U.S. patent application number 16/839435 was filed with the patent office on 2020-07-23 for apparatus and method for performing network entry procedure in cloud cell communication system.
The applicant listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Jae-Weon CHO, Hyun-Jeong KANG, Jung-Shin PARK, Yeong-Moon SON, Rakesh TAORI, Hyun-kyu YU.
Application Number | 20200236706 16/839435 |
Document ID | 20200236706 / US20200236706 |
Family ID | 49982877 |
Filed Date | 2020-07-23 |
Patent Application | download [pdf] |
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United States Patent
Application |
20200236706 |
Kind Code |
A1 |
KANG; Hyun-Jeong ; et
al. |
July 23, 2020 |
APPARATUS AND METHOD FOR PERFORMING NETWORK ENTRY PROCEDURE IN
CLOUD CELL COMMUNICATION SYSTEM
Abstract
A method for performing a network entry procedure by a Mobile
Station (MS) in a cloud cell communication system is provided. The
method includes determining whether there is an arbitrary cloud
cell member candidate Base Station (BS) as a cloud cell member
candidate BS which has transmitted a downlink synchronization
signal with a signal strength, if there is the arbitrary cloud cell
member candidate BS, determining the arbitrary cloud cell member
candidate BS as a final cloud cell member candidate BS which will
perform a cooperative communication with the master BS,
transmitting an access request message including information on the
final cloud cell member candidate BS to the master BS, and
receiving an access response message including information on a
cloud cell member BS from the master BS.
Inventors: |
KANG; Hyun-Jeong; (Seoul,
KR) ; TAORI; Rakesh; (Suwon-si, KR) ; PARK;
Jung-Shin; (Seoul, KR) ; SON; Yeong-Moon;
(Yongin-si, KR) ; CHO; Jae-Weon; (Seongnam-si,
KR) ; YU; Hyun-kyu; (Yongin-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Suwon-si |
|
KR |
|
|
Family ID: |
49982877 |
Appl. No.: |
16/839435 |
Filed: |
April 3, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13905681 |
May 30, 2013 |
10616918 |
|
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16839435 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 74/006 20130101;
H04W 74/004 20130101; H04W 36/0069 20180801; H04W 74/0833 20130101;
H04W 48/16 20130101; H04B 7/022 20130101; H04W 48/20 20130101 |
International
Class: |
H04W 74/00 20060101
H04W074/00; H04B 7/022 20060101 H04B007/022; H04W 48/16 20060101
H04W048/16 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 1, 2012 |
KR |
10-2012-0059197 |
Jul 26, 2012 |
KR |
10-2012-0081904 |
Claims
1. A method by a mobile station (MS) in a communication system, the
method comprising: receiving, from a master node, first information
related to measurement for neighbor nodes; measuring channel
quality of the neighbor nodes based on the first information; and
transmitting, to the master node, a measurement report message
including a measurement result which includes second information
related to a beam identifier (ID) of at least one of the neighbor
nodes.
2. The method of claim 1, wherein the beam ID of the at least one
of the neighbor nodes is a best beam ID of at least one of the
neighbor nodes.
3. The method of claim 2, wherein remaining IDs of the at least one
of the neighbor nodes are beam IDs of which quality is above a
threshold.
4. The method of claim 1, wherein the neighbor nodes operate on a
millimeter wave frequency band.
5. The method of claim 1, wherein the beam ID is associated with
millimeter wave frequency based-beamforming.
6. A method by a master node in a communication system, the method
comprising: transmitting, to a mobile station (MS), first
information related to measurement for neighbor nodes; and
receiving, from the MS, a measurement report message including a
measurement result which includes second information related to a
beam identifier (ID) of at least one of the neighbor nodes, wherein
the measurement result is based on measurement of channel quality
of the neighbor nodes which is based on the first information.
7. The method of claim 6, wherein the beam ID of the at least one
of the neighbor nodes is a best beam ID of at least one of the
neighbor nodes.
8. The method of claim 7, wherein remaining IDs of the at least one
of the neighbor nodes are beam IDs of which quality is above a
threshold.
9. The method of claim 6, wherein the neighbor nodes operate on a
millimeter wave frequency band.
10. The method of claim 6, wherein the beam ID is associated with
millimeter wave frequency based-beamforming.
11. A mobile station (MS) in a communication system, the MS
comprising: a transceiver configured to receive, from a master
node, first information related to measurement for neighbor nodes;
and at least one processor configured to measure channel quality of
the neighbor no des based on the first information, wherein the
transceiver is further configured to transmit, to the master node,
a measurement report message including a measurement result which
includes second in formation related to a beam identifier (ID) of
at least one of the neighbor nodes.
12. The MS of claim 11, wherein the beam ID of the at least one of
the neighbor nodes is a best beam ID of at least one of the
neighbor nodes.
13. The MS of claim 12, wherein remaining IDs of the at least one
of the neighbor nodes are beam IDs of which quality is above a
threshold.
14. The MS of claim 11, wherein the neighbor nodes operate on a
millimeter wave frequency band.
15. The MS of claim 11, wherein the beam ID is associated with
millimeter wave frequency based-beamforming.
16. A master node in a communication system, the master node
comprising: at least one processor; and a transceiver configured
to: transmit, to a mobile station (MS), first information related
to measurement for neighbor nodes; and receive, from the MS, a
measurement report message including a measurement result which
includes second information related to a beam identifier (ID) of at
least one of the neighbor nodes, wherein the measurement result is
based on measurement of channel quality of the neighbor nodes which
is based on the first information.
17. The master node of claim 16, wherein the beam ID of the at
least one of the neighbor nodes is a best beam ID of at least one
of the neighbor nodes.
18. The master node of claim 17, wherein remaining IDs of the at
least one of the neighbor nodes are beam IDs of which quality is
above a threshold.
19. The master node of claim 16, wherein the neighbor nodes operate
on a millimeter wave frequency band.
20. The master node of claim 16, wherein the beam ID is associated
with millimeter wave frequency based-beamforming.
Description
PRIORITY
[0001] This application is a continuation application of prior
application Ser. No. 13/905,681, filed on May 30, 2013, which
issued as U.S. Pat. No. 10,616,918 on Apr. 7, 2020, and which is
based on and claims the benefit under 35 U.S.C. .sctn. 119(a) of a
Korean patent application filed in the Korean Intellectual Property
Office on Jun. 1, 2012 and assigned Serial No. 10-2012-0059197, and
a Korean patent application filed in the Korean Intellectual
Property Office on Jul. 26, 2012 and assigned Serial No.
10-2012-0081904, the entire disclosures of each of which is hereby
incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates to an apparatus and method for
a cloud cell communication system. More particularly, the present
invention relates to an apparatus and method for performing a
network entry procedure in a cloud cell communication system.
2. Description of the Related Art
[0003] A wireless communication system has evolved to provide a
high-speed large-capacity data service according to user's various
requirements. So, the wireless communication system considers using
a high-frequency band such as a millimeter Wave (mmW) in order to
support the high-speed large-capacity data service.
[0004] Recently, a cloud cell communication system in which a
plurality of Base Stations (BSs) provides a service to a Mobile
Station (MS) by cooperating with one another, that is, a multiple
BS cooperation scheme, has been proposed.
[0005] However, if a high-frequency band is used, there is a high
probability for a case where link loss between an MS and a BS is
large, and received signal strength rapidly changes.
[0006] So, in a wireless communication system using a
high-frequency band, if an MS performs a network entry procedure
with one BS, there is a high probability for signal attenuation
between the MS and the BS, so this signal attenuation may cause the
MS to fail in the network entry procedure. Specially, since the
network entry procedure includes procedures for the MS to perform a
communication such as an uplink/downlink synchronization
acquisition procedure, a basic capability negotiation procedure, an
authentication procedure, and a registration procedure, so if the
failure in the network entry procedure occurs, the MS may not
perform a communication operation.
[0007] Therefore, there is a need for a scheme for an MS to
reliably perform a network entry procedure by using a
high-frequency band in a cloud cell communication system.
[0008] The above information is presented as background information
only to assist with an understanding of the present disclosure. No
determination has been made, and no assertion is made, as to
whether any of the above might be applicable as prior art with
regard to the present invention.
