Jee-Hyeon Na

Load balancing among internet gateways in ad hoc networks

Since Internet gateways route all packets to and from the Internet, they are likely to become the traffic bottleneck between Ad Hoc networks and the Internet. Although multiple Internet gateways can be used to distribute the traffic load, the possibility of congestion in some Internet gateway still exists in case of uneven traffic distribution if the default Internet gateway selection scheme based on hop-distance is used. In this paper, we propose a load-based Internet gateway selection scheme to distribute the traffic load over multiple Internet gateways. The proposed Internet gateway selection scheme is applied during the on-demand route discovery and the Mobile IP agent discovery procedure. To allow mobile nodes to select less congested Internet gateway as their default Internet gateway, the proxy route reply and solicited agent advertisement messages are adaptively delayed according to Internet gateways load.

Gateway discovery and routing in ad hoc networks with NAT-based Internet connectivity

The paper presents gateway discovery and routing schemes for ad hoc networks with NAT-based Internet connectivity. To maintain a reachable gateway set (RGS) and up-to-date routes to gateways, an extended HELLO (e-HELLO) message is used. A mobile node includes its RGS in the e-HELLO message and periodically broadcasts it to neighbors. On receiving the e-HELLO message, a mobile node updates its RGS and routes to gateways. To prevent on-going sessions from being broken, the current default gateway is maintained as long as it is in the RGS and there exists any on-going session. A proxy route reply (p-RREP) message is used to allow a source node to change its default gateway during route discovery. Also, a packet routing scheme for subnet-based ad hoc networks with Internet connectivity is presented. The proposed gateway discovery and routing schemes can efficiently support NAT-based Internet connectivity in ad hoc networks.

Resource allocation policy to avoid interference between cellular and D2D Links/ and D2D links in mobile networks

To cope with data communication explosion, the alternative, “D2D communication” which enables mobile devices to communicate each other without base station is studied. D2D providing service at a lower cost than cellular network is advantageous for user and also helpful when infra system is out of order by natural disaster. Even if D2D communication has a lot of benefits, that the D2D communication interferes cellular links as well as D2D link each other should be managed. This paper proposes a radio resource allocation policy for D2D link. Firstly, in frequency domain, by introducing D2D belt concept (the area where users cannot user frequency available only for D2D link) orthogonality between cellular links and D2D links is guaranteed in frequency domain. Secondly, by allocating un-overlapping subframe to D2D links, the interferences between D2D links can be eliminated.

Adaptive Location Update and Paging Scheme for Mobile Broadband Wireless Access Networks

In mobile broadband wireless access networks such as Mobile WiMAX, idle mode is defined to save radio resources and reduce power consumption when a mobile station is not involved in packet transmission and reception. In order to support idle mode, location update and paging should be supported, where location update and paging overheads are affected by paging group size. In this paper, we propose a hierarchical paging group ID structure, an adaptive location update algorithm based on the paging group structure, and a predictive paging scheme for large size paging groups. The performance of the proposed scheme is compared with conventional scheme from the aspect of location update and paging signaling overheads. Numerical results show that the proposed scheme performs well for varying the velocity of mobile stations.

Two Alternative Registration and Paging Schemes for Supporting Idle Mode in IEEE 802.16e Wireless MAN

In IEEE 802.16e Mobile Wireless Metropolitan Area Networks (MAN) system, idle mode and paging are defined in order to save battery power of MS and scarce radio resource. Current IEEE 802.16e standard, however, only specifies physical (PHY) layer and medium access control (MAC) layer protocols and mechanisms on idle mode management and paging in network layer have not been completed yet. In this paper, two alternative registration and paging schemes are proposed in order to support idle mode in IEEE 802.16e Wireless MAN system with location server (LS) and paging controller (PC). These mechanisms can be used in implementing network entities for IEEE 802.16e Wireless MAN system. The performance of the two schemes is analyzed based on mathematical analysis. The results show that there is a tradeoff between two schemes based on mobility and traffic characteristics of MS.

