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This research presents the diversity combining schemes for Multiple Symbol Double Differential Sphere Detection (MSDDSD) in a time-varying amplify-and-forward wireless cooperative communication network. Four diversity combiners, including direct combiner, Maximal Ratio Combiner (MRC), semi MRC and Selection Combiner (SC) are demonstrated and explained in details. A comprehensive error probability and outage probability performance analysis are carried through the flat fading Rayleigh environment for semi MRC and SC. Specifically, error performance analysis is obtained using the PDF for SC detectors. Finally, power allocation expression based on error performance minimization approach is presented for the proposed SC performance optimization. It is observed that the performance analysis matches well with the simulation results. Furthermore, the proposed SC scheme offers better performance among the conventional MRC and direct combiner schemes in the presence of frequency offsets.

This paper presents the design and development of low-cost Internet of Things (IoT) system for remote monitoring of agriculture ecosystem. The aims of the research are to evaluate the accuracy and reliability of data collected and transmitted with developed IoT system and access from remote location. These data are then compared with the readings of the conventional stand-alone sensors or meters. The system is set in the laboratory and utilises low cost microcontroller, sensors, Wi-Fi network communication, cloud storage, mobile and web application. Microcontroller Arduino Uno ATMega328P is used with ESP8266 Wi-Fi module to enable the device to be connected to the Internet. The sensors used in this system are selected base on the plant’s growth factor. All data collected from the sensors are sent to the Cloud platform such as ThingSpeak and Blynk. Periodical monitoring is carried out on laptop and mobile phone. The results showed that the data taken from the soil moisture, soil temperature, light intensity, surrounding temperature and humidity are accurate and reliable.

Providing quality of service (QoS) for converging traffic in wireless local area network (WLAN) is still a major issue for the researchers and industries. Due to the limited bandwidth and exposure to unpredictable interferences in a wireless environment, efficient management and optimization of the access protocols are essential to provide acceptable QoS for real-time traffic and fairness to best-effort traffic. In this paper, we investigate the throughput and delay performance of the legacy IEEE 802.11 and the 802.11e when carrying converging data in WLAN. We evaluate our recently proposed protocol known as wireless token network protocol (WTN) and show that WTN successfully increases performance of converging traffic in WLAN by, first, decreasing the size of the frames and subframes of the MAC header, and second, by implementing centralized polling to reduce collisions of packets.

In this paper, we design an admission control scheme for ad hoc WLAN based on self-restraint mechanism. The self-restraint admission control mechanism is implemented in each of the wireless nodes instead of the access point (AP). It has two important admission control abilities: first, it can restrain itself from joining the network if the network channel is congested; second, a joining node can drop itself from the network if the channel becomes congested as a result of its admission. We simulate an ad hoc WLAN and show that the self-restraining mechanism works effectively in sustaining traffic in ad hoc WLAN and also protects real-time traffic.

In this paper we propose an optimized WLAN MAC protocol for multimedia applications. The proposed MAC protocol consist of 3 main optimizing architectures, traffic segregation, specific service interval (SI) for voice and video traffic and smaller contention window (CW). Traffic segregation segregates real-time traffic from best-effort traffic while specific service interval provides voice and video traffic with the SI based on its mean arrival rate. In the contention time frame, the CW is made smaller to reduce delay and increase throughput. Ns2 is used as a simulating tool to compare the results of our proposed protocol with the legacy 802.11 and the 802.11e protocols. We show that our protocol has significantly better throughput than the legacy 802.11 and the 802.11e. Fluctuations in the throughput is also shown to be lower in our proposed protocol. The technique implemented also provides easier and better management of realtime traffic to support guaranteed quality of service (QoS).

Admission control is an important mechanism for sustaining throughput and supporting quality of service (QoS) for real-time traffic in a wireless local area network (WLAN). In an adhoc WLAN scenario where no access point (AP) is available, admission control has to be self-managed by each node. We propose a self-restraining admission control mechanism that works by monitoring the congestion level of the network in the adhoc WLAN. Wireless nodes can listen to all nodes within their range and be aware of the collision rates. A node wishing to join the network measures the current collision rate, and predicts the post-admission collision rate, on the basis of which the self-restraining mechanism in the node decides if it can join the network. We analyse the impact of key parameters, such as the collision threshold level, on the performance of the self-restraining mechanism and show that this mechanism works effectively in sustaining traffic in an adhoc WLAN.