SUMMARY OF THE INVENTION
[0009] Aspects of the present invention are to address at least the
above-mentioned problems and/or disadvantages and to provide at
least the advantages described below. Accordingly, an aspect of the
present invention is to propose an apparatus and method for
performing a network entry procedure in a cloud cell communication
system.
[0010] Another aspect of the present invention is to propose an
apparatus and method for performing a network entry procedure using
a multiple Base Station (BS) cooperation scheme in a cloud cell
communication system.
[0011] Another aspect of the present invention is to propose an
apparatus and method for forming cloud cell for effectively
performing a network entry procedure in a cloud cell communication
system.
[0012] Another aspect of the present invention is to propose an
apparatus and method for forming cloud cell after performing a
network entry procedure in a cloud cell communication system.
[0013] In accordance with an aspect of the present invention, a
cloud cell communication system is provided. The cloud cell
communication system includes a Mobile Station (MS) for determining
whether there is an arbitrary cloud cell member candidate BS as a
cloud cell member candidate BS which has transmitted a downlink
synchronization signal with a signal strength, which has a
difference from a signal strength of a downlink synchronization
signal, which has been transmitted from a master BS as a cloud cell
member candidate BS which transmits a downlink synchronization
signal with maximal signal strength among a plurality of cloud cell
member candidate BSs, that is less than a preset threshold signal
strength difference value, if there is the arbitrary cloud cell
member candidate BS, determining the arbitrary cloud cell member
candidate BS as a final cloud cell member candidate BS which will
perform a cooperative communication with the master BS,
transmitting an access request message including information on the
final cloud cell member candidate BS to the master BS, and
receiving an access response message including information on a
cloud cell member BS from the master BS.
[0014] In accordance with another aspect of the present invention,
a cloud cell communication system is provided. The cloud cell
communication system includes a master BS for receiving an access
request message including information on a final cloud cell member
candidate BS from an MS, performing a cooperative procedure for
including the final cloud cell member candidate BS to a cloud cell
with the final cloud cell member candidate BS, including the final
cloud cell member candidate BS to the cloud cell, and transmitting
an access response message including information on the cloud cell
member BS to the MS, wherein the master BS is a master BS as a
cloud cell member candidate BS which transmits a downlink
synchronization signal with maximal signal strength among a
plurality of cloud cell member candidate BSs, and the final cloud
cell member candidate BS is a cloud cell member candidate BS which
has transmitted a downlink synchronization signal with a signal
strength which has a difference from a signal strength of a
downlink synchronization signal, which has been transmitted from
the master BS, that is less than a preset threshold signal strength
difference value.
[0015] In accordance with another aspect of the present invention,
a cloud cell communication system is provided. The cloud cell
communication system includes a cloud cell member candidate BS for
receiving a cloud cell formation request message for including the
cloud cell member candidate BS to a cloud cell from a master BS,
performing a cloud cell member BS join procedure for joining the
cloud cell member candidate BS as a cloud cell member BS, and
transmitting a cloud cell formation response message as a response
message to the cloud cell formation request message to the master
BS, wherein the master BS is a master BS as a cloud cell member
candidate BS which transmits a downlink synchronization signal with
maximal signal strength among a plurality of cloud cell member
candidate BSs, and the final cloud cell member candidate BS is a
cloud cell member candidate BS which has transmitted a downlink
synchronization signal with a signal strength which has a
difference from a signal strength of a downlink synchronization
signal which has been transmitted from the master BS, that is less
than a preset threshold signal strength difference value.
[0016] In accordance with another aspect of the present invention,
a cloud cell communication system is provided. The cloud cell
communication system includes an MS for performing a network entry
procedure with a master BS, for receiving neighbor BS information
including information on neighbor BSs from the master BS, for
performing a signal measurement procedure for the neighbor BSs, for
reporting the measured result to the master BS, after reporting the
measured result, for receiving information on a cloud cell member
BS from the master BS, and for performing a cooperative
communication procedure for performing a cooperative communication
with the cloud cell member BS.
[0017] In accordance with another aspect of the present invention,
a cloud cell communication system is provided. The cloud cell
communication system includes a master BS for performing a network
entry procedure with an MS, for transmitting neighbor BS
information including information on neighbor BSs to the MS, for
receiving a signal measurement result on the neighbor BSs from the
MS, for determining whether there is a need for forming a cloud
cell for the MS based on the signal measurement result, for
performing a cloud cell formation procedure for forming a cloud
cell member candidate BS among the neighbor BSs as a cloud cell if
there is a need for forming a cloud cell for the MS, and after
performing the cloud cell formation procedure, for transmitting
information on a cloud cell member BS to the MS.
[0018] In accordance with another aspect of the present invention,
there a method for performing a network entry procedure by an MS in
a cloud cell communication system is provided. The method includes
determining whether there is an arbitrary cloud cell member
candidate BS as a cloud cell member candidate BS which has
transmitted a downlink synchronization signal with a signal
strength, which has a difference from a signal strength of a
downlink synchronization signal which has been transmitted from a
master BS as a cloud cell member candidate BS which transmits a
downlink synchronization signal with maximal signal strength among
a plurality of cloud cell member candidate BSs, that is less than a
preset threshold signal strength difference value, if there is the
arbitrary cloud cell member candidate BS, determining the arbitrary
cloud cell member candidate BS as a final cloud cell member
candidate BS which will perform a cooperative communication with
the master BS, for transmitting an access request message including
information on the final cloud cell member candidate BS to the
master BS, and for receiving an access response message including
information on a cloud cell member BS from the master BS.
[0019] In accordance with another aspect of the present invention,
a method for performing a network entry procedure by a master BS in
a cloud cell communication system is provided. The method includes
receiving an access request message including information on a
final cloud cell member candidate BS from an MS, performing a
cooperative procedure for including the final cloud cell member
candidate BS to a cloud cell with the final cloud cell member
candidate BS, and including the final cloud cell member candidate
BS to the cloud cell, and for transmitting an access response
message including information on the cloud cell member BS to the
MS, wherein the master BS is a master BS as a cloud cell member
candidate BS which transmits a downlink synchronization signal with
maximal signal strength among a plurality of cloud cell member
candidate BSs, and the final cloud cell member candidate BS is a
cloud cell member candidate BS which has transmitted a downlink
synchronization signal with a signal strength which has a
difference from signal strength of a downlink synchronization
signal which has been transmitted from the master BS, that is less
than a preset threshold signal strength difference value.
[0020] In accordance with another aspect of the present invention,
a method for performing a network entry procedure by a cloud cell
member candidate BS in a cloud cell communication system is
provided. The method includes receiving a cloud cell formation
request message for including the cloud cell member candidate BS to
a cloud cell from a master BS, for performing a cloud cell member
BS join procedure for joining the cloud cell member candidate BS as
a cloud cell member BS, and for transmitting a cloud cell formation
response message as a response message to the cloud cell formation
request message to the master BS, wherein the master BS is a master
BS as a cloud cell member candidate BS which transmits a downlink
synchronization signal with maximal signal strength among a
plurality of cloud cell member candidate BSs, and the final cloud
cell member candidate BS is a cloud cell member candidate BS which
has transmitted a downlink synchronization signal with a signal
strength which has a difference from a signal strength of a
downlink synchronization signal which has been transmitted from the
master BS is less than a preset threshold signal strength
difference value.
[0021] In accordance with another aspect of the present invention,
a method for performing a network entry procedure by an MS in a
cloud cell communication system is provided. The method includes
performing a network entry procedure with a master BS, receiving
neighbor BS information including information on neighbor BSs from
the master BS, performing a signal measurement procedure for the
neighbor BSs, and reporting a signal measurement result to the
master BS, after reporting the signal measurement result, receiving
information on a cloud cell member BS from the master BS, and
performing a cooperative communication procedure for performing a
cooperative communication with the cloud cell member BS.
