Energy Sharing Based Content Delivery in Mobile Social Networks

Considering that the future cellular networks are more content-centric, and content sharing among user equipments (UEs) is more universal, device-to-device (D2D) communication techniques become attractive for their applications to content delivery due to the characteristic of proximal transmissions without needs of high-rate backhaul. However, D2D content delivery may not be energy efficient due to shortage of useful contents for neighbor UEs when content caching and delivery are not well designed. In this paper, we propose an architecture using D2D multicast for content delivery in cellular networks and a practical methodology, which can indicate the time for delivery, the content to be disseminated, and the UEs to receive the delivery, to achieve more energy efficient content delivery for future green cellular networks.

With the explosive growth of mobile devices at the edge of mobile social networks (MSNs), the amount of the content that needs to be transmitted is exploded. Traditional content delivery mechanisms leverage only local information to make routing decisions, which results in both high latency and low delivery rate. Software-defined networking (SDN) is a novel network paradigm, the design philosophy of which could be applied to MSN for improving the content delivery performance. In this article, the centralized control thought of SDN is introduced into MSN to efficiently process social information. The classical routing algorithm of BubbleRap is improved from the perspective of network density, which is the basis of designing the sparse and dense routing mechanisms for MSNs. In addition, flexibly switching between these two routing mechanisms is implemented by a discriminating scheme, achieving efficient yet adaptive routing. The experimental results show that the delivery ratio of sparse routing is up to 83%, and the dense routing could reach up to 93%.

Understanding the Design of Mobile Social Networking

In this paper, we present a forwarding algorithm for mobile social opportunistic networks which is both centrality-based and energy-aware. In opportunistic networks, the nodes usually exploit a contact opportunity to perform hop-by-hop routing, since an end-to-end path between the source node and destination node may not exist. Centrality-based forwarding schemes use the structurally important nodes (i.e. nodes having many contacts with neighbors) as message relays and have been shown to be good candidates for social forwarding in opportunistic network environments. However, the most central nodes which are structurally more important than other network nodes, have the disadvantage to be used very frequently as message relays, thus consuming their energy very quickly. Here, we exploit the advantage of using a centrality-based scheme which is distributed and needs only the history of contacts as social information. In addition, we modulate the computed node centrality value using the node energy level in order to avoid transmissions in nodes more central but with a limited energy budget. Simulating three real-world mobility traces, we show that our scheme is able to achieve better delivery ratio and overhead ratio while sensibly reducing the energy consumption of nodes.

In this paper, we propose a nodes identification scheme based on embedded signaling for relay systems where a data sequence transmitted by a source node is forwarded by a selected relay node before reaching the destination node. In the proposed identification scheme, source and relay nodes incorporate precoding sequences, based on codewords generated from block codes, into the data sequence. A soft decoding at the destination node allows it to efficiently recover in one step the identities of transmitting source and relay nodes of received packets. The proposed scheme is an alternative to classical explicit identification scheme based on exchanging signaling information before the data exchange and including identities in the data sequences. We also propose a blind estimation technique allowing the destination to estimate the phase of the channel. We consider the Opportunistic Relay Selection (ORS) and the Partial Relay Selection (PRS) to select relay nodes. Numerical results confirm the performance of the proposed identification scheme.

Power Line Carrier (PLC) and micropower wireless are two mainstream local communication technologies for low-voltage electricity information acquisition system, the cooperation- and complementarity between which-represent the future development trend. Aiming at the high outage probability deficiency- of traditional PLC and micropower wireless cooperative communications and the insufficient utilization of channel diversity gains, an Adaptive Relay Selection (ARS) based PLC and wireless multi-channel cooperative communication method is proposed. When the quality of the PLC link between the source node and the destination node is poor, the data of the source node is first sent to the potential relay node through the micropower wireless channel. Then, based on the channel quality of the PLC link between the relay node and the destination node, as well as the channel capacity between the source node and the relay node, the relay node and relay mode can be confirmed. Thus, a virtual Multi-Input Multi-Output (MIMO) PLC array can be constructed between the relay node and the destination node, and the system reliability can be improved by using distributed space-timecoding scheme. Simulation results show that, compared with traditional methods, ARS can significantly reduce the outage probability of the relay system, and reduce the transmission error rate via transmission diversity gains of multiple relay nodes.

