Shamim Ara Shawkat

IrBurst Modeling and Performance Evaluation for Large Data Block Exchange over High-Speed IrDA Links

IrBurst, recently proposed by IrDA, is a high speed information transmission protocol. In this paper, a mathematical model is developed which leads to derivation of the IrBurst throughput over the IrDA protocol stack. Based on this model, we compare the performance of IrBurst and existing OBEX protocol in order to investigate the suitability of IrBurst protocol for exchange of large data blocks over high-speed IrDA links. Furthermore, the model allows the evaluation of the impact of the link layer parameters, such as window size and frame length, and physical layer parameters, such as minimum turnaround time, on system through-put for high-speed IrDA links and in the presence of transmission errors. Consequently, an effective Automatic Repeat Request (ARQ) scheme is proposed at link layer to maximize the throughput efficiency for IrBurst protocol as well as for next generation high speed IrDA links. Simulation result indicates that employment of our proposed ARQ scheme results in significant improvement of IrBurst throughput efficiency at high bit error rates.

Performance evaluation of saturating class - C driver circuit for inductive wireless power transfer

This paper presents performance evaluation of saturating class - C driver circuit for inductive wireless power transfer. Exact link is designed following link optimization theory to select parameters of the objective circuit. By exploring specific parameters of drain to source voltage effect on overall circuit, single MOSFET is used in the proposed driver circuit design instead of two parallel MOSFETs used in conventional driver circuit. Simulation results show that the proposed driver circuit provides a significant improvement in the driver efficiency (90.34%) as well as in the overall efficiency compared to the existing driver circuit. Furthermore, from the performance comparison, it is observed that the transferred output power (14.94 mW) has also been improved considerably.

BMF-MAC: A Bidirectional Multi-flow MAC Protocol for Multihop Underwater Acoustic Sensor Networks

Due to the atypical characteristics of the physical media in underwater acoustic sensor networks (UW-ASN)--mostly because of long propagation delay, low bandwidth and high error rate--several challenges arise while designing the MAC protocol. In this paper, we propose a Bidirectional Multi-flow MAC protocol (BMF-MAC) for UW-ASN, to efficiently handle multi-hop multi-flow traffic load patterns such a way that multiple streams of data transmissions concurrently proceed while adapting with varying traffic condition. BMF-MAC supports constitution of multi-hop flows by considering all pending packets in routing layer buffer and all flow setups requests from neighbors when setting up a flow, contrary to other underwater MAC protocols. The proposed MAC introduces a data transmission technique using the bidirectional multi-flow packet method for sending multiple data packets of the same flow in the reverse direction and thus improve channel utilization. The protocol is aimed to schedule more data transmission over multiple multi-hop flows, thus permitting rapid distribution of data and reduction of latency. Results show that BMF-MAC protocol outperforms existing CMRT protocol in terms of network throughput and packet delivery latency.

A scheduling scheme for efficient wireless charging of sensor nodes in WBAN

This paper presents a scheduling algorithm for point to point wireless power transfer system (WPTS) to sensor nodes of wireless body area networks (WBAN). Since the sensors of wireless body area networks are continuously monitoring and sending data to remote central unit, power crisis for these sensor nodes degrades the data transfer of patient monitoring system. Although energy harvesting from ambient sources using electromagnetic induction enhances the longevity of sensor performance, continuous operation in the primary side decreases the overall efficiency. With such paradigm in sight, a framework is proposed for increasing the primary battery longevity and reducing the transmission loss, inductive power is transmitted from primary to secondary unit using medium access control (MAC) protocols for underlying the centralized scheduling opportunity in a collision free scheme for channel access of rare yet critical emergency situation. In a preliminary study, the proposed scheduling for charging sensor nodes in a wireless body area network (WBAN) is evaluated in a case consideration.

Priority Aware Interference Mitigation Techniques for Coexistence of Wireless Technologies in Smart Utility Networks

In recent years, Smart Grid (SG) is envisioned to be the next generation electric power system by replacing traditional power grid due to its advantage of using two way communications. To implement reliable SG wireless communication networks, IEEE introduced a new wireless standard (IEEE802.15.4g) for Smart Utility Networks (SUNs). However, SUN operates on 2.4 GHz unlicensed band which is overlapped with Wireless Local Area Networks (WLANs) that leads to coexistence in Smart Utility Networks. In this paper, the coexistence problem of SUN is addressed in terms of homogeneous and heterogeneous interferences. To mitigate the homogeneous interference, Contention Access Period (CAP) and Contention Free Period (CFP) of a super frame of IEEE 802.15.4g is used to access the channel using slotted CSMA/CA algorithm by modifying the Backoff Period (BP) and Clear Channel Assessment (CCA) period for different priority data. An analytical model is developed using Markov chain, through which we demonstrate the accuracy of the proposed model in terms of throughput, channel access delay, probability of successful transmission and collision for nodes with different priority data. Performance evaluation is further investigated by comparing the proposed scheme with the existing PA-MAC. A channel switching mechanism is explored to mitigate the heterogeneous interference by the prediction of Naive Bayes Classifier. Predicted result shows that proposed mechanism effectively mitigates the heterogeneous interference by choosing the non-overlapping and non-coexisting channel.

Application of current limiting inductance effect on class - E driver circuit for inductive wireless power transfer

This paper presents application of class - E driver circuit for inductive wireless power transfer. In this respect, an objective circuit is considered for a non-conductive housing telemetry unit consuming a minimum of 5 mA from a 5.5 V-regulated supply having maximum target distance is 70 mm. For this purpose, link optimization theory is used for designing exact link to select parameters of the objective circuit. In this prospect, a single 12V (drain to source) capacity MOSFET is used in the proposed driver circuit design. Results obtained from simulation shows that the proposed driver circuit provides a 5.5 V DC regulated supply to a distant load. In addition to that, acceptability of wireless power transfer is analysed from the view of performance parametric analysis.

LL-MCLMAC:A low latency multi channel MAC protocol for Wireless Sensor Networks

Schedule based MAC protocols have been proposed to meet the energy constraint of Wireless Sensor Neworks (WSNs). Although existing schedule based MAC protocols such as LMAC and MC-LMAC are energy efficient, they introduce significant end-to-end delivery latency as well as low network throughput. In this paper, a low latency multichannel LMAC protocol, LL-MCLMAC protocol, is presented for WSNs which proposes the solutions of end-to-end delivery latency as well as throughput by allowing a node to send its packet using a channel from multiple channels over two different timeslots in a frame. The effectiveness of the proposed approach is demonstrated through simulations in terms of performance parameters such as number of received packets, end-to-end delay, and energy consumption. Simulation results show that LL-MCLMAC achieves significant improvement in end-to-end delay and network throughput over existing LMAC and MC-LMAC protocols while ensuring an energy-efficient operation.