Title of Invention

SYSTEM AND METHOD FOR NOTIFYING COMPLETION OF NETWORK RE-ENTRY PROCEDURE IN A COMMUNICATION SYSTEM

Abstract Provided is a system and method for notifying completion of a network re-entry procedure in a communication system. In the system, a mobile station (MS) completes the network re-entry procedure with a base station (BS), and then notifies the completion of the network re-entry procedure to the BS.
Full Text -1-
SYSTEM AND METHOD FOR NOTIFYING COMPLETION OF
NETWORK RE-ENTRY PROCEDURE IN A COMMUNICATION
SYSTEM
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a communication system, and in
particular, to a system and method for notifying completion of a network re-entry
procedure in a communication system.
2. Description of the Related Art
In the next generation communication system, active research is being
conducted to provide service capable of transmitting/receiving high-speed, high-
capacity data to/from mobile stations (MSs). A typical example of the next
generation communication system is an Institute of Electrical and Electronics
Engineers (IEEE) 802.16e communication system .
Referring to FIG. 1, herein is a description of an MS performing a process
of a network re-entry procedure with a target base station (BS) after performing
connection switching, e.g., handover, from a serving BS to the target BS in a
general IEEE 802.16e communication system.
FIG. 1 is a signaling diagram illustrating a process of performing a network
re-entry procedure in a general IEEE 802.16e communication system.
Referring to FIG. 1, following handover from a serving BS to a target BS
150, an MS 100 obtains downlink synchronization with the target BS 150, and
receives parameters to be used in an uplink and a downlink, in step 111.
Thereafter, the MS 100 should obtain uplink synchronization by performing a
ranging operation with the target BS 150, and perform an operation of adjusting
transmission power. Therefore, the MS 100 transmits a Ranging Request (RNG-
REQ) message to the target BS 150 in step 113, and the target BS 150 transmits a
Ranging Response (RNG-RSP) message to the MS 100 in response to the RNG-
REQ message in step 115.

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Upon performing the ranging operation as described above, the MS 100
transmits a Subscriber Station Basic Capability Request (SBC-REQ) message to
the target BS 150 to request the basic capabilities of the target BS 150 and the MS
100 in step 117. The SBC-REQ message, which is a Medium Access Control
(MAC) message that the MS 100 transmits to the target BS 150 to request the
basic capabilities, includes therein information on a Modulation and Coding
Scheme (MCS) level supportable by the MS 100. Upon receipt of the SBC-REQ
message from the MS 100, the target BS 150 detects an MCS level supportable by
the MS 100, included in the received SBC-REQ message, and transmits a
Subscriber Station Basic Capability Response (SBC-RSP) message to the MS 100
in reply to the SBC-REQ message in step 119.
Upon receipt of the SBC-RSP message, the MS 100 transmits a Privacy
Key Management Request (PKM-REQ) message to the target BS 150 for MS
authentication and key exchange in step 121. The PKM-REQ message, a MAC
message for MS authentication, includes a certificate (unique information) of the
MS 100. Upon receipt of the PKM-REQ message, the target BS 150 performs
authentication with an Authentication Server (AS) (not shown) using the
certificate of the MS 100, included in the received PKM-REQ message. If the MS
100 is an authenticated MS as a result of the authentication, the target BS 150
transmits a Privacy Key Management Response (PKM-RSP) message to the MS
100 in response to the PKM-REQ message in step 123. The PKM-RSP message
includes an Authentication Key (AK) and a Traffic Encryption Key (TEK)
allocated to the MS 100.
Upon receipt of the PKM-RSP message, the MS 100 transmits a
Registration Request (REG-REQ) message to the target BS 150 in step 125. The
REG-REQ message includes MS registration information for the MS 100. Upon
receipt of the REG-REQ message, the target BS 150 detects MS registration
information included in the received REG-REQ message, registers the MS 100
therein using the MS registration information, and transmits a Registration
Response (REG-RSP) message to the MS 100 in response to the REG-REQ
message in step 127. The REG-RSP message includes the registered MS
registration information. The MS 100 receives the REG-RSP message,
completing its network re-entry procedure to the target BS 150 in step 129. As the

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MS 100 receives the REG-RSP message, a normal operation is performed
between the MS 100 and the target BS 150, completing the network re-entry
procedure. The process of performing the network re-entry procedure in the
general IEEE 802.16e communication system has been described above with
reference to FIG. 1. Next, with reference to FIG. 2, a description will be made of a
process of performing a network re-entry procedure based on Handover Process
Optimization Type/Length/Value (TLV) in a general IEEE 802.16e
communication system.
FIG. 2 is a signaling diagram illustrating a process of performing a network
re-entry procedure based on Handover Process Optimization TLV in a general
IEEE 802.16e communication system.
Referring to FIG. 2, following handover from a serving BS to a target BS
250, an MS 200 obtains downlink synchronization with the target BS 250, and
receives parameters to be used in an uplink and a downlink, in step 211. The MS
200 transmits an RNG-REQ message to the target BS 250 in step 213, and the
target BS 250 transmits an RNG-RSP message to the MS 200 in response to the
RNG-REQ message in step 215. The RNG-RSP message includes HO Process
Optimization TLV, and the HO Process Optimization TLV, an Information
Element (IE) included using a TLV encoding scheme, is an IE of a connection
switched MS, for example, a handover-processed MS, used for supporting a fast
network re-entry procedure with the target BS. That is, the HO Process
Optimization TLV is an IE written to make it possible to omit some or all of the
message transmission/reception processes that should necessarily be performed in
the general network re-entry procedure for the fast network re-entry procedure of
the MS 200.
When the MS 200 performs general handover or idle mode handover, the
target BS 250 can acquire information on the MS 200 via a backbone network
from the system having the information on the MS 200, like the serving BS or a
paging controller, before the MS 200 performs the general handover or idle mode
handover. The information on the MS 200 can be equal to the information
acquired in the process of performing by the MS 200 the network re-entry
procedure after its handover from the serving BS to the target BS 250. In this case,

