William Mark Townsley

Bio: William Mark Townsley is an academic researcher from Cisco Systems, Inc.. The author has contributed to research in topics: Network packet & Node (networking). The author has an hindex of 21, co-authored 62 publications receiving 2469 citations.

A Study of LoRa: Long Range & Low Power Networks for the Internet of Things

Abstract: LoRa is a long-range, low-power, low-bitrate, wireless telecommunications system, promoted as an infrastructure solution for the Internet of Things: end-devices use LoRa across a single wireless hop to communicate to gateway(s), connected to the Internet and which act as transparent bridges and relay messages between these end-devices and a central network server. This paper provides an overview of LoRa and an in-depth analysis of its functional components. The physical and data link layer performance is evaluated by field tests and simulations. Based on the analysis and evaluations, some possible solutions for performance enhancements are proposed.

Layer Two Tunneling Protocol L2TP

Abstract: This document describes the Layer Two Tunneling Protocol (L2TP). STD 51, RFC 1661 specifies multi-protocol access via PPP [RFC1661]. L2TP facilitates the tunneling of PPP packets across an intervening network in a way that is as transparent as possible to both end-users and applications.

Deterministic session load-balancing and redundancy of access servers in a computer network

Abstract: In one embodiment, for each port of an access node in an access-based computer network, one access server of a plurality of access servers is configured as a preferred access server for that port. Upon receiving a session initiation message at a particular port, the access node forwards the session initiation message to one or more of the access servers based on the configured preferred access server for the particular port.

Method and apparatus for packet loss detection

Abstract: Conventional network packet traffic loss/drop monitoring mechanisms, such as that employed for pseudowire, IP flow and tunnel traffic monitoring, do not process or diagnose the aggregate counts from both endpoints of a particular pseudowire. A packet loss and detection mechanism periodically exchanges traffic packet counts to maintain an accurate diagnosis of the pseudowire health from either endpoint. Further, the raw packet counts are analyzed to identify misrouted and lost packets, as both should be considered to assess network health and congestion. The pseudowire statistics are maintained for each pseudowire emanating from a particular edge router, providing a complete view of pseudowire traffic affecting a particular edge router. Such statistics are beneficial for problem detection, diagnosis, and for verification of throughput criteria such as those expressed in Quality of Service (QOS) terms and/or SLAs (service level agreements).

Techniques for replacing point to point protocol with dynamic host configuration protocol

Abstract: Techniques for providing remote access to a service provider network include exchanging multiple Dynamic Host Configuration Protocol (DHCP) formatted messages instead of any Point to Point Protocol (PPP) message to provide all PPP functions for accessing a service provider network from a customer node. The service provider network is on provider premises and the customer node is on customer premises different from the provider premises. The DHCP format is used to exchange authentication messages, user profile data on Authentication, Authorization and Accounting (AAA) servers, or session keep-alive echo messages, alone or in some combination. When all are message types are combined, these techniques provide a remote access server (RAS) with the capability to perform all functions presently provided by PPP processes. In some combinations, these techniques allow a modified DHCP server to replace a legacy AAA server.

Low Power Wide Area Network Analysis: Can LoRa Scale?

Abstract: Low power wide area (LPWA) networks are making spectacular progress from design, standardization, to commercialization. At this time of fast-paced adoption, it is of utmost importance to analyze how well these technologies will scale as the number of devices connected to the Internet of Things inevitably grows. In this letter, we provide a stochastic geometry framework for modeling the performance of a single gateway LoRa network, a leading LPWA technology. Our analysis formulates the unique peculiarities of LoRa, including its chirp spread-spectrum modulation technique, regulatory limitations on radio duty cycle, and use of ALOHA protocol on top, all of which are not as common in today’s commercial cellular networks. We show that the coverage probability drops exponentially as the number of end-devices grows due to interfering signals using the same spreading sequence. We conclude that this fundamental limiting factor is perhaps more significant toward LoRa scalability than for instance spectrum restrictions. Our derivations for co-spreading factor interference found in LoRa networks enables rigorous scalability analysis of such networks.

Personal content server apparatus and methods

Abstract: Personal content server apparatus and associated methods that allow a user (e.g., cable or satellite network subscriber) to access content, such as a video program, from a location outside the subscriber's network. In one embodiment, a personal content server streams the content to the subscriber over a network connection from the local e.g., (subscription) network to a remote network upon authorization by a content manager process. Various access, business or operational rules are applied depending on the content and delivery mode; e.g., to live video broadcast, video-on-demand (VOD), or archived content from the subscriber's digital video recorder (DVR) or networked PVR. In another variant, reservation information (for example program or asset ID information) is cached at a headend or hub server, thereby obviating the subscriber (or the network) having to access the subscriber's premises device. In yet another variant, a “virtual” CPE experience is provided for the remote user.

Mobile networking through Mobile IP

Abstract: Mobile IP is a proposed standard protocol that builds on the Internet Protocol by making mobility transparent to applications and higher level protocols like TCP. Mobile IP (RFC 2002) is a standard proposed by a working group within the Internet Engineering Task Force; it allows the mobile node to use two IP addresses: a fixed home address and a care-of address that changes at each new point of attachment. The article presents the Mobile IP standard in moderate technical detail and points the reader toward a wealth of further information. Is also describes how Mobile IP will change with IP version 6, the product of a major effort within the IETF to engineer an eventual replacement for the current version of IP. Although IPv6 will support mobility to a greater degree than IPv4, it will still need Mobile IP to make mobility transparent to applications and higher level protocols such as TCP. There is a great deal of interest in mobile computing and apparently in Mobile IP as a way to provide for it. A quick Web search for items related to Mobile IP returned over 60,000 hits-impressive even given the notorious lack of selectivity for such procedures. Mobile IP forms the basis either directly or indirectly of many current research efforts and products. The Cellular Digital Packet Data (CDPD), for example, has created a widely deployed communications infrastructure based on a previous draft specification of the protocol. In addition, most major router vendors have developed implementations for Mobile IP.

A Survey of LoRaWAN for IoT: From Technology to Application

Abstract: LoRaWAN is one of the low power wide area network (LPWAN) technologies that have received significant attention by the research community in the recent years. It offers low-power, low-data rate communication over a wide range of covered area. In the past years, the number of publications regarding LoRa and LoRaWAN has grown tremendously. This paper provides an overview of research work that has been published from 2015 to September 2018 and that is accessible via Google Scholar and IEEE Explore databases. First, a detailed description of the technology is given, including existing security and reliability mechanisms. This literature overview is structured by categorizing papers according to the following topics: (i) physical layer aspects; (ii) network layer aspects; (iii) possible improvements; and (iv) extensions to the standard. Finally, a strengths, weaknesses, opportunities and threats (SWOT) analysis is presented along with the challenges that LoRa and LoRaWAN still face.