS seeks to make all the mobile stations

in the BTS cell/sector receive the data having a certain level of quality by determining the

data transmission rate. The data transmission rate can be determined based on payload size,

a number of sub-packets for a Hybrid Automatic Repeat Request (HARQ) scheme,

modulation scheme, and a like.

As mentioned above, since the BCMCS service does not need to send feedback from

the receiving end, the BTS cannot modify data transmission rate according to the channel

environment and sends the subpacket at a fixed rate to all the mobile stations in the

cell/sector. Furthermore, each BTS can set the data rate where a packet error rate (PER)

value is lower than the standard value or some percentage (e.g., 90%) for all the mobile

stations in the cell/sector. The subpacket is then sent at the fixed or set data rate.

The BCMCS includes various functions. A subscription management function

supports the capability to subscribe a user for broadcast/multicast service. After the MS is

subscribed to the system, a service discovery function can be used to discover the BCMCS

program. That is, the service discovery function refers to the procedure a mobile station

(MS) employs to discover the BCMCS programs that can be provided by the system. For

example, an announcement of a BCMCS program can be automatically sent to the BCMCS

capable MS (e.g., a background light blinking a specified number of times whenever a MS

enters a broadcast range or whenever a broadcast program commences).

During operation, an information acquisition function allows the user to acquire the

information needed to receive a BCMCS program. Furthermore, a distribution management

function provides the system the ability to determine the locations where the BCMCS

program is transmitted. As another service function, a radio management function deals

with efficient operation of the radio channels to support the BCMCS. Also, a service

accounting function includes aspects of the service related to billing based on the services

rendered. Lastly, a feature interaction function relates to the aspects of initiating and

operating the BCMCS service simultaneously with other services.

Currently, the BCMCS over cellular networks are based on single-hop networks.

The single hop network refers to a network where all entities/modules are a maximum of

one hop apart. Figure 1 illustrates a plurality of modules that are respectively one hop apart.

In Figure 1, two MSs and a base terminal station (BTS) are one hop apart, respectively.

In the conventional BCMCS environment where the modules are more than one hop

apart, as discussed above, the conventional BCMCS in cellular networks can experience

problems in providing uniform service throughout the coverage area due to obstacles, large

coverage area, and a like.

To improve service throughout the coverage area as well as capacity, multiple hops

(two or more hops) can be used. More specifically, two or more hops through relaying can

be employed to provide more consistent service and improved capacity. To this end, a relay

station (RS) can be introduced in the network.

Figure 2 is a diagram illustrating an example of a RS in a multi-hop system. As

shown in Figure 2, the RS is placed between the BTS and the MS. The function of the RS is

to 'repeat' the BTS signal in a trivial or a smart manner so as to extend the BCMCS

coverage. According to the conventional system, the MSs positioned away from the BTS

(e.g., near the cell border) often experience failed signal (e.g., packet decoding error) due to

weakened signal strength or interference due to signals from neighboring cells/sectors. With

the extended BCMCS coverage, however, the MS's, that would otherwise be unable to

receive strong enough signal, can demodulate and decode the BCMCS signal.

As mentioned above, the function of the RS can be accomplished in a trivial or

smart manner, for example. The trivial manner refers to relaying the signal through simple

signal repetition. Alternatively, the smart manner refers to employing space-time coding to

achieve transmit diversity or incremental redundancy (IR).

To have a successful relayed BCMCS, there are several schemes available.

Figure 3 illustrates a scheme for a relayed BCMCS according to an embodiment of

the present invention. The scheme of Figure 3 can be construed as being similar to

'frequency division multiplexing' in that multiple carrier frequencies are used. That is,

availability of two or more carrier frequencies is assumed.

In Figure 3, a multi-hop system is illustrated having two frequency carriers,

represented by fl and f2, and one RS. From the BTS, the original signals in form of

BCMCS packets (e.g., A, B, C, D) are broadcasted in sequence through a frequency (i.e.,

fl). The sequentially transmitted BCMCS packets are received by the MS and the RS. The

RS received BCMCS packets are then decoded. As illustrated in this figure, the RS first

receives and decodes subpacket A broadcasted from the BTS. Thereafter, the RS transmits a

'relayed signal' A' which can be a simple repetition of the originally transmitted subpacket

A or alternatively, an encoded version of subpacket A (e.g., transmitted with systematic bits

but possibly different parity bits).

