Paul Gardner-Stephen

The village telco project: a reliable and practical wireless mesh telephony infrastructure

VoIP (Voice over IP) over mesh networks could be a potential solution to the high cost of making phone calls in most parts of Africa. The Village Telco (VT) is an easy to use and scalable VoIP over meshed WLAN (Wireless Local Area Network) telephone infrastructure. It uses a mesh network of mesh potatoes to form a peer-to-peer network to relay telephone calls without landlines or cell phone towers. This paper discusses the Village Telco infrastructure, how it addresses the numerous difficulties associated with wireless mesh networks, and its efficient deployment for VoIP services in some communities around the globe. The paper also presents the architecture and functions of a mesh potato and a novel combined analog telephone adapter (ATA) and WiFi access point that routes calls. Lastly, the paper presents the results of preliminary tests that have been conducted on a mesh potato. The preliminary results indicate very good performance and user acceptance of the mesh potatoes. The results proved that the infrastructure is deployable in severe and under-resourced environments as a means to make cheap phone calls and render Internet and IP-based services. As a result, the VT project contributes to bridging the digital divide in developing areas.

The serval mesh: A platform for resilient communications in disaster & crisis

The challenges of many crisis communication needs can be summarised as: the need to allow civilians to safely communicate with one another, and with the outside world, without reliance on any domestic terrestrial infrastructure, or on the import of physical materials. Therefore, any solution should place high precedence on infrastructure-independent operation, and the re-use of existing hardware technology. Expanding on this concept, we present a prototype solution, the Serval Mesh, and briefly discuss the design decisions that were made, and summarise the trial and pilots conducted to date. Together, these show that the Serval Mesh is well placed to provide secure, resilient mobile communications services in a variety of situations, and in conjunction with the air-droppable UHF-packet-radio enabled Serval Mesh Extender concept, to provide such services over longer distances than is possible for Wi-Fi based mobile mesh networks. Thus we argue by example that it is possible to enable effective use of mobile phones during periods of infrastructure-deprivation.

Serval mesh software-WiFi multi model management

This paper describes the WiFi Multi-Modal Management component of the Serval Mesh Software. The Serval Mesh Software is a mobile telephony platform that can operate independent of fixed infrastructure, by using the WiFi capability of the device to automatically form a wireless mesh network that supports the carriage of voice calls, short messages and other modes of communication. Context and use cases for the Serval Mesh Software are included to provide the reader with some context. After describing the lack of inherent ad-hoc WiFi support on Android mobile telephones and the problems that result, this paper describes the WiFi Multi-Modal Management component incorporated into the Serval Mesh Software, that is used to maximize the mesh connectivity options available on any given model of telephone handset. The approach taken is to modularize the detection and control of the WiFi hardware on each model of handset so that support for new handsets can be added without recompiling the software or managing a single byzantine monolithic control script that contains the commands for all supported handset models. This modular approach is then leveraged to facilitate automated acquisition of WiFi ad-hoc mode on hitherto unsupported models of Android telephone handsets, removing the need for labor-intensive manual crafting of these scripts, and the bottleneck and infrastructure-dependence that this previously entailed. The paper concludes with preliminary results indicating the success of the improvements to the Serval Mesh Software project described in this paper, including anecdotal reports from third-party users of the software.

THE RATIONAL BEHIND THE SERVAL NETWORK LAYER FOR RESILIENT COMMUNICATIONS

The Internet Protocol is the dominant network protocol used in public networks today and has proven to be highly effective for wired networks and wireless networks alike, provided network address allocation can be coordinated. Mesh networks consisting of highly mobile devices present new challenges, especially when the assumption of coordination does not apply. One situation where coordination is not readily possible is ad-hoc networks in isolated areas and in disaster zones, both of which are characterized by deprivation of infrastructure. This study describes our realizations of several problems that IPv4 and IPv6 networking faces in such contexts and provides a brief description of an alternative network architecture for such situations, the Serval Network Layer and provides some of the reasoning behind the design decisions made. The Serval Network Layer is implemented as an open-source user-space network layer with strong intrinsic security characteristics and is able to be deployed without any centralized coordination.

DASH: localising dynamic programming for order of magnitude faster, accurate sequence alignment

In this paper we present our genomic and proteomic sequence alignment algorithm, DASH, which results in order of magnitude speed improvement when compared to NCBI-BLAST 2.2.6, with superior sensitivity. Dynamic programming (DP) is the predominant contributor to search time for algorithms such as BLAST and FastA/P. Improving the efficiency of DP provides an opportunity to increase sensitivity, or significantly reduce search times and help offset the effects of the continuing exponential growth in database sizes. Specifically, for nucleotide searching we have demonstrated an order of magnitude speed improvement with significantly improved sensitivity, or alternatively moderate speed up with further sensitivity gains, depending on the parameters selected. Smith-Waterman complete DP is used as the sensitivity benchmark. Similar speed and sensitivity results are presented for protein searching. Since our algorithm is highly parallel, we have developed dedicated hardware which we will present in a companion paper, and a distributed version of our software (DDASH), which we expect to provide linear speedup on a cluster.

