Jan. 2009 IEEE 802.220

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Jan.

200
9


IEEE 802.22
0

Submission

page
1


Cheng Shan, Samsung


IEEE P802.22

1

Wireless RANs

2

Proposed text changes to
section
6.21.2.1.2

of D1.
4


Date:

200
8
-
0
1
-
1
9

Aut hor( s ):

Name

Company

Addres s

Phone

e mai l

S
a
ngbum Ki m

Sa ms ung El ect r oni cs

S. Kor ea

+82 31 279 7092

s b07.ki m@s a ms ung.com

Che ng Sha n

Sa ms ung El ect r oni cs

S. Kor ea

+82 31 279 7557

cheng.s ha n@s a ms ung.com

Eunt ae k Li m

Sa ms ung El ect r oni cs

S. Kor ea

+82 31 279 5917

et.l i m@s a ms ung.com

J unhong Hui

Sa ms ung El ect r oni cs

Chi na

+86

10

5925

3333

3108

jh.hui@samsung.com


3


4


5

6

Abstract

This document proposes

the
related text c
hanges on
CBP Packet Generation

in section
6.21.2.1.2

as the
resolution to comment
#
436
.

And we
add

a new

CBP

IE
into the draft, in order
to quickly share
the
information of pattern period

among the
neighbouring

WRANs in contention
-
free CBP transmission.


Notice:

This document has been prepared to assist IEEE 802.22. It is offered as a basis for discussion and is not binding on the
contributing individual(s) or organization(s). The material in this document is subject to change in form and content after
f
urther study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.


Release:

The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution,
and any modification
s thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE
Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit
others to reproduce in whole o
r in part the resulting IEEE Standards publication. The contributor also acknowledges and
accepts that this contribution may be made public by IEEE 802.22.


Patent Policy and Procedures:

The contributor is familiar with the IEEE 802 Patent Policy and Proc
edures

<
http://standards.ieee.org/guides/bylaws/sb
-
bylaws.pdf
>, including the statement "IEEE standards may include the
known use of patent(s), including patent applications, provided t
he IEEE receives assurance from the patent holder or applicant
with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosur
e
to the Working Group of patent information that might be relevant
to the standard is essential to reduce the possibility for
delays in the development process and increase the likelihood that the draft publication will be approved for publication.
Please notify the Chair <
Ca
rl R. Stevenson
> as early as possible, in written or electronic form, if patented technology (or
technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.22
Working Group.
If you have questions,
contact the IEEE Patent Committee Administrator at <
patcom@ieee.org
>
.

Jan.

200
9


IEEE 802.22
0

Submission

page
2


Cheng Shan, Samsung


I
.
Related
Comment

& Resolution

1


2

Comment:

3



A new comer BS1 shall monitor SCW regular pattern of a discovered neighboring BS0 and then acquires
4

SCW_Active_Repe
ti
tion

value used by BS0. In order to avoid collision of active SCW scheduling, BS1 should set same
5

SCW_Active_Repe
ti
tion

value as that of B
S0. However, when one of the several collocated BSs with synch
ronized SCW
6

wants to change
its own
SCW_Active_Repe
ti
tion

value, how this could

be

done is not clearly addressed. e.g., if the
7

SCW_Active_Repe
ti
tion

is originally set as 4, and the SCWs are bein
g shared by 4 existing BSs, a fifth BS cannot find a
8

possible SCW opportunity.

9


10

Suggested Remedy:

11


Description of how
SCW_Active_Repe
ti
tion

could be adaptively
change
d is necessary.

12


13


14

II
.

Proposed Text Changes

15


16

6.21.2.1.2
CBP Packet Generation

17

802.22 ent
ities (i.e., CPEs and BSs) are capable of transmitting coexistence beacons (see 6.6.1.2) which provide its recipients
18

enough information to achieve satisfactory and good coexistence amongst overlapping 802.22 cells. The CPB also allows the
19

geolocation rang
ing enhancement process between CPEs within a cell (see 6.22.1.21). These beacons are intended for inter
-
20

cell and intra
-
cell communication and carry specific information about a CPE’s cell of attachment and downstream/upstream
21

bandwidth allocations with th
e BS.

