Vasileios Miliotis

CooPNC: A cooperative multicast protocol exploiting physical layer network coding

In this paper we present a multicast protocol for short range networks that exploits the characteristics of physical layer network coding. In our proposed protocol, named CooPNC, we provide a novel cooperative approach that allows collision resolutions with the use of an indirect inter-network cooperation scheme. Through this scheme, we provide a reliable multicast protocol for partially overlapping short range networks with low control overhead. We show that with CooPNC higher throughput and energy efficiency are achieved, while it presents lower delay compared to state of the art multicast protocols. We provide an overview of our protocol with a simple scenario of overlapping networks and we then generalise its operation for a scalable scenario. Through mathematical analysis and simulations we prove that CooPNC presents significant performance gains compared to the state of the art in multicast communications for short range networks.

Offloading with IFOM: The uplink case

Mobile data offloading has been proposed as a solution for network congestion. However, the majority of the state-of-the-art is focused on the downlink offloading, while the change of mobile user habits, like mobile content creation and uploading, makes uplink offloading a rising issue. In this work we focus on the uplink offloading using Ip Flow Mobility (IFOM). IFOM allows a LTE mobile User Equipment (UE) to maintain two concurrent data streams, one through LTE and the other through WiFi access technology, that presents uplink limitations due to the inherent fairness design of IEEE 802.11 DCF. In this paper, we propose two uplink offloading algorithms to improve the energy efficiency of the UEs and to increase the offloaded data volume under the concurrent use of access technologies that IFOM provides. In the first algorithm, UEs with heavy traffic are promoted and are given priority in accessing the WiFi Access Point (AP) to offload their data. In the second algorithm, we propose a proportionally fair bandwidth allocation over the data volume needs of the UEs. We theoretically analyse the proposed algorithms and evaluate their performance through simulations. We compare their performance with the 802.11 DCF access scheme and with a state of the art access algorithm under different number of offloading UEs. Through the provided evaluation we show that there is room for improvement in the uplink access scheme of the WiFi that affects the energy efficiency of a UE during IFOM uplink offloading.

Weighted proportional fairness and pricing based resource allocation for uplink offloading using IP flow mobility

Mobile data offloading has been proposed as a solution for the network congestion problem that is continuously aggravating due to the increase in mobile data demand. However, the majority of the state-of-the-art is focused on the downlink offloading, while the change of mobile user habits, like mobile content creation and uploading, makes uplink offloading a rising issue. In this work we focus on the uplink offloading using IP Flow Mobility (IFOM). IFOM allows a LTE mobile User Equipment (UE) to maintain two concurrent data streams, one through LTE and the other through WiFi access technology, that presents uplink limitations due to the inherent fairness design of IEEE 802.11 DCF by employing the CSMA/CA scheme with a binary exponential backoff algorithm. In this paper, we propose a weighted proportionally fair bandwidth allocation algorithm for the data volume that is being offloaded through WiFi, in conjunction with a pricing-based rate allocation for the rest of the data volume needs of the UEs that are transmitted through the LTE uplink. We aim to improve the energy efficiency of the UEs and to increase the offloaded data volume under the concurrent use of access technologies that IFOM allows. In the weighted proportionally fair WiFi bandwidth allocation, we consider both the different upload data needs of the UEs, along with their LTE spectrum efficiency and propose an access mechanism that improves the use of WiFi access in uplink offloading. In the LTE part, we propose a two-stage pricing-based rate allocation under both linear and exponential pricing approaches, aiming to satisfy all offloading UEs regarding their LTE uplink access. We theoretically analyse the proposed algorithms and evaluate their performance through simulations. We compare their performance with the 802.11 DCF access scheme and with a state-of-the-art access algorithm under different number of offloading UEs and for both linear and exponential pricing-based rate allocation for the LTE uplink. Through the evaluation of energy efficiency, offloading capabilities and throughput performance, we provide an improved uplink access scheme for UEs that operate with IFOM for uplink offloading.

Energy efficient proportionally fair uplink offloading for IP Flow Mobility

The continuous increase of mobile data demand has led to mobile data offloading as a solution for the network congestion problem. The majority of the state-of-the-art is focused on the downlink offloading, while the change of mobile user habits, like mobile content creation and uploading, makes uplink offloading a rising issue. In this work we focus on the uplink offloading using Ip Flow Mobility (IFOM). IFOM allows a LTE mobile User Equipment (UE) to maintain two concurrent data streams, one through LTE and the other through WiFi access technology, that presents uplink limitations due to the inherent fairness design of IEEE 802.11 DCF. In this paper, we propose a weighted Proportionally Fair Bandwidth (PFB) allocation algorithm, for the WiFi access, in conjunction with a pricing-based rate allocation for the LTE uplink, aiming to improve the energy efficiency of the UEs that operate under the concurrent use of access technologies that IFOM provides. We present a theoretical analysis of the proposed schemes and evaluate their performance in terms of energy efficiency through simulations.

