doc.: IEEE 802.19-15/0098r0

Submission

November 2015

Hyunduk Kang et al, ETRISlide 1

Consideration on Neighbor DiscoveryDate: 2015-11-11

Name Company Address Phone E-mail Hyunduk Kang ETRI henry@etri.re.kr

Kwihoon Kim ETRI

Jintae Oh ETRI

Authors:

doc.: IEEE 802.19-15/0098r0

Submission

Interference vs. Neighbor discovery

• Interference among wireless systems is caused by wireless systems located nearby each other

• A first step on interference mitigation might be which wireless systems are interfering me on which channel– Interference on the same operating channel– Interference on the adjacent channel (due to partial channel

overlap)• Neighbor discovery let you know

– Who is your neighbor that can cause co-channel or adjacent channel interference

– What is further information regarding your neighbors such as network type, operating parameters, and so on.

November 2015

Hyunduk Kang et al, ETRISlide 2

doc.: IEEE 802.19-15/0098r0

Submission

Case Study: Interference vs. Neighbor Discovery among WLANs

November 2015

Hyunduk Kang et al, ETRISlide 3

doc.: IEEE 802.19-15/0098r0

Submission

Inter-BSS Interference

• Inter-BSS Interference (IBI) is interference among multiple basic service sets (BSSs), located nearby each other

• There are three types of inter-BSS interference– AP-AP IBI– AP-STA IBI– STA-STA IBI

November 2015

Hyunduk Kang et al, ETRISlide 4

doc.: IEEE 802.19-15/0098r0

Submission

Inter-BSS Interference: AP-AP

• It occurs when a AP receiving data from its associated STA is interfered by a neighbor AP transmitting data to its associated STA, and vice versa.

November 2015

Hyunduk Kang et al, ETRISlide 5

doc.: IEEE 802.19-15/0098r0

Submission

Inter-BSS Interference: AP-STA

• It occurs when a AP receiving data from its associated STA is interfered by a neighbor AP transmitting data to its associated STA, and vice versa.

November 2015

Hyunduk Kang et al, ETRISlide 6

doc.: IEEE 802.19-15/0098r0

Submission

Inter-BSS Interference: STA-STA

• It occurs when a STA receiving data from its associated AP is interfered by a neighbor STA transmitting data to its associated AP, and vice versa.

November 2015

Hyunduk Kang et al, ETRISlide 7

doc.: IEEE 802.19-15/0098r0

Submission

Overlapping Geography

• It is possible to categorize overlapping geography based on IBI classification

• Types of overlapping– AP-AP overlapping– BSS-BSS overlapping– STA-STA overlapping

November 2015

Hyunduk Kang et al, ETRISlide 8

doc.: IEEE 802.19-15/0098r0

Submission

AP-AP Overlapping

November 2015

Hyunduk Kang et al, ETRISlide 9

• AP1 and AP2 directly can hear each other• APs and STAs might suffer from

– AP-AP IBI– AP-STA IBI– STA-STA IBI

doc.: IEEE 802.19-15/0098r0

Submission

BSS-BSS Overlapping

November 2015

Hyunduk Kang et al, ETRISlide 10

• AP1 and AP2 directly can NOT hear each other• APs and STAs might suffer from

– AP-STA IBI– STA-STA IBI

doc.: IEEE 802.19-15/0098r0

Submission

STA-STA Overlapping

November 2015

Hyunduk Kang et al, ETRISlide 11

• AP1 and AP2 directly can NOT hear each other• STAs might suffer from

– STA-STA IBI

doc.: IEEE 802.19-15/0098r0

Submission

No Overlapping: BSS-BSS Separation

November 2015

Hyunduk Kang et al, ETRISlide 12

• There is no interference between BSSs• Ideal spatial reuse is possible

doc.: IEEE 802.19-15/0098r0

Submission

Comparison among Types of Overlap

November 2015

Hyunduk Kang et al, ETRISlide 13

Type of overlapping

Inter-BSS interference: AP-AP

Inter-BSS interference: AP-STA

Inter-BSS interference: STA-STA

Amount of Inter-BSS interference

Hidden neighbor AP

AP-AP YES YES YES Heavy -

BSS-BSS - YES YES Medium YES

STA-STA - - YES Light YES

No - - - - -

• AP-AP could get lot of co-channel interference. However, it might be favorable to mitigate interference since AP can hear each other directly

• BSS-BSS seems to difficult to mitigate co-channel interference since APs are blinded each other

doc.: IEEE 802.19-15/0098r0

Submission

Existing Mechanisms for Neighbor Discovery on WLANs

• Spectrum sensing– CCA-ED (for other wireless system)– CCA-SD (for WLANs, preamble detection is possible)

• Passive scanning– Beacon listening

• Active scanning– Probe request/response

• Virtual carrier sensing– RTS/CTS

• BSS color: 802.11ah-D2.0• Neighbor report• Reduced neighbor report: 802.11af-2012• Radio measurement

November 2015

Hyunduk Kang et al, ETRISlide 14

doc.: IEEE 802.19-15/0098r0

Submission

Possible Mechanisms for Neighbor Discovery among Wireless Systems

November 2015

Hyunduk Kang et al, ETRISlide 15

doc.: IEEE 802.19-15/0098r0

Submission

Spectrum sensing (or radio measurement)

• Each wireless systems perform it by itself• In general, two methods are

– Energy detection (to reveal existence of other wireless systems)• ED Threshold adjustment is one of important issues to deal with

– Feature detection (to identity type of other wireless systems)• Decode preamble information of other wireless systems• Obtain more information based on preamble data

November 2015

Hyunduk Kang et al, ETRISlide 16

doc.: IEEE 802.19-15/0098r0

Submission

Message exchanging

• Neighbor information could be exchanged – Via wireless channel– Via wired channel

• Neighbor information could be exchanged – By directly among neighbors– By indirectly using external entities

• Neighbor information could be obtained by combinations of – Results of spectrum sensing (or radio measurement) by each wireless

systems– Geo-location information if available

November 2015

Hyunduk Kang et al, ETRISlide 17

doc.: IEEE 802.19-15/0098r0

Submission

Concluding Remarks

• Neighbor discovery is the very first step for interference mitigation for better coexistence among wireless systems

• Neighbor discovery among dissimilar wireless systems might be more difficult than that among similar wireless systems– Just to reveal existence of neighbor is not enough for interference

mitigation. – The more information on neighbor, the better coexistence among

neighbor– How/What to exchange among neighbor is one of important issues

November 2015

Hyunduk Kang et al, ETRISlide 18