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by acquiring the information on the MS 200 via the backbone network, the target
BS 250 can omit a particular message transmission/reception process in the
network re-entry procedure due to the handover of the MS 200, and can not only
save the air link resources necessary for the particular message
transmission/reception process but also advance a normal communication restart
time with the MS 200. Therefore, the target BS 250 includes the HO Process
Optimization TLV in order to transmit to the MS 200 a notification indicating the
message transmission/reception process omittable in the process of performing
the network re-entry procedure. A format of the HO Process Optimization TLV is
shown in Table 1 below.
Table 1

HO Process
Optimization For each Bit location, a value of '0' indicates the

associated re-entry management message shall be

required, a value of '1' indicates the re-entry

management messages may be omitted.

Bit #0: Omit SBC-REQ management message during

current re-entry processing

Bit #1: Omit PKM Authentication phase except TEK

phase during current re-entry processing

Bit #2: Omit PKM TEK creation phase during current

re-entry processing

Bit #3: BS shall transmit an unsolicited SBC-RSP

management message with updated capabilities

information in case capabilities of Target BS are

different from the ones of Serving BS

Bit #4: Omit REG-REQ management message during

current re-entry processing

Bit #5: BS shall transmit an unsolicited REG-RSP

management message with updated capabilities

information

Bit #6: BS supports virtual SDU SN. If Bit#6=l and

MS supports SDU SN, it shall issue SN Report header

upon completion of HO to this BS.

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In Table 1, the HO Process Optimization TLV is a type of bitmap
information indicating whether it is possible to omit transmission/reception of a
message in the current network re-entry procedure. That is, the HO Process
Optimization TLV IE is expressed in the form of; for example, a 7-bit bitmap.
Below is a description of each bit of the HO Process Optimization TLV bitmap .
(1) Whether it is possible to omit transmission of an SBC-REQ message is
indicated by a first bit Bit#0. Bit#0 = 0 indicates that the MS 200 should
necessarily transmit the SBC-REQ message, and Bit#0 = 1 indicates that the MS
200 can omit transmission of the SBC-REQ message.
(2) Whether it is possible to omit a PKM authentication process is
indicated by a second bit Bit#l. Bit#l = 0 indicates that the MS 200 should
perform the PKM authentication process including a TEK process, and Bit#l = 1
indicates that the MS 200 can omit the PKM authentication process except for the
TEK process.
(3) Whether it is possible to omit the TEK process is indicated by a third
bit Bit#2. Bit#2 = 0 indicates that the MS 200 should necessarily perform the
TEK process, and Bit#2 = 1 indicates that the MS 200 can omit the TEK process.
(4) Whether it is possible to omit transmission of an SBC-RSP message is
indicated by a fourth bit Bit#3. Bit#3 = 0 indicates that the target BS 250 should
necessarily transmit an unsolicited SBC-RSP, and Bit#3 = 1 indicates that the
target BS 250 can omit transmission of the SBC-RSP message by transmitting the
information included in the SBC-RSP message along with the RNG-RSP message
using the TLV encoding scheme.
(5) Whether it is possible to omit transmission of a REG-REQ message is
indicated by a fifth bit Bit#4. Bit#4 = 0 indicates that the MS 200 should
necessarily transmit the REG-REQ message, and Bit#4 = 1 indicates that the MS
200 can omit transmission of the REG-REQ message.
(6) Whether it is possible to omit transmission of a REG-RSP message is
indicated by a sixth bit Bit#5. Bit#5 = 0 indicates that the target BS 250 should

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target BS 250 can omit transmission ofthe REG-RSP messaged transmitting the
information included in the REG-RSP message along with the RNG-RSP
message using the TLV encoding scheme.
(7) Whether the target BS 250 supports a virtual Service Data Unit (SDU)
Sequence Number (SN) is indicated by a seventh bit Bit#6. if the Bit#6 is set to
T and the MS 200 also supports the virtual SDU SN, the MS 200 should
transmit an SN Report header to the target BS 250 after completing the network
re-entry procedure with the target BS 250.
When Bit#3 and Bit#5 of the HO Processor Optimization TLV included in
the RNG-RSP message are both set to '1', the TLV included in the RNG-RSP
message is shown in Table 2 below.
Table 2
If (HO Process
Optimization [bit#3]==l)
SBC-RSP encoding SBC-RSP TLV items for HO optimization

If (HO Process
Optimization [bit#5]=l)
REG-RSP encoding REG-RSP TLV items for HO optimization

In Table 2, if Bit#3 of the HO Process Optimization TLV is set to '1', it
indicates SBC-RSP encoding information included in the RNG-RSP message. If
Bit#5 of the HO Process Optimization TLV is set to '1', it indicates REG-RSP
encoding information included in the RNG-RSP message.
Thereafter, the MS 200 and the target BS 250 perform the network re-entry
procedure according to the HO Process Optimization TLV. For example, if the
HO Process Optimization TLV bitmap is set to '1110100', the MS 200 omits
transmission of an SBC-REQ message in step 217, the target BS 250 transmits an

