Jitae Shin

Quality-of-service mapping mechanism for packet video in differentiated services network

This paper presents a futuristic framework for quality-of-service (QoS) mapping between practically categorized packet video and relative differentiated service (DiffServ or DS) network employing unified priority index and adaptive packet forwarding mechanism under a given pricing model (e.g., DiffServ level differentiated price/packet). Video categorization is based on the relative priority index (RPI), which represents the relative preference per each packet in terms of loss and delay. We propose an adaptive packet forwarding mechanism for a DiffServ network to provide persistent service differentiation. Effective QoS mapping is then performed by mapping video packets onto different DiffServ levels based on RPI. To verify the efficiency of proposed strategy, the end-to-end performance is evaluated through an error resilient packet video transmission using ITU-T H.263+ codec over a simulated DiffServ network. Results show that the proposed QoS mapping mechanism can exploit the relative DiffServ advantage and result in the persistent service differentiation among DiffServ levels and the enhanced end-to-end video quality with the same pricing constraint.

Dynamic duty cycle and adaptive contention window based QoS-MAC protocol for wireless multimedia sensor networks

Rapid penetration of small, customized wireless devices and enormous growth of wireless communication technologies has already set the stage for large-scale deployment of wireless sensor networks. While the need to minimize the energy consumption has driven significant researches in wireless sensor networks, offering some precise quality of service (QoS) for multimedia transmission over sensor networks has not received significant attention. However, the emerging new applications like video surveillance, telemedicine and traffic monitoring needs transmission of wireless multimedia over sensor networks. Naturally, offering some better QoS for wireless multimedia over sensor networks raises significant challenges. The network needs to cope up with battery-constraints, while providing improved QoS (end-to-end delay and bandwidth requirement). This calls for a suitable sensory MAC protocol capable of achieving application-specific QoS. In this paper, we have proposed a new QoS-based sensory MAC protocol, which not only adapts to application-oriented QoS, but also attempts to conserve energy without violating QoS-constraints. Performance modeling, analysis and simulation results demonstrate that the proposed protocol is capable of providing lower delay and better throughput, at the cost of reasonable energy consumption, in comparison to other existing sensory MAC protocols.

Dynamic Reservation Scheme of Physical Cell Identity for 3GPP LTE Femtocell Systems

A large number of phone calls and data services will take place in indoor environments. In Long Term Evolution (LTE), femtocell, as a home base station for indoor coverage extension and wideband data service, has recently gained significant interests from operators and consumers. Since femtocell is frequently turned on and off by a personal owner, not by a network operator, one of the key issues is that femtocell should be identified autonomously without system information to support handover from macrocell to femtocell. In this paper, we propose a dynamic reservation scheme of Physical Cell Identities (PCI) for 3GPP LTE femtocell systems. There are several reserving types, and each type reserves a different number of PCIs for femtocell. The transition among the types depends on the deployed number of femtocells, or the number of PCI confusion events. Accordingly, flexible use of PCIs can decrease PCI confusion. This reduces searching time for femtocell, and it is helpful for the quick handover from macrocell to femtocell. Simulation results show that our proposed scheme re- duces average delay for identifying detected cells, and increases network capacity within equal delay constraints. The 3rd Generation Partnership Project (3GPP) is work- ing on the standardization of asynchronous communication systems. This technology is being enhanced gradually en- suring higher user data rate, bigger system capacity, and lower cost. The wideband CDMA (WCDMA) system is standardized with 3GPP release 99/4 which is being de- ployed in the world. Release 5 is related to High Speed Downlink Packet Access (HSDPA), and it improves the downlink packet transmission speed theoretically up to 14.4 Mbps. High Speed Uplink Packet Access (HSUPA) is enhanced up to 5.76 Mbps in uplink, and it is standardized with the Release 6. We simply mention both HSDPA and HSUPA as High Speed Packet Access (HSPA). In release 7, High Speed Packet Access Evolution (eHSPA, HSPA+) is standardized. eHSPA is based on the HSPA network with a simple upgrade, and it supports more bandwidth efficiency and lower latency. The maximum data rate is 28.8 Mbps in downlink and 11.5 Mbps in uplink (1). How- ever, users still require further system improvements. The technology is dramatically enhanced in release 8, where the standard of Long Term Evolution (LTE) is currently being established. The main objectives of LTE are higher data rates, lower latency, increased capacity, enhanced coverage, and an optimized system for the packet switching network (2). LTE also considers a femtocell, which is referred to as a home base station for an indoor coverage extension and overall network performance enhancement (3). Recently, LTE-Advanced standard targeting of 1Gbps for low mobil- ity is being discussed in release 9. We look into general features and requirements of fem- tocells. Important issues related to access control are de- scribed, followed by our contributions and organization of the paper.

