Description
Title of Invention: METHOD AND APPARATUS OF
TRANSMITTING AND RECEIVING SYSTEM INFORMATION
IN A WIRELESS SYSTEM
Technical Field
[1] The present invention relates to a wireless communication system, and more p ar
ticularly to a method and apparatus for transmitting and receiving system information
in a wireless communication system.
Background Art
[2] A brief description will be given below of a super frame header (SFH).
[3] A base station (BS) transmits system information to mobile stations (MSs) through
an SFH. The SFH is located in a first subframe contained in one superframe. The SFH
is divided into a primary SFH (P-SFH) and a secondary SFH (S-SFH).
[4] Table 1 shows a P-SFH Information Element (IE).
[5] Table 1
[Table 1]
The P-SFH IE is transmitted at every superframe, and includes 4-bit Least Significant
Bit (LSB) information of the SFN and information associated with the S-SFH IE. The
S-SFH IE - associated information includes an S-SFH change count that indicates
version information of a currently transmitted S-SFH; S-SFH scheduling information
that indicates which secondary super frame header subpacket information element
(S-SFH SP IE) is included in the corresponding superframe; S-SFH size that indicates
the number of LRUs allocated for S-SFH transmission; S-SFH number of repetition
that indicates a transmission format of the S-SFH; and S-SFH SP change bitmap that
indicates which S-SFH SP IE is changed. The size of the S-SFH SP change bitmap
field is identical to a total number of S-SFH SP IEs.
Table 2 shows the S-SFH IE format. The S-SFH transmits actual system information.
The system parameter and system configuration information transmitted through the SSFH
are classified into S-SFH SPl IE, S-SFH SP2 IE, and S-SFH SP3 IE. S-SFH SPl
IE includes network reentry information. S-SFH SP2 IE includes initial network entry
and network discovery information. S-SFH SP3 IE includes the remaining requisite
system information for network entry or network reentry.
Table 2
[Table 2]
[9] S-SFH SPl IE, S-SFH SP2 IE and S-SFH SP3 IE having different periodicities are
transmitted at different times. Table 3 shows transmission periods of S-SFH SPl IE, SSFH
SP2 IE and S-SFH SP3 IE. The transmission periodicities of S-SFH SPl IE, SSFH
SP2 IE and S-SFH SP3 IE are signaled through the S-SFH SP3 IE.
[10] Table 3
[Table 3]
[11] A method for controlling a mobile station (MS) to update S-SFH SP IE (secondary
super frame header subpacket information element) information will hereinafter be
described in detail.
[12] The mobile station (MS) receives P-SFH IE to confirm the S-SFH change count
field. The base station (BS) increases a value assigned to the S-SFH change count field
by one whenever the S-SFH IE information is updated (changed).
[13] If the value of the S-SFH change count field is different from a value assigned to the
MS, the MS determines that the S-SFH SP IE has been updated (changed), and
recognizes the S-SFH SP change bitmap of the P-SFH IE such that it can confirm
which S-SFH SP has been updated (changed).
[14] In addition, P-SFH IE confirms the S-SFH scheduling information field to recognize
which S-SFH SP IE is transmitted through a current superframe. When transmitting the
S-SFH SP IE to be updated (stored and updated) in the current SFH, the corresponding
S-SFH SP IE is confirmed and updated (stored and updated). In addition, in the case
where the S-SFH SP IE to be updated (stored and updated) is not transmitted through
the current SFH, the S-SFH SP IE is received at the next period in which the S-SFH SP
IE to be updated (stored and updated) is transmitted, such that the received SFH SP IE
is updated (stored and updated).
[15] According to the conventional art, the MS must decode the POSFH at every su
perframe, confirm the S-SFH change count, and confirm whether the S-SFH SP IEs are
changed, resulting in an increase in power consumption of the MS.
[16] Next, a sleep mode operation according to the conventional art will hereinafter be
described with reference to FIG. 1. While a mobile station (MS) communicates with a
base station (BS) in a normal mode or an active mode, if there is no more traffic to be
transmitted/received to/from the BS, the MS transmits a sleep request (hereinafter
referred to as AAI_SLP-REQ) message requesting that the BS transition to a sleep
mode. In response to the AAI_SLP-REQ message, the BS transmits a sleep response
(hereinafter referred to as AAI_SLP-RSP) message to the MS. The MS having
received the AAI_SLP-RSP message transitions to sleep mode using sleep parameters
(such as a sleep cycle, a listening window, etc.) contained in the AAI_SLP-RSP
message. In addition, the BS transmits an unsolicited AAI_SLP-RSP message to the
MS such that the MS may transition to sleep mode.
[17] FIG. 1 is a conceptual diagram illustrating a sleep mode operation of the MS
according to the conventional art. Referring to FIG. 1, after the MS transitions from
normal mode to sleep mode, an initial sleep cycle is applied to the MS such that the
MS operates in the sleep mode. Upon completion of the transition to the sleep mode, a
first sleep cycle includes only a sleep window.
[18] From a second sleep cycle located after a first sleep cycle, the MS operates in the
sleep mode using the sleep cycle including both the listening window and the sleep
window. If the MS receives a traffic indication (TRF-IND) message including a
negative indication message during the listening window, the MS detects the absence
of downlink (DL) transmission traffic, and doubles a current sleep cycle. After the
doubled sleep cycle ends, if the MS receives a TRF-IND message including a positive
indication message during a listening window of the next sleep cycle, the MS resets a
current sleep cycle to an initial sleep cycle.
[19] The MS in the sleep mode has to include the latest system information transmitted
through the SFH such that it can freely communicate with the BS using the latest
system information. However, if a frame for P-SFH transmission is present in a sleep
window of the MS, the MS is unable to receive the P-SFH.
[20] In accordance with the above-mentioned conventional art, the MS needs to decode PSFH
at every superframe so as to determine whether S-SFH SP IEs are changed,
resulting in an increase in MS power consumption. In addition, in the case of the MS
operating in the sleep mode, if a frame for S-SFH transmission is present in the MS
sleep window, the MS is unable to receive the P-SFH.
Disclosure of Invention
Technical Problem
[21] Accordingly, the present invention is directed to an apparatus and method for
transmitting and receiving a demodulation reference signal (RS) that substantially
obviate one or more problems due to limitations and disadvantages of the related art.
[22] An object of the present invention devised to solve the problem lies on a method for
transmitting and receiving system information so as to reduce power consumption of a
mobile station (MS).
[23] Another object of the present invention devised to solve the problem lies on a method
for transmitting and receiving system information so as to allow an MS operating in a
sleep mode to effectively receive system information.
[24] It will be appreciated by persons skilled in the art that the objects that can be
achieved with the present invention are not limited to what has been particularly
described hereinabove and the above and other objects that the present invention can
achieve will be more clearly understood from the following detailed description taken
in conjunction with the accompanying drawings.
Solution to Problem
[25] The object of the present invention can be achieved by providing a method for
receiving system information by a mobile station (MS) of a wireless communication
system, the method including receiving a secondary superframe header (S-SFH)
change cycle from a base station (BS); and receiving a primary superframe header in
formation element (P-SFH IE) including a first field indicating a change count of a
plurality of secondary superframe header subpacket information elements (S-SFH SP
IEs) from the base station (BS), wherein, once each of the plurality of S-SFH SP IEs is
changed, each of the plurality of S-SFH SP IEs remains unchanged during one or more
S-SFH change cycle periods.
[26] A value of the first field may be changed only in a superframe satisfying that a
remainder obtained when a superframe number (SFN) of the superframe is divided by
the S-SFH change cycle is a predetermined number.
[27] The S-SFH change cycle may be indicated in one of the S-SFH SP IEs.
[28] The method may further include receiving at least one S-SFH SP IE among the
plurality of S-SFH SP IEs, and updating the received S-SFH SP IE if a value of the
first field is different from an S-SFH change count stored in the mobile station (MS).
[29] The receiving at least one s-SFH SP IE may include receiving only one or more SSFH
SP IEs whose bit in an S-SFH SP change bitmap is set to 1 and updating the
received one or more S-SFH SP IEs if a difference between the value of the first field
and the S-SFH change count stored in the mobile station (MS) is 1, wherein the S-SFH
SP change bitmap indicates whether each of the plurality of P-SFH SP IEs is changed.
[30] The receiving at least one S-SFH SP IE may include receiving and updating all of the
plurality of S-SFH SP IEs if a difference between the value of the first field and the SSFH
change count stored in the mobile station (MS) is greater than 1.
