Annals of Telecommunications

An international journal publishing original peer-reviewed papers

Open Topics

Vol. 68, n° 9-10, September-October 2013
Content available on Springerlink

DEC-MAC: delay- and energy-aware cooperative medium access control protocol for wireless sensor networks

Mohammad Helal Uddin Ahmed1, Md. Abdur Razzaque2, and Choong Seon Hong1
1 Kyung Hee University, Suwon, South Korea
2 University of Dhaka, Bangladesh

Abstract This paper deals with two critical issues in wireless sensor networks: reducing the end-to-end packet delivery delay and increasing the network lifetime through the use of cooperative communications. Here, we propose a delay- and energy-aware cooperative medium access control (DEC-MAC) protocol, which trades off between the packet delivery delay and a node’s energy consumption while selecting a cooperative relay node. DEC-MAC attempts to balance the energy consumption of the sensor nodes by taking into account a node’s residual energy as part of the relay selection metric, thus increasing the network’s lifetime. The relay selection algorithm exploits the process of elimination and the complementary cumulative distribution function for determining the most optimal relay within the shortest time period. Our numerical analysis demonstrates that the DEC-MAC protocol is able to determine the optimal relay in no more than three mini slots. Our simulation results show that the DEC-MAC protocol improves the end-to-end packet delivery latency and the network lifetime significantly compared to the state-of-the-art protocols, LC-MAC and CoopMAC.

Keywords End-to-end packet delay – Network lifetime Cooperative communicationProcess of eliminationComplementary cumulative distribution function

Channel estimation in high date rate UWB system with unknown narrowband interference

S. M. Riazul Islam1, Sana Ullah2,  and Kyung-Sup Kwak3  
1 University of Dhaka, Bangladesh
2 Pervasive and Mobile Computing, King Suad University, Riyadh, Saudi Arabia
3 Inha University, Incheon, South Korea

Astract Interference degrades the performance of a correct data signal detection and decoding. This problem becomes rigorous when interferences are present during the period of channel estimation. This will wipe out the accuracy of channel estimation and will eventually result in a severe degradation in the performance of signal detection and decoding in the entire data packet/frame. In this article, we propose improved channel estimation techniques for multiband orthogonal frequency division multiplexing ultra-wideband system in narrowband interfering environment. In particular, we work towards preamble-based channel estimation techniques in the presence of unknown narrowband interference. The interference power on each subcarrier is considered as a nuisance parameter and is averaged out from the corresponding likelihood function. The later is then optimized in an iterative manner according to the quasi-Newton algorithm. Furthermore, we address highly accurate channel estimation in a time-variant channel due to sudden channel change and propose an iterative interpolation method and weighted channel estimation approach to reduce the effect of abrupt channel changes. Link level simulation results indicate that our proposed approaches outperform the conventional estimation methods.

Keywords Ultra-wideband (UWB) – Multiband – Channel estimation – ECMA-368 – Wireless personal area network (WPAN)

A polarization-amplitude-phase modulation scheme for improving the power amplifier energy efficiency

Dong Wei, Chunyan Feng, and Caili Guo
Beijing University of Posts and Telecommunications, China

Abstract To improve the power amplifier (PA) energy efficiency, a polarization–amplitude–phase modulation (PAPM) scheme in wireless communication is proposed. The proposed scheme introduces the signal’s polarization state (PS), amplitude, and phase as the information-bearing parameters. Thus, the data rate can be further enhanced on the basis of the traditional amplitude–phase modulation. Also, since the transmitted signal’s PS completely manipulated by orthogonally dual-polarized antennas is unaffected by PA, PAPM can let PA work in its nonlinear region to acquire high PA efficiency. To further optimize the PA energy efficiency based on PAPM, a constrained optimization problem regarding the output back-off value and the ratio between the data carried by the PS and the amplitude–phase is formulated, and the distribution of the optimum solutions is presented. The simulation results show that PAPM can improve the PA energy efficiency significantly.