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unsolicited SBC-RSP message to the MS 200 in step 219, the MS 200 omits
transmission of a PKM-REQ message in step 221, the target BS 250 omits
transmission of a PKM-RSP message in step 223, the MS 200 omits transmission
of an REG-REQ message in step 225, and finally, the target BS 250 transmits an
unsolicited REG-RSP message to the MS 200 in step 227.
As another example, if the HO Process Optimization TLV bitmap is set to
'1111110', the target BS 250 should transmit the information included in both the
SBC-RSP message and the REG-RSP message along with the TLV of the RNG-
RSP message. In this case, the MS 200 and the target BS 250 can normally
complete the network re-entry procedure in step 229, even though they omit all
the message transmission/reception processes shown in steps 217 to 227.
As described above, in the course of performing the network re-entry
procedure, the MS and the target BS can omit some or all of the message
transmission/reception processes in the network re-entry procedure according to
the HO Process Optimization TLV.
Although the MS fails to normally receive the RNG-RSP message from
the target BS, it is impossible for the target BS to recognize the MS's failure to
normally receive the RNG-RSP message. In this case, though the target BS
performs the network re-entry procedure according to the HO Process
Optimization TLV, the MS may perform the general network re-entry procedure,
causing mis-synchronization of the message transmission/reception process
between the MS and the target BS.
In addition, if the target BS transmits an unsolicited SBC-RSP message or
an unsolicited REG-RSP message without a request of the MS, i.e., if the target
BS unilaterally transmits the message to the MS without performing the general
message transmission/reception process, it is impossible for the target BS to
recognize whether the MS has normally received the unsolicited SBC-RSP
message or the unsolicited REG-RSP message.
Therefore, there is a need for a scheme in which the target BS can
recognize whether the MS has normally received an unsolicited message that the

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target BS transmitted without the request of the MS, or a message included in the
HO Process Optimization TLV, while the MS and the target BS are performing
the network re-entry procedure according to the HO Process Optimization TLV.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a system and
method for notifying completion of a network re-entry procedure in a
communication system.
It is another object of the present invention to provide a system and
method for notifying normal reception of particular messages in a network re-
entry procedure in a communication system.
It is further another object of the present invention to provide a system and
method for notifying normal reception of an unsolicited message transmitted by a
target BS in a network re-entry procedure in a communication system.
According to one aspect of the present invention, there is provided a
system for notifying completion of a network re-entry procedure in a
communication system. The system includes a mobile station (MS) for, after
completing the network re-entry procedure with a base station (BS), notifying the
completion of the network re-entry procedure to the BS.
According to another aspect of the present invention, there is provided a
method for notifying completion of a network re-entry procedure by a mobile
station (MS) in a communication system. The method includes the steps of
completing the network re-entry procedure with a base station (BS); and notifying
the completion of the network re-entry procedure to the BS.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present
invention will become more apparent from the following detailed description
when taken in conjunction with the accompanying drawings in which:

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FIG. 1 is a signaling diagram illustrating a process of performing a network
re-entry procedure in a general IEEE 802.16e communication system;
FIG. 2 is a signaling diagram illustrating a process of performing a network
re-entry procedure based on Handover Process Optimization TLV in a general
IEEE 802.16e communication system;
FIG. 3 is a signaling diagram illustrating a process of performing a network
re-entry procedure based on HO Process Optimization TLV in an IEEE 802.16e
communication system according to the present invention;
FIGs. 4A and 4B are flowcharts illustrating an operation process of an MS
in a network re-entry procedure based on HO Process Optimization TLV in an
IEEE 802.16e communication system according to the present invention; and
FIGs. 5A and 5B are flowcharts illustrating an operation process of a target
BS in a network re-entry procedure based on HO Process Optimization TLV in an
IEEE 802.16e communication system according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will now be described in
detail with reference to the annexed drawings. In the following description, a
detailed description of known functions and configurations incorporated herein
has been omitted for clarity and conciseness.
The present invention provides a system and method for notifying
completion of a network re-entry procedure in a communication system, for
example, an Institute of Electrical and Electronics Engineers (IEEE) 802.16e
communication system. In addition, the present invention provides a system and
method for notifying whether a mobile station (MS) has normally received an
unsolicited message transmitted by a target base station (BS) in the course of
performing a network re-entry procedure according to Handover Process
Optimization Type/Length/Value (TLV) in an IEEE 802.16e communication
system. Although the present invention will be described with reference to the
IEEE 802.16e communication system for convenience, the scheme provided in
the present invention is applicable to other communication systems.

