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Consideration on Neighbor Discovery

Explore the complexities of interference among nearby wireless systems and strategies for effective coexistence through neighbor discovery. Learn about types of interference, overlapping geography, spectrum sensing methods, and mechanisms for neighbor discovery.

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Consideration on Neighbor Discovery

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  1. Consideration on Neighbor Discovery Authors: Date: 2015-01-15 Hyunduk Kang et al, ETRI

  2. 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) Interference vs. Neighbor discovery Hyunduk Kang et al, ETRI

  3. 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 Case Study: Interference vs. Neighbor Discovery among WLANs Hyunduk Kang et al, ETRI

  4. 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. Inter-BSS Interference: AP-AP Hyunduk Kang et al, ETRI

  5. 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. Inter-BSS Interference: AP-STA Hyunduk Kang et al, ETRI

  6. 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. Inter-BSS Interference: STA-STA Hyunduk Kang et al, ETRI

  7. Itis possible to categorize overlapping geography based on IBI classification • Types of overlapping • AP-AP overlapping • BSS-BSS overlapping • STA-STA overlapping Overlapping Geography Hyunduk Kang et al, ETRI

  8. AP-AP Overlapping • AP1 and AP2 directly can hear each other • APs and STAs might sufferfrom • AP-AP IBI • AP-STA IBI • STA-STA IBI Hyunduk Kang et al, ETRI

  9. BSS-BSS Overlapping • AP1 and AP2 directly can NOT hear each other • APs and STAs might sufferfrom • AP-STA IBI • STA-STA IBI Hyunduk Kang et al, ETRI

  10. STA-STA Overlapping • AP1 and AP2 directly can NOT hear each other • STAs might sufferfrom • STA-STA IBI Hyunduk Kang et al, ETRI

  11. No Overlapping: BSS-BSS Separation • There is no interference between BSSs • Ideal spatial reuse is possible Hyunduk Kang et al, ETRI

  12. Comparison among Types of Overlap • 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 Hyunduk Kang et al, ETRI

  13. 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 Existing Mechanisms for Neighbor Discovery on WLANs Hyunduk Kang et al, ETRI

  14. Spectrum sensing (or radio measurement) • Each wireless systems perform it by itself • In general, two methods are • Energy detection (to reveal existence of wireless systems) • Feature detection (to identity type of wireless systems) • Message exchanging (directly or indirectly) • Neighbor information could be exchanged • Via wireless channel • Via wired channel • Neighbor information could be obtained by combinations of • Results of spectrum sensing (or radio measurement) by each wireless systems • Geo-location information if available Possible Mechanisms for Neighbor Discovery among Wireless Systems Hyunduk Kang et al, ETRI

  15. Which system is interfering on which channel? (Seen/Hidden) • How to identify neighbor systems which interfere my system • “Stay on the channel” or “Switch to new channel” • Determination based on what grounds? • What is useful information for decision? • Stay on the channel with which channel sharing method? • Existing methods, e.g., LBT, are enough or we need a new one? • Select to new channel with which channel allocation method? • Existing methods, e.g., DFS, are enough or we need a new one? Intuition on Interference Mitigation for Coexistence Hyunduk Kang et al, ETRI

  16. 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 • Neighbor discovery without geo-location informationwould be a challenging issue on unlicensed frequency bands Concluding Remarks Hyunduk Kang et al, ETRI

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