[0022] In accordance with another aspect of the present invention,
a method for performing a network entry procedure by a master BS in
a cloud cell communication system is provided. The method includes
performing a network entry procedure with an MS, transmitting
neighbor BS information including information on neighbor BSs to
the MS, receiving a signal measurement result on the neighbor BSs
from the MS, determining whether there is a need for forming a
cloud cell for the MS based on the signal measurement result,
performing a cloud cell formation procedure for forming a cloud
cell member candidate BS among the neighbor BSs as a cloud cell if
there is a need for forming a cloud cell for the MS, and after
performing the cloud cell formation procedure, transmitting
information on a cloud cell member BS to the MS.
[0023] Other aspects, advantages, and salient features of the
invention will become apparent to those skilled in the art from the
following detailed description, which, taken in conjunction with
the annexed drawings, discloses exemplary embodiments of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The above and other aspects, features and advantages of
certain exemplary embodiments of the present invention will be more
apparent from the following description taken in conjunction with
the accompanying drawings, in which:
[0025] FIG. 1 schematically illustrates a structure of a cloud cell
communication system according to an exemplary embodiment of the
present invention;
[0026] FIGS. 2A to 2C are signal flow diagrams schematically
illustrating a process for performing a network entry procedure in
a cloud cell communication system according to an exemplary
embodiment of the present invention;
[0027] FIG. 3 is a flowchart illustrating a process for performing
a network entry procedure in a Mobile Station (MS) in a cloud cell
communication system according to an exemplary embodiment of the
present invention;
[0028] FIG. 4 is a flowchart illustrating a process for performing
a network entry procedure in a master Base Station (BS) in a cloud
cell communication system according to an exemplary embodiment of
the present invention;
[0029] FIG. 5 is a flowchart illustrating a process for performing
a network entry procedure in a cloud cell member candidate BS in a
cloud cell communication system according to an exemplary
embodiment of the present invention;
[0030] FIG. 6 schematically illustrates an internal structure of an
MS in a cloud cell communication system according to an exemplary
embodiment of the present invention;
[0031] FIG. 7 schematically illustrates an internal structure of a
master BS in a cloud cell communication system according to an
exemplary embodiment of the present invention;
[0032] FIG. 8 schematically illustrates an internal structure of a
cloud cell member candidate BS in a cloud cell communication system
according to an exemplary embodiment of the present invention;
[0033] FIG. 9 schematically illustrates a process for forming a
cloud cell after completing a network entry procedure in a cloud
cell communication system according to an exemplary embodiment of
the present invention; and
[0034] FIGS. 10A to 10B are signal flow diagrams schematically
illustrating a process for performing a network entry procedure in
a cloud cell communication system according to another exemplary
embodiment of the present invention.
[0035] Throughout the drawings, like reference numerals will be
understood to refer to like parts, components, and structures.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0036] The following description with reference to the accompanying
drawings is provided to assist in a comprehensive understanding of
exemplary embodiments of the invention as defined by the claims and
their equivalents. It includes various specific details to assist
in that understanding but these are to be regarded as merely
exemplary. Accordingly, those of ordinary skilled in the art will
recognize that various changes and modifications of the embodiments
described herein can be made without departing from the scope and
spirit of the invention. In addition, descriptions of well-known
functions and constructions may be omitted for clarity and
conciseness.
[0037] The terms and words used in the following description and
claims are not limited to the bibliographical meanings, but, are
merely used by the inventor to enable a clear and consistent
understanding of the invention. Accordingly, it should be apparent
to those skilled in the art that the following description of
exemplary embodiments of the present invention is provided for
illustration purpose only and not for the purpose of limiting the
invention as defined by the appended claims and their
equivalents.
[0038] It is to be understood that the singular forms "a," "an,"
and "the" include plural referents unless the context clearly
dictates otherwise. Thus, for example, reference to "a component
surface" includes reference to one or more of such surfaces.
[0039] The present disclosure proposes an apparatus and method for
performing a network entry procedure in a cloud cell communication
system.
[0040] The present disclosure proposes an apparatus and method for
performing a network entry procedure using a multiple Base Station
(BS) cooperation scheme in a cloud cell communication system.
[0041] The present disclosure proposes an apparatus and method for
forming a cloud cell for effectively performing a network entry
procedure in a cloud cell communication system.
[0042] The present disclosure proposes an apparatus and method for
forming a cloud cell after performing a network entry procedure in
a cloud cell communication system.
[0043] Further, it will be understood by those of ordinary skill in
the art that an apparatus and method for performing a network entry
procedure proposed in the present disclosure may be applied to both
a case where a Mobile Station (MS) performs an initial network
entry procedure and a case where the MS performs a network re-entry
procedure after waking up from an idle mode.
[0044] FIG. 1 schematically illustrates a structure of a cloud cell
communication system according to an exemplary embodiment of the
present invention.
[0045] Referring to FIG. 1, the cloud cell communication system
includes an Internet 111, a gateway 113, a master BS 115, slave BSs
117, 119, 121, and an MS 123. The master BS 115 and the slave BSs
117, 119, 121 forms a cloud cell, BSs included in the cloud cell,
i.e., the master BS 115 and the slave BSs 117, 119, 121 joins in
data transmission for the MS 123 using a multiple BS cooperation
scheme. In FIG.1, the number of slave BSs is 3, however, it will be
understood by those of ordinary skill in the art that the number of
the slave BSs is not limited. Specially, in an exemplary embodiment
of the present invention, a network entry procedure in which the MS
123 performs an authentication and capacity negotiation procedure
after forming the slave BSs 117, 119, 121 as a cloud cell with the
master BS 115 is proposed. The network entry procedure will be
described below, so a detailed description for the network entry
procedure will be omitted herein for brevity.
[0046] FIGS. 2A to 2C are signal flow diagrams schematically
illustrating a process for performing a network entry procedure in
a cloud cell communication system according to an exemplary
embodiment of the present invention.
[0047] Referring to FIGS. 2A to 2C, the cloud cell communication
system includes an MS 200, a BS #1 210, a gateway #1 220, an
Authorization, Authentication and Accounting (AAA) server 230, a BS
#2 240, and a gateway #2 250. In FIGS. 2A to 2C, the BS #1 210 and
the gateway #1 220 are implemented as separate entities. However,
it will be understood by those of ordinary skill in the art that
the BS #1 210 and the gateway #1 220 may be implemented as an
integrative entity. Similarly, the BS #2 240 and the gateway #2 250
are implemented as separate entities. However, it will be
understood by those of ordinary skill in the art that the BS #2 240
and the gateway #2 250 may be implemented as an integrative entity.
In FIGS. 2A to 2C, cloud cell member candidate BSs for forming a
cloud cell are the BS #1 210 and the BS #2 240, however, it will be
understood by those of ordinary skill in the art that the number of
the cloud cell member candidate BSs is equal to or greater than
3.
[0048] Firstly, each of the BS #1 210 and the BS #2 240 transmits a
downlink Synchronization Channel (SCH) signal and a Broadcast
Channel (BCH) signal in steps 301 and 302. If the cloud cell
communication system supports a beamforming scheme, the BCH signal
transmitted from each of the BS #1 210 and the BS #2 240 includes a
beam IDentifier (ID) as well as System Information (SI). In FIGS.
2A to 2C, a downlink synchronization signal is a downlink SCH
signal, however, it will be understood by those of ordinary skill
in the art that the downlink synchronization signal is changed to
another signal from which the MS 200 may acquire
synchronization.
[0049] The MS 200 receives the downlink SCH signal and the BCH
signal transmitted from each of the BS #1 210 and the BS #2 240,
and measures signal strength of the received downlink SCH signal,
e.g., Signal to Interference and Noise Ratio (SINR). In FIGS. 2A to
2C, the MS 200 measures an SINR of a downlink SCH signal in order
to select cloud cell member candidate BSs, however, it will be
understood by those of ordinary skill in the art that the MS 200
may select the cloud cell member candidate BSs by measuring other
parameters such as a Signal to Noise Ratio (SNR), or a Received
Signal Strength Indication (RSSI) as well as the SINR. If there is
an SINR which is equal to or greater than a preset threshold SINR
among the measured SINRs, the MS 200 stores information on a BS
which has transmitted a related downlink SCH signal. In FIGS. 2A to
2C, the cloud cell member candidate BSs are the BS #1 210 and the
BS #2 240, however, it will be understood by those of ordinary
skill in the art that the number of the cloud cell member candidate
BSs is equal to or greater than 3, so there are a plurality of
cloud cell member candidate BSs which have transmitted a downlink
SCH signal with an SINR equal to or greater than the threshold
SINR.