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FIG. 3 is a signaling diagram illustrating a process of performing a
network re-entry procedure based on HO Process Optimization TLV in an IEEE
802.16e communication system according to the present invention.
Referring to FIG. 3, after handover from a serving BS to a target BS 350,
an MS 300 acquires downlink (DL) synchronization with the target BS 350, and
receives parameters to be used in an uplink (UL) and a downlink, in step 311. The
MS 300 transmits a Ranging Request (RNG-REQ) message to the target BS 350
in step 313, and the target BS 350 transmits a Ranging Response (RNG-RSP)
message to the MS 300 in response to the RNG-REQ message, in step 315. The
RNG-RSP message includes HO Process Optimization TLV, and the HO Process
Optimization TLV, an Information Element (IE) included using a TLV encoding
scheme, is an IE of a handover-processed MS 300, used for supporting a fast
network re-entry procedure with the target BS 350. That is, the HO Process
Optimization TLV is an IE written to make it possible to omit some or all of the
message transmission/reception processes that should necessarily be performed in
the general network re-entry procedure for the fast network re-entry procedure of
the MS 300. A detailed description of the HO Process Optimization TLV is set
forth in Table 1 herein.
Upon reception of the RNG-RSP message including the HO Process
Optimization TLV from the target BS 350, the MS 300 transmits an RNG-RSP
Acknowledge (ACK) message indicating normal receipt of the RNG-RSP
message to the target BS 350, in step 317. The target BS 350, as it receives the
RNG-RSP ACK message from the MS 300, recognizes that the MS 300 has
normally received the RNG-RSP message.
The target BS 350 transmits an unsolicited Subscriber Station Basic
Capability Response (SBC-RSP) message to the MS 300 in step 319, regardless
of receipt from the MS 300 a Subscriber Station's Basic Capability Negotiation
Request (SBC-REQ) message for negotiation of the basic capability of the MS
300.
Upon reception of the unsolicited SBC-RSP message from the target BS
350, the MS 300 transmits an SBC-RSP ACK message indicating normal receipt

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of the unsolicited SBC-RSP message, to the target BS 350 in step 321. The target
BS 350, as it receives the SBC-RSP ACK message from the MS 300, recognizes
that the MS 300 has normally received the SBC-RSP message.
The target BS 350 transmits an unsolicited Registration Response (REG-
RSP) message to the MS 300 in step 323, regardless of receipt from the MS 300 a
Registration Request (REG-REQ) message. Upon reception of the unsolicited
REG-RSP message from the target BS 350, the MS 300 transmits a REG-RSP
ACK message indicating normal receipt of the unsolicited REG-RSP message to
the target BS 350 in step 325.
The target BS 350, as it receives the REG-RSP ACK message from
the MS 300, recognizes that the MS 300 has normally received the unsolicited
REG-RSP message, thereby completing the network re-entry procedure in step
327. As a result, as the MS 300 receives the unsolicited REG-RSP message, a
normal operation is performed between the MS 300 and the target BS 350,
thereby completing the network re-entry procedure.
Although FIG. 3 illustrates a preferred case in which the target BS 350
transmits the unsolicited SBC-RSP message and unsolicited REG-RSP message
according to the HO Process Optimization TLV, if the information included in the
unsolicited SBC-RSP message and the unsolicited REG-RSP message as
described with reference to Table 2 is already included in the RNG-RSP message,
the processes in steps 319 to 325 are not performed. In addition, although FIG. 3
illustrates a preferred case in which the target BS 350 transmits both the
unsolicited SBC-RSP message and the unsolicited REG-RSP message according
to the HO Process Optimization TLV, the process may also include other message
transmission/reception processes included in the network re-entry procedure, like
the message transmission/reception process for Privacy Key Management (PKM)
authentication according to the HO Process Optimization TLV.
The RNG-RSP ACK message, SBC-RSP ACK message, and REG-RSP
ACK message can be implemented in the same format, i.e. can be implemented
using a Network re-entry confirm extended sub-header including a Network re-
entry confirm field, shown in Table 3 below.

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Table 3
Name Size (bits) Description
Network re-entry
confirm 3 Bit #0: set to 1 to indicate an
acknowledgement for RNG-RSP
message
Bit #1: set to 1 to indicate an
acknowledgement for unsolicited SBC-
RSP message
Bit #2: set to 1 to indicate an
acknowledgement for unsolicited REG-
RSP message
Reserved 5 Shall be set to zero
As shown in Table 3, the Network re-entry confirm field of the Network
re-entry confirm extended sub-header includes bitmap information indicating the
message, upon reception, the MS transmits the current ACK message. That is, in
the Network re-entry confirm field, Bit#0 = 1 indicates that the MS transmits the
current ACK message in response to the RNG-RSP message, Bit#l = 1 indicates
that the MS transmits the current ACK message in response to the unsolicited
SBC-RSP message, and Bit#2 = 1 indicates that the MS transmits the current
ACK message in response to the unsolicited REG-RSP message.
In addition, a Reserved field of the Network re-entry confirm extended
sub-header maintains the number of bits of the Network reentry confirm extended
sub-header at eight (8), and is a field reserved for future use. For example, this
field is set to '0'.
In transmitting ACK messages in response to the RNG-RSP message,
unsolicited SBC-RSP message and unsolicited REG-RSP message, the MS sets
bitmap information indicating the ACK messages for all of the RNG-RSP
message, unsolicited SBC-RSP message and unsolicited REG-RSP message to
transmit the ACK messages through one Network re-entry confirm extended sub-
header, or separately sets bitmap information indicating an ACK message for
each of the RNG-RSP message, unsolicited SBC-RSP message and unsolicited
REG-RSP message to transmit the ACK messages through three Network re-

