Johanna Nieminen

How low energy is bluetooth low energy? Comparative measurements with ZigBee/802.15.4

Ultra low power communication mechanisms are essential for future Internet of Things deployments. Bluetooth Low Energy (BLE) is one promising candidate for such deployments. We study the energy consumption of BLE by measuring real devices with a power monitor and derive models of the basic energy consumption behavior observed from the measurement results. We investigate also the overhead of Ipv6-based communication over BLE, which is relevant for future IoT scenarios. We contrast our results by performing similar measurements with ZigBee/802.15.4 devices. Our results show that when compared to ZigBee, BLE is indeed very energy efficient in terms of number of bytes transferred per Joule spent. In addition, IPv6 communication energy overhead remains reasonable. We also point out a few specific limitations with current stack implementations and explain that removing those limitations could improve energy utility significantly.

Networking solutions for connecting bluetooth low energy enabled machines to the internet of things

The next wave driving the expansion of the Internet will come from the Internet of Things. Bluetooth LE is a rapidly emerging ultra-low-power radio technology expected to be incorporated in billions of IoT devices in the next few years. Consequently, it is particularly important to specify Internet connectivity solutions for Bluetooth LE. In this article we present such solutions based on the ongoing standardization work in the IETF and Bluetooth Special Interest Group. We prove the feasibility of a complete IP-based protocol stack on constrained devices and illustrate its performance, highlighting key trade-offs. In addition, we discuss gateway operation covering global IPv6 connectivity and proxy-cache functionality.

Adding semantics to internet of things

The development of Internet of Things (IoT) applications can be facilitated by encoding the meaning of the data in the messages sent by IoT nodes, but the constrained resources of these nodes challenge the common Semantic Web solutions for doing this. In this article, we examine enabling technologies for adding semantics to the IoT. Especially, we analyze data formats, which enable IoT applications consume semantic IoT data in a straightforward and general fashion, and evaluate resource usage of different alternatives with a sensor system. Our experiment illustrates encoding and decoding of different data formats and shows how big a difference a data format can make in energy consumption. Copyright

Energy-adaptive scheduling and queue management in wireless LAN mesh networks

Energy efficiency is of critical importance in future wireless communication systems where networked low-power devices relying on batteries should be able to communicate transparently. We present a novel cross-layer energy-adaptive scheduling and queue management framework EAED (Energy Aware Early Detection) for minimizing energy consumption in WLAN mesh networks. EAED aims at saving energy by delaying and early dropping packets with respect to target delay and packet loss constraints. We argue that gracefully trading off energy against QoS is justified by future networking scenarios where high connectivity is more important than bandwidth. We show performance results of EAED with real-time traffic in realistic WLAN Mesh network simulation scenarios and discuss possible use-cases for EAED framework. We conclude that considerable energy savings can be obtained with our scheme under certain limitations and propose ideas for further improvement.

Performance Analysis of the IEEE 802.11s PSM

With the introduction of IEEE 802.11 power save mode (PSM), a lot of work has been done to enhance the energy saving ability of the wireless nodes. The ultimate goal of the research is to make the networking equipment carbon neutral and prolong the lifetime of the energy limited device for various applications; in some cases it is a trade-off between energy efficiency and delay. However, few studies have been made until now in the area of IEEE 802.11s based link specific power mode. The essence of this method is the ability of a node to maintain different power modes with its different peer nodes at the same time. A new peer service period (PSP) mechanism is also proposed in IEEE 802.11s amendment for transmitting to a receiver operating in PSM. In this paper the performance of the link specific power mode is studied for a single- and a multilink network in terms of energy, delay throughput, and sleep duration. It is found that at small load the energy saving could be as high as eighty percent when compared with the active mode operation. A stochastic model, based on discrete time discrete state Markov chain, is developed for one peer link operation to study the system behavior closely during PSM operation.