In this embodiment and other embodiments to follow, the RS serves various

functions. For example, the RS can receive, decode, and/or transmit the subpackets. That is,

in transmitting the subpackets, the RS can "amplify and forward" and/or "decode and

forward." The transmitted signal typically includes noise. In the former, the received signal

is amplified and transmitted. In the latter, the received signal is first decoded. If the

decoding is successful, then the originally transmitted signal from the BTS can be re¬

constructed and transmitted. This transmitted signal typically has no noise. In addition, the

RS requires a certain minimum amount of time to decode the received packet before it can

be transmitted (relayed) to the MS. As such, the timing of the relayed transmissions from

the RS can be altered.

Furthermore, the RS can be equipped with multiple antennas to achieve transmit

diversity. A multi-input, multi-output (MIMO) can provide transmit diversity to increase

efficiency of wireless resources. The use of multiple antennas provides the RS and other

terminals (e.g., mobile station) to achieve diversity gain without increase in bandwidth. For

example space-time code (STC) can be used to increase reliability of communication links,

spatial multiplexing (SM) can be used to increase transmission capacity, or a foil diversity

foil rate space time code (FDFR-STC) can be used to achieve foil diversity.

Figure 4 illustrates an example of a transmitting end having multiple antennas. In

Figure 4, a channel encoder 41 performs channel encoding operation according to a fixed

algorithm on inputted data bits. When performing channel encoding operation, redundancy

bits are added to generate robust signal to better withstand noise. A mapper 42 performs

constellation mapping to convert the channel encoded bits to symbols. Furthermore, a

serial-to-parallel converter 43 converts symbols outputted from the mapper 42 to parallel

symbols so that the symbols can be transmitted via the multiple antennas. In addition, a

multiple antenna encoder 44 converts the channel symbols inputted in parallel to multiple

antenna symbols and then transmits.

Figure 5 is an example of a receiving end having multiple antennas. In Figure 5, the

multiple antenna decoder 51 receives the multiple antenna symbols and converts them to

channel symbols. A parallel-to-serial converter 52 converts the channel symbols inputted in

parallel to serial channel symbols. A demapper 53 performs constellation demapping to

convert the inputted channel symbols to bits. Thereafter, a channel decoder 54 performs

decoding operation on bits received from the demapper 53.

If multiple encoding is performed, diversity gain of multiple antennas can vary

based on which encoding scheme is employed. Therefore, it is necessary to have an

encoding matrix which can provide foil diversity and foil rate space time coding.

As discussed above, the MIMO scheme can be used to increase transmission

capacity in a wireless communication system. An Alamouti space-time coding uses multiple

antennas in the transmitting end and possibly multiple antennas in the receiving end to

overcome fading in wireless channels. More specifically, the Alamouti scheme introduces

two transmitting antennas which achieves diversity gain by using a multiple number of

transmitting antennas and possibly a multiple number of receiving antennas (for details of

Alamouti scheme, see Alamouti, S. M. A Simple Transmit Diversity Technique for Wireless

Communications, IEEE Journal on Select Areas in Communications, Vol. 16, No. 8,

(October 1998), pp. 1453-1458)

The transmission of subpacket A' to the MS can be made on a different frequency

(i.e., £2). An important feature to note is that transmission of subpacket A' need not be time

aligned with transmission of subpacket A. As shown in Figure 6, subpacket A is first

broadcasted on fl by the BTS. The RS receives and decodes subpacket A and transmits

subpacket A' (repetition or encoded version of subpacket A, for example) to the MS in the

next transmission time slot. At the same transmission time slot, the BTS also broadcasts

packet B which in turn is received and decoded by the RS before being transmitted during

the subsequent transmission time slot to the MS. Subsequently, packets C and D are

broadcasted on fl and packet B' and C are transmitted to the MS on £2 during the same

transmission time slots, respectively. Here, the original packet and the relayed packets are

transmitted at different transmission time slots. With this arrangement, not only can

information contained in the packets be received with more accuracy, interferences can be

reduced as well.

Further, a mechanism can be used to maintain timing of the RS (e.g., GPS). Here,

the timing can be derived from the BTS signal, similar to the MS in which timing is derived

from the BTS in a single hop system.

Figure 6 illustrates a scheme for a relayed BCMCS according to another

embodiment of the present invention. In Figure 6, a space-time coding is introduced in a

multi-hop system having two frequency carriers (i.e., fl and f2) and two hops and two types

ofRS.

Similar to Figure 3, the BTS broadcasts BCMCS packets (e.g., A, B, C, D) in

sequence on a frequency (i.e., fl). The RS then receives the broadcasted BCMCS packets

and decodes them before transmitting a 'relayed signal' to the MS. That is, for example,

after the RS receives subpacket A broadcasted from the BTS on fl and decodes subpacket

A, the RS can then transmit subpacket Al' and subpacket A2' (also referred to as 'relayed

signals') to the MS using a different frequency (i.e., fl). The relayed signals can be based

on simple repetition or space-time encoding, for example. For simple repetition, subpackets

Al' and A2' would simply relay the original signal subpacket A. Alternatively, space-time

coding can be used to exploit transmit diversity. For example, sub-packets Al' and A2' can

be a second-order space-time code such as the Alamouti code.