22


23

Coexistence beacons are scheduled by the BS through the use of Coexistence IUC (both Passive and Active). The US
-
MAP
24

can be used to indicate a Coexistence IUC in Active or Passive mode (see
Error! Reference source not found.
), whereas the
25

DS
-
MAP
can only be used to indicate a Coexistence IUC in Passive mode (see Table 33). When scheduling a Coexistence
26

UIC, the connection ID contained in the MAP IE indicates which CPEs shall send the beacon, in case of Active mode, or
27

which CPEs shall listen to th
e medium for beacon, in case of Passive mode, within the specified scheduled time. This
28

connection ID can be either unicast (e.g., a CPE’s primary connection ID), multicast (i.e., a multicast management
29

connection ID), or even the broadcast ID. In case of
multicast, the BS can implement clustering algorithms that improve
30

spectrum utilization and maximize the effectiveness of the coexistence beacons, as multiple CPEs would transmit a
31

coexistence beacon during the same scheduled time. Irrespective of the type

of connection ID, the CPE shall always verify if
32

the connection ID specified by the BS includes itself or not. This will determine the CPE’s behavior during the scheduled
33

Coexistence IUC. CBP packet transmissions shall be performed in the operating channe
l, but base stations and CPEs shall be
34

capable of receiving CBP packets in any channel it is capable of operating in. The BS specifies the channel number in which
35

the CPE shall listen to the medium for a coexistence beacon (SCW in Passive mode). The channe
l number is included in the
36

US
-
MAP using the US
-
MAP CBP Channel IE described in 6.8.4.1.2.3. This allows the coexistence amongst 802.22 systems
37

operating in the same or in different channels.

38


39

The Coexistence IUC defines a period of time where channel acce
ss shall be contention based. In other words, during this
40

time CPEs shall use the contention access mechanism described in 6.14 to gain access to the medium and transmit the
41

coexistence beacon. The contention
-
based access mechanism maximizes the spectrum u
sage in case multiple CPEs in the
42

same cell (multicast management connections can be used for this purpose


see 6.8.10 and 6.19) or in different cells attempt
43

to send coexistence beacons. Furthermore, when combined with the clustering algorithms (see 6.21
.6), the efficiency of this
44

contention based is maximized because, for the same Coexistence IUC, the BS will only schedule CPEs not belonging to the
45

same physical cluster.

46


47

The BS shall decide which CPEs transmit CBP packets at each Coexistence UIC in Acti
ve mode. Example of mechanisms
48

that can be used by the BS for the selection of which CPEs are to transmit at each Coexistence UIC in Active mode can be
49

based on location information, clustering, or be as simple as selecting all CPEs.

50


51

The CBP protocol can
be used for communication and coexistence of WRANs on the same operating channel as well as
52

across channels, which is enabled by through the US
-
MAP CBP Channel IE as described above. Note that different CPEs
53

associated to the same BS can simultaneously com
municate using CBP. For example, if two CPEs are associated with the
54

same BS, during the same self
-
coexistence window one of them can be transmitting a CBP packet on the operating channel
55

Jan.

200
9


IEEE 802.22
0

Submission

page
3


Cheng Shan, Samsung


while the other could be receiving over another channel. This is con
trolled by the BS when it schedules the self
-
coexistence
1

windows in the US
-
MAP.

2


3

In order to facil
it
a
te network discovery and coexistence with neighboring WRANs, the BS shall maintain a minimal regular
4

pattern of SCWs in Active mode, although the BS may al
so schedule SCWs in Active and Passive mode on an on
-
demand
5

basis, e.g., to enable over
-
the
-
air geolocation or inter
-
WRAN communi
c
ation.