[31] The method may further include applying contents of the at least one S-SFH SP IE
simultaneously at the latest superframe among superframes immediately following
after each of the at least one S-SFH SP IE is regularly transmitted a predetermined
number of times.
[32] The P-SFH IE may further include a second field indicating S-SFH SP IEs applied in
a superframe in which the P-SFH IE is transmitted.
[33] In another aspect of the present invention, provided herein is a method for
transmitting system information by a base station (BS) of a wireless communication
system, the method including transmitting a secondary superframe header (S-SFH)
change cycle to a mobile station (MS), and transmitting a primary superframe header
information element (P-SFH IE) including a first field indicating a change count of a
plurality of secondary superframe header subpacket information elements (S-SFH SP
IEs) to the mobile station (MS), wherein, once each of the plurality of S-SFH SP IEs is
changed, each of the plurality of S-SFH SP IEs remains unchanged during one or more
S-SFH change cycle periods.
[34] In another aspect of the present invention, provided herein is a mobile station (MS)
for use in a wireless communication system, the mobile station (MS) including a
reception (Rx) module for receiving a secondary superframe header (S-SFH) change
cycle from a base station (BS), and receiving a primary superframe header information
element (P-SFH IE) that includes a first field indicating a change count of a plurality of
superframe header subpacket information elements (S-SFH SP IEs) from the base
station (BS), wherein, once each of the plurality of S-SFH SP IEs is changed once,
each of the plurality of S-SFH SP IEs remains unchanged during one or more S-SFH
change cycle periods.
[35] In another aspect of the present invention, provided herein is a base station (BS) for
use in a wireless communication system, the base station (BS) including a transmission
(Tx) module for transmitting a secondary superframe header (S-SFH) change cycle to a
mobile station (MS), and transmitting a primary superframe header information
element (P-SFH IE) that includes a first field indicating a change count of a plurality of
secondary superframe header subpacket information elements (S-SFH SP IEs) to the
mobile station (MS), wherein, once each of the plurality of S-SFH SP IEs is changed,
each of the plurality of S-SFH SP IEs remains unchanged during one or more S-SFH
change cycle periods.
[36] In another aspect of the present invention, provided herein is a mobile station (MS)
for use in a wireless communication system, the mobile station (MS) including: a
central processing unit (CPU) for controlling overall operations of the mobile station
(MS); a memory for storing information related to communication with a base station
(BS); and a communication module for controlling communication with the base
station (BS), wherein the communication module includes a reception (Rx) module,
the reception (Rx) module receiving a secondary superframe header (S-SFH) change
cycle from a base station (BS), and receiving a primary superframe header information
element (P-SFH IE) that includes a first field indicating a change count of a plurality of
secondary superframe header subpacket information elements (S-SFH SP IEs) from the
base station (BS), wherein, once each of the plurality of S-SFH SP IEs is changed,
each of the plurality of S-SFH SP IEs remains unchanged during one or more S-SFH
change cycle periods.
[37] In another aspect of the present invention, provided herein is a base station (BS) for
use in a wireless communication system, the base station (BS) including: a central
processing unit (CPU) for controlling overall operations of the base station (BS); a
memory for storing information related to communication; and a communication
module for controlling communication, wherein the communication module includes a
transmission (Tx) module, the transmission (Tx) module transmitting a secondary superframe
header (S-SFH) change cycle to a mobile station (MS), and transmitting a
primary superframe header information element (P-SFH IE) that includes a first field
indicating a change count of a plurality of secondary superframe header subpacket in
formation elements (S-SFH SP IEs) to the mobile station (MS), wherein, once each of
the plurality of S-SFH SP IEs is changed, each of the plurality of S-SFH SP IEs
remains unchanged during one or more S-SFH change cycle periods.
Advantageous Effects of Invention
[38] Exemplary embodiments of the present invention have the following effects. If each
of several S-SFH SP IEs is changed once, each S-SFH SP IE remains unchanged
during one or more S-SFH change cycles, such that the embodiments of the present
invention decode the P-SFH IE only when a validity check of each S-SFH SP IE is
needed, and recognize whether each S-SFH SP IE is changed on the basis of the
decoded result, resulting in a reduction in MS power consumption.
[39] It will be appreciated by persons skilled in the art that that the effects that can be
achieved through the present invention are not limited to what has been particularly
described hereinabove and other advantages of the present invention will be more
clearly understood from the following detailed description taken in conjunction with
the accompanying drawings.
Brief Description of Drawings
[40] The accompanying drawings, which are included to provide a further understanding
of the invention, illustrate embodiments of the invention and together with the de
scription serve to explain the principle of the invention.
[41] In the drawings:
[42] FIG. 1 is a conceptual diagram illustrating a sleep mode operation of a mobile station
(MS) according to the conventional art.
[43] FIG. 2 is a flowchart illustrating a method for receiving system information of a
mobile station (MS) according to an exemplary embodiment of the present invention.
[44] FIG. 3 shows application time points when one S-SFH SP IE is changed in one
transmission time interval according to the present invention.
[45] FIG. 4 shows application time points when several S-SFH SP IEs are changed in one
transmission time interval.
[46] FIG. 5 shows application time points according to a second method.
[47] FIG. 6 shows exemplary application time points according to a third method.
[48] FIG. 7 shows another example of an application time point according to a third
method.
[49] FIG. 8 shows application time points according to a fourth method.
[50] FIG. 9 shows one example of an application time point according to a fifth method.
[51] FIG. 10 shows another example of an application time point according to a fifth
method.
[52] FIG. 11 is a flowchart illustrating operations of a mobile station (MS) according to a
sixth method.
[53] FIG. 12 shows one example of an application time point according to a sixth method.
[54] FIG. 13 shows another example of an application time point according to a sixth
method.
[55] FIG. 14 shows still another example of an application time point according to a sixth
method.
[56] FIG. 15 is a conceptual diagram illustrating that S-SFH SP2 IEs are irregularly
transmitted.
[57] FIG. 16 is a block diagram illustrating an advanced mobile station (AMS) and an
advanced base station (ABS) for use in embodiments of the present invention.
Best Mode for Carrying out the Invention
[58] Reference will now be made in detail to the preferred embodiments of the present
invention, examples of which are illustrated in the accompanying drawings. The
detailed description, which will be given below with reference to the accompanying
drawings, is intended to explain exemplary embodiments of the present invention,
rather than to show the only embodiments that can be implemented according to the
present invention. The following detailed description includes specific details in order
to provide a thorough understanding of the present invention. However, it will be
apparent to those skilled in the art that the present invention may be practiced without
such specific details. For example, the following description will be given centering
upon a mobile communication system serving as a 3rd Generation Partnership Project 2
(3GPP2) 802.16 system, but the present invention is not limited thereto and the
remaining parts of the present invention other than unique characteristics of the 3GPP2
802.16 system are applicable to other mobile communication systems.
[59] In some cases, in order to prevent ambiguity of the concepts of the present invention,
conventional devices or apparatuses well known to those skilled in the art will be
omitted and denoted in the form of a block diagram on the basis of the important
functions of the present invention. Wherever possible, the same reference numbers will
be used throughout the drawings to refer to the same or like parts.
[60] In the following description, "terminal" may refer to a mobile or fixed user
equipment (UE), for example, a user equipment (UE), a mobile station (MS) and the
like. Also, "base station" (BS) may refer to an arbitrary node of a network end which
communicates with the above terminal, and may include a Node B (Node-B), an
eNode B (eNode-B) and the like.
[61] A method for transmitting and receiving system information according to the em
bodiments of the present invention will hereinafter be described with reference to the
accompanying drawings.
[62] According to the embodiments of the present invention, whenever it is necessary for
a mobile station (MS) to perform a validity check of each S-SFH SP IE (secondary
super frame header subpacket information element) stored in the MS, the MS decodes
a P-SFH IE (primary super frame header information element) to check whether each
S-SFH SP IE is changed.
[63] FIG. 2 is a flowchart illustrating a method for receiving system information of a
mobile station (MS) according to an exemplary embodiment of the present invention.
[64] Referring to FIG. 2, the MS receives an S-SFH change cycle from the BS at step
S210. In this case, the MS may receive the S-SFH change cycle through the S-SFH
SP3 IE.
