<January 2002> doc.: IEEE 802.15-<02/139r0> May, 2008 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [ Anti-blocking Mechanism by PNC] Date Submitted: [May 12, 2008] Source: Hyoungjin Kwon, Jinkyeong Kim, Seungeun Hong, Yongsun Kim, Kyeongpyo Kim, Wooyong Lee Company: [Electronics and Telecommunications Research Institute (ETRI)] Address: [ETRI, 161 Gajeong-dong, Yuseong-gu, Daejeon, 305-700, Republic of Korea] Voice: [], FAX: [], E-Mail: kwonjin@etri.re.kr , jkkim@etri.re.kr, iptvguru@etri.re.kr, doori@etri.re.kr, kpkim@etri.re.kr, wylee@etri.re.kr Re: [] Abstract: [In order to avoid blocking in line-of-sight, anti-blocking mechanism via PNC is introduced.] Purpose: [To be considered in IEEE 802.15.3c standard] Notice: This document has been prepared to assist the IEEE P802.15. 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 further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. ETRI Chuck Brabenac, Intel Labs

Contents Human Blocking Anti-blocking Mechanism by PNC Link Setup May, 2008 Contents Human Blocking Anti-blocking Mechanism by PNC Link Setup Normal Data Transmission via PNC Blocking Detection and Avoidance Recovery of Blocked Link Amplify and Forward Operation Conclusion ETRI

Human Blocking In general, a device uses single (direct) link. May, 2008 Human Blocking In general, a device uses single (direct) link. If there is a (human) blocking, the direct link is cut off. Slide 3 ETRI

Anti-blocking by PNC (1) May, 2008 Anti-blocking by PNC (1) To overcome the human blocking, there is a beam steering mechanism. However, it has a limitation. Once the steered signal is reflected, its power is degraded more than 20dBs. Motivated by this, an anti-blocking mechanism using relay link via PNC is introduced. DEVs exchange data directly or via the PNC. However, in case of passing through PNC, transmission time will be doubled compared to the transmission time via direct link, because the data packet received should be decoded and then forwarded to destination DEV. Slide 4 ETRI

Anti-blocking by PNC (2) May, 2008 Anti-blocking by PNC (2) Therefore, we introduce new functionality in order to avoid blocking as well as meet delay constraint. The new functionality of PNC is the capability to relay packets from source DEV to destination DEV. Assumption of PNC for anti-blocking mechanism Amplify and forward (AF) on RF level Have at least two RF chains for receiving signal and at the same time, sending it Switch the mode of two RF chains, (Rx->Tx and Tx->Rx) It is named Relay-PNC ETRI

Link setup A pair of devices sets up 2 relay links with a Relay-PNC. May, 2008 Link setup A pair of devices sets up 2 relay links with a Relay-PNC. If there is a Relay-PNC, a pair of devices request association to Relay-PNC. If the Relay-PNC grants access to its use, then do beam-forming sequentially with a pair of devices in CAP, if necessary. Do beam-forming inbetween a pair of devices in CTAP, if necessary. Relay-PNC Relay link Relay link Direct link [Configuration of a pair of devices and PNC] ETRI

Normal Data Transmission via PNC May, 2008 Normal Data Transmission via PNC Then a device can use a direct link and a relay link via PNC for data transmission. In this “example”, we assume data transmission uses two links alternatively for easy explanation of our proposed scheme. The source DEV transmits its data and receives acknowledgment in response to the data. Then, the a pair of devices switch their transmission path and exchange data again. Relay link Direct link ETRI

Blocking Detection and Avoidance May, 2008 Blocking Detection and Avoidance If there is no acknowledgement frame in response to data frame sent from chosen link, a source device considers the link blocked. Then, the device should use another link to avoid the blocking. The pair of devices move to detour link and exchange data via the detour link. Relay link Direct link ETRI

Recovery of the Blocked Link May, 2008 Recovery of the Blocked Link Sometimes later (or periodically), the device can check whether the blocked link is available or not because the human blocking may be temporary. If it is still impossible to exchange data through the direct link, the device use only the relay link for data transmission and repeat checking the availability of the direct link. Otherwise, the source device can send data via the recovered direct link. Relay link Direct link ETRI

AF operation of Relay-PNC May, 2008 AF operation of Relay-PNC During beacon period and CAP, the relay-PNC is operating as normal PNC. So, both antennas are being operated in the same Rx mode or Tx mode. In CTAP, the relay-PNC does amplify-and-forward. Thus, a source-sided antenna is being operated in Rx mode and the other one is in Tx mode first. Anti-blocking mechanism is based on ACK frame. Therefore, after relaying from source to destination, the antenna mode of relay-PNC should be switched in order to relay ACK frame from destination to source. ETRI

May, 2008 Conclusion Advantages of introduced anti-blocking mechanism based on ACK via PNC When the human blocking occurs, seamless communication can be achieved by detour link via PNC. Simple blocking avoidance mechanism Power efficient solution compared to beam steering technology ETRI