Keywords Polarization–amplitude–phase modulation – Energy efficiency – Power amplifier nonlinearity – Polarization dependent loss

Proportional fair scheduling with superposition coding in a cellular cooperative relay system

Megumi Kaneko1 , Kazunori Hayashi1, Petar Popovski2, and Hideaki Sakai1  
1 Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan
2 Department of Electronic Systems, Aalborg University, Niels Jernes Vej 12, Aalborg, 9220, Denmark

Abstract Many works have tackled on the problem of throughput and fairness optimization in cellular cooperative relaying systems. Considering firstly a two-user relay broadcast channel, we design a scheme based on superposition coding (SC) which maximizes the achievable sum-rate under a proportional fairness constraint. Unlike most relaying schemes where users are allocated orthogonally, our scheme serves the two users simultaneously on the same time-frequency resource unit by superposing their messages into three SC layers. The optimal power allocation parameters of each SC layer are derived by analysis. Next, we consider the general multi-user case in a cellular relay system, for which we design resource allocation algorithms based on proportional fair scheduling exploiting the proposed SC-based scheme. Numerical results show that the proposed algorithms allowing simultaneous user allocation outperform conventional schedulers based on orthogonal user allocation, both in terms of throughput and proportional fairness. These results indicate promising new directions for the design of future radio resource allocation and scheduling algorithms.

Keywords Cellular relay system – Cooperative communication – Superposition coding – Proportional fair scheduling

Link failure and congestion-aware reliable data delivery mechanism for mobile ad hoc networks

Manowarul Islam1, Abdur Razzaque2, Mahfuzur Rahman Bosunia2, Atif Alamri3, and Mohammad Mehedi Hassan3  
1 Mawlana Bhashani Science and Technology University, Bangladesh
2 University of Dhaka, Dhaka, Bangladesh
3 King Saud University, Riyadh, Kingdom of Saudi Arabia

Abstract Link failures and packet drops due to congestion are two frequently occurring problems in mobile ad hoc networks, degrading the network performance significantly. In this paper, we propose a link failure and congestion-aware reliable data delivery (LCRDD) mechanism that jointly exploits local packet buffering and multilevel congestion detection and control approaches for increasing the data delivery performance. On the detection of link failure or congestive state, an LCRDD intermediate node buffers the incoming data packets at the transport layer queue and resumes transmission when the route is repaired locally. In addition, LCRDD’s multilevel congestion detection helps it to take the most appropriate action proactively. Thus, it offers increased reliability and throughput and decreased end-to-end packet delivery delay and routing overhead compared to state-of-the-art protocols, as shown in results of performance evaluations carried out in network simulator v-2.34.

Keywords Mobile ad hoc network – Reliable data delivery – Link failure handling – Congestion control – Packet buffering

Residual resources aware distributed admission control mechanism in mobile multi-hop network

Dapeng Wu, Puning Zhang, and Ruyan Wang
Chongqing University of Posts and Telecommunications, China

Abstract Without considering current residual resources of the medium, nodes in mobile ad hoc networks (MANETs) admit the data flow arbitrarily, and the quality of service (QoS) of the data flows deteriorates. To release the contending on the resources induced by the overloaded flows, the admission control mechanism can effectively keep the balance between injected data flows and network capacity, and it is viewed as the most important technology in MANET. A novel distributed residual resources aware admission control mechanism is proposed in this paper, where the residual resources and the service rate are studied thoroughly. Considering the medium utilization, frame retransmission and backoff procedure, the passive method is applied to predict the residual resources, and the binomial distribution is utilized to model the medium status; moreover, based on the cooperation between the source node and intermediate nodes, the path meeting the resource demand is probed across the network, and the flows are rejected while the residual resources cannot meet its demand. Results show that the network load can be constrained by our proposed admission control mechanism, and the QoS of the data flows can be guaranteed effectively.
Keywords Mobile ad hoc networkAdmission controlResidual resourceService rate

WCDMA uplink capacity of high-altitude platforms (HAPs) macrocells with incorporated HSUPA service

Bazil Taha Ahmed, and Enrique Rebollo García
Universidad Autonoma de Madrid, Spain

Abstract The multiservice (voice, data, and high-speed uplink packet access (HSUPA)) uplink capacity and the interference statistics of high-altitude platforms wideband code-division multiple access macrocell are studied. The free-space propagation loss model with a log-normal shadowing is used in the analysis. It is concluded that the voice and data service are significantly affected by HSUPA users and that the macrocell capacity decreases dramatically when one of these users gets connected to it in the case that they share the same frequency band. Also, it is concluded that the capacity decrement is highly sensitive to the location of the HSUPA users. When the HSUPA users did not share the same frequency band with the voice and traditional data users, macrocell capacity will be 3 HSUPA users with a processing gain of 8 or 5.3 HSUPA users with a processing gain of 16.

Keywords Uplink capacity – HAPs – Power control – WCDMA HSUPA

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