[0050] In FIGS. 2A to 2C, it will be assumed that each of the BS #1
210 and the BS #2 240 is a cloud cell member candidate BS which has
transmitted a downlink SCH signal with an SINR equal to or greater
than a threshold SINR. The threshold SINR is an SINR which is
determined by considering channel status on which link status on
which the MS 200 may normally perform the network entry procedure
may be provided, and it will be understood by those of ordinary
skill in the art that a scheme for determining the threshold SINR
may be implemented in various forms. If the cloud cell
communication system supports a beamforming scheme, the MS 200
selects a master BS by performing a beam acquisition procedure on
which the MS 200 measures an SINR for a downlink SCH signal and
selects an optimal beam direction by considering each beam
direction in step 303. The MS 200 does not perform a beam
acquisition procedure for all cloud cell member candidate BSs, but
only performs a beam acquisition procedure for a cloud cell member
candidate BS which has transmitted a downlink SCH signal with an
SINR equal to or greater than the threshold SINR. In FIGS. 2A to
2C, it will be assumed that each of downlink SCH signals which have
been transmitted from the BS #1 210 and the BS #2 240 has an SINR
equal to or greater than the threshold SINR, so the MS 200 performs
the beam acquisition procedure for each of the BS #1 210 and the BS
#2 240. In FIGS. 2A to 2C, it will be assumed that an SINR of a
downlink SCH signal which has transmitted from the BS #1 210 has a
maximal SINR among SINRs of downlink SCH signals which have
transmitted from all of the cloud cell member candidate BSs, so the
BS #1 210 becomes a master BS of the MS 200.
[0051] The MS 200 performs an uplink synchronization acquisition
procedure with the BS #1 210 as the master BS in step 304. The MS
200 determines whether there is an arbitrary cloud cell member
candidate BS as a cloud cell member candidate BS which has
transmitted a downlink SCH signal with an SINR, which has a
difference from an SINR of a downlink SCH signal which has been
transmitted from the BS #1 210 is less than a preset threshold SINR
difference value A, and selects a final cloud cell member candidate
BS according to the determined result in step 305. The threshold
SINR difference value is determined by considering an SINR on which
a cooperative communication gain may be acquired if the master BS,
i.e., the BS #1 210 and an arbitrary BS perform cooperative
communication. That is, the threshold SINR difference value is set
for selecting a cloud cell member candidate BS which may perform
cooperative communication with the master BS, i.e., the BS #1 210
upon performing the network entry procedure for the MS 200. If
there is the arbitrary cloud cell member candidate BS, the MS 200
selects the arbitrary cloud cell member candidate BS as the final
cloud cell member candidate BS. In FIGS. 2A to 2C, it will be
assumed that the BS #2 240 is selected as the final cloud cell
member candidate BS.
[0052] The MS 200 transmits an access request message to the BS #1
210 in step 306. The access request message includes information on
the selected final cloud cell member candidate BS, i.e., the BS #2
240, and the information on the selected final cloud cell member
candidate BS includes information on the downlink SCH signal which
has transmitted from the arbitrary cloud cell member candidate BS,
BS ID information, SINR information of the downlink SCH signal. If
the cloud cell communication system supports a beamforming scheme,
the information on the selected final cloud cell member candidate
BS includes optimal beam ID information selected for the final
cloud cell member candidate BS. If the MS 200 performs a cloud cell
communication through one or more than BSs, the information on the
selected final cloud cell member candidate BS includes capability
information which the MS 200 may support.
[0053] The BS #1 210 performs a cloud cell formation procedure for
including the final cloud cell member candidate BS, i.e., BS #2 240
to a cloud cell member BS based on the access request message, and
a detailed description thereof will be provided below.
[0054] The BS #1 210 transmits a cloud cell formation request
message to the BS #2 240 in step 307. The cloud cell formation
request message includes an MS ID of the MS 200, and a beam ID for
the BS #2 240 which the MS 200 has selected if the cloud cell
communication system supports the beamforming scheme. The cloud
cell formation request message includes indication information
indicating whether the BS #2 240 will use a cloud cell upon serving
downlink data and uplink data, or downlink data, or uplink data for
the MS 200. The cloud cell formation request message may include
capability information used for the BS #2 240 to provide cloud cell
communication to the MS 200 by cooperating with the BS #1 210 based
on the capability information, and the capability information
includes system load information of the BS #2 240, BS communication
capability information of the BS #2 240, etc.
[0055] The cloud cell formation response message includes
capability information used for the BS #2 240 to provide cloud cell
communication to the MS 200, and the capability information
includes the BS communication capability information of the BS #2
240, the system load information of the BS #2 240, etc. If the BS
#2 240 joins in a cloud cell communication for providing uplink
data service for the MS 200, the cloud cell formation response
message includes uplink random access information for the BS #2
240, and the uplink random access information includes Random
Access Channel (RACH) information. Upon receiving the cloud cell
formation request message from the BS #1 210, the BS #2 240
performs a cloud cell member BS join procedure for joining the BS
#2 240 as a cloud cell member BS for the MS 200, and transmits a
cloud cell formation response message as a response message to the
cloud cell formation request message to the BS #1 210 in step 308.
The uplink random access information includes information on a
dedicated uplink random access resource which only the MS 200 may
use. The cloud cell formation response message includes Channel
Quality Indicator (CQI) information which the MS 200 will use for
communicating with the BS #2 240 and HARQ channel information. The
cloud cell member BS join procedure includes a signal
transmitting/receiving procedure among the gateway #1 220, the AAA
server 230, and the gateway #2 250, and includes a path
establishment procedure used for the BS #1 210 and the BS #2 240 to
provide a cooperative communication to the MS 200, etc. The cloud
cell member BS join procedure may include various procedures as
well as the path management procedure, a detailed description for
the cloud cell member BS join procedure will be omitted for
brevity.
[0056] After receiving the cloud cell formation response message
from the BS #2 240, the BS #1 210 transmits an access response
message as a response message to the access request message to the
MS 200 in step 309. The access response message includes cloud cell
member BS information for the BS #2 240 as a cloud cell member BS
which is formed as a cloud cell for the MS 200. The cloud cell
member BS information includes a BS ID, uplink random access
information, CQI channel information, HARQ channel information for
a related BS. The access response message includes capability
information which the MS 200 should support upon performing cloud
cell communication through the one or more than BSs.
[0057] The MS 200 receiving the access response message from the BS
#1 210 performs a cooperative communication procedure for
performing cooperative communication with the BS #2 240, i.e.,
uplink synchronization acquisition procedure and a beam acquisition
procedure using information included in the access response message
in step 310. Upon completing the cooperative communication
procedure with the MS 200, the BS #2 240 transmits a cloud cell
formation complete message to the BS #1 210 in step 311. The cloud
cell formation complete message includes MS ID information of the
MS 200.
[0058] After completing the cloud cell formation, the BS #1 210
performs an uplink resource assignment procedure with the BS #2 240
for allocating an uplink resource to the MS 200 in order that the
MS 200 may transmit a pre-auth capability negotiation request
message in step 312.
[0059] Once the uplink resource assignment procedure is completed,
the MS 200 transmits a pre-auth capability negotiation request
message to the BS #1 210 and the BS #2 240 in steps 313, and 314.
The pre-auth capability negotiation request message transmitted
from the MS 200 includes capability information used for the MS 200
to communicate using a multiple BS cooperative scheme, i.e., a
cloud cell. If the MS 200 receives a downlink service using the
multiple BS cooperation scheme, the pre-auth capability negotiation
request message further includes a parameter which the MS supports
in a downlink communication with one or more than one BSs. If the
MS 200 further receives an uplink service using the multiple BS
cooperation scheme, the pre-auth capability negotiation request
message further includes a parameter which the MS supports in an
uplink communication with one or more than one BSs. After receiving
the pre-auth capability negotiation request message, the BS #2 240
detects the pre-auth capability negotiation information of the MS
200 included in the received pre-auth capability negotiation
request message, processes the pre-auth capability negotiation
information of the MS 200 using the detected pre-auth capability
negotiation information, includes the processed pre-auth capability
negotiation information into an MS-info transfer message, and
transmits the MS-info transfer message to the BS #1 210 in step
315.