[65] The S-SFH change cycle is indicative of a minimum period in which S-SFH remains
unchanged. Each of the S-SFH SP IEs may be changed only once during the S-SFH
change cycle. That is, provided that each S-SFH SP IE is changed only once, it remains
unchanged during one or more S-SFH change cycles. The S-SFH change cycle may be
established in all of the S-SFH SP IEs, or may also be established in each S-SFH SP
IE.
[66] The S-SFH change time may be represented in either a time unit (e.g., ms) or a superframe
unit. If the S-SFH change cycle is not established in each S-SFH SP IE, the
S-SFH change cycle may be represented by a total number of S-SFH SP IEs that are
transmitted during the S-SFH change cycle.
[67] In the case where the S-SFH change cycle is established for the entirety of several SSFH
SP IEs, the S-SFH change count information indicating the S-SFH version
contained in the primary superframe header information element (P-SFH IE) can be
increased only once during the S-SFH change cycle. In this case, the S-SFH change
count information may be increased only in specific superframes that are dependent
upon a change cycle and a superframe number (SFN). For example, if the S-SFH
change cycle is established in units of a superframe, the S-SFH change count can be
increased only in a superframe having an SFN in which SFN modulo S-SFH change
cycle is equal to a specific value. In this case, the specific number may be set to zero.
If the S-SFH change cycle is 32, the S-SFH change count may be increased only in a
superframe in which the SFN is a multiple of 32.
[68] In addition, the changed S-SFH SP IE is transmitted through some superframes
scheduled for the changed S-SFH SP IE, from among a first superframe where the SSFH
change count is changed and other superframes subsequent to the first su
perframe.
[69] Next, the case in which the S-SFH change cycle is established for each S-SFH IE
will hereinafter be described in detail. A base station (BS) may change the corre
sponding S-SFH SP IE at a specific time point that is decided using the S-SFH change
cycle and the SFN that belong to each S-SFH SP IE. That is, the S-SFH SP IE may be
changed in a superframe that satisfies 'f(SFN, S-SFH change cycle) = x'. In this case,
'x' may be preset to a specific value, and may be transmitted through the S-SFH. In
addition, 'x' must be lower than "Transmission Period of Corresponding S-SFH SP IE /
Period of one superframe". For example, provided that the S-SFH SPl IE transmission
period is 40ms and one superframe period is 20ms, 'x' must be lower than '2'. For con
venience of description and better understanding of the present invention, it is assumed
that one superframe interval is 20ms in the following description.
[70] In the case where the S-SFH change cycle is represented by a total number of S-SFH
SP IEs that are transmitted during the S-SFH change cycle, the S-SFH SP IE may be
changed only in a superframe having an SFN where SFN mod (S-SFH change cycle *
S-SFH SP IE transmission period / 20) is equal to a specific value. For example,
provided that the S-SFH SPl IE transmission period is 40ms, the change cycle is 3,
and the S-SFH SPl IE is changed every superframe that satisfies SFN mod (S-SFH
change cycle * S-SFH SP IE transmission period / 20ms) = 1, S-SFH SPl IE may be
changed in a superframe having an SFN of 1, 7, 13 or 19.
[71] If the S-SFH change cycle is represented by a time unit (ms), the S-SFH SP IE may
be changed only in a superframe where SFN mod (S-SFH change cycle / 20ms) is
equal to a specific value. In this case, it is necessary for the S-SFH change cycle to be
an integer multiple of the corresponding S-SFH SP IE transmission period. For
example, provided that the S-SFH SPl IE change cycle is 80ms and S-SFH SPl IE is
changed at every superframe that satisfies SFN mod (S-SFH change cycle / 20ms) = 1,
S-SFH SPl IE may be changed in a superframe having an SFN of 1, 5, 9 or 13.
[72] If the S-SFH change cycle is represented in units of a superframe, the S-SFH SP IE
may be changed only in a superframe having an SFN where SFN mod S-SFH change
cycle is equal to a specific value. In this case, it is necessary for the S-SFH change
cycle to be an integer multiple of a specific value in which the corresponding S-SFH
SP IE transmission period is represented by the number of superframes. For example,
provided that the S-SFH change cycle of the S-SFH SPl IE is 4, and the S-SFH SPl IE
is changed at every superframe that satisfies 'SFN mod S-SFH change cycle = 1', SSFH
SPl IE may be changed in a superframe having an SFN of 1, 5, 9 or 13.
[73] Referring back to FIG. 2, a mobile station (MS) receives a P-SFH IE having the SSFH
change count field at step S220. The S-SFH change count field may indicate the
number of change times of S-SFH SP IEs that are transmitted during the current S-SFH
change cycle. That is, the S-SFH change count field may indicate version information
of the S-SFH SP IEs. If at least one of the S-SFH SP IEs is changed, the value of the SSFH
change count is increased.
[74] In this case, since the MS has already recognized the S-SFH change cycle, the MS
decodes the P-SFH IE whenever a validity check of S-SFH SP IEs stored in the MS is
needed, such that the S-SFH change count field value of the P-SFH SP IE may be
compared with the S-SFH change count stored in the MS.
[75] Provided that the S-SFH change count is changed only in specific superframes that
are decided according to the change cycle and the SFN, the MS may calculate a superframe
where the S-SFH change count can be changed using the SFN and the S-SFH
change cycle.
[76] The MS operating in a normal mode decodes the P-SFH IE in the calculated superframe,
such that it can recognize whether the S-SFH SP IEs are changed.
[77] If the calculated superframe is contained in the sleep window, the MS operating in a
sleep mode can receive the P-SFH IE at a superframe via which a P-SFH including the
S-SFH change count changed is transmitted just before the listening window. For
example, provided that superframes (z and z+n) that are capable of changing the SSFH
change count are contained in the sleep window, the MS operates in a superframe
'z+n' without operating in a superframe 'z' such that it can receive P-SFH IE. If the
calculated superframe is not contained in the sleep window, the MS need not be
operated because the BS can change the S-SFH IE only once within the abovementioned
change cycle. That is, this means that the S-SFH IE remains unchanged
while the MS stays in the sleep window.
[78] In addition, the MS receives the S-SFH SP IE and updates it at step S230.
[79] If the value of the S-SFH change count field of the P-SFH SP IE is different from the
S-SFH change count stored in the MS, the MS receives at least one of the S-SFH SP
IEs, and updates the received S-SFH SP IE. Otherwise, if the value of the S-SFH
change count field of the P-SFH SP IE is identical to the S-SFH change count stored in
the MS, the MS does not decode the S-SFH SP IE before the value of the S-SFH
change count is changed to another value.
[80] If a difference between a value of the S-SFH change count field of the P-SFH SP IE
and the S-SFH change count value stored in the MS is 1, the MS receives only the SSFH
SP IE where a bit of the S-SFH SP change bitmap of the P-SFH SP IE is set to 1,
and updates the received S-SFH SP IE. The S-SFH SP change bitmap indicates
whether each S-SFH SP IE is changed. That is, provided that the S-SFH SP change
bitmap field is 'XYZ', 'Z' may indicate whether S-SFH SP1 is changed, may
indicate whether S-SFH SP2 is changed, and 'X' may indicate whether S-SFH SP3 is
changed. For example, if 'Z' is set to T , 'Z = means that S-SFH SP1 is changed. If 'Z'
is set to '', '= 0' means that S-SFH SP1 remains unchanged. If Ύ ' is set to T , Ύ = 
means that S-SFH SP2 is changed. If Ύ ' is set to '', Ύ = 0' means that S-SFH SP2
remains unchanged. If 'X' is set to Ί ', 'X = means that S-SFH SP3 is changed. If 'X'
is set to '', 'X = means that S-SFH SP3 remains unchanged.
[81] If a difference between the value of the S-SFH change count field of the P-SFH SP
IE and the S-SFH change count value stored in the MS is higher than T , the MS
receives and updates all the S-SFH SP IEs.
[82] The MS applies content contained in the changed S-SFH SP IE after a specific time
point at step S240.
[83] If the S-SFH SP IE is changed, the BS and the MS may apply content including the
changed S-SFH SP IE after a specific time point.
[84] The embodiments of the present invention provide six methods that decide a specific
time point at which content contained in the changed S-SFH SP IE is applied.
[85] First, a first method that decides a specific time point at which content contained in
the changed S-SFH SP IE is applied will hereinafter be described in detail. In ac
cordance with a first method, content contained in the changed S-SFH SP IE begins
from a specific superframe decided by a superframe having the changed S-SFH SP IE.