6


7

The BS shall start a regular pattern of SCWs in Active mode when the BS initiates its normal operation. For that, the
BS shall
8

select a frame to open its first SCW window in Active mode, and a repe
ti
tion rate defined by the
SCW_Active_Repe
ti
tion

9

parameter in number of frames. The SCW pattern consists of a sequence of SCWs in Active mode equally spaced by
10

SCW_Active_Repe
ti
tion
frames. For instance,

if the
SCW_Active_Repe
ti
tion

is set to 8
,
the BS will schedule a SCW in Active
11

mode at every 8 frames after its first SCW. This regular schedule of SCWs in Active mode allows ne
i
gh
b
oring WRANs to
12

adjust their SCWs in passive mode

so that they can easily capture information from the neighboring WRANs.

13


14

The
SCW_Active_Repe
ti
tion
parameter should be set according to the requirements for coexistence and inter
-
WRAN
15

communications, and it determines a trade
-
off between the performance o
f inter
-
WRAN communications and the overhead
16

represented by the SCWs.

17


18

Multiple WRANs operating on the same channel may share the same SCWs in Active mode or each WRAN may reserve its
19

own SCWs depending on how they set up their regular SCWs patterns. If n
eighboring WRANs on the same channel decide to
20

share their SCWs in Active mode, the random backoff mechanism described in Section 6.14.2 shall be used in order to
21

reduce the collision probability in CBP transmissions. Sharing of SCWs may reduce the total o
verhead in the channel, but on
22

the other hand, reservation of SCWs enables contention
-
free CBP transmissions. The decision on whether to share or reserve
23

SCWs in Active mode will depend on the total overhead generated by SCWs and the coexistence scenarios
(e.g. number of
24

neighboring WRANs on the same channel). Moreover, the WRANs may change their schedule of the SCWs dynamically and
25

therefore they may adjust the schedule to adapt to the coexistence scenarios.

26


27

The reservation of SCWs facilitates the content
ion
-
free CBP transmissions among the neighboring WRAN cells sharing the
28

channel, and it can be achieved by scheduling the regular SCW pattern such that it does not overlap with the SCW pattern of
29

other neighboring WRANs. The procedure for that is as follow
s:

30


31



During the initialization stage, the WRAN monitors the channel to discover neighboring WRANs and identifies their
32

SCW regular patterns. For instance, the regular SCW pattern can be identified by receiving a sequence of CBP
33

packets from a neighboring WR
AN.

34


35



If a WRAN indentifies another WRAN’s regular SCW pattern, it shall regard these SCWs as reserved and shall set
36

its own regular pattern so that it does not overlap with the SCWs reserved by the neighboring WRAN.

37


38

(Remove the
following

text

described i
n current draft v1.0)

39


40



Once the WRAN starts its own regular SCW pattern, it shall maintain this pattern for a number of super
-
frames
41

specified by the
SCWActive_Reservation_Period

parameter.

42


43

(
Since th
ere is a change on

the period whenever the new comer or
the existing WRAN tries to contend for SCW slots,
it
44

could be

impossible to maintain
a pattern during a specific period.)

45


46

(
Insert the following text
s)

47


48



If
a

WRAN cannot set up its regular active SCW pattern due to the lack of vacant slots available,

the

W
RAN

shall
49

reserve its SCW regular pattern by contending on active SCW slot
s

occupied by a
n

existing

neighboring
WRAN
.

50

The WRAN can retry to contend on another active SCW slot until it wins.

The contention mechanism is described in
51

6.15.2.


52


53



When t
he neighb
oring
WRAN

loses the contention, it
shall double the
SCW_Active_Repetition

value by
releasing

54

those SCW slots every other frame from the contended one

in its reserved pattern

and then share slots with the
55

winner
.

The w
inn
ing WRAN

shall set its
SCW active p
attern
period to
the
same value
as

that of

the neighboring
56

WRAN.

57


58



A
WRAN can change its current SCW pattern by occupying available vacant slots.

59

Jan.

200
9


IEEE 802.22
0

Submission

page
4


Cheng Shan, Samsung



1



If the multiple WRANs attempt to
occupy the same one or several vacant slots when updating their regular patte
rn
,
2

th
ose

WRANs shall resolve th
e occupa
ncy

of those slots
through contention

and shall set up their SCW pattern
3

accordingly
.