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entry confirm extended sub-headers.
In addition, the RNG-RSP ACK message, SBC-RSP ACK message and
REG-RSP ACK message can be implemented using Reserved bits of a Channel
Quality Information Channel (CQICH) Allocation Request (CQICH Allocation
Request) message header, shown in Table 4 below.
Table 4
HT=
1(1) EC=0
(1) Type (3) =
Obi 11 Feedback
Type (3) FBSSI
(1) Preferre
d-
Period
(3) Network
reentry
confirm
indicator
(1) Network
reentry
conform
(3)
Reserved (8) CID MSB (8)
CID LSB (8) HCS (8)
As shown in Table 4, the header of the CQICH Allocation Request
message includes a Type field indicating a type of the currently transmitted
header, a Fast BS Switching Indicator (FBSSI) field indicating that the MS
transmits the header to request CQICH allocation when performing a Fast BS
Switching (FBSS) operation, a Feedback Type field indicating a type for
distinguishing the information for feeding back the CQICH, a Preferred-Period
field indicating a CQICH allocation period preferred by the MS, a CID field
indicating a Basic Connection Identifier (CID) of the MS that transmits the
header, an HCS field indicating a Header Check Sequence (HCS) used for
checking integrity of the header, a Network re-entry confirm indicator field
indicating whether a Network re-entry confirm field indicating transmission/non-
transmission of an ACK for the RNG-RSP ACK message, SBC-RSP ACK
message and REG-RSP ACK message during the network re-entry procedure is
included in the header of the CQICH Allocation Request message, i.e. indicating
that the header of the CQICH Allocation Request message is used for transmitting
an ACK for the RNG-RSP ACK message, SBC-RSP ACK message and REG-
RSP ACK message, and the Network reentry confirm field. In Table 4, if a value
of the FBSSI field is set to '1', the Feedback Type field value and the Preferred-
Period field value are ignored. A description will now be made of the bitmap

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information of the Network reentry confirm field.
Below is a description of each bit of the Network re-entry confirm field .
Bit#0 = 1 indicates an ACK message for the RNG-RSP message, Bit#l = 1
indicates an ACK message for the unsolicited SBC-RSP message, and Bit#2 = 1
indicates an ACK message for the unsolicited REG-RSP message.
If the Network re-entry confirm indicator field in the header of the CQICH
Allocation Request message is set to T, then the FBSSI field, Feedback Type
field and Preferred-Period field in the header of the CQICH Allocation Request
message are neglected.
In transmitting an ACK message in reply to the RNG-RSP message,
unsolicited SBC-RSP message and unsolicited REG-RSP message, the MS can
set bitmap information indicating ACK messages for all of the RNG-RSP
message, unsolicited SBC-RSP message and unsolicited REG-RSP message to
transmit the ACK messages through one CQICH Allocation Request message
header, or separately sets bitmap information indicating an ACK message for
each of the RNG-RSP message, unsolicited SBC-RSP message and unsolicited
REG-RSP message to transmit the ACK messages through three CQICH
Allocation Request message headers.
The RNG-RSP ACK message, SBC-RSP ACK message and REG-RSP
ACK message can be implemented using a header of a Bandwidth Request
message, as shown in Table 5 below.
Table 5
HT=
1(1) EC=0
(1) Type(3) =
ObOOO/ObO
01 BR MSB (11)
BR LSB (8) CID MSB (8)
CID LSB (8) HCS (8)
As shown in Table 5, the header of the Bandwidth Request message
includes a Type field indicating a type of the currently transmitted header, a CID

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field indicating a Basic CID of the MS that transmits the header of the Bandwidth
Request message, an HCS field indicating an HCS used for checking integrity of
the header of the Bandwidth Request message, and a BR field.
A value of the Type field set to '000' indicates whether a bandwidth
allocation request of the MS is incremental, i.e. a value set later in the BR field
indicates the bandwidth that the MS requests to be additionally allocated later.
That is, the values of the Type field set to '000' and the BR field set to '200'
indicate that the MS requests additional allocation of a bandwidth of 200.
If the value of the Type field is set to '001', it indicates whether the
bandwidth allocation request is aggregate, i.e. a value set later in the BR field
indicates the required full bandwidth that the MS should be allocated. That is, if
the value of the Type field is set to '001' and the value of the BR field is set to
'800', it indicates that a bandwidth of 800, determined by summing up the MS's
presently allocated bandwidth and the bandwidth the MS will be allocated
through the bandwidth allocation request, is allocated to the MS.
When transmitting the header of the Bandwidth Request message as an
ACK message for the RNG-RSP message, unsolicited SBC-RSP message and
unsolicited REG-RSP message in the network re-entry procedure, the MS sets a
value of the BR field to '0'. Upon reception of the header of the Bandwidth
Request message with the BR field = 0, the target BS that performs the network
re-entry procedure with the MS recognizes the ACK message for the RNG-RSP
message, unsolicited SBC-RSP message or unsolicited REG-RSP message.
Referring to FIGs. 4A and 4B, a description will be made of an operation
process of an MS in the network re-entry procedure based on the HO Process
Optimization TLV in the IEEE 802.16e communication system according to the
present invention.
FIGs. 4A and 4B are flowcharts illustrating an operation process of an MS
in a network re-entry procedure based on HO Process Optimization TLV in an
IEEE 802.16e communication system according to the present invention.
Referring to FIGs. 4A and 4B, in step 411, an MS, after handover from a