That is, after the changed S-SFH SP IE is regularly scheduled a predetermined number
of times from the superframe decided by the above-mentioned calculation method,
content contained in the changed S-SFH SP IE may be applied to the next superframe,
such that a predetermined time in which each MS can receive the changed S-SFH SP
IE can be guaranteed. In this case, the predetermined number of times may be preset to
a fixed value, or may be dynamically decided by the BS.
[86] For example, provided that S-SFH SP1 IE is changed, after the S-SFH change count
field is increased by one in a superframe decided by the above-mentioned calculation
method, and the changed S-SFH SP1 IE is regularly scheduled two times, content
contained in the changed S-SFH SP IE may be applied to the next superframe.
Provided that S-SFH SP2 IE is changed, after the S-SFH change count field is
increased by one in a superframe decided by the above-mentioned calculation method,
and the changed S-SFH SP2 IE is regularly scheduled two times, content contained in
the changed S-SFH SP IE may be applied to the next superframe. In addition, provided
that S-SFH SP3 IE is changed, after the S-SFH change count field is increased by one
in a superframe decided by the above-mentioned calculation method, and the changed
S-SFH SP3 IE is regularly scheduled once, content contained in the changed S-SFH SP
IE may be applied to the next superframe.
[87] If several S-SFH SP IEs are changed in one S-SFH change cycle, information
contained in the changed S-SFH SP IEs is simultaneously applied to the last superframe
among predetermined superframes for respective S-SFH SP IEs. That is, after
individual S-SFH SP IEs are regularly scheduled a predetermined number of times for
individual S-SFH SP IEs, and the scheduled S-SFH SP IEs are transmitted, information
contained in several S-SFH SP IEs is simultaneously applied to the latest superframe
among subsequent superframes.
[88] In addition, the BS includes the S-SFH application hold indicator in a P-SFH, and
transmits the resultant P-SFH to the MS. The S-SFH application hold indicator may
indicate whether content of S-SFH SP IEs associated with the S-SFH change count is
applied to a current superframe. In other words, if the S-SFH application hold indicator
is set to zero '', the S-SFH application hold indicator of 0 indicates that content of SSFH
SP IEs associated with the S-SFH change count contained in a P-SFH transmitted
in a current superframe is applied to the current superframe. In contrast, if the S-SFH
application hold indicator is set to T , this means that content of S-SFH SP IEs a s
sociated with an expression ('S-SFH change count contained in the P-SFH transmitted
in the current superframe' - 1) can be applied to the current superframe.
[89] FIG. 3 shows application time points when one S-SFH SP IE is changed in one
transmission time interval according to the present invention.
[90] As can be seen from FIG. 3, provided that the S-SFH change cycle is set to 16, after
S-SFH SPl IE is changed and the S-SFH change count field is increased by one in a
superframe decided by the above-mentioned calculation method, the changed S-SFH
SPl IE is transmitted two times, and then content contained in the changed S-SFH SPl
IE may be applied to the next superframe.
[91] In FIG. 3, 'CC indicates the S-SFH change count, 'CB' indicates the S-SFH SP
change bitmap, 'SI' indicates S-SFH scheduling information, 'CB' indicates the S-SFH
SP change bitmap, and 'SI' indicates S-SFH scheduling information, and 'Flag'
indicates the S-SFH application hold indicator. The above-mentioned parameters are
contained in the P-SFH IE, and are then transmitted. Although the S-SFH count
indicates the S-SFH change count associated with S-SFH SP IEs applied to the corre
sponding superframe, the S-SFH count need not be contained in the P-SFH IE.
[92] In FIG. 3, in a superframe having an SFN decided by the above-mentioned cal
culation method, the S-SFH change count is changed from 0 to 1, the S-SFH SP
change bitmap is set to '00 so as to indicate the changed S-SFH SPl IE. In addition,
the changed S-SFH SPl IE is transmitted via each superframe having an SFN of 17 or
19. In addition, content of the changed S-SFH SPl IE is applied to superframes starting
from a superframe having an SFN of 20.
[93] FIG. 4 shows application time points when several S-SFH SP IEs are changed in one
transmission time interval.
[94] As can be seen from FIG. 4, provided that the S-SFH change cycle is set to 16, SSFH
SPl IE and S-SFH SP2 IE are changed after the S-SFH change count field is
increased by one in a superframe decided by the above-mentioned calculation method.
After the changed S-SFH SPl IE is transmitted two times and the next superframe and
the changed S-SFH SP2 IE are then transmitted two times, contents of the changed SSFH
SPl IE and S-SFH SP2 IE are simultaneously applied in the range from the latest
superframe among subsequent superframes.
[95] In FIG. 4, in a superframe having an SFN decided by the above-mentioned cal
culation method, the S-SFH change count is changed from 0 to 1, and the S-SFH SP
change bitmap is set to ', Ό1indicating that the S-SFH SPl IE and the S-SFH
SP2 IE are changed. In addition, the changed S-SFH SPl IE is transmitted via each su
perframe having an SFN of 17 or 19, and the changed S-SFH SP2 IE is transmitted via
each superframe having an SFN of 18 or 22. Therefore, a superframe, that is located
just after the changed S-SFH SPl IE has been transmitted two times, is a superframe
having an SFN of 20, and a superframe, that is located just after the changed S-SFH
SP2 IE is transmitted two times, is a superframe having an SFN of 23. Therefore,
contents of the changed S-SFH SPl IE and S-SFH SP2 IE may be applied after the
later one of the superframe having an SFN of 20 and another superframe having an
SFN of 23.
[96] Next, a second method of deciding a specific time point at which content contained
in the changed S-SFH SP IE is applied will hereinafter be described in detail. In ac
cordance with the second method, the BS informs MSs whether S-SFH SP IEs are
changed at a specific reference time point, and informs each MS of the application
time point using the flag. In addition, the changed S-SFH SPl IEs are applied to an ap
plication time point indicated through the flag.
[97] A specific reference point may be superframes that satisfy SFN mod x = 0. In this
case, if the S-SFH change cycle is represented in a time unit (e.g., ms), 'x' is denoted
by (S-SFH change cycle / 20ms). If the S-SFH change cycle is represented by a total
number of S-SFH SP IEs that can be transmitted during the S-SFH change cycle, 'x' is
denoted by (S-SFH change cycle * S-SFH SP IE change cycle * S-SFH SP IE
transmission period / 20). If the S-SFH change cycle is represented in units of a su
perframe, 'x' is an S-SFH change cycle.
[98] Table 4 shows a flag for use in the second method under the condition that the S-SFH
change cycle is represented by a total number of S-SFH SP IEs that can be transmitted
during the S-SFH change cycle.
[99] Table 4
[Table 4]
[100] FIG. 5 shows application time points according to a second method.
[101] In FIG. 5, the S-SFH change cycle is composed of 32 superframes.
[102] In FIG. 5, a specific reference point is set to superframes having SFNs of 32 and 64,
the S-SFH change count is changed to in a superframe having an SFN of 32, and the
S-SFH change bitmap is set to Ό1, indicating that the S-SFH SPl IE and the S-SFH
SP2 IE are changed. In addition, since the flag is set to '10', contents of the changed SSFH
SPl IE and S-SFH SP2 IE are applied in the range from a 48-day superframe cor
responding to an SFN indicating a specific position spaced apart from a specific
reference point by 16 superframes.
[103] In a superframe having an SFN of 64, the S-SFH change count is changed to '2', and
the S-SFH SP change bitmap is set to Ό, indicating that S-SFH SPl IE is changed.
In addition, since the flag is set to Ό, content of the changed S-SFH SPl IE is applied
from a superframe having an SFN of 72, the superframe corresponding to a specific
position spaced apart from a specific reference point by 8 superframes.
[104] If the MS having the stored S-SFH change count of 0 receives the S-SFH change
count of 1 through the P-SFH, the MS can recognize that the S-SFH SP IE is changed.
Since a difference between the S-SFH change count stored in the MS and the other SSFH
change count received through P-SFH is T , the MS can recognize that S-SFH
SPl IE and S-SFH SP2 IE are changed by recognizing the S-SFH change bitmap.
Therefore, at transmission time points of the S-SFH SPl IE and the S-SFH SP2 IE, the
MS receives the changed S-SFH SPl IE and S-SFH SP2 IE. In addition, the MS
checks the flag such that it can recognize application time points of the changed S-SFH
SPl IE and S-SFH SP2 IE.