Paris Metro Pricing for 5G HetNets

Heterogeneous network access has been proposed as a solution for the continuously deteriorating congestion problem of cellular infrastructures. In this paper we focus on a multi- Radio Access Technology (RAT) environment and we provide a solution based on the Paris Metro Pricing (PMP) scheme, which was first applied in Paris metro. The concept of this pricing scheme was to provide differentiated service classes for customers who desired to avoid being congested, while maintaining the same wagons, characterized only by a different ticket price. The proposed solution extends the classic PMP policy by inducing dynamic prices formed by the congestion of each available technology. We investigate the performance of our dynamic PMP scheme taking into consideration a mobility model of the interested users. Through simulations and testbed experimentation we provide evaluation results on the average throughput, the acceptance capability of the incoming users and how these performance metrics are affected under different mobility conditions.

Multicast performance bounds exploiting cooperative Physical Layer Network Coding

In this paper we exploit the characteristics of Physical layer Network Coding (PNC) in multicast short range networks. We present a scalable scenario of partially overlapping short range networks, where collisions are resolved through indirect inter-group cooperation based on the features of PNC. Our scenario consists of a central network, which is our network of interest, and several surrounding networks. Exploring the worst case scenario of the proposed scheme, we aim to unveil the lower achievable bounds of throughput and energy efficiency and the higher bounds of delay for the network of interest. We evaluate our proposed scheme and prove that even in its lower performance it outperforms the conventional cooperative approach in terms of throughput, delay and energy efficiency.

Resource Allocation Techniques for Heterogeneous Networks Under User Misbehavior

In this letter, we focus on the uplink offloading with IP flow mobility (IFOM). With IFOM a user equipment (UE) is able to maintain concurrently two data streams, one through LTE and the other through WiFi. We consider the existence of malicious UEs that aim to exploit the WiFi bandwidth against their truthful peers, in order to upload less data through the energy demanding LTE uplink and a reputation based method is proposed to combat the selfish operation. The WiFi bandwidth is allocated based on weighted proportional fairness and the LTE rate is defined through an exponential pricing algorithm. We theoretically analyze our approach and evaluate the performance of the malicious and the truthful UEs in terms of energy efficiency and throughput, through simulations. We show that while the malicious UEs present better energy efficiency before being detected, their performance is significantly degraded with the proposed reaction method.

Combating selfish misbehavior with reputation based uplink offloading for IP Flow Mobility

In this paper we focus on the uplink offloading based on IP Flow Mobility (IFOM). With IFOM a User Equipment (UE) is able to maintain concurrently two data streams, one through LTE and the other through WiFi. We propose a weighted proportionally fair algorithm for the WiFi access and a linear pricing based algorithm for the LTE access. The existence of a malicious UE is considered that aims to exploit the WiFi bandwidth against its peers in order to upload less data through the energy demanding LTE uplink and a reputation based method is proposed to combat its selfish operation. We theoretically analyse our approach and evaluate the performance of the malicious and the truthful UEs in terms of energy efficiency through simulations. We show that while the malicious UE presents better energy efficiency before being detected, its performance is significantly degraded with the proposed reaction methIn this paper we focus on the uplink offloading based on IP Flow Mobility (IFOM). With IFOM a User Equipment (UE) is able to maintain concurrently two data streams, one through LTE and the other through WiFi. We propose a weighted proportionally fair algorithm for the WiFi access and a linear pricing based algorithm for the LTE access. The existence of a malicious UE is considered that aims to exploit the WiFi bandwidth against its peers in order to upload less data through the energy demanding LTE uplink and a reputation based method is proposed to combat its selfish operation. We theoretically analyse our approach and evaluate the performance of the malicious and the truthful UEs in terms of energy efficiency through simulations. We show that while the malicious UE presents better energy efficiency before being detected, its performance is significantly degraded with the proposed reaction method.od.

Digital and physical layer network coding performance in the context of enforced fairness

In this paper, we investigate the performance of the so-called Cross Network operating under diverse Network Coding (NC) techniques. We study the impact of Medium Access Control (MAC) layer fairness on the throughput performance of the network for the cases of pure relaying, digital NC with and without overhearing and physical layer NC with and without overhearing. We provide a comparison among these techniques and we discuss the throughput bounds, due to MAC layer limitations, imposed to the system operation by broadly adopted short range communication protocols that provide for fair resource allocation such as IEEE 802.11. Furthermore, we show that significant coding gains are achieved with digital and physical layer NC and we discuss on the energy efficiency performance of each NC case when applied on the Cross Network.

The impact of cooperative physical layer network coding on multicast short range networks

In this paper, we exploit the characteristics of physical layer network coding (PNC) in multicast short range communication (SRC) networks. We present a scalable scenario of partially overlapping SRC networks, where collisions are resolved through indirect inter-group cooperation based on the features of PNC. Our scenario consists of a central network and several peripheral networks. In our previous work we proved that the central network presents significant gains in terms of throughput, delay and energy efficiency when applying the proposed scheme. Here we explore the impact of that scenario on the peripheral networks through a decomposition approach and we prove that they also present significant performance gains.