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serving BS to a target BS, acquires downlink synchronization with the target BS,
and receives parameters to be used in a downlink and an uplink. In step 413, the
MS transmits an RNG-REQ message to the target BS. In step 415, the MS
receives an RNG-RSP message including HO Process Optimization TLV from
the target BS in response to the RNG-REQ message. In step 417, the MS
transmits an RNG-RSP ACK message indicating normal reception of the RNG-
RSP message from the target BS. The RNG-RSP ACK message, as described
with reference to Table 3 to Table 5, can be implemented using the Network re-
entry confirm extended sub-header, the CQICH Allocation Request message
header, or the Bandwidth Request message header, and a detailed description
thereof is given above.
In step 419, the MS analyzes the HO Process Optimization TLV received
through the RNG-RSP message and determines whether there is a need to receive
an unsolicited SBC-RSP message and an unsolicited REG-RSP message from the
target BS. Upon determining that there is a need to receive the unsolicited SBC-
RSP message and the unsolicited REG-RSP message from the target BS, the MS
receives the unsolicited SBC-RSP message from the target BS in step 421.
Thereafter, in step 423, the MS transmits an SBC-RSP ACK message indicating
normal reception of the unsolicited SBC-RSP message to the target BS. The SBC-
RSP ACK message, as described with reference to Table 3 to Table 5, can be
implemented using the Network reentry confirm extended sub-header, the
CQICH Allocation Request message header or the Bandwidth Request message
header, and a detailed description thereof is given above.
In step 425, the MS receives the unsolicited REG-RSP message from the
target BS. In step 427, the MS transmits an REG-RSP ACK message indicating
normal reception of the unsolicited REG-RSP message to the target BS. The
REG-RSP ACK message, as described with reference to Table 3 through Table 5,
can be complemented using the Network re-entry confirm extended sub-header,
the CQICH Allocation Request message header or the Bandwidth Request
message header, and a detailed description thereof is given above. In step 429, the
MS completes the network re-entry procedure with the target BS, and then ends
the operation process.

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However, upon determining in step 419 that there is no need to receive
both the unsolicited SBC-RSP message and the unsolicited REG-RSP message
from the target BS, the MS determines in step 431 whether there is a need to
receive only the unsolicited SBC-RSP message from the target BS. If there is a
need to receive only the unsolicited SBC-RSP message from the target BS, the
MS receives the unsolicited SBC-RSP message from the target BS in step 433.
Thereafter, in step 435, the MS transmits an SBC-RSP ACK message indicating
normal reception of the unsolicited SBC-RSP message to the target BS, and then
proceeds to step 429.
However, upon determining in step 431 that there is no need to receive the
unsolicited SBC-RSP message from the target BS, the MS determines in step 437
whether there is a need to receive only the unsolicited REG-RSP message from
the target BS. Upon determining that there is a need to receive only the
unsolicited REG-RSP message from the target BS, the MS receives the
unsolicited REG-RSP message from the target BS in step 439. Thereafter, in step
441, the MS transmits a REG-RSP ACK message indicating normal reception of
the unsolicited REG-RSP message to the target BS, and then proceeds to step 429.
However, if it is determined in step 437 that there is no need to receive the
unsolicited REG-RSP message from the target BS, i.e. if there is no more network
re-entry procedure to perform other than the RNG-RSP message reception
process according to the HO Process Optimization TLV, the target BS and the
MS support a virtual SDU SN, and a value of Bit#6 of the HO Process
Optimization TLV bitmap is set to T, then the target BS allocates an uplink
resource with which the MS can transmit an SN Report header, and the MS
transmits the SN Report header to the target BS using the uplink resource
allocated from the target BS. In this case, the MS transmits the SN Report header
without transmitting the ACK message having the format described with
reference to Table 3 to Table 5, replacing the transmission of the ACK message
for the RNG-RSP message. Given that a format of the SN Report header is not
directly related to the gist of the present invention, a detailed description thereof
is omitted herein.
The operation process of the MS in the network re-entry procedure based

-18-
on the HO Process Optimization TLV in the IEEE 802.16e communication
system according to the present invention has been described herein with
reference to FIGs. 4A and 4B. Next, with reference to FIGs. 5A and 5B, a
description will be made of an operation process of a target BS in a network re-
entry procedure based on HO Process Optimization TLV in an IEEE 802.16e
communication system according to the present invention.
FIGs. 5 A and 5B are flowcharts illustrating an operation process of a target
BS in a network re-entry procedure based on HO Process Optimization TLV in an
IEEE 802.16e communication system according to the present invention.
Referring to FIGs. 5A and 5B, in step 511, the target BS receives an RNG-
REQ message from an MS. In step 513, the target BS transmits an RNG-RSP
message including HO Process Optimization TLV to the MS in response to the
RNG-REQ message. In step 515, the target BS receives an RNG-RSP ACK
message indicating normal reception of the RNG-RSP message from the MS. The
RNG-RSP ACK message, as described herein with reference to Table 3 to Table
5, can be implemented using the Network re-entry confirm extended sub-header,
the CQICH Allocation Request message header or the Bandwidth Request
message header, for which a detailed description thereof is set forth above.
In step 517, the target BS determines whether there is a need to transmit
both of an unsolicited SBC-RSP message and an unsolicited REG-RSP message
to the MS. If it is determined that there is a need to transmit both of the
unsolicited SBC-RSP message and the unsolicited REG-RSP message to the MS,
the target BS transmits the unsolicited SBC-RSP message to the MS in step 519.
In step 521, the target BS receives an SBC-RSP ACK message indicating
normal reception of the unsolicited SBC-RSP message from the MS. The SBC-
RSP ACK message, as described with reference to Table 3 to Table 5, can be
implemented using the Network re-entry confirm extended sub-header, the
CQICH Allocation Request message header or the Bandwidth Request message
header, and a detailed description thereof is given above.
In step 523, the target BS transmits an unsolicited REG-RSP message to

