Cooperative and fair MAC protocols for cognitive radio ad-hoc networks

Wireless Networks - A secondary user (SU) in multichannel cognitive radio ad hoc network (CRAHN) has a limited transmission range, which may raise a hidden multichannel sensing problem. In...     

An efficient resource allocation to improve QoS of 5G slicing networks using general processor sharing‐based scheduling algorithm

Fifth generation (5G) slicing is an emerging technology for software‐defined networking/network function virtualization–enabled mobile networks. Improving the utilization and throughput to meet the quality of service (QoS) requirements of 5G slicing is very important for the operators of mobile networks. With growing data traffic from different applications of numerous smart mobile devices having several QoS requirements, we expect networks to face problems of congestion and overload that prevent the effective functioning of a radio access network (RAN). This paper proposes a more effective packet‐based scheduling scheme for data traffic by 5G slicing with two operation modes for improving the resource utilization of 5G cloud RAN and providing an efficient isolation of the 5G slices. These two operation modes are referred to as static sharing resource (SSR) scheme and dynamic sharing resources (DSR) scheme. The SSR scheme is a modified version of an existing method. The goal of this approach is to reallocate the shared available resources of 5G network fairly and maximize the utilization of bandwidth while protecting a 5G slice from overwhelming other 5G slices. Throughput and delays of the system model are also discussed to show its performance limits. On the basis of the simulation outcomes, we observed that the proposed DSR scheme outperforms the SSR scheme in terms of provided delay and throughput. In addition, the token bucket parameters together with the assigned capacity weight for each slice can be selected and configured based on the required QoS. Finally, a good estimate for the maximum delay bounds of the slices is provided by the derived theoretical delay bound.     

Highly sensitive alkane odour sensors based on functionalised gold nanoparticles

We deposit dense, ordered, thin films of Au–dodecanethiol core/shell nanoparticles by the Langmuir–Schäfer (LS) printing method, and find that their resistance at ambient temperature responds selectively and sensitively to alkane odours. Response is a rapid resistance increase due to swelling, and is strongest for alkane odours where the alkane chain is similar in length to the dodecane shell. For decane odours, we find a response to concentrations as low as 15 ppm, about 600 times below the lower explosive limit. Response is weaker, but still significant, to aromatic odours (e.g. Toluene, Xylene), while potential interferants such as polar and/or hydrogen-bonding odours (e.g. alcohols, ketones, water vapour) are somewhat rejected. Resistance is weakly dependent on temperature, and recovers rapidly and completely to its original value within the error margin of measurement.     

Analysis of resource splitting scheme with cognitive based admission control for femto-WiFi wireless networks

The coexistence of femtocell and WiFi networks in a heterogeneous spectrum environment with licensed and unlicensed bands will support multi-mode femtocell users (FUs) to simultaneously transmit on both licensed and unlicensed bands. The efficient integration of both femtocell and WiFi technologies is seen as crucial for supporting the offloading of femtocell traffic to WiFi networks. To successfully deploy these integrated technologies, the overall licensed and unlicensed spectrum usage must be efficiently managed. Thus, we propose a new cognitive-based connection-level admission control with access retrial for a femtocell network that operates under a mixed spectrum of unlicensed and licensed bands. By deploying cognitive radio concepts, the FUs will utilize the unused spectrum of the existing unlicensed spectrum of the WiFi network in an opportunistic manner in addition to using the licensed spectrum. By using the retrial phenomenon policy, the blocked FUs can retry the access, which can reduce their loss probability. An analytical model using a three-dimensional continuous time Markov chain with a level-dependent quasi birth-and-death structure was developed to evaluate and study the performance of the proposed scheme. The matrix analytic method was used to obtain the steady state probability and performance measures. The result shows that the performance of FUs for integrated femtocell-WiFi networks using the proposed scheme significantly improved in terms of FUs throughput and loss probability. The results also show that the retrial phenomenon of FUs enhances their performance.     

Cache Memory Design for Single Bit Architecture with Different SenseAmplifiers

Most modern microprocessors have one or two levels of on-chip caches to make things run faster, but this is not always the case. Most of the time, these caches are made of static random access memory cells. They take up a lot of space on the chip and use a lot of electricity. A lot of the time, low power is more important than several aspects. This is true for phones and tablets. Cache memory design for single bit architecture consists of six transistors static random access memory cell, a circuit of write driver, and sense amplifiers (such as voltage differential sense amplifier, current differential sense amplifier, charge transfer differential sense amplifier, voltage latch sense amplifier, and current latch sense amplifier, all of which are compared on different resistance values in terms of a number of transistors, delay in sensing and consumption of power. The conclusion arises that single bit six transistor static random access memory cell voltage differential sense amplifier architecture consumes 11.34 μW of power which shows that power is reduced up to 83%, 77.75% reduction in the case of the current differential sense amplifier, 39.62% in case of charge transfer differential sense amplifier and 50% in case of voltage latch sense amplifier when compared to existing latch sense amplifier architecture. Furthermore, power reduction techniques are applied over different blocks of cache memory architecture to optimize energy. The single-bit six transistors static random access memory cell with forced tack technique and voltage differential sense amplifier with dual sleep technique consumes 8.078 μW of power, i.e., reduce 28% more power that makes single bit six transistor static random access memory cell with forced tack technique and voltage differential sense amplifier with dual sleep technique more energy efficient.     

Analysis of an Adaptive Priority Based Resource Allocation Control for LTE-Advanced Communications with Type I Relay Nodes

Relaying is emerging as one of the key radio access techniques for LTE-Advanced (LTE-A) networks to fulfill the LTE-Advanced coverage and capacity requirements in a cost-efficient way. Relaying enables improved high data rate coverage for indoor environments or at the cell edge by deploying a low power base station. Type I in-band relaying supports a relaying mode where the backhaul link transmission is time-division multiplexed with the access link reception, whereas macro users share the same resources with the relays. Therefore, in LTE-A networks deployed with type I relay nodes, resource partitioning is required to support in-band relaying. Consequently, it is very important to know how to partition system resources to attain improved fairness and efficiency. The main contribution of this paper is to design and analyze a novel admission control with an adaptive resource partitioning (AC-ARP) scheme to facilitate the operation of fixed relay stations in the OFDMA-based relay enhanced LTE-Advanced networks in a more efficient way. Its analytical model using multi-dimensional continuous time Markov chains is derived and explained. In addition, its performance comparisons with conventional admission control with a fixed resource partitioning (AC-FRP) scheme is presented and discussed. We present numerical examples to demonstrate the performance of the proposed AC-ARP scheme, and we show that analytical and simulation results are in complete agreement. The results also indicate the superiority of AC-ARP because it is able to achieve a better balance between system utilization and QoS provisioning compared to the AC-FRP scheme.     

A route stability-based multipath QoS routing protocol in cognitive radio ad hoc networks

Wireless Networks - Secondary user (SU) mobility, primary user activity, and spectrum sensing inaccuracy are the main challenges to the stability of a quality of service (QoS) route in cognitive...     

Barriers of managing cloud outsource software development projects: a multivocal study

Multimedia Tools and Applications - Management of COSD projects is a challenging task due to number of distant development locations in different time zones, client and vendor organizations,...     

Supporting QoS requirements provisions on 5G network slices using an efficient priority-based polling technique

Wireless Networks - Mobile operators aim to enhance the Quality of Service (QoS) in each new mobile network generation. The upcoming 5G mobile network is expected to make a revolutionary...