An efficient Diameter-based accounting scheme for wireless metropolitan area network (WMAN)

In order to provide accounting for a wireless metropolitan area network (WMAN) based on Mobile IP (MIP), the MIP accounting application should be considered in addition to the basic network access server (NAS) application in the Diameter protocol. In the conventional Diameter accounting scheme, these two applications are processed separately. In this paper, we propose a new Diameter accounting application supporting various service classes for WMAN by using both NAS and MIP applications. Then, an efficient Diameter-based accounting scheme for the proposed accounting application is proposed. The performance of the proposed scheme is analyzed. The results show that the proposed scheme performs better than the conventional scheme, especially when either the cell update rate (mobility) or subsession arrival rate is high.

Adaptive Mobility Load Balancing Algorithm for LTE Small-Cell Networks

Small cells were introduced to support high data-rate services and for dense deployment. Owing to user equipment (UE) mobility and small-cell coverage, the load across a small-cell network recurrently becomes unbalanced. Such unbalanced loads result in performance degradation in throughput and handover success and can even cause radio link failure. In this paper, we propose a mobility load balancing algorithm for small-cell networks by adapting network load status and considering load estimation. To that end, the proposed algorithm adjusts handover parameters depending on the overloaded cells and adjacent cells. Resource usage depends on signal qualities and traffic demands of connected UEs in long-term evolution. Hence, we define a resource block-utilization ratio as a measurement of cell load and employ an adaptive threshold to determine overloaded cells, according to the network load situation. Moreover, to avoid performance oscillation, the impact of moving loads on the network is considered. Through system-level simulations, the performance of the proposed algorithm is evaluated in various environments. Simulation results show that the proposed algorithm provides a more balanced load across networks (i.e., smaller standard deviation across the cells) and higher network throughput than previous algorithms.

Mobility Load Balancing Enhancement for Self-Organizing Network over LTE System

Mobility load balancing (MLB) is a function where cells suffering from overload forward their load to other cells, which perform early handover for load balancing by adjusting handover parameters. The downlink user traffic performance impacts by the proposed MLB operation has been evaluated and compared through computer simulations in the paper. According to the results, we found that the proposed MLB algorithm achieve MLB gain of as much as 4.1% in average throughput and 12.9% in average delay, and MLB cost of as much as 1.3% in average standard deviation on mobile user equipments (UEs). On the other hand, with regard to fixed UEs, we obtained no MLB gain in average throughput, and MLB cost of as much as 5.5% in average delay and 2.7% in average standard deviation. These results inform that the proposed MLB algorithm is more efficient to mobile UEs than fixed UEs in association with user traffic impact aspect.

QoS-based AMC and dynamic SINR margin scheduling in wireless multimedia transmission systems

This paper presents the performance of scheduling for adaptive modulation and coding based on the dynamic margin control. To cover various wireless channel conditions and requirements for multimedia traffic QoS, the selection of suitable MCS (Modulation and Coding Scheme) is important technique in real deployment and management fields. In this paper, we propose dynamic margin control schemes based on feedback information and measurement values without some efforts for optimizing additional parameters for the algorithm. Compared with existing algorithms, simulation results show that the proposed scheme is well adapted to dynamically change in the radio environment, while ensuring the QoS performance.

Network capacity and reliable transmission in ultra-dense networks sharing multiple carriers

Explosive demands for mobile data are leading to fundamental changes in the design of future fifth generation (5G) cellular networks to meet the challenging requirements of higher capacity and improved quality of user experience. To be close to these requirements, advanced technologies have been studied, such as user-centric architectures, massive MIMO, millimeter wave, heterogeneous networking, advanced self-configuration and optimization technologies, etc. This paper is focused on analytical models for performance evaluation of ultra-dense networks. Using the stochastic geometry approach, the SINR distributions and the outage probabilities are derived in circumstance with heterogeneous radio access systems and multiple carrier deployment. Moreover, the network capacity is defined in terms of performance metric of ultra-dense networks. We also show numerical results in various deployment scenarios and discuss them.