Mobility Management Survey for Home-eNB Based 3GPP LTE Systems

Abstract: The specification of the Home Evolved NodeB (Home-eNB), which is a small base station designed for use in residential or small business environment, is currently ongoing in 3GPP LTE (Long Term Evolution) systems. One of the key requirements for its feasibility in the LTE system is the mobility management in the deployment of the numerous Home-eNBs and other 3GPP network. In this paper, we overview the characteristic of Home-eNB and also describe the mobility management issues and the related approaches in 3GPP LTE based Home-eNB systems. Keywords : Home-eNB, 3GPP LTE (Long Term Evolution), Mobility Management 1. Introduction issues of HeNB in 3GPP LTE systems and related approaches A significant interest within the telecommunications industry has recently focused on the femto-cell which is defined broadly as low-cost, low-power cellular base stations that operate in licensed spectrum to connect conventional, unmodified mobile terminals to a mobile operator’s network [1][2][3]. Femto-cell has been actively discussed in 3

An Efficient Resource Allocation in OFDMA Femtocells Networks

Femtocell is one of promising key technologies to increase the efficiency and coverage of next generation broadband wireless networks. However, there exists interference problem between femtocells and macrocell due to co-channel operation. In this paper, we propose an efficient frequency resource allocation scheme for newly deployed femtocells in the legacy OFDMA networks in order to maximize the throughput of both macrocell/femtocell users without severe degradation to the existing macrocell users. Under the pre-allocated frequency bands for the macrocell users with the sectored-FFR is given, the proposed scheme allocates sub-bands to the femtocells efficiently to consider macrocell users having a priority over femtocell users. Simulation results show that the proposed one obtains higher total/edge throughputs than compared schemes.

Multi-objective handover in LTE macro/femto-cell networks

One of the key elements in the emerging, packet-based long term evolution (LTE) cellular systems is the deployment of multiple femtocells for the improvement of coverage and data rate. However, arbitrary overlaps in the coverage of these femto-cells make the handover operation more complex and challenging. As the existing handover strategy of LTE systems considers only carrier to interference plus noise ratio (CINR), it often suffers from resource constraints in the target femtocell, thereby leading to handover failure. In this paper, we propose a new efficient, multi-objective handover solution for LTE cellular systems. The proposed solution considers multiple parameters like signal strength and available bandwidth in the selection of the optimal target cell. This results in a significant increase in the handover success rate, thereby reducing the blocking of handover and new sessions. The overall handover process is modeled and analyzed by a three-dimensional Markov chain. The analytical results for the major performance metrics closely resemble the simulation results. The simulation results show that the proposed multi-objective handover offers considerable improvement in the session blocking rates, session queuing delay, handover latency, and goodput during handover.

Resource allocation analysis in OFDMA femtocells using Fractional Frequency Reuse

Femtocells are being deployed for coverage extension and higher data rates. However, interference problem between macrocell and femtocells should be solved before massive deployment. In this paper, we analyze the possible cases of frequency resource allocation in the OFDMA femtocell systems using Fractional Frequency Reuse (FFR) in order to minimize the interference between both cells. Under the assumed pre-allocation of macrocell users with the FFR, the allocable cases of sub-bands for the femtocells are investigated. Efficient and practical guidelines for femtocells resource allocation are suggested with the consideration of macrocell users having a priority over femtocell users and of enhancing overall throughputs. Simulation results show the enhanced throughputs of both macrocell users and combined total users through practical interference-avoidance guidelines.

Interference management in OFDMA Femtocell systems using Fractional Frequency Reuse

This paper presents an interference management scheme for OFDMA Femtocell systems. Femtocell is recently introduced for indoor coverage extension. However, interference problem between the femtocell and the macrocell should be solved in advance. In this paper, we propose an efficient interference management scheme in the OFDMA femtocell systems using Fractional Frequency Reuse (FFR) in order to minimize the interference between both cells. Under the pre-allocated frequency band within a macrocell through the FFR optimally, the proposed scheme allocates sub-bands the femtocells efficiently to consider macrocell having a priority over femtocells and total/edge throughputs. Simulation results show that proposed scheme enhances the throughputs performance in overall network, especially for the macrocell users and cell edge users.

A QoS-Based Energy-Aware MAC Protocol for Wireless Multimedia Sensor Networks

Emerging applications like video surveillance, telemedicine and traffic monitoring requires multimedia transmission over wireless sensor networks. Offering some precise QoS-guarantee (e.g.end-to-end delay and bandwidth requirement) for wireless multimedia over already battery-constrained sensor networks raises significant challenges. This demands for a suitable sensory MAC protocol capable of achieving application- specific QoS. In this paper we have proposed a new QoS-based sensory MAC protocol, which not only adapts to application-oriented QoS, but also attempts to conserve energy without violating QoS-constraints. Performance modelling, analysis and simulation results demonstrate that the proposed protocol is capable of providing lower delay and better throughput, at the cost of reasonable energy consumption, in comparison to other existing sensory MAC protocols.

Dynamic QoS Mapping Control for Streaming Video in Relative Service Differentiation Networks

A dynamic quality of service (QoS) mapping control scheme, which includes feedforward and feedback QoS control, is proposed for the differentiated services (DiffServ) networks in this work. To achieve reliable and con- sistent end-to-end video streaming with relative service differentiation, the proposed solution consists of two parts: (I) relative priority-based indexing and categorization of streaming video content at the sending end-system and (2) dynamic and aggregate QoS mapping control with packet, session, and class-based gnnularity level for categorized packets at the edge of the DiffServ domain, called the video gateway (VG), based upon the load variation of the network. In particular, we focus on dynamic solutions to handle QoS demand variations of continuous media applications (e.g. varying priori- ties from aggregatedcategorizedpackets) and QoS supply variations of the DiffServ network (e.g. varying loss/delay due to fluctuating network loads). Thus, with the proposed dynamic QoS mapping control, video streaming with enhanced quality is demonstrated under a pricing model.