[0060] The BS #1 210 processes pre-auth capability negotiation
information using information used in the pre-auth capability
negotiation request message received from the MS 200 and the
MS-info transfer message received from the BS #2 240, and generates
a pre-auth capability negotiation response message as a response
message to the pre-auth capability negotiation request message in
step 316. The BS #1 210 includes information for the pre-auth
capability negotiation response message into an MS-info transfer
message and transmits the MS-info transfer message to the BS #2
240, and performs a downlink resource allocation procedure with the
BS #2 240 in order to transmit the pre-auth capability negotiation
response message to the MS 200 in step 317. Each of the BS #1 210
and the BS #2 240 transmits the pre-auth capability negotiation
response message to the MS 200 using a downlink resource allocated
according to the downlink resource allocation procedure described
in step 317 in steps 318, and 319. After transmitting the pre-auth
capability negotiation response message to the MS 200, the BS #1
210 performs an authorization and authentication procedure for the
MS 200 with the AAA server 230 in step 320. The authorization and
authentication procedure is performed using an MS ID of the MS 200,
there may be various schemes for performing the authorization and
authentication procedure, and a detailed description will be
omitted for brevity. After performing the authorization and
authentication procedure for the MS 200 with the AAA server 230,
the BS #1 210 transmits authorization and authentication
information for the MS 200 acquired from the authorization and
authentication procedure to the BS #2 240, and performs a procedure
for allocating a downlink5 resource to be used for transmitting an
auth request message #1 to the MS 200 with the BS #2 240 in step
321.
[0061] Each of the BS #1 210 and the BS #2 240 transmits an auth
request message #1 to the MS 200 using a downlink resource
allocated according to the downlink allocation procedure described
in step 321 in steps 322, and 323. After receiving the auth request
message #1 from each of the BS #1 210 and the BS #2 240, the MS 200
performs a related authentication operation and transmits an auth
response message #1 as a response message to the auth request
message #1 to each of the BS #1 210 and the BS #2 240 in steps 324,
and 325.
[0062] The BS #2 240 includes information included in the auth
response message #1 received from the MS 200 into an MS-info
transfer message and transmits the MS-info transfer message to the
BS #1 210 in step 326. The BS #1 210 performs an authorization and
authentication procedure with the AAA server 230 using information
on the auth response message #1 received from the MS 200 described
in step 324 and information on the auth response message #1 of the
MS 200 included in the MS-info transfer message received from the
BS #2 240 described in step 326 in step 327. The authorization and
authentication procedure is performed using an MS ID of the MS
200.
[0063] The MS 200 performs an MS security context establishment
procedure with the AAA server 230 in step 328. The MS security
context establishment procedure includes a procedure in which the
MS generates a security key used for communicating with each of the
BS #1 210 and the BS #2 240.
[0064] The BS #1 210 and the AAA server 230 perform an
authorization and authentication procedure for the MS 200 using the
MS ID of the MS 200 and a security context in step 329. After
performing the authorization and authentication procedure with the
AAA server 230, the BS #1 210 transmits authorization and
authentication information for the MS 200 acquired from the
authorization and authentication procedure to the BS #2 240, and
performs a procedure for allocating a downlink resource to be used
for transmitting an auth request message #2 to the MS 200 with the
BS #2 240 in step 330. Each of the BS #1 210 and the BS #2 240
transmits an auth request message #2 to the MS 200 using a downlink
resource allocated according to the downlink resource allocation
procedure described in step 330 in steps 331, and 332.
[0065] After receiving the authentication request message #2 from
each of the BS #1 210 and the BS #2 240, the MS 200 performs a
cloud cell based security key processing procedure for generating
security key information used for a cloud cell operation in step
333. After performing the cloud cell based security key processing
procedure, the MS 200 transmits an authentication response message
#2 including security key information generated according to the
cloud cell based security key processing procedure to each of the
BS #1 210 and the BS #2 240 in steps 334, and 335.
[0066] After receiving the authentication response message #2, the
BS #2 240 includes security key information included in the
authentication response message #2 into an MS-info transfer message
and transmits the MS-info transfer message to the BS #1 210 in step
336. If the security key information used for the cloud cell
operation is managed per each cloud cell member BS, step 336 may be
omitted. The BS #1 210 transmits information used for transmitting
an authentication request message #3 to the MS 200 to the BS #2
240, and performs a downlink resource allocation procedure for
allocating a downlink resource to be used for transmitting the
authentication request message #3 to the MS 200 with the BS #2 240
in step 337.
[0067] Each of the BS #1 210 and the BS #2 240 transmits the
authentication request message #3 to the MS 200 using the downlink
resource allocated in step 337 in steps 338, and 339. After steps
301 to step 339 have been completed, the BS #1 210 and the BS #2
240 share cloud cell security key information to be applied to the
MS 200.
[0068] After receiving the authentication request message #3 from
each of the BS #1 210 and the BS #2 240, the MS 200 transmits a
post-auth capability negotiation request message to each of the BS
#1 210 and the BS #2 240 in steps 340, and 341. An uplink resource
used for transmitting the post-auth capability negotiation request
message is allocated by performing an uplink resource allocation
procedure between the BS #1 210 and the BS #2 240 after steps 338
and 339 (not shown in FIGS. 2A to 2C).
[0069] After receiving the post-auth capability negotiation request
message from the MS 200, the BS #2 240 includes post-auth
capability negotiation information into an MS-info transfer message
and transmits the MS-info transfer message to the BS #1 210 in step
342. The BS #1 210 transmits information on a post-auth capability
negotiation response message for the MS 200, and performs a
procedure for allocating a downlink resource to be used for
transmitting the post-auth capability negotiation response message
to the MS 200 with the BS #2 240 in step 343. Each of the BS #1 210
and the BS #2 240 transmits a post-auth capability negotiation
response message to the MS 200 using the downlink resource
allocated in step 343 in steps 344, and 345. Hence, a default
bearer connection is established between the MS receiving the
post-auth capability negotiation response message and the BS #1 210
in step 346. The default bearer connection may be used for a cloud
cell communication among the MS 200, the BS #1 210 and the BS #2
240, and information such as an ID of the default bearer
connection, and a Quality of Service (QoS) parameter is shared with
the BS #1 210 and the BS #2 240. If the cloud cell communication is
used for only one of a downlink data service and an uplink data
service, a parameter for a used service is only shared among the
BSs which consist of the cloud cell.
[0070] Messages related to the network entry procedure among the MS
200, the BS #1 210 and the BS #2 240 in steps 318 to 319, 322 to
325, 331 to 332, 334 to 335, 338 to 341, and 344 to 345 include
parameters used for the MS 200 to perform the network entry
procedure with the cloud cell member BSs included in the cloud cell
and to perform a data transmitting/receiving operation. Here, the
parameters are set to a value which all of the cloud cell member
BSs included in the cloud cell, i.e., the BS #1 210 and the BS #2
240 may support. If all of the cloud cell member BSs included in
the cloud cell may not support the same value, all of the cloud
cell member BSs are not selected as cloud cell member BSs for the
MS 200. Selecting or deleting a cloud cell member BS according to a
parameter value to be used in a cooperative communication with the
MS 200 is performed during a cloud cell formation negotiation
procedure in steps 307 to 308 or a network entry procedure in steps
313 to 345. On the other hand, the parameter is set to a value
which the cloud cell member BSs, i.e., each of the BS #1 210 and
the BS #2 240 supports. If the parameter is set to a value
different per each cloud cell member BS, the parameter is included
into a network entry procedure associated message transmitted from
the MS, or network entry procedure associated message received in
the MS 200.
[0071] FIG. 3 is a flowchart illustrating a process for performing
a network entry procedure in an MS in a cloud cell communication
system according to an exemplary embodiment of the present
invention.
