Sanjoy Paul – A Wireless Networking Expert
In the year 1995, computers used to be connected to the Internet over either low-speed dial-up modems (56 Kbps) or higher-speed (10 Mbps) Ethernet cables. There was no notion of connecting a computer over a wireless channel except using indoor wireless technologies that were precursors to 802.11. Outdoor wireless data connection was simply non-existent. There was an early attempt to send data over the outdoor cellular wireless network through a concept called Cellular Digital Packet Data (CDPD) that stole cycles from voice connections to send data packets opportunistically. These wireless channels comprised distinct characteristics from conventional wireline networks. The bandwidth was low, while error rates were high and packets were lost in bursts when there was a phenomenon called fading in the wireless channel. The existing data-link layer protocols designed for wireline networks did not work as they were not designed to cope with the distinct characteristics of the outdoor wireless channel. It created a growing need for new data link-layer protocols to accommodate the specific properties of the wireless channel efficiently so that a wireless terminal with better performance, lower power, and a smaller size could be designed.
Sanjoy Paul, along with his team, proposed such a protocol by envisioning a network architecture comprising a wired network as its backbone with base stations on it acting as access points for the mobile terminals. The team designed an asymmetric novel link-layer protocol for a digital cellular channel called AIRMAIL (Asymmetric Reliable Mobile Access In Link-layer). The asymmetry is needed in the design because the mobile terminals have limited power and smaller processing capability than the base stations. The asymmetric protocol design placed the bulk of the intelligence in the base station as opposed to placing it symmetrically, by making the mobile terminal combine several acknowledgments into a single acknowledgment to conserve power, and making the base stations send periodic status messages while making the acknowledgment from the mobile terminal event-driven. The asymmetry in the protocol design resulted in a one-third reduction of compiled code at the mobile terminal. The protocol also incorporated adaptive forward error correction techniques. The motivation for using a combination of forward error correction and link-layer retransmissions was to obtain better performance in terms of end-to-end throughput and latency by correcting errors in an unreliable wireless channel in addition to end-to-end correction rather than by correcting errors only by end-to-end retransmissions. Sanjoy and Team were one of the first teams in the industry to design such a unique data-link-layer protocol that could enable reliable transmission of data over an error-prone outdoor wireless channel. [i]
Born on January 22, 1962, Sanjoy Paul cemented himself as one of the early pioneers in the fold of technology. He revolutionized the practice and processes of industrial manufacturing, automobile, and aerospace industries through his innovations and passion to create efficient and improved technology. Eventually, he went on to accomplish his objectives, with the creation of the Digital Twin platform for Industry 4.0, and digital customer care initiatives leveraging the latest Artificial Intelligence (AI) algorithms in Natural Language Processing (NLP), Knowledge Graph, and Omni-channel communication. After earning a bachelor’s degree in electronics and electrical communications engineering (ECE) in 1985 from the Indian Institute of Technology, Kharagpur, a doctorate in electrical engineering in August 1992 from the University of Maryland at College Park, and a master of business administration (MBA) from the University of Pennsylvania’s Wharton Business School in 2005, Sanjoy has served as an Adjunct Professor in the Department of Computer Science at San Jose State University (2020), Global Digital Head of Manufacturing and Technology at Wipro, Ltd. (2016-2020), Managing Director at Accenture (2011-16), Associate Vice President & General Manager at Infosys (2007-11), Founder & CEO at RelevantAd Technologies (2005-07), Research Professor at Rutgers University (2005-07), Research Director at Bell Labs, Lucent Technologies (2001-05), Chief Technology Officer at Edgix (1999-2001), and a Distinguished Member of Technical Staff at AT&T Bell Labs (1992-99).
Currently, serving as the global managing director at Accenture, leading R&D in systems and platforms, and serving as a part-time teaching faculty in the Computer Science Department of Rice University, Sanjoy’s entrepreneurial zeal propelled him to establish and lead several successful companies, such as RelevantAd Technologies Inc., a contextual advertising company; DigiNotebooks, an EdTech company, and Almawiz Inc., a digital contact center and lead generation company. He is well-regarded for pioneering research and contributing significantly for over a decade and a half to the area of Wireless Networking, starting with designing protocols to enable reliable communication of content over cellular networks back in the early-mid nineties, to designing hybrid 802.11/3G networks, recommending improvements to TCP/IP protocol over 802.11 networks, designing a wireless edge router in CDMA2000 networks and cache-and-forward network architecture for mobile content delivery in 2008. He is also recognized for his contributions to the Internet of Things (IoT), Digital Twin, Artificial Intelligence/Machine Learning (AI/ML), Computer Networks, 5G and Wireless Networks, Multimedia Streaming, and Content Distribution.
