Talk More Listen Less: Energy-Efficient Neighbor Discovery in Wireless Sensor Networks

Neighbor discovery is a fundamental service for initialization and managing network dynamics in wireless sensor networks and mobile sensing applications. In this paper, we present a novel design principle named Talk More Listen Less (TMLL) to reduce idle-listening in neighbor discovery protocols by learning the fact that more beacons lead to fewer wakeups. We propose an extended neighbor discovery model for analyzing wakeup schedules in which beacons are not necessarily placed in the wakeup slots. Furthermore, we are the first to consider channel occupancy rate in discovery protocols by introducing a new metric to trade off among duty-cycle, latency and channel occupancy rate. Guided by the TMLL principle, we have designed Nihao, a family of energy-efficient asynchronous neighbor discovery protocols for symmetric and asymmetric cases. We compared Nihao with existing state of the art protocols via analysis and real-world testbed experiments. The result shows that Nihao significantly outperforms the others both in theory and practice.Comment: 9 pages, 14 figures, published in IEEE INFOCOM 201

Low Power, Low Delay: Opportunistic Routing meets Duty Cycling

Traditionally, routing in wireless sensor networks consists of two steps: First, the routing protocol selects a next hop, and, second, the MAC protocol waits for the intended destination to wake up and receive the data. This design makes it difficult to adapt to link dynamics and introduces delays while waiting for the next hop to wake up. In this paper we introduce ORW, a practical opportunistic routing scheme for wireless sensor networks. In a dutycycled setting, packets are addressed to sets of potential receivers and forwarded by the neighbor that wakes up first and successfully receives the packet. This reduces delay and energy consumption by utilizing all neighbors as potential forwarders. Furthermore, this increases resilience to wireless link dynamics by exploiting spatial diversity. Our results show that ORW reduces radio duty-cycles on average by 50% (up to 90% on individual nodes) and delays by 30% to 90% when compared to the state of the art

Let the Tree Bloom: Scalable Opportunistic Routing with ORPL

Routing in battery-operated wireless networks is challenging, posing a tradeoff between energy and latency. Previous work has shown that opportunistic routing can achieve low-latency data collection in duty-cycled networks. However, applications are now considered where nodes are not only periodic data sources, but rather addressable end points generating traffic with arbitrary patterns. We present ORPL, an opportunistic routing protocol that supports any-to-any, on-demand traffic. ORPL builds upon RPL, the standard protocol for low-power IPv6 networks. By combining RPL's tree-like topology with opportunistic routing, ORPL forwards data to any destination based on the mere knowledge of the nodes' sub-tree. We use bitmaps and Bloom filters to represent and propagate this information in a space-efficient way, making ORPL scale to large networks of addressable nodes. Our results in a 135-node testbed show that ORPL outperforms a number of state-of-the-art solutions including RPL and CTP, conciliating a sub-second latency and a sub-percent duty cycle. ORPL also increases robustness and scalability, addressing the whole network reliably through a 64-byte Bloom filter, where RPL needs kilobytes of routing tables for the same task

RTXP : A Localized Real-Time Mac-Routing Protocol for Wireless Sensor Networks

Protocols developed during the last years for Wireless Sensor Networks (WSNs) are mainly focused on energy efficiency and autonomous mechanisms (e.g. self-organization, self-configuration, etc). Nevertheless, with new WSN applications, appear new QoS requirements such as time constraints. Real-time applications require the packets to be delivered before a known time bound which depends on the application requirements. We particularly focus on applications which consist in alarms sent to the sink node. We propose Real-Time X-layer Protocol (RTXP), a real-time communication protocol. To the best of our knowledge, RTXP is the first MAC and routing real-time communication protocol that is not centralized, but instead relies only on local information. The solution is cross-layer (X-layer) because it allows to control the delays due to MAC and Routing layers interactions. RTXP uses a suited hop-count-based Virtual Coordinate System which allows deterministic medium access and forwarder selection. In this paper we describe the protocol mechanisms. We give theoretical bound on the end-to-end delay and the capacity of the protocol. Intensive simulation results confirm the theoretical predictions and allow to compare with a real-time centralized solution. RTXP is also simulated under harsh radio channel, in this case the radio link introduces probabilistic behavior. Nevertheless, we show that RTXP it performs better than a non-deterministic solution. It thus advocates for the usefulness of designing real-time (deterministic) protocols even for highly unreliable networks such as WSNs

Community-based asynchronous wakeup protocol for wireless peer-to-peer file sharing networks

Ubiquitous Peer-to-Peer (P2P) networking is widely expected to be manifested in a wireless environment in the near future. However, to realize such an interesting mobile computing platform, energy efficiency is one of the most critical resources management issues yet to be tackled. Unfortunately, energy efficient wireless P2P networking is still a relatively less explored topic as it is quite challenging to tackle the energy management problem without centralized control. In this paper, we meet this research challenge by proposing a new distributed protocol, called Community-Based Asynchronous Wakeup Protocol, CAWP, for energy conservation in wireless P2P file sharing networks. Simulation results show that our proposed CAWP is found to be highly effective in that it can remarkably increase the energy efficiency of the participants in a wireless P2P system. © 2005 IEEE.published_or_final_versio