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the MS. In step 525, the target BS receives an REG-RSP ACK message indicating
normal reception of the unsolicited REG-RSP message from the MS. The REG-
RSP ACK message, as described with reference to Table 3 to Table 5, can be
implemented using the Network re-entry confirm extended sub-header, the
CQICH Allocation Request message header or the Bandwidth Request message
header, and a detailed description thereof is given above. In step 527, the target
BS completes the network re-entry procedure with the MS, and then ends the
operation process.
However, upon determining in step 517 that there is no need to transmit
both of the unsolicited SBC-RSP message and the unsolicited REG-RSP message
to the MS, the target BS determines in step 529 whether there is a need to
transmit only the unsolicited SBC-RSP message to the MS. Upon determining
that there is a need to transmit only the unsolicited SBC-RSP message to the MS,
the target BS transmits the unsolicited SBC-RSP message to the MS in step 531.
Thereafter, in step 533, the target BS receives an SBC-RSP ACK message
indicating normal reception of the unsolicited SBC-RSP message from the MS,
and then proceeds to step 527.
However, if it is determined in step 529 that there is not need to transmit
only the unsolicited SBC-RSP message to the MS, the target BS determines in
step 535 whether there is a need to transmit only the unsolicited REG-RSP
message to the MS. If it is determined that there is a need to transmit only the
unsolicited REG-RSP message to the MS, the target BS transmits the unsolicited
REG-RSP message to the MS in step 537. Thereafter, in step 539, the target BS
receives a REG-RSP ACK message indicating normal reception of the unsolicited
REG-RSP message from the MS, and then proceeds to step 527.
However, if it is determined in step 535 that there is no need to transmit
only the unsolicited REG-RSP message to the MS, i.e. if there is no more network
re-entry procedure to perform other than the RNG-RSP message transmission
process according to the HO Process Optimization TLV, the target BS and the
MS support a virtual SDU SN, and a value of Bit#6 of the HO Process
Optimization TLV bitmap is set to '1', then the target BS allocates an uplink
resource with which the MS can transmit an SN Report header. Thereafter, the

-20-
target BS receives the SN Report header that the MS transmits using the uplink
resource allocated thereto. In this case, the target BS receives the SN Report
header without receiving the ACK message having the format described with
reference to Table 3 to Table 5, replacing the reception of the ACK message for
the RNG-RSP message.
As can be understood from the foregoing description, in the
communication system, when an MS performs a network re-entry procedure with
a target BS after its connection switching to the target BS, the MS can transmit a
notification indicating completion of the network re-entry procedure to the target
BS, thereby preventing a possible delay from occurring between the MS and the
target BS and improving the entire system performance.
While the invention has been shown and described with reference to a
certain preferred embodiment thereof, it will be understood by those skilled in the
art that various changes in form and details may be made therein without
departing from the spirit and scope of the invention as defined by the appended
claims.

-21-
WHAT IS CLAIMED IS:
1. A method for notifying completion of a network re-entry procedure
by a mobile station (MS) in a communication system, the method comprising:
completing the network re-entry procedure with a base station (BS); and
notifying the completion of the network re-entry procedure to the BS.
2. The method of claim 1, wherein the step of completing the network
re-entry procedure with a BS comprises :
receiving, from the BS, information indicating whether to omit each of
processes necessary for performing the network re-entry procedure with the BS;
and
performing the network re-entry procedure with the BS according to the
received information.
3. The method of claim 2, wherein if the information indicates
possibility of omitting all of the processes necessary for performing the network
re-entry procedure, the step of notifying the completion of the network re-entry
procedure to the BS comprises transmitting a response indicating normal
reception of the information to the BS.
4. The method of claim 2, wherein if the information indicates
possibility of omitting at least one of the processes necessary for performing the
network re-entry procedure, the step of notifying the completion of the network
re-entry procedure to the BS comprises notifying the completion of the network
re-entry procedure to the BS upon completing the remaining processes except for
an omittable process among the processes necessary for performing the network
re-entry procedure.
5. The method of claim 1, wherein the step of completing the network
re-entry procedure with a BS comprises completing the network re-entry
procedure with the BS upon reception of an unsolicited registration response
(REG-RSP) message from the BS.
6. The method of claim 5, wherein the step of notifying the completion

-22-
of the network re-entry procedure to the BS comprises transmitting a REG-RSP
acknowledge (ACK) message indicating normal reception of the unsolicited
REG-RSP message to the BS.
7. The method of claim 6, wherein the REG-RSP ACK message is a
Bandwidth Request message header, and the Bandwidth Request message header
includes a Bandwidth Request field indicating that the Bandwidth Request
message header is the REG-RSP ACK message.
8. The method of claim 1, wherein the step of completing the network
re-entry procedure with a BS comprises : receiving, from the BS, a
Ranging Response (RNG-RSP) message including information of a REG-RSP
message for performing the network re-entry procedure with the BS; and
completing the network re-entry procedure with the BS upon reception of a
RNG-RSP message from the BS according to the information.
9. The method of claim 8, wherein the step of notifying the completion
of the network re-entry procedure to the BS comprises transmitting an RNG-RSP
ACK message indicating normal reception of the RNG-RSP message to the BS.
10. The method of claim 9, wherein the RNG-RSP ACK message is a
Bandwidth Request message header, and the Bandwidth Request message header
includes a Bandwidth Request field indicating that the Bandwidth Request
message header is the RNG-RSP ACK message.
11. A system for notifying completion of a network re-entry procedure
in a communication system, the system comprising:
a mobile station (MS) for, after completing the network re-entry procedure
with a base station (BS), notifying the completion of the network re-entry
procedure to the BS.
12. The system of claim 11, wherein the MS comprises:
receiving, from the BS, information indicating whether to omit each of
processes necessary for performing the network re-entry procedure with the BS;
and