During his time at Lucent Technologies Inc., Sanjoy did instrumental work in pushing the Internet Protocol (IP) stack closer to the base station, an architecture that has become part of the 3GPP standard today, and developed the Wireless Edge Router. At Lucent, Sanjoy along with Sampath Rangarajan and John Lin undertook, The Open Access Research Test-bed for Wireless Networks (ORBIT), which was a collaborative project funded by the National Science Foundation (NSF). The project comprised two components: an indoor lab test bed of a grid of wireless fidelity (WiFi) access points (APs) and a campus-wide field-trial outdoor network that attempted to create a hybrid network of wireless networks by combining third-generation (3G), fixed 802.11, and ad-hoc 802.11 networks.[ii]
The Open Access Research Test-bed for Wireless Networks (ORBIT) also assisted Sanjoy in quantifying the effects of interference in small office and home (SOHO) environments. Sanjoy realized that the increasing number of devices led to an increased data rate of unlicensed band wireless signals in SOHO scenarios ultimately leading to significant inter- and intra-radio interference problems. He realized that multiple competing standards near each other had the potential to cause significant performance degradation. This is where ORBIT allowed Sanjoy and his team to measure the effects of these interferences and diagnose the multi-radio interference in the unlicensed band. [iii]
Sanjoy also spearheaded a novel architectural design for the Internet called “A Cache-and-Forward Architecture for the Future Internet,” a research project with the collaboration of Rutgers University and the University of Massachusetts. This initiative led to a multi-million-dollar multi-university grant from NSF led by WINLAB, Rutgers University with subsequent evolution and funding from NSF for a novel Internet architecture spanning the wireless networks called “Mobility First.” This architecture could be executed on top of the Internet Protocol (IP), or as a fresh protocol for next-generation networks, based on the concept of routers with large storage, facilitating opportunistic delivery to mobile users that are frequently out of touch by caching in-network content. The CNF protocol proposed by Sanjoy and his team uses reliable hop-by-hop transfer of large data files between CNF routers instead of an end-to-end transport protocol like TCP. This innovative approach spearheaded by Sanjoy and his fellow researchers serves mobile users with intermittent connectivity, while also reducing self-interference problems which are common in multi-hop wireless scenarios. Another key feature of the proposed CNF protocol is the incorporation of address-based and content-based routing to support various content delivery modes and use the in-network storage to our advantage.[iv]
Sanjoy’s research domain also includes an extensive study into the TCP Dynamics in 802.11 Wireless Local Area Networks. Back in 2007, he debated that certain popular optimizations of TCP, namely, fast recovery, worsen the performance by causing deadlocks that terminate with timeouts in 802.11 wireless links with disabled MAC retries, as the data and ACK packets within a TCP session collide resulting in packet losses. His main contribution through this research was the visualization of TCP dynamics to capture MAC layer collisions between DATA and ACK packets of a TCP session, and the differences in the behavior of protocols in that situation. This case of poor TCP performance due to self-inflicted losses eventually led to decoupling error and flow control algorithms for transport over 802.11 wireless networks.[v]
Sanjoy also pioneered research on a wireless edge router, a network processor-based packet data serving node for a CDMA2000∗ network. As the year 2005 saw network processing units (NPU) becoming increasingly popular for building custom packet-processing gateways, Sanjoy and his team presented an NPU-based design and architecture for a packet data serving node (PDSN) in a CDMA2000∗ network. Their design involved a complete separation of the control plane, implemented in the core processor, and the data plane, executed using a multistage packet pipeline mapped onto the packet-processing engines. They also detailed resource allocation schemes for packet buffering and processing as well as a flexible communication method with the core processor. Alongside this, they also presented a prototype implementation of the PDSN on an NPU to show its superiority to commercial products using measurement experiments. [vi]
Finally, Sanjoy has worked closely with WINLAB, Rutgers University to contribute to the development of the ORBIT Lab which received the Schwarzkopf Prize for Technological Innovation.[vii] In his capacity as a pioneer in wireless communication and during his time at WINLAB, Sanjoy served as the editor for Requirements for Wireless GENI Management and Control, a document describing the requirements for defining, running, and controlling an experiment in wireless networks. Sanjoy’s seminal works in the context of ORBIT Lab were focused on the “slicing” of wireless networks which became a core part of 3GPP standards for all future wireless networks.
[i] http://www.ece.uci.edu/~ayanoglu/ayanoglu95airmail.pdf
[ii] https://onlinelibrary.wiley.com/doi/abs/10.1002/bltj.20092
[iii] https://ieeexplore.ieee.org/abstract/document/5779219
[iv] https://ieeexplore.ieee.org/abstract/document/4542289
[v] https://ieeexplore.ieee.org/abstract/document/4288988
[vi] https://ieeexplore.ieee.org/abstract/document/6770046
[vii] https://www.rutgers.edu/news/rutgers-wireless-networking-laboratory-awarded-alexander-schwarzkopf-prize-technological