Minimizing the Energy Consumption in Wireless Sensor Networks

تمثل الطاقة في شبكات الاستشعار اللاسلكية عاملاً اساسياً في تصميم ومراقبة وتشغيل هذه الشبكات. تعد عملية التقليل من الطاقة المستهلكة في شبكات الاستشعار اللاسلكية وتطبيقاتها مسألة حيوية بالنسبة لفعالية وكفاءة الشبكة من حيث العمر والتكلفة والتشغيل. تم اقتراح وتنفيذ العديد من الخوارزميات والبروتوكولات لتقليل استهلاك الطاقة.  شبكات الاستشعار اللاسلكية تعتمد على اجهزة الاستشعارتعمل ببطارية. بطاريات اجهزة الاستشعار لايمكن اعادة شحنها بسهولة على الرغم من طاقتها محدودة. كثيراً مايحدث الفشل في الشبكة نتيجة عدم كفاية طاقة اجهزة الاستشعار. حققت بروتوكولات مراقبة الدخول المتوسط (MAC) في شبكات الاستشعار اللاسلكية انخفاض في دورة اشتغاله من خلال توظيف مبدا النوم (السكون) والاستيقاض الدوري. حقق بروتوكول مراقبة الدخول المتوسط ذات الاستيقاظ التنبؤئ استفادة من مبدأ دورة الاشتغال غير المتزامن.    يقلل هذا البروتوكول من استهلاك العقدة للطاقة من خلال السماح للمرسلين بالتنبؤ باوقات استيقاظ المستقبلين.  يجب تطبيق شبكة الاستشعار اللاسكلية بطريقة فعالة لتوظيف عقد الاستشعار وطاقتها لضمان انتاجية شبكة كفوءة. ان التنبؤ بعمر شبكة الاستشعار اللاسلكية قبل بناءها يمثل اهتماما كبيرا . لضمان توفر طاقة كفؤءة يجب ضبط دورات تشغيل المستشعرات بدقة مناسبة لتحقيق متطلبات ازدحام الشبكة. كما تم تقدير كمية الطاقة المستهلكة في كل عقدة نتيجة التحول بين حالة النشاط وحالة الخمول. تم افتراض نشر أجهزة الاستشعار بطريقة عشوائية. تهدف هذه الدراسة الى تحسين عمر الشبكة المنشورة عشوائيا العشوائي من خلال جدولة تاثير الارسال والاستقبال وحالات السكون على عمليات استهلاك الطاقة في عقد الاستشعار اللاسلكي. تم دراسة ومناقشة نتائج هذه الحالات باستخدام العديد من مقايسس الاداء.Energy in Wireless Sensor networks (WSNs) represents an essential factor in designing, controlling and operating the sensor networks. Minimizing the consumed energy in WSNs application is a crucial issue for the network effectiveness and efficiency in terms of lifetime, cost and operation. Number of algorithms and protocols were proposed and implemented to decrease the energy consumption. Principally, WSNs operate with battery-powered sensors. Since Sensor's batteries have not been easily recharge.  Therefore, prediction of the WSN represents a significant concern. Basically, the network failure occurs due to the inefficient sensor's energy. MAC protocols in WSNs achieved low duty-cycle by employing periodic sleep and wakeup. Predictive Wakeup MAC (PW-MAC) protocol was made use of the asynchronous duty cycling. It reduces the consumption of the node energy by allowing the senders to predict the receiver′s wakeup time. The WSN must be applied in an efficient manner to utilize the sensor nodes and their energy to ensure effective network throughput. To ensure energy efficiency the sensors' duty cycles must be adjusted appropriately to meet the network traffic demands. The energy consumed in each node due to its switching between the active and idle states was also estimated. The sensors are assumed to be randomly deployed. This paper aims to improve the randomly deployed network lifetime by scheduling the effects of transmission, reception and sleep states on the energy consumption of the sensor nodes. Results for these states with much performance metrics were also studied and discussed.  &nbsp

On the Medium Access Control Protocols Suitable for Wireless Sensor Networks – A Survey

A MAC (Medium Access Control) protocol has direct impact on the energy efficiency and traffic characteristics of any Wireless Sensor Network (WSN). Due to the inherent differences in WSN’s requirements and application scenarios, different kinds of MAC protocols have so far been designed especially targeted to WSNs, though the primary mode of communications is wireless like any other wireless network. This is the subject topic of this survey work to analyze various aspects of the MAC protocols proposed for WSNs. To avoid collision and ensure reliability, before any data transmission between neighboring nodes in MAC layer, sensor nodes may need sampling channel and synchronizing. Based on these needs, we categorize the major MAC protocols into three classes, analyze each protocol’s relative advantages and disadvantages, and finally present a comparative summary which could give a snapshot of the state-of-the-art to guide other researchers find appropriate areas to work on. In spite of various existing survey works, we have tried to cover all necessary aspects with the latest advancements considering the major works in this area