For transmit diversity, in Figure 6, the BCMCS packets transmitted to the MS by the

RS are divided into two types — Type 1 and Type 2. Here, the RS can be divided into two

types (i.e., Type 1 and Type 2) based on the RS sharing one frequency and/or based on the

RS having two antennas. However, the RS is not limited to having two antennas but can

have more than two antennas. As discussed above, the RS decodes the BTS' transmission of

subpacket A and transmits the 'relayed signals' Al ' and A2' for RS of Type 1 and RS of

Type 2, respectively. For example, the RS Type 1 transmits the same signal or repeated

packet (e.g., subpacket A') such that subpacket A = subpacket Al'. At the same time, the

RS Type 2 transmits a space-time encoded version, subpacket A2', instead to provide

transmit diversity. Here, the space-time code can be based on an Alamouti scheme, for

example (for details of Alamouti scheme, see Alamouti, S. M. A Simple Transmit Diversity

Technique for Wireless Communications, IEEE Journal on Select Areas in Communications,

Vol. 16, No. 8, (October 1998), pp. 1453-1458). Since subpacket Al' and subpacket A2'

are sent on the same frequency (i.e., f2) at the same transmission time slot, the relayed

signal for Type 1 and Type 2 should be in a different format. That is, if Type 1 is a simple

repetition of the original packet, then Type 2 is space-time encoded, and vice versa.

Further, the RS(s) can transmit relayed signal A' (e.g., subpacket Al ' and subpacket

A2') which can be a simple repetition of the originally transmitted subpacket A or an

encoded version of subpacket A. The encoded version includes space time coding as well as

incremental redundancy which uses different parity bits than the original packet

transmission.

In schemes introduced with respect to Figures 3 and 6, preferably, a pilot can be

removed from the transmission of subpacket A' in a IxEV-DO slot. Moreover, a Medium

Access Control (MAC) burst can also be removed in the IxEV-DO slot. The removal of the

pilot and the MAC burst in the RS transmission can enable backward compatibility. The

pilot and the MAC burst removal is necessary to make sure that legacy MSs can estimate

the correct channel quality information (CQI) which is used to generate data rate control

(DRC) information. Otherwise, the legacy MSs will measure increased interference and

report a lower CQI. Although it is preferable to remove the pilot from the transmission of

subpacket A' in IxEV-DO, alternatively, the pilot can also be kept in transmitting

subpacket A' in a IxEV-DO slot.

Furthermore, absent the pilot and/or the MAC burst, the MS does not falsely believe

that the received signal is the original signal. In addition, the removal would help reduce

interference.

Figure 7 illustrates a scheme for a relayed BCMCS according another embodiment

of the present invention. In Figure 7, a single frequency carrier having a time-division

multiplexing (TDM) is applied in a multi-hop system.

Since the BTS and the MS share the same spectrum in a time division multiplexing

(TDM) fashion, the transmission time for a single packet is doubled. As described above,

the BTS broadcasts the original signal (i.e., subpacket A) during the first transmission time

slot. The RS then receives and decodes the BTS' transmission of subpacket A. Thereafter,

the RS transmits a 'relayed signal' A2' during the subsequent transmission time slot. Here,

subpacket A2' can be a simple repetition of subpacket A or can be space-time encoded.

Alternatively, subpacket A2' can be a simple repetition of subpacket Al' or a space-time

coded version of subpacket Al'. At the same transmission time slot, the BTS retransmits

subpacket A now in form of subpacket Al ' . Here, subpacket Al ' can be simple repetition of

subpacket A, space-time encoded subpacket A, or packet(s) having different parity bits than

subpacket A.

That is, there are a number of options for designing the relayed signal A2' and the

BTS retransmitted signal Al'. For example, both subpacket Al' and subpacket A2' can be

simple repetition where subpacket A2' = subpacket Al' or subpacket A2' = subpacket A. It

is important to note that the information carried by the subpackets are the same.

Alternatively, subpacket Al' and subpacket A2' can both be space-time encoded. For

example, subpacket A2' can be space-time coded version of subpacket Al' while subpacket

Al' is a repetition of subpacket A. Further, as another example, subpacket Al ' can be

different channel encoded version of subpacket A (e.g., same payload but different parity

bits) while subpacket A2' can be a space-time coded version of subpacket Al ' or a replica

(simple repetition) of subpacket Al'.

Similar arrangement can be applied to subsequent BTS transmissions (e.g., packet B

and packets B 17B2').