[105] If the MS having the stored S-SFH change count of 0 receives the S-SFH change
count of 2 through the P-SFH, the MS can recognize that the S-SFH SP IE has been
changed. Since a difference between the S-SFH change count stored in the MS and the
other S-SFH change count received through a P-SFH is denoted by 2, the MS has to
receive all the S-SFH SP IEs. In addition, the MS recognizes the S-SFH change bitmap
such that it can recognize that S-SFH SP IE changed in the corresponding S-SFH
change cycle is identical to S-SFH SPl IE. The MS uses a flag to recognize an ap
plication time point of the changed S-SFH SPl IE, and can also recognize that S-SFH
SP2 IE and S-SFH SP3 IE have already been applied.
[106] Next, a third method of deciding a specific time point at which content contained in
the changed S-SFH SP IE is applied will hereinafter be described in detail. In ac
cordance with a third method, the BS informs MSs whether each S-SFH SP IE is
changed within the S-SFH change cycle, and also informs each MS of an application
time point using a flag. The changed S-SFH SP IEs are simultaneously applied to an
application time point indicated through a flag. In this case, information about whether
each S-SFH SP IE is changed may be transmitted to MSs in a superframe that initially
receives each S-SFH SP IE within the S-SFH change cycle.
[107] A specific reference point is determined in the same manner as in the second method,
and the flag serves the same purpose as in Table 4.
[108] FIG. 6 shows exemplary application time points according to a third method.
[109] In FIG. 6, the S-SFH change cycle is composed of 32 frames.
[110] In FIG. 6, a specific reference point is set to superframes having SFNs of 32 and 64,
the S-SFH change count is changed to in a superframe having an SFN of 33 via
which the changed S-SFH SPl IE is initially transmitted within the S-SFH change
cycle, and the S-SFH change bitmap is set to Ό0, indicating that the S-SFH SPl IE is
changed. In addition, in a superframe having an SFN of 34 via which the changed SSFH
SP2 IE is initially transmitted within the S-SFH change cycle, the S-SFH change
count is changed to 2, and the S-SFH SP change bitmap is set to '010', indicating that
the S-SFH SP2 IE is changed. In addition, since the flag is set to '10', contents of the
changed S-SFH SPl IE and the S-SFH SP2 IE are applied in the range from a specific
position spaced apart from a specific reference point by 16 superframes.
[Ill] The MS operating in the sleep mode can recognize whether each of S-SFH SPl IE,
S-SFH SP2 IE 2 and S-SFH SP3 IE is changed at a specific position where each of SSFH
SPl IE, S-SFH SP2 IE and S-SFH SP3 IE is initially transmitted within a
previous listening window. For example, the MS that has a listening window corre
sponding to an SFN of 43 can recognize whether the S-SFH SP3 IE is changed at a su
perframe of 32, can recognize whether the S-SFH SPl IE is changed at a superframe of
33, and can recognize whether the S-SFH SP2 IE is changed at a superframe of 34. The
MS can recognize that S-SFH SPl IE and S-SFH SP2 IE 2 are changed. In addition,
the MS can recognize that contents of the changed S-SFH SPl IE and S-SFH SP2 IE
are applied in the range from a specific position spaced apart from a specific reference
point by 16 superframes.
[112] FIG. 7 shows another example of an application time point according to a third
method.
[113] In FIG. 7, the S-SFH change cycle is composed of 32 superframes.
[114] In FIG. 7, if the S-SFH change count is increased within one S-SFH change cycle,
only a bit corresponding to the changed S-SFH SP IE of the S-SFH SP change bitmap
is set to 1. In addition, if the S-SFH change count is increased in the corresponding SSFH
change cycle, a bit corresponding to the changed S-SFH SP IE of the S-SFH SP
change bitmap is additionally set to .
[115] In FIG. 7, provided that S-SFH SP1 IE is changed in a superframe having an SFN of
5, the S-SFH SP change bitmap is set to Ό0. In addition, provided that the S-SFH
SP2 IE is changed in a superframe having an SFN of 10, the S-SFH SP change bitmap
is set to 'Oil'.
[116] Next, a fourth method of deciding a specific time point at which content contained in
the changed S-SFH SP IE is applied will hereinafter be described in detail. In ac
cordance with the fourth method, a flag may be interpreted in different ways according
to superframes. Content contained in the changed S-SFH SP IE may be simultaneously
applied according to the corresponding flag values.
[117] Table 5 shows different meanings of a flag according to a fourth method.
[118] Table 5
[Table 5]
[119] In the case where the S-SFH change count is initially increased in one S-SFH change
cycle, only a bit corresponding to the changed S-SFH SP IE of the S-SFH SP change
bitmap is set to . In addition, if the S-SFH change count is increased in the corre
sponding S-SFH change cycle, a bit corresponding to the currently changed S-SFH SP
IE of the S-SFH SP change bitmap is additionally set to .
[120] FIG. 8 shows application time points according to a fourth method.
[121] In FIG. 8, the S-SFH change cycle is composed of 32 superframes.
[122] In FIG. 8, provided that S-SFH SPl IE is changed in a superframe having an SFN of
5, the S-SFH SP change bitmap is set to Ό0. Provided that S-SFH SP2 IE is changed
in a superframe having an SFN of 10, the S-SFH SP change bitmap is set to Ό 1. In
addition, since the flag is set to '10', contents of the changed S-SFH SPl IE and S-SFH
SP2 IE are applied in the range from a specific position spaced apart from a specific
reference point by 16 superframes.
[123] If the SFN of the current superframe is larger than an SFN of the application time
point indicated by the flag, this means that the changed S-SFH SP IE has already been
applied.
[124] A flag of a superframe via which the S-SFH SP IE that causes the S-SFH change
count to be increased in one S-SFH change cycle may indicate an application time
point of the S-SFH SP IE. In addition, a superframe via which the remaining S-SFH SP
IEs are transmitted and a flag of a superframe via which the S-SFH SP IE is not
transmitted may indicate the S-SFH change count associated with the S-SFH SP IEs
currently applied in the current superframe.
[125] In FIG. 8, the oblique part may indicate superframes that indicate the S-SFH change
count related to the S-SFH SP IEs currently applied to the current superframe.
[126] Provided that the S-SFH change cycle is changed, a flag indicates the S-SFH change
count related to the S-SFH SP IEs currently applied to the current superframe before
the S-SFH change count is increased.
[127] Next, a fifth method of deciding a specific time point at which content contained in
the changed S-SFH SP IE is applied will hereinafter be described in detail. In ac
cordance with the fifth method, a flag may be interpreted in different ways according
to superframes. The BS informs MSs whether each S-SFH SP IE is changed at a su
perframe via which each of the changed S-SFH SP IEs is transmitted in the S-SFH
change cycle, and informs each MS of the application time point using the flag. In
addition, each changed S-SFH SP IE is independently applied at an application time
point indicated by each flag value.
[128] In the fifth method, a specific reference point is decided in the same manner as in the
second method.
[129] In the case where the S-SFH change count is increased in one S-SFH change cycle,
only a bit corresponding to the changed S-SFH SP IE of the S-SFH SP change bitmap
is set to . In addition, if the S-S-SFH change count is increased in the corresponding
S-SFH change cycle, a bit corresponding to the currently changed S-SFH SP IE of the
S-SFH SP change bitmap is additionally set to .
[130] FIG. 9 shows one example of an application time point according to a fifth method.
Refer to Table 5 for the flag meaning. FIG. 10 shows another example of an ap
plication time point according to a fifth method. The flag meanings refer to Table 6.
[131] Table 6 shows the meanings of flags shown in FIG. 10 according to the fifth method.
[132] Table 6
[Table 6]
[133] In FIGS. 9 and 10, the S-SFH change cycle is composed of 32 superframes.
[134] In FIGS. 9 and 10, if the S-SFH SP1 IE is changed in a superframe having an SFN of
5, the S-SFH SP change bitmap is set to Ό0. If the S-SFH SP2 IE is changed in a su
perframe having an SFN of 10, the S-SFH SP change bitmap is set to Ό 1.
[135] In addition, if the SFN of the current superframe is greater than an SFN of the ap
plication time point indicated by the flag, this means that the changed S-SFH SP IE has
already been applied.
