Please use this identifier to cite or link to this item: http://localhost/handle/Hannan/617977
 Title: Less Transmissions, More Throughput: Bringing Carpool to Public WLANs Authors: Wei Wang;Yingjie Chen;Qian Zhang;Kaishun Wu;Jin Zhang subject: media access control (MAC)|contention reduction|Frame aggregation|phase offset side channel|cross-layer Year: 2016 Publisher: IEEE Abstract: A typical scenario for public WLANs is large audience environment where Wi-Fi hotspots serve scores of mobile devices. The performance of those Wi-Fi hotspots is extremely poor in terms of low goodput and severe delay due to heavy contention and MAC inefficiency. After carefully investigating the traffic patterns in public WLANs, we propose Carpool, a practical design that facilitates transmission sharing among multiple receivers, to tackle this problem. The key idea is to reduce contention by feeding frames for multiple destinations into one transmission at physical layer (PHY). As such, each downlink transmission carries payloads for multiple receivers, which reduces contention overhead and enables in-time response to concurrent requests from multiple users. To achieve efficient and reliable transmission in Carpool, we propose i) a lightweight frame structure to support multiple receivers, and ii) a real-time channel estimation scheme to continuously calibrate channel estimation during the transmission of a Carpool frame. We have implemented the entire PHY of Carpool on the GNURadio/USRP platform and tested it in various indoor environments. Furthermore, our trace-driven MAC evaluation shows that Carpool achieves up to $3.2 \times$ goodput gain and reduces up to $75$ percent delay compared to the IEEE 802.11n MAC frame aggregation scheme. Description: URI: http://localhost/handle/Hannan/148445http://localhost/handle/Hannan/617977 ISSN: 1536-1233 volume: 15 issue: 5 Appears in Collections: 2016

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 Title: Less Transmissions, More Throughput: Bringing Carpool to Public WLANs Authors: Wei Wang;Yingjie Chen;Qian Zhang;Kaishun Wu;Jin Zhang subject: media access control (MAC)|contention reduction|Frame aggregation|phase offset side channel|cross-layer Year: 2016 Publisher: IEEE Abstract: A typical scenario for public WLANs is large audience environment where Wi-Fi hotspots serve scores of mobile devices. The performance of those Wi-Fi hotspots is extremely poor in terms of low goodput and severe delay due to heavy contention and MAC inefficiency. After carefully investigating the traffic patterns in public WLANs, we propose Carpool, a practical design that facilitates transmission sharing among multiple receivers, to tackle this problem. The key idea is to reduce contention by feeding frames for multiple destinations into one transmission at physical layer (PHY). As such, each downlink transmission carries payloads for multiple receivers, which reduces contention overhead and enables in-time response to concurrent requests from multiple users. To achieve efficient and reliable transmission in Carpool, we propose i) a lightweight frame structure to support multiple receivers, and ii) a real-time channel estimation scheme to continuously calibrate channel estimation during the transmission of a Carpool frame. We have implemented the entire PHY of Carpool on the GNURadio/USRP platform and tested it in various indoor environments. Furthermore, our trace-driven MAC evaluation shows that Carpool achieves up to $3.2 \times$ goodput gain and reduces up to $75$ percent delay compared to the IEEE 802.11n MAC frame aggregation scheme. Description: URI: http://localhost/handle/Hannan/148445http://localhost/handle/Hannan/617977 ISSN: 1536-1233 volume: 15 issue: 5 Appears in Collections: 2016
 Title: Less Transmissions, More Throughput: Bringing Carpool to Public WLANs Authors: Wei Wang;Yingjie Chen;Qian Zhang;Kaishun Wu;Jin Zhang subject: media access control (MAC)|contention reduction|Frame aggregation|phase offset side channel|cross-layer Year: 2016 Publisher: IEEE Abstract: A typical scenario for public WLANs is large audience environment where Wi-Fi hotspots serve scores of mobile devices. The performance of those Wi-Fi hotspots is extremely poor in terms of low goodput and severe delay due to heavy contention and MAC inefficiency. After carefully investigating the traffic patterns in public WLANs, we propose Carpool, a practical design that facilitates transmission sharing among multiple receivers, to tackle this problem. The key idea is to reduce contention by feeding frames for multiple destinations into one transmission at physical layer (PHY). As such, each downlink transmission carries payloads for multiple receivers, which reduces contention overhead and enables in-time response to concurrent requests from multiple users. To achieve efficient and reliable transmission in Carpool, we propose i) a lightweight frame structure to support multiple receivers, and ii) a real-time channel estimation scheme to continuously calibrate channel estimation during the transmission of a Carpool frame. We have implemented the entire PHY of Carpool on the GNURadio/USRP platform and tested it in various indoor environments. Furthermore, our trace-driven MAC evaluation shows that Carpool achieves up to $3.2 \times$ goodput gain and reduces up to $75$ percent delay compared to the IEEE 802.11n MAC frame aggregation scheme. Description: URI: http://localhost/handle/Hannan/148445http://localhost/handle/Hannan/617977 ISSN: 1536-1233 volume: 15 issue: 5 Appears in Collections: 2016