Tariq M. Jadoon

Indoor Positioning Using Visible LED Lights: A Survey

Visible light LEDs, due to their numerous advantages, are expected to become the dominant indoor lighting technology. These lights can also be switched ON/OFF at high frequency, enabling their additional use for wireless communication and indoor positioning. In this article, visible LED light--based indoor positioning systems are surveyed and classified into two broad categories based on the receiver structure. The basic principle and architecture of each design category, along with various position computation algorithms, are discussed and compared. Finally, several new research, implementation, commercialization, and standardization challenges are identified and highlighted for this relatively novel and interesting indoor localization technology.

Assessment of VoIP quality over access networks

This paper assesses VoIP quality over access networks in Pakistan using a delay jitter measurement methodology for evaluating the perceptual quality of voice calls using the ITU-T G.107 speech quality E-model. Passive measurements for voice calls in the presence of background Internet data traffic for G.723.1 and G.729a codecs are carried out using a non-intrusive parametric model. The R-factor and resultant Mean Opinion Scores (MOS) were calculated at different link loads and congestion hot spots were identified. The study highlights the inadequacy of access networks for handling VoIP traffic at current in Pakistan and suggests alleviating congestion by increasing capacity in access networks

Evaluation of VoIP quality over the pakistan internet exchange (PIE) backbone

This paper assesses VoIP quality over the Pakistan Internet Exchange (PIE) backbone between major cities of Pakistan. Passive measurements for voice calls in the presence of background Internet data traffic for different speech codecs such as the ITU-T G.711, G.723.1 and G.729 were carried out. Interpacket delay and jitter were measured over the PIE IP/ATM backbone and the corresponding inter-packet delay densities were calculated for evaluating the perceptual quality of computer telephony calls using the ITU-T G.107 E-model. The transmission quality (R-factor) and resultant Mean Opinion Scores (MOS) were calculated for both backbone and access links of ISPs. The study highlights the growth of VoIP as a significant component of the PIE backbone traffic in Pakistan as well as reconfirms the presence of congestion hot spots in the access links.

Comparison of S-MAC & TDMA-W Protocols for Energy Efficient Wireless Sensor Networks

Energy efficiency is a major consideration while designing wireless sensor network nodes. Most sensor network applications require energy autonomy for the complete lifetime of the node, which may span up to several years. These energy constraints require that the system be built such that each component consumes minimum possible power. Consequently, the main objective is to devise strategies for energy reduction in different physical components while implementing all layers of the network protocol stack within a node. This paper compares S-MAC (a random access MAC Protocol) and TDMA-W (a scheduled MAC protocol) for wireless sensor networks in terms of their energy efficiency. The network layer protocol is assumed to be fixed for this comparison and is the energy aware routing protocol. This paper presents initial results while comparing different S-MAC and TDMA-W schemes

Seamless handoff based on Network Discovery for Future Heterogeneous Mobile Networks

The aim of this article is to present a novel handover algorithm to decrease the handoff latency in all-IP based Future Heterogeneous Mobile Communication System (FHMCS). The reduction in handoff latency is achieved by employing Mobile Network Discovery Technique which will decrease the delays due to movement detection, new Care of Address Configuration and Duplicate Address Detection (DAD). The decrease in handoff latency will reduce the probability of packet loss and handoff failures thus provide seamless communication and support for real time applications. The Network Discovery is achieved by using our proposed Mobile Network Information Repository, available at the site of Mobile Virtual Network Operator (MVNO), a third party operator. This network information will be available to legitimate users of all Mobile Network Operators having a single Service Level Agreement (SLA) with MVNO. In this article, we propose an intelligent handover algorithm to decrease the handover delay and thus optimizing the inter-technology handover for all-IP based Future Heterogeneous Mobile Communication System.

Architecture of IP based future heterogeneous mobile network using network discovery for seamless handoff

This article presents an architecture of all-IP Based Future Heterogeneous Mobile Communication System (FHMCS). In this architecture Mobile Virtual Network Operator (MVNO) network has been proposed as an integral part of FHMCS that will facilitate the Mobile Station/User Equipment (MS/UE) in Network Discovery. The Network Discovery is achieved by using Mobile Network Information Repository (MNIR), embedded at the MVNO site. The network discovery will help reduce handoff latency, decreasing the probability of packet loss and handoff failures. In this article the population and updation of MNIR is presented. The network information will only be available to legitimate users of all Mobile Network Operators having a single Service Level Agreement (SLA) with the MVNO.

Effect of Speech Activity Detection in IEEE 802.11 Wireless Networks

VoIP over Wireless-LAN (VoWLAN) is gaining importance due to its excellent potential in wireless voice communication. With the rapid deployment of WLANs, there is a growing demand for WLANs to support voice applications. In this research paper we present simulation results by enabling the Speech Activity Detection (SAD) for seven codecs, i.e. G.711, G.723.1, G.729, G.726 (ADPCM), G.728 (LD-CEPT), G.729 (CS-ACELP), and GSM under similar load conditions for interactive Voice over WLAN system on the IEEE 802.11 wireless LAN standard. Additionally, results have also been obtained by disabling Speech Activity Detection and both sets of results have been compared. The primary metric used in the comparison is packet end-to-end delay. From our results we conclude that the use of the Speech Activity Detection significantly improves the Average Packet end-to-end delay and slightly improves the Average Packet Delay variation for all of the aforementioned vocoders. The G.723.1 vocoder provides the least end-to-end delay and packet delay variation under both conditions, i.e. with enabled and disabled SAD. With enabled SAD, the average end-to-end delay improves by approximately 58% for our experiments.