[136] A flag of a superframe via which the S-SFH SP UE that causes the S-SFH change
count to be increased in one S-SFH change cycle may indicate an application time
point of the S-SFH SP IE. In addition, a superframe via which the remaining S-SFH SP
IEs are transmitted and a flag of a superframe via which the S-SFH SP IE is not
transmitted may indicate the S-SFH change count associated with the S-SFH SP IEs
currently applied in the current superframe.
[137] In FIG. 9, the oblique part may indicate superframes that indicate the S-SFH change
count related to the S-SFH SP IEs currently applied to the current superframe.
[138] In FIG. 10, after each changed S-SFH SP IE is applied, the flag indicates the S-SFH
change count related to the S-SFH SP IEs currently applied to the current superframe.
That is, as can be seen from FIG. 10, content of the S-SFH SPE IE is applied in the
range from an SFN of 8, and a flag is set to '0' in the range from a superframe where
the S-SFH SPl IE is transmitted from the corresponding SFN. Since content of the
changed S-SFH SP2 IE is applied to a superframe having an SFN of 16, all the
changed S-SFH IEs are applied, such that all frames are set to zero in the range from a
superframe having an SFN of 16.
[139] If the S-SFH change cycle is changed, the flag indicates the S-SFH change count
related to the S-SFH SP IEs currently applied to the current superframe before the SSFH
change count is increased.
[140] If a difference between the S-SFH change count stored in the MS and the other SSFH
change count of the received P-SFH is set to T , the MS receives only the S-SFH
SP IE in which the bit of the S-SFH change bitmap is set to and updates the received
S-SFH SP IE. If a difference between the S-SFH change count stored in the MS and
the other S-SFH change count of the received P-SFH is greater than T , the MS
receives and updates all the S-SFH SP IEs.
[141] The MS can recognize an application time point of the changed S-SFH SPl IE
through the flag of a superframe via which S-SFH SPl IE is transmitted, and can
recognize an application time point of the changed SFH SP2 IE through the flag of a
superframe via which S-SFH SP2 IE is transmitted. In addition, through a flag of a su
perframe via which S-SFH SP3 IE is transmitted and a flag of a superframe via which
S-SFH SP IE is not transmitted, the MS can recognize whether the S-SFH SP IEs a s
sociated with the S-SFH change counts are currently applied to the corresponding su
perframe.
[142] In FIGS. 9 and 10, since the flag of the superframe via which the changed S-SFH
SPl IE is transmitted is set to Ό, content of the changed S-SFH SPl IE is applied in
the range from a superframe having an SFN of 8 spaced apart from a specific reference
point by 8 superframes. Since the flag of the superframe via which the changed S-SFH
SP2 IE is transmitted is set to '10', content of the changed S-SFH SP2 IE is applied in
the range from a superframe having an SFN of 16 spaced apart from a specific
reference point by 16 superframes.
[143] S-SFH SPl IE and S-SFH SP2 IE include permutation information and are associated
with each other. Therefore, in the case where a difference between one S-SFH change
count stored in the MS and another S-SFH change count of the received P-SFH is
larger than T , the MS must communicate with the BS after confirming all the ap
plication time points of S-SFH SPl IE and S-SFH SP2 IE. That is, although the MS
receives the transmitted S-SFH SPl IE and recognizes that the received S-SFH SPl IE
has already been applied, the MS has to wait a predetermined time to confirm the SSFH
SP2 IE.
[144] Next, a sixth method of deciding a specific time point at which content contained in
the changed S-SFH SP IE is applied will hereinafter be described in detail. In ac
cordance with the sixth method, it is assumed that respective S-SFH SP IEs have
different S-SFH change cycles.
[145] In accordance with the sixth method, the BS increases the S-SFH change count by
one whenever an S-SFH SP IE is changed, and sets a bit corresponding to the changed
S-SFH SP IE of the S-SFH SP change bitmap to T . In addition, the bit of the S-SFH
SP change bitmap corresponding to the S-SFH SP IE applied to the corresponding su
perframe is set to ''.
[146] FIG. 11 is a flowchart illustrating operations of a mobile station (MS) according to a
sixth method.
[147] Referring to FIG. 11, the MS receives the P-SFH, and compares the S-SFH change
count stored in the MS with the S-SFH change count of the received P-SFH. If the SSFH
change count stored in the MS is identical to the S-SFH change count of the
received P-SFH, the MS need not decode S-SFH SP IEs. If the S-SFH change count
stored in the MS is different from the S-SFH change count of the received P-SFH, the
MS has to decode S-SFH SP IEs and update the decoded S-SFH SP IEs.
[148] In the case where a difference between the S-SFH change count stored in the MS and
the S-SFH change count of the received P-SFH is identical to the number of bits (each
of which is set to ) of the S-SFH SP change bitmap, the MS needs to decode the SSFH
SP IEs corresponding to bits (each of which is set to ) of the S-SFH SP change
bitmap, and then updates the decoded S-SFH SP IEs. In addition, if a difference
between the S-SFH change count stored in the MS is different from the S-SFH change
count of the received P-SFH is different from the number of bits (each of which is set
to ) of the S-SFH SP change bitmap of the P-SFH, the MS receives and updates all
the S-SFH SP IEs. In this case, given that the MS can implicitly recognize the changed
S-SFH SP IE using the change cycle, the MS may decode the S-SFH SP IE corre
sponding to a bit of the S-SFH SP change bitmap and the implicitly recognized SSFH
SP IE, and then update it.
[149] The MS recognizes an S-SFH change count and the number of bits (each of which is
set to ) of the S-SFH SP change bitmap, such that it can recognize the S-SFH change
count related to the currently- applied S-SFH SP IEs using the recognized result.
Provided that the MS has S-SFH SP IEs, it can normally communicate with the BS.
Otherwise, provided that the MS does not have S-SFH SP IEs, the MS can normally
communicate with the BS after receiving and updating the S-SFH SP IEs.
[150] FIG. 12 shows one example of an application time point according to a sixth method.
[151] In FIG. 12, the BS uses contents of S-SFH SP IEs associated with the S-SFH change
count '25' in a first superframe. The S-SFH change count applied to the corresponding
superframe may be calculated by an expression 'S-SFH change count - Numbers of bits
(each of which is set to ) of the S-SFH SP change bitmap'. That is, the S-SFH change
count applied to a first superframe of FIG. 12 is 25 (i.e., 25 - 0).
[152] Provided that S-SFH SP1 IE is changed in a second superframe, the BS increases the
S-SFH change count up to 26, and the S-SFH SP change bitmap is set to '00 .
Therefore, the S-SFH change count applied to each of second, third, and fourth superframes
is set to 25 (i.e., 26 - 1).
[153] In FIG. 12, after the changed S-SFH SP1 IE is transmitted twice, content of the
changed S-SFH SP1 IE is applied in the range from the next superframe. In order to
guarantee a specific time in which MSs can receive the changed S-SFH SP IE, after the
changed S-SFH SP IE is transmitted at least a predetermined number of times, content
of the changed S-SFH SP1 IE is utilized. In this case, the predetermined number of
times may be defined as a predetermined fixed value, and may be dynamically decided
by the BS. Therefore, content of the changed S-SFH SP1 IE is applied to a fifth su
perframe.
[154] In addition, the BS sets a bit corresponding to the changed S-SFH SP IE of the SSFH
SP change bitmap to '0' at an application time point of the changed S-SFH SP IE,
such that the S-SFH SP change bitmap is set to '000' in the fifth superframe.
[155] In FIG. 12, it is assumed that the S-SFH change count stored in the MS in a first su
perframe is set to 25. The MS recognizes the S-SFH change count applied to a first su
perframe using not only the S-SFH change count of the first superframe but also the
number of bits (each of which is set to ) of the S-SFH SP change bitmap.
[156] The MS compares the S-SFH change count received via the first superframe with the
S-SFH change count stored in the MS. If the S-SFH change count received via the first
superframe is identical to the S-SFH change count stored in the MS, this means that the
S-SFH SP IEs are not changed. In addition, since the S-SFH change count is 25 and the
number of bits (each of which is set to ) of the S-SFH SP change bitmap is zero, it
can be recognized that the S-SFh change count applied to a first superframe is 25.
[157] In the second superframe, the MS recognizes that a difference between the received
S-SFH change count and the other S-SFH change count stored in the MS is set to T ,
such that the MS can recognize the changed S-SFH SP IE. In addition, the MS can
recognize that the S-SFH SP1 IE is changed through the S-SFH SP change bitmap, and
can also recognize that the applied S-SFH change count is 25 (i.e., 26 - 1).