Providing quality of service (QoS) for multimedia applications in wireless local area networks (WLAN) is a very challenging task. This is mainly due to the real-time nature of multimedia traffic such as voice and video applications, that are sensitive to delay and jitter. QoS guarantees for real-time traffic must be imposed in WLAN so as to enable WLAN users to fully benefit from multimedia applications. The current medium access control (MAC) protocol that is widely used is the legacy IEEE 802.11, but this protocol does not support QoS for realtime traffic. To enhance the legacy 802.11, the IEEE 802.11e protocol was introduced to support QoS through prioritization of traffic. The 802.11e introduces a new co-ordination function known as hybrid coordination function (HCF). In this paper we study the performance of multimedia traffic in the legacy 802.11 and 802.11e and propose a technique to improve realtime traffic in multimedia applications by traffic segregation. We show that segregation of multimedia traffic improves delay and jitter performance of real-time traffic.

Since the introduction of 802.11 MAC protocol standards for wireless local area network (WLAN) in 1999 by the IEEE task force group, WLAN has experienced tremendous growth. This can be observed by the increasing number of “hotspots” in public places such as airports, train stations, shopping complexes and private organisation such as universities and hospitals, and also at many homes where the use of wireless routers is very common. As more users embrace WLAN technology, the demand for more advanced services such as multimedia is increasing. Unfortunately, the current technology is still not able to provide adequate QoS support as demanded by these services. There are three versions of 802.11 MAC protocol available in the market today: 802.11a, 802.11b and 802.11g; but none of these can adequately support QoS for real-time traffic. Some enhanced protocols that have been proposed are 802.11e and 802.11n. The former enhances QoS support to a certain degree, although it still faces many weaknesses such as suppression of the best-effort (BE) service and packet collisions, while the latter is expected to increase the throughput by increasing physical channel rate to up to 600 Mbit/s. In addition, 802.11n adopts the MAC protocol used in 802.11b and 802.11g, which is exposed to packets collision and delay due to contention backoff. The aim of this research is to design WLAN MAC protocol to support QoS for real-time traffic in multimedia applications. Three novel designs are developed in this research. The first is the Segregation Hybrid Coordination Function (SHCF) MAC protocol. This protocol is based on traffic segregation, where real-time traffic is segregated from non real-time traffic. This enables the real-time traffic to avoid competition from the non real-time traffic to access the channel and provides easy management to support QoS for real-time traffic. In the SHCF, we introduce two service intervals (SI), one each for voice and video traffic. Each service interva

Voice over IP (VoIP) and voice-video over IP (VIoIP) are becoming very popular and widespread. These types of real-time services produce streams that are almost symmetrical in nature. A new token passing media access control (MAC) developed by our group, called wireless token network (WTN), has been designed with QoS guarantees in mind. We have previously shown in our previous paper (2006) that WTN supports a higher number of VoIP clients compared to 802.11e due to its higher channel efficiency. In this paper we show that WTN also provides superior QoS for bidirectional streams such as VIoIP due to a higher proportion of channel access given to the access point (AP). Performance results are generated by benchmarking WTN against IEEE 802.11 DCF, IEEE 802.11e EDCA and SpectraLink SVP MAC protocols. These results show that whilst appropriate for unidirectional traffic, these current popular solutions do not provide QoS for streams in both directions, due to design constraints which treat the access point as a single client node.

In an attempt to close the digital gap between the developed urban and the technologically impoverished rural communities, telecentres have been identified as one of the most acknowledged solution. A baseline study was done on the Long Bedian community to determine its communication pattern taking into consideration certain recommended steps. Findings from the study revealed that the Long Bedian community was deprived of the modern ICT benefits and there is a distinct information gap between the Long Bedian community and the urban community. Implication of the findings for the development of a telecentre is discussed., See also ADM001766. Presented at the International Conference on Work with Computing Systems (7th) WWCS 2004 held in Kuala Lumpur, Malaysia on 29 Jun-2 Jul 2004. Pub. in Proceedings of the International Conference on Work with Computing Systems, p271-276 Jun 2004. The original document contains color images.