Seung-Que Lee

Performance analysis of sleep mode operation in IEEE 802.16e

The paper investigates the queueing behavior of the sleep mode operation in IEEE 802.16e for conserving the power of an mobile station (MS) in terms of the dropping probability and the mean waiting times of packets in the base station (BS) queue. In the sleep mode, when an MS wakes up at the end of each sleep interval and there is traffic addressed to it, this is notified in the listening interval immediately following the sleep interval. Otherwise, an MS again enters the sleep mode with a sleep interval which is double the length of the previous one. We modeled this sleep mode operation as M/GI/1/N with multiple vacations whose periods depend on the previous one. Our work may be a rough guide to understanding the BS queueing behavior according to parameters such as the minimum and maximum sleep interval, the BS queue size and the arrival rate of packets at a BS.

Call admission control for hybrid access mode femtocell system

This paper deals with a call admission control method for hybrid mode femtocell base stations. Femtocell base station is a small scale base station which is used for home, office and apartment. On the hybrid access mode, the femtocell base station allows cell entrance for both member subscribers and non-member subscribers. Originally, the base station was owned by member subscribers, it is required a discrimination for service between members and non-members. In this paper, we propose a model of call admission control which has different admit policies for CSG(Closed Subscriber Group) members. We present analytic model for the proposed model to verify its work. The analytic results show that the system applies different call admission policies for CSG members with high priority and adapts to the situation of increasing incoming call rate of CSG members.

Performance Analysis of a Type-II Hybrid-ARQ in a TDMA System with Correlated Arrival over a Non-Stationary Channel

In this work, queueing performance of a type-II hybrid ARQ (automatic repeat request) scheme in a TDMA/TDD system with Markovian source over a non-stationary channel is analyzed by assuming infinite queue size. The system of interest can be described by an embedded Markov chain of M/G/1 type which can be solved by matrix analytic method of M/G/1 type. In the numerical examples, power and coding gains are expressed in terms of mean packet delay and dropping probability with various source and channel correlation

Local breakout of mobile access network traffic by mobile edge computing

Rapid growth of mobile traffic can be load of mobile operators core network. Local breakout is a offloading solution of access network to save core network load and to reduce end-to-end latency. This paper proposes local breakout system in base station with Mobile Edge Computing(MEC) infrastructure. We present the service framework and interfaces for MEC server and also present architecture based on Network Function Virtualization (NFV). By running on the commercial LTE based test-bed, we can show that the system works properly and gives us about 58 percent local breakout ratio.

Queueing for handover calls in a hierarchical cellular network

In this work, the performance of queues for handover calls in both a micro- and a macrocell is analysed by varying the number of microcells under a macrocell, arrival rates of new calls in micro- and macrocells, cell dwell times, signal degradation interval, and queue size of both micro- and macrocells. In the model, the role of a macrocell is as a secondary server for handover calls overflowed from microcells and the overflow process of handover calls from microcells is modelled by Poisson and Markov modulated Poisson process (MMPP) approximations. In the numerical examples, it is found that Poisson approximation optimistically estimates call performance compared to MMPP, and that queues in a macrocell are more effective than those in microcells.

Queueing behavior of a type-II hybrid-ARQ in a TDMA system over a Markovian channel

In this paper, the queueing performance of a type-II hybrid ARQ (automatic repeat request) scheme in a TDMA system over a Markovian channel is analyzed by assuming infinite queue size. The system of interest can be described by an embedded Markov chain of M/G/I type, which can be solved by a well-known matrix analytic method of M/G/I type. In the numerical examples, the mean delay and the packet dropping probability obtained using the infinite queue assumption are examined under varying the mobile velocity, average received signal-to-noise ratio (SNR) and coding rate.

An Execution Model of MAC on System Kernel for WiBro Access Terminal

The WiBro (wireless broadband) system is designed to be able to provide a variety of information and multimedia contents services through high speed wireless Internet access via various user terminals such as PC, PDA and hand-held PC. The WiBro system can be considered as a system that integrates services in wired-realm and a wireless service. The WiBro system consists of three major entities; WiBro-AT(Access terminal), WiBro-AP(Access Point) and PAR(Packet Access Router). WiBro-AT provides interface with users of WiBro service, it is the most important factor for successful launching and fast expansion of commercial WiBro service. In this paper, we present an execution model of MAC on system kernel for uplink packet transmission of WiBro Access Terminal. It uses tasklet and kernel thread for a data processing an it also uses circular queue for delayed function call of queue operation. It gives stable running of WiBro-AT in spite of non-atomic execution property of tasklet.

Evolving Toward Virtualized Mobile Access Platform for Service Flexibility

This paper deals with the application of virtualization technology, which is regarded as important technology for securing service flexibility in 5G mobile communication system, to base stations. 5G mobile communication should provide users with personalized, localized and intelligent new concept services. Therefore, it is necessary to secure design and implementation technology that guarantees flexibility of its structure in addition to communication technology such as high speed, low delay, and concatenation. The 5G mobile communication infrastructure with virtualization can adapt and reconfigure communication functions adaptively to the environment, so that it can quickly reflect the needs of users and markets. The services of the 5G can be accommodated by sharing resources in one equipment, rather than requiring different devices for execution. In this paper, we design a virtualized access platform with Cloud, Virtualization, and SDN concepts. This includes the virtualization design of wireless transport modem, wireless access protocol, and radio resource management functions. The design is implemented as Service Virtualization subset where SON and RRM are virtualized and confirmed that LTE basic service and SON Network Monitoring functions operate in the standard including commercial user terminal and core network.

Small cell offloading algorithm based on the social context

Traffic demand increases explosively due to the developed services and it becomes the mobile networks load. One of these services, social networking, generates a large amount of traffic. To solve it, we propose a small cell offloading algorithm using social context. In the proposed algorithm, to satisfy the effective data rate maximally, we estimate the application selection probability using social context and determine the offloading ratio according to this. By simulation, the effective data rate achievement level of the proposed algorithm is higher than the conventional one with similar offloading ratio.

Evolving toward ubiquitous access by femtocell systems

Femtocell is a small scale base station installed at home, apartment or office connecting core network of mobile company via broadband wired internet of indoors. In this paper, we introduce the femtocell systems considered as ubiquitous access by giving wireless Internet access in home at anytime while on moving with a low access cost and high data rate. An overview of the femtocell system is presented and its additional features are explored followed by migrating from the macrocell systems to the femtocell systems.