[158] In the fifth superframe, the MS can recognize that the applied count is 26 (i.e., 26 -
0).
[159] FIG. 13 shows another example of an application time point according to a sixth
method.
[160] In a first superframe, the BS increases the S-SFH change count by one so as to
change the S-SFH SP1 IE, such that it sets the S-SFH change count to '26' and the SSFH
SP change bitmap is set to '00 . In addition, the S-SFH change count applied to
the first superframe is 25 (i.e., 26 - 1).
[161] If the S-SFH SP2 IE is changed in the second superframe, the BS increases the SSFH
change count by one such that it sets the S-SFH change count to '27' and sets the
S-SFH SP change bitmap to Ό1. The S-SFH change count applied to each of the
second, third, and fourth superframes is 25 (i.e., 27 - 2).
[162] If contents of the changed S-SFH SPl IE and S-SFH SP2 IE are simultaneously
utilized, the BS sets the S-SFH SP change bitmap of the fifth superframe to ''.
Therefore, the S-SFH change count applied to the fifth superframe is set to 27 (i.e., 27
- 0).
[163] Alternatively, the BS may apply contents of the changed S-SFH SPl IE and S-SFH
SP2 IE at different time points as necessary.
[164] FIG. 14 shows still another example of an application time point according to a sixth
method.
[165] In the first superframe, the BS increases the S-SFH change count by two so as to
change the S-SFH SPl IE and the S-SFH SP2 IE, such that the S-SFH change count is
set to '27' and the S-SFH SP change bitmap is set to '01 . In addition, the S-SFH
change count applied to the first superframe is set to 25 (i.e., 27 - 2).
[166] If contents of the changed S-SFH SPl IE and S-SFH SP2 IE are simultaneously
utilized, the BS sets the S-SFH SP change bitmap to '000' in a fifth superframe.
Therefore, the S-SFH change count applied to the fifth superframe is 27 (i.e., 27 - 0).
[167] The above-mentioned description has disclosed that S-SFH SP IEs are transmitted in
the regularly scheduled transmission period. However, the scope or spirit of the present
invention is not limited thereto, and the S-SFH SP IEs may also be irregularly
transmitted as necessary.
[168] FIG. 15 is a conceptual diagram illustrating that S-SFH SP2 IEs are irregularly
transmitted.
[169] In this case, the irregularly transmitted S-SFH SP IE may be limited to the changed
S-SFH SP IE. In addition, if several S-SFH SP IEs are simultaneously changed, each
irregularly transmitted S-SFH SP IEs may be an S-SFH SP IE having the longest
transmission period from among several S-SFH SP IEs.
[170] However, the MS may fail to recognize irregular transmission of the S-SFH SP IE.
[171] If the MS does not receive transmission period information through the S-SFH SP3
IE, the MS may implicitly recognize a transmission period from an irregular reception
time of the S-SFH SP IE to a reception time of the next S-SFH SP IE. As a result, the
MS may erroneously recognize the transmission period of the S-SFH SP IE.
[172] If the MS receives the transmission period information through S-SFH SP3 IE, the
MS determines a specific position, that is spaced apart from an irregular reception time
point of the S-SFH SP IE by a transmission period, to be a transmission time point of
the S-SFH SP IE. Therefore, the MS may erroneously decide the transmission time
point of the S-SFH SP IE.
[173] Therefore, the embodiments of the present invention provide the following methods
that can prevent the MS from erroneously deciding the S-SFH SP IE transmission
period or the S-SFH SP IE transmission time point due to the irregular transmission of
the S-SFH IE.
[174] The first method from among the five methods confirms a P-SFH until the MS
receives the S-SFH SP IEs having the same transmission period.
[175] The second method allows the BS to explicitly indicate whether S-SFH SP IE is
regularly or irregularly transmitted through P-SFH.
[176] The third method allows the BS to explicitly indicate whether S-SFH SP IE is
regularly transmitted through each S-SFH SP IE.
[177] In accordance with the fourth method, a specific value (Obi 111) from among
transmission period information of individual S-SFH SP IEs is adapted to indicate
irregular transmission. In this case, the corresponding specific value may be predefined
or it is necessary for the BS to inform each MS of the corresponding specific value.
[178] In accordance with the fifth method, a specific value (Obi 111) from among S-SFH
SP scheduling information transmitted through P-SFH is adapted to indicate irregular
transmission.
[179] Two or more methods from among the above-mentioned five methods may be simul
taneously utilized as necessary.
[180] The changed S-SFH SP IE may be applied after being transmitted N times in a
regular period. In this case, the number of irregular transmissions may be different
from N.
[181] In the case where a difference between the S-SFH change count of the MS and the SSFH
change count transmitted through P-SFH is at least 2 and the changed S-SFH SP
IE is S-SFH SP3 IE, it is necessary for the MS to explicitly recognize an application
time point of the changed information. In other words, since the transmission period
may be changed in the changed S-SFH SP3 IE, the MS has to monitor the P-SFH until
application time point information transmitted through P-SFJ appears.
[182] FIG. 16 is a block diagram illustrating detailed constituent components of an
advanced mobile station (AMS) and an advanced base station (ABS) that can be im
plemented through the above-mentioned embodiments.
[183] Referring to FIG. 16, each of the AMS 510 and the ABS 500 may include an antenna
for transmitting and receiving information, data, signals and/or messages, a commu
nication module 520 or 530 including a Transmission (Tx) module for transmitting
messages by controlling the antenna and a Reception (Rx) module for receiving
messages by controlling the antenna, a memory 560 or 570 for storing information
related to communication, and a central processing unit (CPU) 540 or 550 for con
trolling the communication module 520 or 530 and the memory 560 or 570.
[184] The CPUs 540 and 550 generally provide overall control to the AMS and the ABS,
respectively. Especially, the CPUs 540 and 550 may perform a control function for im
plementing the above-described exemplary embodiments of the present invention, a
variable MAC frame control function based on service characteristics and a
propagation environment, a handover function, an authentication and encryption
function, etc. In addition, each of the CPUs 540 and 550 may include an encryption
module for controlling encryption of various messages and a timer module for con
trolling transmission and reception of various messages.
[185] If the S-SCH change count of the P-SFH IE is different from the S-SFH change
count stored in the MS, the CPU 550 of the AMS receives at least one S-SFH SP IE
from among several S-SFH SP IEs, and updates it.
[186] The transmission (Tx) modules may encode and modulate transmission data
scheduled by the CPUs according to a predetermined coding and modulation scheme
and provide the modulated data to the antennas. The reception (Rx) modules may
recover original data by demodulating and decoding data received through the
antennas and provide the recovered data to the CPUs.
[187] The Tx module of the ABS 500 transmits P-SFH IE including a first field to the
AMS. In this case, the first field includes the S-SFH change cycle and the change
count of several S-SFH SP IEs.
[188] The Rx module of the AMS 510 receives P-SFH IE including a first field from the
ABS, wherein the first field includes the S-SFH change cycle and the change count of
several S-SFH SP IEs.
[189] The memories may store programs for processing and control of the CPUs and tem
porarily store input/output data (on the side of the AMS, an uplink grant received from
the ABS, system information, a station identifier (STID), a flow identifier (FID), an
action time, and the like).
[190] Each of the memories may include at least one type of storage media such as a flash
memory, a hard disk, a multimedia card micro, a card-type memory (e.g. a Secure
Digital (SD) or eXtreme Digital (XD) memory), a Random Access Memory (RAM), a
Static Random Access Memory (SRAM), a Read-Only Memory (ROM), an Elec
trically Erasable Programmable Read-Only Memory (EEPROM), a Programmable
Read-Only Memory, a magnetic memory, a magnetic disc, an optical disc, etc.
[191] The detailed description of the exemplary embodiments of the present invention has
been given to enable those skilled in the art to implement and practice the invention.
Although the invention has been described with reference to the exemplary embodiments,
those skilled in the art will appreciate that various modifications and
variations can be made in the present invention without departing from the spirit or
scope of the invention described in the appended claims. For example, those skilled in
the art may use each construction described in the above embodiments in combination
with each other.
[192] Accordingly, the invention should not be limited to the specific embodiments
described herein, but should be accorded the broadest scope consistent with the
principles and novel features disclosed herein.
[193] The exemplary embodiments of the present invention are applicable to various
wireless access systems.