A new hardware architecture for genomic and proteomic sequence alignment

We describe a novel hardware architecture for genomic and proteomic sequence alignment which achieves a speed-up of two to three orders of magnitude over Smith-Waterman dynamic programming (DP) in hardware. In our previous papers, we introduce several features of our search algorithm, DASH, which outperforms NCII-Blast (BLAST) by an order of magnitude in software, and has better sensitivity. Indeed, DASH has been shown to have excellent sensitivity compared to Smith-Waterman. It is designed around the principle of considering genomic and proteomic sequence alignments to typically consist of regions of high homology (the diagonals) interspersed with regions of low homology. In DASH, the optimal solution consists of such diagonals joined by regions of exact DP. This is affordable due to the small area of these interconnecting regions. Accordingly, we have designed a chip which finds the diagonals and performs the inter-region DP directly in hardware. On a Xilinx Vitex II, XC2V6000, FPGA, it performs over 10/sup 12/ base comparisons/second.

An experimental evaluation of delay-tolerant networking with serval

Serval is an open-source, delay-tolerant wireless ad-hoc networking system designed to allow communications anywhere and anytime, despite the total loss of supporting telecommunications infrastructures provided by mobile phone operators. In emergency situations, Serval can be used to establish a disaster-response communications network spontaneously formed by mobile phones and/or battery powered wireless routers. In this paper, we present an in-depth experimental evaluation of Serval for various network setups and usage patterns, including simulated long term use. The focus of our evaluation is on the delay-tolerant aspects of Serval, providing insights into the scenarios where Serval can be deployed with satisfactory quality and performance characteristics. Furthermore, since mobile phones have a limited battery capacity, we take a closer look at the battery drain resulting from using Serval over different communication links, such as WiFi and Bluetooth. Our purpose in providing these analyses is to understand the current capability of Serval and identify any areas where further improvement is required, and to provide a summary of current readiness of Serval in advance of planned pilots in the Pacific region.

A Biologically Inspired Method of SPAM Detection

Many traditional SPAM filters work by analyzing the content of each email message in turn against a set of rules that are used to measure the spaminess of the message. Unfortunately, because spammers have access to these rules, the content of SPAM messages continually changes to evade detection. This is similar to the difficulties the immune system faces in identifying and clearing the Human Immuno-Deficiency Virus (HIV). Intriguingly, some individuals are resistant to HIV. We explore the parallels between HIV and SPAM in order to deduce a method of identifying SPAM that transcends the polymorphic nature of the SPAM message body. This proposed method is based on the group behavior of SPAM messages, rather than on the content of a SPAM message. We are in the process of implementing a SPAM filter that uses the proposed method.

Survey and Systematization of Secure Device Pairing

Secure device pairing (SDP) schemes have been developed to facilitate secure communications among smart devices, both personal mobile devices and Internet of Things devices. Comparison and assessment of SDP schemes is troublesome, because each scheme makes different assumptions about out-of-band channels and adversary models, and are driven by their particular use-cases. A conceptual model that facilitates meaningful comparison among SDP schemes is missing. We provide such a model. In this paper, we survey and analyze a wide range of SDP schemes that are described in the literature, including a number that have been adopted as standards. A system model and consistent terminology for SDP schemes are built on the foundation of this survey, which are then used to classify existing SDP schemes into a taxonomy that, for the first time, enables their meaningful comparison and analysis. The existing SDP schemes are analyzed using this model, revealing common systemic security weaknesses among the surveyed SDP schemes that should become priority areas for future SDP research, such as improving the integration of privacy requirements into the design of SDP schemes. Our results allow SDP scheme designers to create schemes that are more easily comparable with one another, and to assist the prevention of persisting the weaknesses common to the current generation of SDP schemes.

The exploration of alternative phone charging strategies for disaster or emergency situations

The battery life of most mobile phones is insufficient to enable their effective use throughout a disaster or emergency situation, without requiring recharging. Therefore in this paper we survey and classify a number of strategies that can be used in either disaster response or for people living beyond the reach of ubiquitous reliable mains electricity supply. In doing so, we aim to make available the wisdom of those who have had to face the challenge of finding alternative mobile telephone charging solutions, so that other practitioners may benefit from this. We present a simple methodology and results for a sample of mobile telephone charging products and techniques to their allow meaningful comparison and assessment, and limit our sample of solutions to those readily purchasable, with the intention of making our findings realistic and directly actionable by disaster response practitioners.