Performance Study of IEEE 802.11s PSM in FTP-TCP

With the introduction of IEEE 802.11 power save mode (PSM), a lot of work has been done to enhance the energy saving ability of the nodes. The ultimate goal of the research is to make the networking equipments carbon neutral and prolong the lifetime of the energy limited devices for various applications; in some cases it is a trade-off between energy efficiency and delay. However, few studies have been made until now in the area of IEEE 802.11s based link specific power save mode. The link specific power save mode is a totally new concept. The essence of this method is the ability of a node to maintain different power save modes with its peer nodes. In this paper, the performance of the link specific PSM for FTP-TCP traffic is studied from the energy efficiency point of view. The throughput, the percentage of energy saving and the flow level fairness are examined in this study. Our results indicate that for a suitable combination of link specific PSM, the network not only achieves the same throughput as the active mode operation offers but also saves a significant amount of energy. The study also suggests that there is a trade-off among throughput, percentage of energy saving and fairness.

Implementation and performance measurements of a delay-bounded HPD algorithm in an ALTQ-based router

In this paper we show the first working implementation of an adaptive, measurement-based scheduling algorithm called delay-bounded hybrid proportional delay (DBHPD) in a FreeBSD based ALTQ prototype router. We describe how we have implemented DBHPD and discuss what kind of difficulties were encountered in the implementation. We present measurement results of the DBHPD implementation with FTP, HTTP, Video Streaming and VoIP traffic in underload, overload and heavy overload conditions. We show that the algorithm operates well according to the theoretical model and preserves the desired delay-bound as well as the delay ratios between the classes. We also compare DBHPD to an existing Class-Based-Queueing (CBQ) algorithm that is widely used both in research and in the industry. We show that DBHPD is able to achieve at least as good link utilization as CBQ and in addition results in much better and predictable differentiation in terms of delays and more controlled packet losses.

Full length article: Performance of On-Off scheduling strategy in the presence of transmit beamforming

We consider a multi-antenna downlink transmission system with multiple users on a shared channel. Transmit beamforming is based on antenna selection and closed-loop (CL) diversity modes adopted from the Universal Mobile Telecommunications System (UMTS) with generalization to more than two antennas. The main contribution of the paper is to compare the performance gain of three physical layer scheduling algorithms: On-Off scheduling, Maximum signal-to-noise ratio (SNR), and Round Robin. The latter two represent respective upper and lower bounds for the scheduling gain while On-Off scheduling is a practical scheme requiring limited feedback. In particular, we concentrate on the joint effect of transmit beamforming together with scheduling. Furthermore, for scheduling we analyze the effect of feedback errors. We see that the use of transmit beamforming with an increased number of antennas reduces the gain from scheduling, but the combined gain remains substantial. We show that the On-Off strategy can reach the performance of the ideal Maximum SNR strategy if the feedback threshold is optimized. However, a low feedback bit error rate (BER) already causes degradation of the performance.

Implementation and Simulation of DBHPD and CBQ scheduling - A Comparative Study

In this paper we analyze the operation of two scheduling algorithms, class based queuing (CBQ) and delay bounded hybrid proportional delay (DBHPD). We compare results obtained from simulations and measurements in a reasonably equivalent setup and state that considerable differences can be observed in the results produced by these two methods. We also perform kernel profiling to investigate the resource overhead caused by these algorithms. Kernel profiling results support the observation that deviations between simulations and measurements are mainly caused by complex measurement and calculation procedures that generate extra delays in real implementations. As a conclusion we suggest criticism to be used when making judgements about algorithm performance based on simulation results.

Challenges in Packet Scheduling in 4G Wireless Networks

Network information theory states that novel methods, such as, cooperative communication and relaying can increase the overall network transport capacity. These methods are not utilized in current networking technologies. The 3G RAN will not scale up to meet the requirements set for telecommunication in the next decade. We need a novel fourth generation (4G) RAN design. This paper analyses challenges in wireless packet scheduling algorithms for 4G systems and proposes energy efficient scheduling and queue management solutions for the 4G wireless environment. Focus in our work is kept on a relay networking scenarios, which comprise of operator managed RAN including relays together with user controlled mobile routers