-23-
performing the network re-entry procedure with the BS according to the
received information.
13. The system of claim 12, wherein if the information indicates
possibility of omitting all of the processes necessary for performing the network
re-entry procedure, the MS notifies the completion of the network re-entry
procedure by transmitting a response indicating normal receipt of the information
to the BS.
14. The system of claim 12, wherein if the information indicates
possibility of omitting at least one of the processes necessary for performing the
network re-entry procedure, the MS notifies the completion of the network re-
entry procedure to the BS after completing the remaining processes except for the
omittable process among the processes necessary for performing the network re-
entry procedure.
15. The system of claim 11, wherein the MS completes the network re-
entry procedure with the BS upon reception of an unsolicited registration
response (REG-RSP) message from the BS.
16. The system of claim 15, wherein the MS notifies the completion of
the network re-entry procedure to the BS by transmitting a REG-RSP
acknowledge (ACK) message indicating normal reception of the unsolicited
REG-RSP message to the BS.
17. The system of claim 16, wherein the REG-RSP ACK message is a
Bandwidth Request message header, and the Bandwidth Request message header
includes a Bandwidth Request field indicating that the Bandwidth Request
message header is the REG-RSP ACK message.
18. The system of claim 11, wherein the MS comprises:
receiving, from the BS, a Ranging Response (RNG-RSP) message
including information of a REG-RSP message for performing the network re-
entry procedure with the BS; and
completing the network re-entry procedure with the BS upon receipt of a

-24-
RNG-RSP message from the BS according to the information.
19. The system of claim 18, wherein the MS notifies the completion of
the network re-entry procedure to the BS by transmitting an RNG-RSP ACK
message indicating normal reception of the RNG-RSP message to the BS.
20. The system of claim 19, wherein the RNG-RSP ACK message is a
Bandwidth Request message header, and the Bandwidth Request message header
includes a Bandwidth Request field indicating that the Bandwidth Request
message header is the RNG-RSP ACK message.

Provided is a system and method for notifying completion of a network
re-entry procedure in a communication system. In the system, a mobile station
(MS) completes the network re-entry procedure with a base station (BS), and
then notifies the completion of the network re-entry procedure to the BS.

Documents:


Patent Number 259241
Indian Patent Application Number 4834/KOLNP/2007
PG Journal Number 10/2014
Publication Date 07-Mar-2014
Grant Date 04-Mar-2014
Date of Filing 12-Dec-2007
Name of Patentee SAMSUNG ELECTRONICS CO. LTD.
Applicant Address 416, MAETAN-DONG, YEONGTONG-GU, SUWON-SI, GYEONGGI-DO
Inventors:
# Inventor's Name Inventor's Address
1 HYOUNG-KYU LIM #105-2305, SAMHWAN APT., GAEBONG 2-DONG, GURO-GU, SEOUL
2 HYUN-JEONG KANG #GA-603, DONGSIN APT., DOGOK 1-DONG, GANGNAM-GU, SEOUL
3 HONG-SUNG CHANG #435-1802, CHEONGMYEONGMAEUL SAMSUNG RAEMIAN, YEONGTONG-DONG, YEONGTONG-GU, SUWON-SI, GYEONGGI-DO
4 PAN-YUH JOO #311-402, SINBANPO HANSHIN APT., JAMWON-DONG, SEOCHO-GU, SEOUL
5 SUNG-JIN LEE #133-1701, HWANGGOLMAEUL 1-DANJI APT., YEONGTONG-DONG, YEONGTONG-GU, SUWON-SI, GYEONGGI-DO
6 SONG-NAM HONG #211-208, JUGONG APT., GODEOK-DONG, GANGDONG-GU, SEOUL
7 JUNG-JE SON #306-901, MUJIGAEMAEUL SINHAN APT., GAUMI-DONG, BUNDANG-GU, SEONGNAM-SI, GYEONGGI-DO
8 YOUNG-HO KIM #106, 200-51, MAETAN 4-DONG, YEONGTONG-GU, SUWON-SI, GYEONGGI-DO
9 YEONG-MOON SON #102, JEONGU VILLA, 897-1, ANYANG 3-DONG, MANAN-GU, ANYANG-SI, GYEONGGI-DO
10 MI-HYUN LEE #202, 602-182, NAMHYEON-DONG, GWANAK-GU, SEOUL
11 JAE-WEON CHO #944-1110, BYUCKJEOKGOL 9-DANJI LOTTE APT., YEONGTONG-DONG, YEONGTONG-GU, SUWON-SI, GYEONGGI-DO
PCT International Classification Number H04B 7/26
PCT International Application Number PCT/KR2006/002623
PCT International Filing date 2006-07-05
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10-2005-0060944 2005-07-06 Republic of Korea