[194] 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
invention. Therefore, the above-mentioned detailed description must be considered
only for illustrative purposes instead of restrictive purposes. The scope of the present
invention must be decided based upon a rational analysis of the claims, and all modi
fications within the equivalent range of the present invention are within the scope of
the present invention.
PCT/KR2011/000019
Claims
A method for receiving system information by a mobile station (MS) of
a wireless communication system, the method comprising:
receiving a secondary superframe header (S-SFH) change cycle from a
base station (BS); and
receiving a primary superframe header information element (P-SFH IE)
including a first field indicating a change count of a plurality of
secondary superframe header subpacket information elements (S-SFH
SP IEs) from the base station (BS),
wherein, once each of the plurality of S-SFH SP IEs is changed, each of
the plurality of S-SFH SP IEs remains unchanged during one or more
S-SFH change cycles periods.
The method according to claim 1, wherein a value of the first field can
be changed only in a superframe satisfying that a remainder obtained
when a superframe number (SFN) of the superframe is divided by the
S-SFH change cycle is a predetermined number.
The method according to claim 1, wherein the S-SFH change cycle is
indicated in one of the S-SFH SP IEs.
The method according to claim 1, further comprising:
receiving at least one S-SFH SP IE among the plurality of S-SFH SP
IEs, and updating the received S-SFH SP IE if a value of the first field
is different from an S-SFH change count stored in the mobile station
(MS).
The method according to claim 4, wherein the receiving at least one s-
SFH SP IE includes:
receiving only one or more S-SFH SP IEs whose bit in an S-SFH SP
change bitmap is set to 1 and updating the received one or more S-SFH
SP IEs if a difference between the value of the first field and the S-SFH
change count stored in the mobile station (MS) is 1,
wherein the S-SFH SP change bitmap indicates whether each of the
plurality of P-SFH SP IEs is changed.
The method according to claim 4, wherein the receiving at least one SSFH
SP IE includes:
receiving and updating all of the plurality of S-SFH SP IEs if a
difference between the value of the first field and the S-SFH change
count stored in the mobile station (MS) is greater than 1.
The method according to claim 4, further comprising:
PCT/KR2011/000019
applying contents of the at least one S-SFH SP IE simultaneously at the
latest superframe among superframes immediately following after each
of the at least one S-SFH SP IE is regularly transmitted a prede
termined number of times.
The method according to claim 1, wherein the P-SFH IE further
includes a second field indicating S-SFH SP IEs applied in a su
perframe in which the P-SFH IE is transmitted.
A method for transmitting system information by a base station (BS) of
a wireless communication system, the method comprising:
transmitting a secondary superframe header (S-SFH) change cycle to a
mobile station (MS); and
transmitting a primary superframe header information element (P-SFH
IE) including a first field indicating a change count of a plurality of
secondary superframe header subpacket information elements (S-SFH
SP IEs) to the mobile station (MS),
wherein, once each of the plurality of S-SFH SP IEs is changed, each of
the plurality of S-SFH SP IEs remains unchanged during one or more
S-SFH change cycle periods.
The method according to claim 9, wherein a value of the first field can
be changed only in a superframe satisfying that a remainder obtained
when a superframe number (SFN) of the superframe is divided by the
S-SFH change cycle is a predetermined number.
The method according to claim 9, wherein the S-SFH change cycle is
indicated in one of the S-SFH SP IEs.
The method according to claim 9, wherein the mobile station (MS)
receives at least one S-SFH SP IE among the plurality of S-SFH SP IEs
and updates the received S-SFH SP IE if a value of the first field is
different from an S-SFH change count stored in the mobile station
(MS).
The method according to claim 12, wherein:
the mobile station (MS) receives only one or more S-SFH SP IEs
whose bit in an S-SFH SP change bitmap is set to 1 and updates the
received one or more S-SFH SP IEs if a difference between the value of
the first field and the S-SFH change count stored in the mobile station
(MS) is set to 1,
wherein the S-SFH SP change bitmap indicates whether each of the
plurality of P-SFH SP IEs is changed.
The method according to claim 12, wherein the mobile station (MS)
PCT/KR2011/000019
receives and updates all of the plurality of S-SFH SP IEs if a difference
between the value of the first field and the S-SFH change count stored
in the mobile station (MS) is greater than 1.
The method according to claim 9, wherein the P-SFH IE further
includes a second field indicating S-SFH SP IEs applied in a superframe
in which the P-SFH IE is transmitted.
A mobile station (MS) for use in a wireless communication system, the
mobile station (MS) comprising:
a reception (Rx) module for receiving a secondary superframe header
(S-SFH) change cycle from a base station (BS), and receiving a
primary superframe header information element (P-SFH IE) that
includes a first field indicating a change count of a plurality of su
perframe header subpacket information elements (S-SFH SP IEs) from
the base station (BS),
wherein, once each of the plurality of S-SFH SP IEs is changed once,
each of the plurality of S-SFH SP IEs remains unchanged during one or
more S-SFH change cycle periods.
The mobile station (MS) according to claim 16, wherein a value of the
first field can be changed only in a superframe satisfying that a
remainder obtained when a superframe number (SFN) of the su
perframe is divided by the S-SFH change cycle is a predetermined
number.
The mobile station (MS) according to claim 16, wherein the S-SFH
change cycle is indicated in one of the S-SFH SP IEs.
The mobile station (MS) according to claim 16, further comprising:
a central processing unit (CPU) for receiving at least one S-SFH SP IE
among the plurality of S-SFH SP IEs, and updating the received S-SFH
SP IE if a value of the first field is different from an S-SFH change
count stored in the mobile station (MS).
The mobile station (MS) according to claim 19, wherein the central
processing unit (CPU) applies contents of the at least one S-SFH SP IE
simultaneously at the latest superframe among superframes im
mediately following after each of the at least one S-SFH SP IE is
regularly transmitted a predetermined number of times.
A base station (BS) for use in a wireless communication system, the
base station (BS) comprising:
a transmission (Tx) module for transmitting a secondary superframe
header (S-SFH) change cycle to a mobile station (MS), and transmitting
WO 2011/081506 PCT/KR2011/000019
a primary superframe header information element (P-SFH IE) that
includes a first field indicating a change count of a plurality of
secondary superframe header subpacket information elements (S-SFH
SP IEs) to the mobile station (MS),
wherein, once each of the plurality of S-SFH SP IEs is changed, each of
the plurality of S-SFH SP IEs remains unchanged during one or more
S-SFH change cycle periods.
[Claim 22] The base station (BS) according to claim 21, wherein a value of the
first field can be changed only in a superframe satisfying that a
remainder obtained when a superframe number (SFN) of the su
perframe is divided by the S-SFH change cycle is a predetermined
number.
[Claim 23] The base station (BS) according to claim 21, wherein the S-SFH
change cycle is indicated in one of the S-SFH SP IEs.
[Claim 24] A mobile station (MS) for use in a wireless communication system, the
mobile station (MS) comprising:
a central processing unit (CPU) for controlling overall operations of the
mobile station (MS);
a memory for storing information related to communication with a base
station (BS); and
a communication module for controlling communication with the base
station (BS),
wherein the communication module includes a reception (Rx) module,
the reception (Rx) module receiving a secondary superframe header
(S-SFH) change cycle from a base station (BS), and receiving a
primary superframe header information element (P-SFH IE) that
includes a first field indicating a change count of a plurality of
secondary superframe header subpacket information elements (S-SFH
SP IEs) from the base station (BS), wherein, once each of the plurality
of S-SFH SP IEs is changed, each of the plurality of S-SFH SP IEs
remains unchanged during one or more S-SFH change cycle periods.
[Claim 25] A base station (BS) for use in a wireless communication system, the
base station (BS) comprising:
a central processing unit (CPU) for controlling overall operations of the
base station (BS);
a memory for storing information related to communication; and
a communication module for controlling communication,
wherein the communication module includes a transmission (Tx)
PCT/KR2011/000019
module, the transmission (Tx) module transmitting a secondary su
perframe header (S-SFH) change cycle to a mobile station (MS), and
transmitting a primary superframe header information element (P-SFH
IE) that includes a first field indicating a change count of a plurality of
secondary superframe header subpacket information elements (S-SFH
SP IEs) to the mobile station (MS), wherein, once each of the plurality
of S-SFH SP IEs is changed, each of the plurality of S-SFH SP IEs
remains unchanged during one or more S-SFH change cycle periods.