Laihyuk Park
  Woongsoo Na
  Hyoungchel Bae
  In this research, core technologies supporting 3Gbps WLAN will be studied in order to accommodate uncompressed HDTV video and very high throughput applications. For very high throughput, we will develop a contention based directional MAC protocol using circular RTS/CTS in 60GHz bands in order to fully utilize merit of the spatial reuse and to tackle the problems of deafness and hidden node.
Examples of applications supporting more than Gbps data rate

  Standardization organizations such as IEEE802.11ad and IEEE802.15.3c recommend 60GHz spectrum for very high throughput communication. Although IEEE802.15.3c exploiting reservation based directional antenna is currently being standardized, there are still lots of technical challenges to be improved, e.g., contention based directional MAC is not incorporated in the standard. In this work, we will develop a contention based directional MAC protocol using circular RTS/CTS in order to tackle the problems of deafness and hidden node. The proposed protocol will maximize the spatial reuse and thus improve overall throughput even under node mobility and infrastructureless deployment.
Example of the deafness problem

  In order to achieve very high throughput communication, the following core functions need to be developed for contention based directional MAC:
  (1) Minimizing Circular RTS/CTS Overhead: CRTS/CCTS mechanism has a significant number of transmissions for RTS/CTS. In this work, we will minimize the unnecessary overhead.
  (2) Efficient DNAV(Directional NAV) Computation: We will synchronize the DNAV time among neighboring nodes to avoid deafness problem.
  (3) RTS/CTS Retransmission Scheme to resolve Deafness Problem: Nodes suffering from deafness will keep sending RTS to designated receiver resulting in unnecessary power consumption. We will rectify this problem using DNAV value for each beam.
  (4) Intelligent Communication Range Control for Spatial Reuse: Using distance computation from sender to receiver, we will minimize hidden node and deafness problems.
  (5) Reliable Multicasting: By using reliable and energy-efficient multicasting algorithm, we will minimize the number of ACKs and ACK transmission time.
  (6) Directional MAC Simulator based on NS-2: we will evaluate the performance of the proposed directional MAC using NS-2 simulator and optimize any performance parameters.
60GHz대역 무선 근거리 통신을 위한 경쟁 기반 지향성 MAC 프로토콜 개발 (Contention based Directional MAC Protocol for 60GHz Wireless LAN), NRF, 2010.09~2013.08 [Progress Report]
초고속 근거리 무선 네트워크에서의 협력통신 연구 (Cooperative Communication for High Speed Local Area Network), ETRI, 2009.05~2009.11 [Progress Report] [Final Report]
L. Park, C.-G. Lee, and S. Cho, " SPARM: Spatially Pipelined ACK Aggregation for Reliable Multicast in Directional MAC," to appear in IEEE Communications Letters, vol. xx, no. xx, pp. xxx-xxx, xxxxx 201x. [PDF]
L. Park, J. Yu, C.-G. Lee, and S. Cho, " BTRB: Beam Table-based Reliable Broadcast for Directional Antennas," IEICE Transactions on Communications, vol. E95-B, no. 10, pp. 3307-3311 October 2012. [PDF]

W. Lee, S. Hong, Y. Kim, H. Chung, S. Cho, L. Park, and H. Lim, "Contention-based Directional MAC Protocols: A Survey," IEEE P802.11 TGad standardization, July 2009. (Doc#: IEEE 802. 11-09-0796-00-00ad)
W.Lee, S.Hong, Y. Kim, H. Chung, S. Cho, L. Park, and H. Lim, "Topology Considerations on Contention-based Directional MAC Simulation," IEEE P802.11 TGad standardization, July 2009. (Doc#: IEEE 802. 11-09-0797-02-00ad)
W. Na, L. Park, and S. Cho "Deafness-aware MAC Protocol for Directional Antennas," in Proc. of IEEE ICCE, Las Vegas, USA, January 2013. [PDF]
W. Na, L. Park, G. Lee, and S. Cho, "Performance Analysis of Circular Directional MAC Protocol," in Proc. of ICUFN, Jeju, Korea, June 2010. [PDF]
나웅수, 조성래, "지향성 안테나 기반 경쟁 MAC 프로토콜의 성능 분석(Performance Analysis of Contention based Directional MAC Protocol)," 한국통신학회논문지, 제36권, 제7호, July 2011. [PDF]