[0072] Referring to FIG. 3, an MS selects a master BS among cloud
cell member candidate BSs in step 411. The selecting operation is
performed in a manner described before with reference to FIGS. 2A
to 2C. The MS determines whether there is an arbitrary cloud cell
member candidate BS as a cloud cell member candidate BS which has
transmitted a downlink SCH signal with an SINR, which has a
difference from an SINR of a downlink SCH signal which has been
transmitted from the master BS is less than a preset threshold SINR
difference value A in step 413. If there is no arbitrary cloud cell
member candidate BS, the MS transmits an access request message to
the master BS in step 415. Since there is no arbitrary cloud cell
member candidate BS, that is, there is no cloud cell member
candidate BS which may transmit a signal to the MS by cooperating
with the master BS, the access request message does not include
information on a cloud cell member candidate BS in step 415. An
operation from steps 411 to 415 corresponds to a cloud cell member
BS selection procedure. The MS performs a remaining network entry
procedure with the master BS.
[0073] If there is the arbitrary cloud cell member candidate BS,
the MS determines the arbitrary cloud cell member candidate BS as a
final cloud cell member candidate BS, and transmits an access
request message including information on the final cloud cell
member candidate BS to the master BS in step 419. The information
on the final cloud cell member candidate BS may include downlink
SCH signal information, BS ID information, and SINR information of
a downlink SCH signal, and further include an optimal beam ID for
the final cloud cell member candidate BS if the cloud cell
communication system supports a beamforming scheme.
[0074] The MS receives an access response message as a response
message to the access request message from the master BS in step
421. The MS determines whether the access response message includes
information on a cloud cell member BS in step 423. Here, steps 411
to 413, and 419 to 423 correspond to a cloud cell formation
procedure. If the access response message does not include the
information on the cloud cell member BS, the MS performs a
remaining network entry procedure with the master BS in step
425.
[0075] If the access response message includes the information on
the cloud cell member BS, the MS performs a cooperative
communication procedure for performing a cooperative communication
with the cloud cell member BS, i.e., an uplink synchronization
acquisition procedure and a beam acquisition procedure in step 427.
Here, steps 411 to 413, 419 to 423, and 427 correspond to a cloud
cell formation procedure. The MS performs a remaining network entry
procedure with the master BS and the cloud cell member BS in step
429.
[0076] FIG. 4 is a flowchart illustrating a process for performing
a network entry procedure in a master BS in a cloud cell
communication system according to an exemplary embodiment of the
present invention.
[0077] Referring to FIG. 4, a master BS performs an uplink
synchronization acquisition procedure with an MS in step 511. The
uplink synchronization acquisition procedure is performed in a
manner described before with reference to FIGS. 2A to 2C. The
master BS receives an access request message from the MS in step
513.
[0078] The master BS determines whether the access request message
includes information on a final cloud cell member candidate BS in
step 515. The information on the final cloud cell member candidate
BS may include downlink SCH signal information, BS ID information,
and SINR information of a downlink SCH signal, and further include
an optimal beam ID for the final cloud cell member candidate BS if
the cloud cell communication system supports a beamforming scheme.
Here, steps 511 to 515 correspond to a cloud cell formation
procedure. If the access request message does not include
information on the final cloud cell member candidate BS, the master
BS performs a remaining network entry procedure with the MS in step
517.
[0079] If the access request message includes information on the
final cloud cell member candidate BS, the master BS performs a
negotiation procedure for forming the final cloud cell member
candidate BS as a cloud cell member BS, i.e., a procedure for
transmitting/receiving a cloud cell formation request message/cloud
cell formation response message with the final cloud cell member
candidate BS in step 519. The master BS determines the final cloud
cell member candidate BS as a cloud cell member BS using the
information acquired in the negotiation procedure for forming the
final cloud cell member candidate BS as the cloud cell member BS in
step 521. The master BS transmits an access response message
including information on the determined cloud cell member BS to the
MS in step 523. Here, steps 511 to 515, and 519 to 523 correspond
to a cloud cell formation procedure. The master BS performs a
remaining network entry procedure with the MS and the cloud cell
member BS in step 525.
[0080] FIG. 5 is a flowchart illustrating a process for performing
a network entry procedure in a cloud cell member candidate BS in a
cloud cell communication system according to an exemplary
embodiment of the present invention.
[0081] Referring to FIG. 5, a cloud cell member candidate BS
transmits a downlink SCH signal and a BCH signal in step 611. The
cloud cell member candidate BS determines whether a cloud cell
formation request message is received from a master BS in step 613.
If the cloud cell formation request message is not received from
the master BS, the cloud cell member candidate BS returns to step
613.
[0082] If the cloud cell formation request message has been
received from the master BS, the cloud cell member candidate BS
proceeds to step 615. Here, the fact that the cloud cell formation
request message has been received from the master BS means that the
cloud cell member candidate BS became a final cloud cell member
candidate BS.
[0083] The cloud cell member candidate BS performs a negotiation
procedure for forming the cloud cell member candidate BS as a cloud
cell member BS, i.e., a procedure for transmitting/receiving a
cloud cell formation request message/cloud cell formation response
message with the master BS in step 615. The cloud cell member
candidate BS performs an uplink synchronization acquisition
procedure with a related MS in step 617. The cloud cell member
candidate BS performs a remaining network entry procedure with the
MS in step 619.
[0084] FIG. 6 schematically illustrates an internal structure of an
MS in a cloud cell communication system according to an exemplary
embodiment of the present invention.
[0085] Referring to FIG. 6, an MS 700 includes a transmitter 711, a
controller 713, a receiver 715, and a storage unit 717.
[0086] The controller 713 controls the overall operation of the MS
700, and controls the overall operation related to a network entry
procedure described before with reference to FIGS. 2A to 2C, and
FIG. 3. The storage unit 717 stores a program and data related to
an operation of the MS 700.
[0087] The transmitter 711 transmits messages to a master BS, cloud
cell member candidate BSs and cloud cell member BSs under a control
of the controller 713. The receiver 715 receives messages from the
master BS, the cloud cell member candidate BSs and the cloud cell
member BSs under a control of the controller 713.
[0088] While the receiver 711, the controller 713, the transmitter
715, and the storage unit 717 are shown in FIG. 6 as separate
units, it is to be understood that this is for merely convenience
of description. In other words, the receiver 711, the controller
713, the transmitter 715, and the storage unit 717 may be
incorporated into a single unit.
[0089] FIG. 7 schematically illustrates an internal structure of a
master BS in a cloud cell communication system according to an
exemplary embodiment of the present invention.
[0090] Referring to FIG. 7, a master BS 800 includes a transmitter
811, a controller 813, a receiver 815, and a storage unit 817.
[0091] The controller 813 controls the overall operation of the
master BS 800, and controls the overall operation related to a
network entry procedure described before with reference to FIGS. 2A
to 2C, and FIG. 4. The storage unit 817 stores a program and data
related to an operation of the master BS 800.
[0092] The transmitter 811 transmits messages to an MS, cloud cell
member candidate BSs and cloud cell member BSs under a control of
the controller 813. The receiver 815 receives messages from the MS,
the cloud cell member candidate BSs and the cloud cell member BSs
under a control of the controller 813.
[0093] While the receiver 811, the controller 813, the transmitter
815, and the storage unit 817 are shown in FIG. 7 as separate
units, it is to be understood that this is for merely convenience
of description. In other words, the receiver 811, the controller
813, the transmitter 815, and the storage unit 817 may be
incorporated into a single unit.
[0094] FIG. 8 schematically illustrates an internal structure of a
cloud cell member candidate BS in a cloud cell communication system
according to an exemplary embodiment of the present invention.
[0095] Referring to FIG. 8, a cloud cell member candidate BS 900
includes a transmitter 911, a controller 913, a receiver 915, and a
storage unit 917.
[0096] The controller 913 controls the overall operation of the
cloud cell member candidate BS 900, and controls the overall
operation related to a network entry procedure described before
with reference to FIGS. 2A to 2C, and FIG. 5. The storage unit 917
stores a program and data related to an operation of the cloud cell
member candidate BS 900.
[0097] The transmitter 911 transmits messages to an MS, a master BS
and cloud cell member candidate BSs under a control of the
controller 913. The receiver 915 receives messages from the MS, the
master BS and the cloud cell member candidate BSs under a control
of the controller 913.