We consider a dynamic content fetching, caching and delivery problem wherein the contents get updated at a central server, and local copies of a subset of the contents are cached at an edge cache associated with a base station (BS). Upon being requested, the BS can fetch the requested content from the central server and serve or can serve the locally cached version or can deny service. Fetching a content incurs a fixed fetching cost, serving a cached version incurs an ageing cost proportional to the age-of-version (AoV) of the content, and denying service incurs a fixed missing cost. Furthermore, due to unreliability of the channel between the BS and the users, a content delivery can fail, again resulting in a missing cost. We formulate an optimal content fetching, caching and delivery problem to minimize the average cost subject to the cache capacity constraint. This problem belongs to the class of continuous time restless multi-armed bandit (RMAB) problems with state dependent feasible action sets. We show that the single content problem is indexable, derive its Whittle indices and provide a Whittle index based policy for the original multi-content problem. Finally, we numerically evaluate the performance of the proposed policy and compare it to the existing works. We demonstrate that the proposed policy substantially outperforms the existing ones and, performance-wise, is very close to the optimal policy.

PurposeToday, consumers play an active role in creating, generating and distributing the electronic word of mouth (eWOM) independent of marketers. Customer acquisition through referrals and word of mouth (WOM) has thus become an important goal for firms. In addition, mobile social networks have created valuable opportunities for eWOM. People are now able to discuss products and services of brands with their friends and acquaintances. The purpose of this paper is to examine the influence of eWOM information on consumers’ behavioral intentions in mobile social networks.Design/methodology/approachThis study employed the information adoption model (IAM), theory of reasoned action and social exchange theory to investigate the influence of eWOM information on consumers’ behavioral intentions in mobile social networks. The study used 394 respondents to evaluate the proposed model using SmartPLS software.FindingsResults show that the quality and credibility of eWOM information has a positive direct effect on perceived information usefulness. Attitude toward eWOM information mediates the influence of perceived information usefulness on information adoption. Also, attitude toward eWOM information has a significant positive influence on behavioral intentions, such as purchase intention and forwarding of eWOM information. However, information adoption does not have any significant relationship with the forwarding of eWOM information.Research limitations/implicationsThis study seeks to address the dearth of research in the field of mobile social networks, especially regarding eWOM information. The study proposes a new model and empirically validates the hypothesized relationships. This research can serve as a stepping-stone for future research in this field.Practical implicationsThis research is one of the first studies focusing on the influence of eWOM information, especially in mobile social networks. The research offers comprehensive and empirically validated factors pertaining to eWOM information in mobile social networks. The results of this study may be useful also for practitioners and managers of online companies.Originality/valueA new eWOM IAM in mobile social networks is proposed based on information characteristics and consumer behavior. The model is validated afterward.

Recent research has shown that the cooperative diversity can efficiently combat the fading effects caused by the hostile wireless channels just as the multiple-input multiple-output (MIMO) antenna systems do. Besides, due to the inherent cost and size constraints by many small area wireless networks, e.g. wireless ad hoc networks and wireless sensor networks, in such environments, it would be almost impossible to deploy the antenna array in a mobile node. However, cooperative diversity can provide an economical and viable solution by sharing each mobile node’s single-antenna with others to form a virtual antenna array, while it still can maintain significant performance gains similar to MIMO systems. Meanwhile, the adaptive modulation is a proven technique which can significantly increase the spectral efficiency when perfect channel estimation can be achieved, and many wireless standards have adopted it as an implementation option. It also has been shown that combining these two techniques can greatly raise the system efficiency. Nevertheless, in the multiple nodes cooperative communication networks, the randomness of demodulation process at each relay node makes the task of correctly selecting the forwarding relay nodes very complicated. In view of this problem, a novel adaptive node selection algorithm is proposed for the destination node to effectively select the forwarding relay nodes to help the source node transfer the signals. In this paper, the decode-and-forward (DF) protocol is employed as the cooperative diversity signaling, and the constant-power variable-rate M-ary phase shift keying (M-PSK) is adopted as the adaptive modulation scheme. At the destination node, the maximal-ratio-combining (MRC) method is used to combine all of the signals from diversity branches with the main path transmitted directly from the source node. Because of the random phenomenon of the demodulation process, the outage requirement is used as the baseline in the first stage of the proposed node selection algorithm to choose the maximal transmission rate. Hence the maximal overall system throughput in terms of rate can be achieved. In the meantime, the first candidate forwarding sets of the relay nodes which collectively meet the required outage probability are also been chosen. Then in the second stage, we can further refine the number of the relay nodes among the first candidate forwarding sets by using the following criterion — maximum average rate per node. It will screen out the first candidate sets with the minimum number of the relay nodes. If only one candidate set is left at the end of the second stage, it will be the end of the proposed algorithm. However, if the result of the screening still has more than one set, then the final election among the second candidate sets would be the one which can give the minimum outage probability. In the simulation results, our proposed node selection algorithm can even further improve the spectral efficiency while the deleteriously fading effect induced by the wireless channels can also be effectively removed.

