Topology control is one of the key issues in wireless networks. In this letter, we propose a simple topology control algorithm based on Connected Dominant Set (CDS) theory. The proposed algorithm uses less memory and less overhead cost than other existing schemes, and is therefore appropriate for implementation in wireless sensor networks. We will prove that the algorithm can form a CDS and guarantee network connectivity. The performance of our algorithm is demonstrated by simulation results.

It has been a very important issue to evaluate the performance of transmission control protocol (TCP), and the importance is still growing up because TCP will be deployed more widely in future wireless as well as wireline networks. It is also the reason why there have been a lot of efforts to analyze TCP performance more accurately. Most of these works are focusing on overall TCP end-to-end throughput that is defined as the number of bytes transmitted for a given time period. Even though each TCP's fast recovery strategy should be considered in computation of the exact time period, it has not been considered sufficiently in the existing models. That is, for more detailed performance analysis of a TCP implementation, the fast recovery latency during which lost packets are retransmitted should be considered with its relevant strategy. In this paper, we extend the existing models in order to capture TCP's loss recovery behaviors in detail. On the basis of the model, the loss recovery latency of three TCP implementations can be derived with considering the number of retransmitted packets. In particular, the proposed model differentiates the loss recovery performance of TCP using selective acknowledgement (SACK) option from TCP NewReno. We also verify that the proposed model reflects the precise latency of each TCP's loss recovery by simulations.

OFDMA femtocells in the macrocellular network of which frequency reuse factor is 1 cause serious interference to macrocell users, while the femtocells improve the performance of indoor users. In this letter, a novel downlink resource allocation algorithm for OFDMA femtocell networks is proposed to reduce interference between the macrocells and the femtocells. This algorithm allocates femtocell subchannels to avoid interference to macrocell users in the femtocell coverage, and minimizes the total transmission power of the femtocell to reduce the negative effect on the performance of the macrocell. Simulation results are provided to present the performance of the proposed algorithm.

Hierarchical Mobile IPv6 (HMIPv6) was proposed by the Internet Engineering Task Force (IETF) for efficient mobility management. HMIPv6 reduces the amount of signaling in the wired network link that exists in Mobile IPv6. But, HMIPv6 cannot reduce the signaling cost in the wireless link. In mobile networks, the wireless link has far less available bandwidth resources and limited scalability compared with the wired network link. Therefore, the signaling overhead associated with mobility management severely degrades the wireless link. In this paper, we propose virtual-IP (VIP) allocation scheme with dynamic VIP zone to reduce the wireless signaling cost in mobile networks. The performance of the proposed scheme is compared with HMIPv6. Based on the numerical analysis and simulation, we show that VIP allocation scheme reduces the wireless signaling cost under various system conditions.

In wireless adaptive modulation and coding (AMC) systems, modulation type of a user's connection can change and the ongoing connection might fail due to the change of modulation. In this paper, we approach the AMC-induced call admission control (CAC) problem by focusing on the guaranteed connection. Three classes of calls, new, handoff, and modulation-changed, are considered. We modify the guard-channel CAC scheme such that the modulation-changed calls, in addition to the handoff calls, are allowed to use the guard channel. Then we analyze a Markov model for the CAC scheme designed with long-term AMC in mind. The proposed approach will be an essential tool to determine the guard-channel thresholds in the wireless AMC networks.

With the spread of smart cities through 5G and the development of IoT devices, the number of services requiring firm assurance of high capacity and ultra-low delay quality in various forms is increasing. However, continuous growth of large data makes it difficult for a centralized cloud to ensure quality of service. For this, a variety of distributed application architecture researches, such as MEC (Mobile|Mutli-access Edge Computing), are in progress. However, vendor-dependent MEC technology based on VNF (Virtual Network Function) has performance and scalability issues when deploying a variety of 5G-based services. This paper proposes PRISM-MECR, an SDN (Software Defined Network) based hardware accelerated MEC router using P4[3] programmable chip, to improve forwarding performance while minimizing load of host CPU cores in charge of forwarding among MEC technologies.

This letter proposes a new retransmission persistence management scheme for selective repeat automatic repeat request (SR-ARQ). By considering the overall traffic load that has to be managed by SR-ARQ, the proposed scheme arbitrates the retransmission persistence to prevent an abrupt delay increment due to excessive link-level local retransmissions. OPNET simulations show that SR-ARQ performs better with the proposed scheme than with a fixed value of retransmission persistence in terms of the throughput of transmission control protocol (TCP).

Increasing demand for multicast transmission necessitates service-specific and precise quality-of-service (QoS) control. Since existing works provided limited methodologies such as best path selection, their ability is restricted by the given topology and the congestion status of the network. This paper proposes a fanout set partition (FSP) scheme to realize QoS-guaranteed multicast transmission. The FSP scheme adjusts the delay of the multicast flow by dividing its fanout set into smaller subsets. Since it is carried out based on the service requirement, service-specific QoS control is implemented. Mathematical analysis investigates the trade-offs, and the performance evaluation results show significant improvements under various traffic conditions.