[0098] While the receiver 911, the controller 913, the transmitter
915, and the storage unit 917 are shown in FIG. 8 as separate
units, it is to be understood that this is for merely convenience
of description. In other words, the receiver 911, the controller
913, the transmitter 915, and the storage unit 917 may be
incorporated into a single unit.
[0099] FIG. 9 schematically illustrates a process for forming a
cloud cell after completing a network entry procedure in a cloud
cell communication system according to the present invention.
[0100] Referring to FIG. 9, the cloud cell communication system
includes an MS 1000, a BS #1 1050, a BS #2 1060, and a BS #3
1070.
[0101] The MS 1000 completes a network entry procedure with a BS #1
1050 in step 1002, and receives information on neighbor BSs, e.g.,
the BS #2 1060 and the BS #3 1070, i.e., neighbor BS information
from the BS #1 1050 in step 1004. The MS 1000 performs a signal
measurement procedure for the BS #2 1060 and the BS #3 1070
corresponding to the neighbor BS information in step 1006, and
reports the signal measurement result to the BS #1 1050 in step
1008. If the cloud cell communication system supports a beamforming
scheme, the signal measurement result for the neighbor BSs reported
in step 1008 may include an optimal beam identifier for the
neighbor BSs.
[0102] For example, a criteria used for reporting the signal
measurement result may be set as a case where SINRs of the downlink
SCH signals transmitted from the BS #2 1060 and the BS #3 1070 are
equal to or greater than a threshold SINR, or a case where a
difference value between the SINRs of the downlink SCH signals
transmitted from the BS #2 1060 and the BS #3 1070 and an SINR of
the downlink SCH signal transmitted from the BS #1 1050 is less
than a threshold SINR difference value.
[0103] The BS #1 1050 determines whether there is a need for
forming a cloud cell for the MS 1000 based on the signal
measurement result received from the MS 1000. The BS #1 1050
determines a cloud cell member candidate BS for the MS 1000 based
on the signal measurement result received from the MS 1000,
locations of the MS 1000, the BS #2 1060 and the BS #3 1070, amount
of used resources/available resources for the BS #1 1050, the BS #2
1060 and the BS #3 1070, etc. in step 1010. In FIG. 9, it will be
assumed that the BS #2 1060 is determined as a cloud cell member
candidate BS for the MS 1000.
[0104] The BS #1 1050 transmits a cloud cell formation request
message to the BS #2 1060 as the determined a cloud cell member
candidate BS in step 1012. The cloud cell formation request message
includes an MS ID, and further includes a beam ID for the BS #2
1060 selected by the MS 1000 if the cloud cell communication system
supports a beamforming scheme. Further, the cloud cell formation
request message includes cloud cell security key information and
service connection information for the MS 1000, e.g., a service
connection ID, service QoS parameter information, etc.
[0105] After receiving the cloud cell formation request message,
the BS #2 1060 performs a cloud cell member BS join procedure for
joining the BS #2 1060 as a cloud cell member BS for the MS 1000,
and transmits a cloud cell formation response message as a response
message to the cloud cell formation request message to the BS #1
1050 in step 1014. The cloud cell formation response message
includes uplink random access information for the BS #2 1060, and
the uplink random access information includes RACH information. The
cloud cell member BS join procedure includes a signal
transmitting/receiving procedure among each BS, a gateway connected
to each BS, and an AAA server, e.g., a path establishment procedure
used for the BS #1 1050 and the BS #2 1060 to provide a cooperative
communication to the MS 1000.
[0106] After receiving the cloud cell formation response message
from the BS #2 1060, the BS #1 1050 transmits a cloud cell
formation notification message to the MS 1000 in step 1016. The
cloud cell formation notification message includes information on
the BS #2 1060 as a cloud cell member BS which is formed as a cloud
cell, i.e., cloud cell member BS information, and the cloud cell
member BS information includes a BS ID of a related BS and random
access information.
[0107] After receiving the cloud cell formation notification
message, the MS 1000 performs a cooperative communication procedure
for performing a cooperative communication with the BS #2 1060,
i.e., an uplink synchronization acquisition procedure and a beam
acquisition procedure using information included in the cloud cell
formation notification message in step 1018. After completing the
cooperative communication procedure, the BS #2 1060 transmits a
cloud cell formation complete message to the BS #1 1050 in step
1020. The cloud cell formation complete message includes MS ID
information of the MS 1000. Hence, a forming a cloud cell in which
the BS #1 1050 is a master BS and the BS #2 1060 is a slave BS is
completed in step 1022.
[0108] In FIG. 9, the formed cloud cell may be applied if all of
the cloud cell member candidate BSs selected in step 1010 are used
for providing a multiple cooperative communication to the MS 1000,
or the BS #1 1050 separately selects a cloud cell member candidate
BS which provides the multiple cooperative communication to the MS
1000 by applying another threshold SINR different from the
threshold SINR applied to forming the cloud cell.
[0109] FIGS. 10A to 10B are signal flow diagrams schematically
illustrating a process for performing a network entry procedure in
a cloud cell communication system according to another exemplary
embodiment of the present invention.
[0110] Referring to FIGS. 10A to 10B, the cloud cell communication
system includes an MS 1100, a BS #1 1150, a BS #2 1160, and an AAA
server 1170. In FIGS. 10A to 10B, each of the BS #1 1150 and the BS
#2 1160 may be implemented as an entity including a gateway. In
FIGS. 10A to 10B, cloud cell member candidate BSs are the BS #1
1150 and the BS #2 1160, however, it will be understood by those of
ordinary skill in the art that the number of the cloud cell member
candidate BSs is not limited.
[0111] Each of the BS #1 1150 and the BS #2 1160 transmits a
downlink SCH signal and a BCH signal in steps 1102 and 1104. If the
cloud cell communication system supports a beamforming scheme, the
BCH signal transmitted from each of the BS #1 1150 and the BS #2
1160 includes a beam ID as well as system information. In FIGS. 10A
to 10B, a downlink synchronization signal is the downlink SCH
signal, however, it will be understood by those of ordinary skill
in the art that the downlink synchronization signal is changed to
another signal from which an MS 1100 may acquire synchronization as
well as the downlink SCH signal. The MS 1100 receives the downlink
SCH signal and the BCH signal transmitted from each of the BS #1
1150 and the BS #2 1160, and measures signal strength, e.g., an
SINR of the received downlink SCH signal in step 1106. In FIGS. 10A
to 10B, the signal strength is the SINR, however, it will be
understood by those of ordinary skill in the art that the signal
strength may be an SNR, or a RSSI. If there is an SINR greater than
or equal to a preset threshold SINR among the measured SINRs, the
MS 1100 stores information on a BS which has transmitted a downlink
SCH signal with the SINR greater than or equal to the threshold
SINR. In FIGS. 10A to 10B, the cloud cell member candidate BSs are
the BS #1 1150 and the BS #2 1160, however, it will be understood
by those of ordinary skill in the art that there may be more than
three cloud cell member candidate BSs, so there are plurality of
cloud cell member candidate BSs which have transmitted a downlink
SCH signal with an SINR greater than or equal to the threshold
SINR.
[0112] In FIGS. 10A to 10B, it will be assumed that the BS #1 1150
and the BS #2 1160 are cloud cell member candidate BSs which have
transmitted a downlink SCH signal with an SINR greater than or
equal to the threshold SINR. The threshold SINR is an SINR which is
determined by considering channel status on which link status on
which the MS 1100 may normally perform a network entry procedure
may be provided, and it will be understood by those of ordinary
skill in the art that a scheme for determining the threshold SINR
may be implemented in various forms. If the cloud cell
communication system supports a beamforming scheme, the MS 1100
selects a master BS by performing a beam acquisition procedure on
which the MS 1100 measures an SINR for a downlink SCH signal and
selects an optimal beam direction by considering each beam
direction in step 1108. The MS 1100 does not perform a beam
acquisition procedure for all cloud cell member candidate BSs, but
only performs a beam acquisition procedure for a cloud cell member
candidate BS which has transmitted a downlink SCH signal with an
SINR equal to or greater than the threshold SINR. In FIGS. 10A to
10B, it will be assumed that each of downlink SCH signals which
have been transmitted from the BS #1 1150 and the BS #2 1160 has an
SINR equal to or greater than the threshold SINR, so the MS 1100
performs the beam acquisition procedure for each of the BS #1 1150
and the BS #2 1160. In FIGS. 10A to 10B, it will be assumed that an
SINR of a downlink SCH signal which has transmitted from the BS #1
1150 has a maximal SINR among SINRs of downlink SCH signals which
have transmitted from all of the cloud cell member candidate BSs,
so the BS #1 1160 becomes a master BS of the MS 1100.