Mobile social network is made up of people with certain social relations through some wireless devices connected together, which is a virtual interactive community based on wireless network service. Aiming at multimedia application scenario, such as video conference or multimedia contents sharing, how to improve the transmission efficiency for the data sensitive to time and ensure users' smooth and stable service experience is our object. This paper presents a selecting and repairing method for service routing in mobile social network. During the selection process for service routing, the source node which provides multimedia content adjusts the transmission rate. When the service routing is failed, the method repairs the service routing in time. The simulation results show that the proposed method can reduce the packet loss rate greatly.

A new cooperative communication algorithm for improving connectivity in the event of network failure in VANETs

In Mobile Social Networks (MSN) individuals with similar interests or commonalities connect to each other using the mobile phones. MSN are special kind of Ad-hoc Networks in which wireless connectivity (i.e. encounters and re-encounters) with social peers is predictable. Most of the recent research proposes routing framework to exploit these predictable patterns to identify the best information carriers. The best information carriers are selected based on the high probability of encounter with potential information recipients. In these approaches an important variable is ignored i.e. time of encounter. Considering encounter time in the protocol gives time assurance of message delivery for time critical application. Therefore in this paper we address the research question, how to exploit people's predictable social patterns to improve the content delivery performance and lower end-to-end delay in time critical applications? Our assumption is that the people follow similar mobility patterns daily (i.e. Monday to Friday). In this paper we verify our research question and assumption using real trace data of 100 users carrying Nokia 6600 smart phones over the course of nine months. Furthermore we model, analyze and propose algorithms for social encounter based content delivery system for time critical applications. The simple heuristics and initial study presented in this paper achieve a timely content delivery using predictable patterns while lowering system wide traffic flooding.

A geo-temporal mobility prediction method for cooperative time-validity-constrained content delivery in opportunistic networks

Rate adaptation is an effective approach to achieve high spectrum efficiency under varying channel condition, especially for wireless communication. This paper proposes rate adaptation at receiver for wireless relay system. In this scheme, source node uses a new modulation technology, called random projections code (RPC), to achieve rate adaptation. Both relay node and destination node decode the received RPC encoding signals. If destination does not decode RPC correctly, relay node will act compressing and forwarding role by performing LDPC syndrome encoding and sending syndrome coded information to destination node. We discuss how to jointly decode at destination node when it receives RPC coded information from source node and syndrome coded information from relay node. Finally, we evaluate the scheme by bit-error-rate (BER) and good put evaluation metrics. Simulation results show that the coding gain is about 4 dB, 3.1 dB, 2.2 dB and 1.6 dB for LDPC coding rate 0.8, 0.89, 0.94, 0.99 at BER 10-5 respectively. The throughput of the schemes is at least 0.3 bit/s/Hz higher than RPC at SNR ranging from 5 dB to 25 dB.

This paper focuses on relay semantic communication systems and deeply investigates their outage probability performance under different conditions. First, a three-point, two-link communication transmission model is constructed, which includes the source node, relay node, and destination node. The relay operates in half-duplex mode and is based on the DeepSC communication transmission model, with semantic and channel encoding/decoding implemented at both the source and relay nodes. Next, depending on the computational capabilities of the destination node, background knowledge, and channel conditions, the channel transmission strategies are classified into four scenarios: 1) Both the SR and RD links use semantic transmission, with the source and destination nodes having either the same or different background knowledge; 2) Both the SR and RD links use semantic transmission, but the signal is impaired, preventing the destination node from decoding; 3) The SR link uses semantic transmission, while the RD link performs bit transmission. For each scenario, the channel capacity formula and outage probability expressions are derived. In calculating the outage probability, the results are obtained by analyzing and deriving the distributions and conditions of relevant variables. Finally, Monte Carlo simulations are used to validate the theoretical analysis. The research results provide a theoretical basis for comprehensively understanding the performance of relay semantic communication systems and are of significant importance for advancing semantic communication technology.