Figure 8 illustrates a scheme for a relayed BCMCS according to another

embodiment of the present invention. In Figure 8, a single frequency carrier is used in a

multi-hop system. The BTS broadcasts subpacket A during a first transmission time slot.

The RS receives the broadcasted subpacket A and decodes it. The decoded subpacket A is

then transformed into subpacket A2' and subpacket A3' depending on the RS Type. As

described above with respect to Figure 4, the transmission of packets from the RSs can be

divided into Type 1 and Type 2 where one type can be simple repetition. Alternatively, both

types can be space-time encoded. In addition, the BTS retransmits subpacket A in a form of

subpacket Al'. Here, subpacket Al' can be simple repetition of subpacket A or can be

space-time encoded.

As illustrated in Figure 8, subpacket Al', subpacket A2', and subpacket A3' are

transmitted to the MS at the subsequent transmission time slot. In this transmission, for

example, all packets can be simple repetition where subpacket Al' = subpacket A2' =

subpacket A3'. Alternatively, all packets can be space-time encoded or a combination of

simple repetition and space-time encoded packets.

Further, the transmission of the subpackets (e.g., subpacket Al ', A2', and A3') can

be performed in various combinations of encoded subpackets. For example, subpacket A2'

and subpacket A3' can be any one of space-coded subpacket or a repeated broadcast

subpacket, respectively. Moreover, subpacket A2' and subpacket A3'can have different

parity bits than the retransmitted subpacket Al ' or the original subpacket A.

For example, subpackets A2' = subpacket Al' and subpacket A3' = a space-time

encoded version of subpacket A2' where subpacket Al ' can be either a replica (e.g., simple

repetition) of subpacket A or different encoded version (e.g., incremental redundancy with

different parity bits). Another example is where subpackets Al ', A2', and A3' can be third-

order transmit diversity scheme where the three subpackets are distinct. As before,

subpacket Al' can be either a replica (e.g., simple repetition) or subpacket A or a different

encoded version (e.g., incremental redundancy with different parity bits.

Here, subpacket Al ' is a re-transmission after subpacket A for the same payload (or

packet) (where subpacket Al' can be identical to subpacket A or be different with different

parity bits) from the BTS. Subpackets A2' and A3' are transmitted from a RS of Type 1 and

another RS of Type 2, respectively, all in the same time slot. Here, as described in Figure 8,

the RS can be divided into two types (i.e., Type 1 and Type 2) based on the RS sharing the

same frequency with the BTS and/or based on the RS having two antennas sharing the same

frequency with the BTS. However, the RS is not limited to having two antennas but can

have more than two antennas. As discussed above, the RS decodes the BTS' transmission of

subpacket A and transmits the 'relayed signals' A2' and A3' for RS of Type 1 and RS of

Type 2, respectively. For example, RS Type 1 transmits subpacket A2' = subpacket Al ' and

RS Type 2 transmit subpacket A3' = subpacket Al'. The subpacket can be a simple

repetition of subpacket A or a differently encoded version (e.g., incremental redundancy

from the same information payload.)

In another example, subpackets Al', A2', and A3' can be third-order transmit

diversity scheme. In another example, subpackets Al', A2', and A3' can be a second order

transmit diversity such as the Alamouti scheme. For example, subpacket A2' can be a

replica of subpacket Al' and subpacket A3' can be a space-time encoded version of

subpacket Al '. As before, subpacket Al ' can be either a replica of subpacket A, or it can be

a differently encoded version.

In addition, the packets transmitted form the RS can be independent of subpacket

Al'. Typically, packets transmitted from the RS(s) are repeated or space-time coded based

on the retransmitted subpacket Al'. However, the packets transmitted form the RS(s) do not

necessarily have to be based on subpacket Al'. In other words, for example, if subpacket

A2' = subpacket Al' (e.g., subpacket A2' is a simple repetition of subpacket Al'),

subpacket A3' does not have to be dependent on or directly related to Al'. That is,

subpacket A3' can be dependent from subpacket A (e.g., subpacket A3' is a simple

repetition or space-time coded from subpacket A). Similarly, subpacket A3' can be

associated with subpacket Al' while subpacket A2' is dependent on subpacket A, for

example.

The embodiments described above can be applied to the BCMCS system to reduce

coverage holes and limited capacity. In effect, the embodiments of the present invention can

be applied to significantly extend the BCMCS coverage and increase broadcast-multicast

system capacity.

It will be apparent to those skilled in the art that various modifications and variations

can be made in the present invention without departing from the spirit or scope of the

inventions. Thus, it is intended that the present invention covers the modifications and

variations of this invention provided they come within the scope of the appended claims and

their equivalents.