T
he
WRANs

should

release previously occupied slots

but not includ
ing

those in
the
newly
updated

4

regular pattern
.

5


6

A BS can schedul
e CPEs in passive mode during SCWs reserved by other neighboring WRANs in order to receive CBP
7

packets from the neighboring WRANs, which may operate on the same channel or on a different channel. Note that WRANs
8

on different operating channels could reserv
e the same SCW for transmitting CBP packets. For the SCW in passive mode, the
9

BS shall define the schedule such that it can capture the required coexistence information from neighboring WRANs that
10

may impact the WRAN operation. Note that SCWs in passive mo
de does not increase the overhead in the channel since it
11

only requires listening for other CBP transmissions from neighboring cells. Therefore, they may be scheduled depending on
12

the availability of the CPEs.

13


14

The BS could also use other information avail
able at the MAC layer to decide when and in which mode to generate a
15

Coexistence UIC window, as long as above generation rules are satisfied. One example can be found in 6.8.22.3.1.3, where
16

the BS uses the CPE statistics report as the basis for triggering
the execution of CBP. For example, a decision criterion may
17

be defined such that if the PER experienced by one or more CPEs (e.g., if clustering is employed) exceeds a predetermined
18

threshold value PERCBP, this would trigger the BS to schedule a Coexistenc
e IUC for at least the corresponding CPEs.

19


20


21

6.7.1.2.1
CBP Information Elements

22

CBP packets shall carry at least one information element (IE) in their payload among the set described in
0

since it provides
23

the basic infor
mation required to enable self
-
coexistence. CBP packets shall at least carry a Backup Channel information
24

element (IE) in their payload. This is to allow WRANs to execute the spectrum etiquette mechanism before deciding to
25

execute the other spectrum sharin
g mechanisms described in 6.21.2.3.

26


27

(Insert

a new IE in Table 6 CBP IEs)

28


29


30

Table 6


CBP IEs

31

Element ID

Name

0

Backup Channel IE

1

Inter
-
BS Capabilities IE

2

CC_REQ IE

3

CC_RSP IE

4

CC_ACK IE

5

RR
-
REQ IE

6

RA
-
RSP IE

7

RA
-
ACK IE

8

RC
-
REQ IE

9

RC
-
RSP IE

10

RC
-
ACK IE

11

RE
-
REQ IE

12

RE
-
RSP IE

13

RE
-
ACK IE

14

RS
-
SEM IE

15

RS
-
ADV IE

16

BS Channel Parameter IE

17

CBP Location IE

18

CBP Geolocation IE

19

CBP Pattern Identification IE


32


33


34

Jan.

200
9


IEEE 802.22
0

Submission

page
5


Cheng Shan, Samsung


(Add

a new session as follows)

1


2

6.7.1.2.1.22

CBP
Pattern Identificat
ion

IE

3


4

The CBP Pattern Identification IE
defined

in Table 28 is used
in order that a WRAN

quickly
inform
s

the neighboring
5

WRANs of
its
own CBP transmission period.
If a CBP packet doesn

t include the IE, it is not transmitted based on the
6

contention
-
free
CBP transmission described in 6.21.2.1.2. The IE can
alternatively
indicate the period as well as the location
7

of next SCW slot to be transmitted.
The

value of

location is counted from the start of the current slot.
By this option, WRAN
8

can
inform the
chan
ge
of
its pattern
.


9


10

Table 28


CBP
Pattern Identification

IE format

11

Syntax

Size

Notes

Period
_Information() {



Element ID

8 bits


Type

indicator

1
bit

0: Type indicating the value of period

1: Type indicating the location of next SCW slot directly

Pa
ttern Period

4

bits

This field specifies

t
he v
alue of
SCW_Active_Repetition

(if
the
type is
set to 0) or
t
he
offset (in units of slots)
from the current slot to the slot
in which next CBP packet will be transmitted

(if the type is set to 1)
.

Reserved

3 bi
ts

S
hall be set to zero

}




12


13