[0113] The MS 1100 performs an uplink synchronization acquisition
procedure with the BS #1 1150 as the master BS in step 1110. The MS
1100 determines whether there is an arbitrary cloud cell member
candidate BS as a cloud cell member candidate BS which has
transmitted a downlink SCH signal with an SINR, which has a
difference from an SINR of a downlink SCH signal which has been
transmitted from the BS #1 1150 is less than a preset threshold
SINR difference value A, and selects a final cloud cell member
candidate BS according to the determined result in step 1112. The
threshold SINR difference value is determined by considering an
SINR on which a cooperative communication gain may be acquired if
the master BS, i.e., the BS #1 1150 and an arbitrary BS perform
cooperative communication. That is, the threshold SINR difference
value is set for selecting a cloud cell member candidate BS which
may perform cooperative communication with the master BS, i.e., the
BS #1 1150 upon performing the network entry procedure for the MS
1100. If there is the arbitrary cloud cell member candidate BS, the
MS 1100 selects the arbitrary cloud cell member candidate BS as the
final cloud cell member candidate BS. In FIGS. 10A to 10B, it will
be assumed that the BS #2 1160 is selected as the final cloud cell
member candidate BS.
[0114] The MS 1100 transmits an access request message to the BS #1
1150 in step 1114. The access request message includes information
on the selected final cloud cell member candidate BS, i.e., the BS
#2 1160, and the information on the selected final cloud cell
member candidate BS includes information on the downlink SCH signal
which has transmitted from the arbitrary cloud cell member
candidate BS, BS ID information, SINR information of the downlink
SCH signal. If the cloud cell communication system supports a
beamforming scheme, the information on the selected final cloud
cell member candidate BS includes optimal beam ID information
selected for the final cloud cell member candidate BS. If the MS
1100 performs a cloud cell communication through one or more than
BSs, the information on the selected final cloud cell member
candidate BS includes capability information which the MS 1100 may
support.
[0115] The BS #1 1150 performs a cloud cell formation procedure in
step 1116 for including the final cloud cell member candidate BS,
i.e., BS #2 1160 to a cloud cell member BS based on the access
request message, and a detailed description is provided below.
[0116] The BS #1 1150 transmits a cloud cell formation request
message to the BS #2 1160. The cloud cell formation request message
includes an MS ID of the MS 1100, and a beam ID for the BS #2 1160
which the MS 1100 has selected if the cloud cell communication
system supports the beamforming scheme. The cloud cell formation
request message includes indication information indicating whether
the BS #2 1160 will use a cloud cell upon serving downlink data and
uplink data, or downlink data, or uplink data for the MS 1100. The
cloud cell formation request message may include capability
information used for the BS #2 1160 to provide cloud cell
communication to the MS 1100 by cooperating with the BS #1 1150
based on the capability information, and the capability information
includes system load information of the BS #2 1160, BS
communication capability information of the BS #2 1160, etc.
[0117] The cloud cell formation response message includes
capability information used for the BS #2 1160 to provide cloud
cell communication to the MS 1100, and the capability information
includes the BS communication capability information of the BS #2
1160, the system load information of the BS #2 1160, etc. If the BS
#2 1160 joins in a cloud cell communication for providing uplink
data service for the MS 1100, the cloud cell formation response
message includes uplink random access information for the BS #2
1160, and the uplink random access information includes RACH
information. Upon receiving the cloud cell formation request
message from the BS #1 1150, the BS #2 1160 performs a cloud cell
member BS join procedure for joining the BS #2 1160 to a cloud cell
member BS for the MS 1100, and transmits a cloud cell formation
response message as a response message to the cloud cell formation
request message to the BS #1 1150. The uplink random access
information includes information on a dedicated uplink random
access resource which only the MS 1100 may use. The cloud cell
formation response message includes CQI information which the MS
1100 will use for communicating with the BS #2 1160 and HARQ
channel information. The cloud cell member BS join procedure
includes a signal transmitting/receiving procedure between the AAA
server 1170 and a gateway, and includes a path establishment
procedure used for the BS #1 1150 and the BS #2 1160 to provide a
cooperative communication to the MS 1100, etc. The cloud cell
member BS join procedure may include various procedures as well as
the path establishment procedure, a detailed description for the
cloud cell member BS join procedure will be omitted for
brevity.
[0118] After completing the cloud cell formation procedure
described in step 1116, a cloud cell including the BS #2 1160 as a
slave BS is formed in step 1118. Here, if a slave BS for the MS
1100 is not determined, a cloud cell for the MS 1110 only including
the BS #1 1150 is formed.
[0119] The BS #1 1150 receiving the cloud cell formation response
message from the BS #2 1160 transmits an access response message as
a response message to the access request message to the MS 1100 in
step 1120. The access response message includes cloud cell member
BS information for the BS #2 1160 as a cloud cell member BS which
is formed as a cloud cell for the MS 1100. The cloud cell member BS
information includes a BS ID, uplink random access information, CQI
channel information, HARQ channel information for a related BS. The
access response message includes capability information which the
MS 1100 should support upon performing cloud cell communication
through the one or more than BSs.
[0120] After receiving the access response message from the BS #1
1150, the MS 1100 performs a cooperative communication procedure
for performing cooperative communication with the BS #2 1160, i.e.,
uplink synchronization acquisition procedure and a beam acquisition
procedure using information included in the access response message
in step 1122. Upon completing the cooperative communication
procedure with the MS 1100, the BS #2 1160 transmits a cloud cell
formation complete message to the BS #1 1150.
[0121] After completing the cloud cell formation, the MS 1100
performs a pre-auth capability negotiation request procedure with
the BS #1 1150 and the BS #2 1160 through a cloud cell
communication service in step 1124. In the pre-auth capability
negotiation request procedure, the MS 1100 further negotiates
capability information used for performing a communication using a
multiple BS cooperative scheme with the BS #1 1150 and the BS #2
1160. The capability information includes information used for the
MS 1100 to receive a downlink service and an uplink service using
the multiple BS cooperative scheme.
[0122] After completing the pre-auth capability negotiation request
procedure described in step 1124, the MS 1100 performs an
authorization and authentication procedure using a multiple BS
cooperative scheme with the BS #1 1150 and the BS #2 1160 in step
1126. The authorization and authentication procedure includes an MS
security context establishment procedure performed with the AAA
server 1170, and is performed using an MS ID of the MS 1100. Here,
there may be various schemes for performing the authorization and
authentication procedure, and a detailed description thereof will
be omitted for brevity. The authorization and authentication
procedure described in step 1126 includes a cloud cell based
security key processing procedure for generating security
information used for a cloud cell operation used for serving the MS
1100.
[0123] After the authorization and authentication procedure, the MS
1100 performs a post-auth capability negotiation request procedure
through a multiple BS cooperative scheme between the BS #1 1150 and
the BS #2 1160 in step 1128. After completing the post-auth
capability negotiation request procedure, the MS 1110 successfully
completes a registration to a network in step 1130.
[0124] The MS 1100 performs a bearer communication using a multiple
BS cooperative communication between the BS #1 1150 and the BS #2
1160 in step 1132. The MS 1100, the BS #1 1150 and the BS #2 1160
may perform a cloud cell update procedure in which a cloud cell
member BS for the MS 1100 is changed in step 1134.
[0125] As is apparent from the foregoing description, the exemplary
embodiments of the present invention enable an MS to reliably
perform a network entry procedure in a cloud cell communication
system, hence total system performance of the cloud cell
communication system increases.
[0126] In addition, the exemplary embodiments of the present
invention enable an MS to perform a network entry procedure using a
multiple BS cooperative scheme in a cloud cell communication
system, hence total system reliability of the cloud cell
communication system increases.
[0127] While the invention has been shown and described with
reference to certain exemplary embodiments 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 and
their equivalents.
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