Sunil Keshavji Vadgama

Adaptive control of link adaptation for high speed downlink packet access (HSDPA) in W-CDMA

In HSDPA, a set of modulation and coding schemes (MCS) are applied in downlink data transmission. These MCS schemes are adaptively selected in response to channel propagation conditions. During the selection process, adaptive threshold values at the switching points are needed so that the maximum channel capacity is utilized in terms of bits/s/Hz. It has been suggested (see NEC and Telecom Modus, 3GPP TSG RAN WG1, Technical Document R1-01-0589, 2001) to use SIR as well as ACK/NACK information of the HARQ scheme to control threshold values that decide modulation and coding schemes. We further develop this algorithm to provide more stable, and hence higher, throughput results. In cooperation with ACK/NACK information of the HARQ scheme, the threshold values are only updated when the downlink SIR falls close (i.e. /spl plusmn//spl alpha/ dB) to one of the current threshold values of the received MCS level, otherwise the threshold value remains at its current level. Simulation results show that the proposed algorithm provides a significant increase of throughput performance in different radio propagation conditions.

A Hierarchical Clustering Method in Wireless Ad Hoc Sensor Networks

Bandwidth and energy reservation is a major challenge in a large scale wireless ad-hoc sensor network, such as IEEE802.15.4-based LR-WPAN. To prolong lifetime of the whole network, improve network throughput, and support a simple topology management method in a large scale sensor network, a hierarchical clustering algorithm is proposed in this paper. This algorithm can be used for a network consisting of various capability devices, such as IEEE802.15.4-based LR- WPAN. Through computing and comparing the potential of serving as a cluster-head device (PSCD) in distributed manner, devices with more capability are chosen for cluster heads and PNC (Piconet coordinator). Comparing with other methods, such as LEACH (low energy adaptive clustering hierarchy) (Hernzelman et al., 2000) and direct communication, simulation results show this method saves energy with significantly high throughput.

Hybrid genetic packet scheduling and radio resource management for high speed downlink packet access

Simple wireless scheduling techniques, such as maximum carrier-to-interference ratio (Max. C/I) or round robin (RR), fail to take into account all aspects of quality of service (QoS) provisioning. The fundamentals of evolutionary computation (genetic algorithms) and conventional wireless scheduling techniques are combined and the weaknesses of the existing known techniques are exploited to propose a novel hybrid genetic packet scheduler (HGPS) for high speed downlink packet access (HSDPA). The proposed HGPS outperforms the Max. C/I packet scheduler in terms of total delivered throughput within low delay thresholds.

QoE-Oriented Mobile Edge Service Management Leveraging SDN and NFV

5G envisages a “hyperconnected society” where trillions of diverse entities could communicate with each other anywhere and at any time, some of which will demand extremely challenging performance requirements such as submillisecond low latency. Mobile Edge Computing (MEC) concept where application computing resources are deployed at the edge of the mobile network in proximity of an end user is a promising solution to improve quality of online experience. To make MEC more flexible and cost-effective Network Functions Virtualisation (NFV) and Software-Defined Networking (SDN) technologies are widely adopted. It leads to significant CAPEX and OPEX reduction with the help of a joint radio-cloud management and orchestration logic. In this paper we discuss and develop a reference architecture for the orchestration and management of the MEC ecosystem. Along with the lifecycle management flows of MEC services, indicating the interactions among the functional modules inside the Orchestrator and with external elements, QoS management with a focus on the channel state information technique is presented.

A radio aware random iterative scheduling technique for high speed downlink packet access

The overall performance of the high speed downlink packet access (HSDPA) proposal in 3GPP in terms of delay and throughput for various possible radio resource allocation and scheduling algorithms is evaluated using a system level simulator. By exploiting the weaknesses of the conventional wireless scheduling techniques under extreme scenarios, a novel random iterative hybrid scheduling (RIIHS) and radio aware wireless resource allocation technique for HSDPA is introduced. The algorithm has the unique ability of reaching the maximum possible levels of the throughput and fairness and minimum possible level of the delay at the same time.

Modelling interference margins in FFR enabled WiMAX systems for cell dimensioning

The interference margins (I m) for the downlink and uplink of a FFR enabled WiMAX network are modelled in this paper. This simple yet accurate model is suited for cell dimensioning applications and it draws many of the input parameters from cell dimensioning. The average collision probabilities are modelled first and then related to the interference margins. The results show the similarities in collision probability and I m for both the downlink and uplink and the impact of FFR in reducing interference.

Performance of site selection diversity transmission in WCDMA

Soft handoff is considered to be essential in direct sequence-code division multiple access (DS-CDMA) based mobile communication systems. However the interference resulting from the transmissions from multiple base sites in the forward link during the soft handoff constrains the multiple access capacity. Site selection diversity transmission (SSDT) technique is able to mitigate the interference caused by transmissions from the multiple base sites. The 3/sup rd/ Generation Partnership Project (3GPP) has specified this technique for the W-CDMA FDD component of UMTS. This paper describes the SSDT technique and presents capacity simulation results. It is shown that the capacity gain is dependent on the Doppler speed of mobile terminals and correlation of shadow fading between adjacent cells.

D2D for energy efficient communications in disaster and emergency situations

We present a novel, D2D based messaging solution to overcome the UE power limitation problems faced by cellular RATs (GSM, UMTS, LTE) in disaster and emergency situations. Through simulations comparing the direct messaging and the proposed messaging schemes, we highlight the possible power savings for the UEs in need of emergency assistance. We utilize a simple energy consumption model for our evaluations, extracted from published measurement results.

An inter-cell co-operative interference cancellation scheme for 4G MIMO networks

This paper discusses MIMO pre-coding based interference cancellation schemes for 4G networks, which are currently being considered in LTE-A and WiMAX IEEE 802.16m standardization processes. A novel user selection algorithm for inter-cell coordination of MIMO pre-coding is proposed. This is shown to provide a net capacity benefit in the downlink, through simulations based on measured MIMO channel data.

Short paper: Vehicle emission control in Smart Cities

This paper describes a novel pollution-aware approach for intelligent switching between electric and conventional propulsion in hybrid electric vehicles (HEVs). The switching is based on pollution information and pollution control zones location and size, combined with travel route and destination information, estimated travel distance on current charge level of battery and, in certain instances, with traffic congestion information, thereby enabling the journey to be completed such that adequate battery charge is available to transit all relevant pollution control zones in Smart Cities of the future. Additionally we outline a method for inferring the mode (specific combination of power or fuel sources) an HEV is running in, using roadside thermal cameras, enabling efficient enforcement of low-emission zones in future Smart Cities.