Traffic Asymmetry Research Articles

Network neutrality debate and ISP inter-relations: traffic exchange, revenue sharing, and disconnection threat

The network neutrality debate originally stems from the growing traffic asymmetry between ISPs, questioning the established peering or transit agreements. That tendency is due to popular content providers connected to the network through a single ISP whose traffic is not charged by distant ISPs. We propose in this paper to review the economic transit agreements between ISPs in order to determine their best strategy. We define a model with two ISPs, each providing direct connectivity to a fixed proportion of the content and competing in terms of price for end users, who select their ISP based on the price per unit of available content. We analyze and compare thanks to game-theoretic tools three different situations: the case of peering between the ISPs, the case where ISPs do not share their traffic (exclusivity arrangements), and the case where they fix a transfer price per unit of volume. Our results suggest that a minimal regulation, consisting in letting ISPs choose transit prices but imposing peering in case no agreement is reached, leads to satisfying outcomes in terms of user welfare while still leaving some decision space to ISPs, hence answering a concern they have regarding regulation in the Internet market.

A Location-Based Duplex Scheme for Cost Effective Rural Broadband Connectivity Using IEEE 802.22 Cognitive Radio Based Wireless Regional Area Networks

The search for a method of utilizing the scarce spectrum in an efficient manner is an active area of research in both academic and industrial communities. IEEE 802.22 is a standard for wireless regional area network (WRAN) based on cognitive radio (CR) that operates over underutilized portions of TV bands (54–862 MHz). Time division duplex (TDD)-based WRAN cells have such advantages as dynamic traffic allocation, traffic asymmetry to users and ease of spectrum allocation. However, these cells suffer from severe cross time slot (CTS) interference when the frames of the cells are not synchronized with adjacent WRAN cells. In this paper, we evaluate the location-based duplex (LBD) scheme for eliminating the CTS interference. The proposed LBD system is much more flexible and efficient in providing asymmetric data service and eliminating CTS interference by exploiting the advantages of both TDD and frequency division duplex (FDD) schemes. We also compare the performance of LBD systems with virtual cell concepts. Furthermore, our simulation results reveal that LBD-based systems outperform the virtual cell approach in terms of the low signal-to-interference (SIR) ratio requirement by mitigating the effects of CTS.

Performance Evaluation of Light-Tree Schemes in Flexgrid Optical Networks

New applications require conveying huge bitrate from a source node to multiple destinations. As a result, point-to-multipoint (P2MP) connections need to be established on the optical layer. In this paper, the P2MP routing and spectrum allocation (RSA) problem is formally stated and modelled as an Integer Linear Program (ILP). Exhaustive numerical results show that creating several transparent sub-trees noticeably improves the performance obtained by serving the demand using one single tree. Moreover, cost savings from exploiting traffic asymmetry can be obtained by installing directed optical transponders consisting of one single module.

Interference Resolving Radio Resource Allocation Scheme in a TDD-OFDMA/FDD-CDMA Hierarchical Over lay Cellular System

In order to support a cell-independent traffic asymmetry, the conventional TDD system cannot avoid crossed time slot (CTS) interference. Moreover, the TDD/FDD hierarchical overlay cellular systems is taken into account as a generally accepted cell model in a heterogeneous radio environment. In this paper, we propose an interference resolving radio resource allocation technique in a TDD-OFDMA cellular system that overlays a FDD-CDMA cell. In our proposed scheme, we exploit under-used FDD-CDMA uplink resource by TDD mobile abiding by a region based time slot(TS) allocation which in turn mitigates CTS interference considerably. It is demonstrated that combined with under-used resource utilization scheme based on mobile's location, the proposed technique can reduce CTS interference considerably and support the asymmetric traffic in TDD system.

Regulatory Policies in Relation to Metrics and Data Collection for Measuring the Emergent Internet

The Internet is currently undergoing a major process of change and transformation. It is moving away from a basic model of layered architecture to a modular architecture with integrated provisioning of digital services and products to users (Garud, Kumaraswamy et al. 2003; Clark 2004; Fransman, 2010 and Yoo 2010). Furthermore traffic volumes and asymmetry of traffic information available for analysis makes it difficult to gain a full overview of and understand these changes (Hallingby et al, 2012 and Liebenau et al, 2012). Hence studying Internet as a whole is difficult, and there are many issues with data collection, with the academic and commercial literature providing plenty of references to such problems. The analysis is made even more complicated when trying to address medium and long-term sustainability of the telecom and Internet industries (Yoo, 2012). Value creation and capturing is a growing challenge to Internet ecosystem stakeholders, seeking to re-innovate a sustainable system. Hence the emergent Internet also changes the actions of national and regional regulators. Regulators are normative acting on behalf of consumers and ensuring adequate investments in society critical infrastructure (FCC, 2011). Their goals are to provide mediation using competition laws and rules as the recent French case Cogent vs. France Telecom shows (ARCEP, 2012b). This is particularly due to fast convergence of Internet and telecom. The transforming state of Internet has led many regulators around the world to make efforts to collect data for such regulatory purposes but with variable degree of success. Thus measuring Internet remains a huge challenge, and we will suggest some ways forward in this paper. Norway is a relatively small country “in the world of the emergent Internet” (Hallingby and Erdal, 2011). However the size and other aspects of the Nordic culture (e.g. openness to accountability, sense of community at all levels of society, etc.) have created an environment in which the national regulator (NPT) has multiple sources of data (NPT, 2012b), and also with correlated Internet data that are collected by diverse institutions. This has resulted in a clear and well explained ability to describe the Norwegian Internet (Hallingby and Erdal, 2011). There is also a culture of regulatory pro-active engagement with changes to the earliest emerging of issues e.g. CDNs legal forms (NPT, 2012a). This article discusses possible type of metrics required to explain the link between Internet network measures and Internet economic variables. First of all we are describing the emerging Internet in Norway, also indicating a more generic change supporting the modularity observed elsewhere. Second, and more important for the purpose of this article, we believe the metrics displayed are very valuable to companies, users, regulators and any other stakeholders. Specifically, we show the case of Norway as an example of the type of knowledge that may be developed, how these mappings can be performed, the scope and limitations of such methodology, and how it can be used by regulatory authorities to monitor but not obstruct the development of business activities. Finally, we also review the usefulness of this type of measurement in the context of a recent regulatory analysis of CDNs in Norway.

Using traffic asymmetry to enhance TCP performance

A wealth of recent work has gone into optimizing the performance of Transmission Control Protocol (TCP) on the downlink channel of wireless networks such as for example, honing its congestion awareness mechanism so that it is minimally affected by random wireless losses, and optimizing achieved fairness of the end-to-end TCP rates. Other work has gone into balancing the allocation of a shared resource between the downlink and uplink in order to optimize TCP performance. We build on such previous research by proposing a cross-layer algorithm for resource allocation in OFDMA systems aiming not only to achieve optimal throughput for competing TCP flows but also to allocate resources appropriately between the downlink and uplink. This is important due to the increasing number of Internet applications where the mobile terminal is the TCP sender (social networking, peer-to-peer, etc.). Therefore, our scheme makes use of the asymmetry in the traffic and by defining the boundary between downlink and uplink capacity dynamically, enhance the TCP performance. Through numerical investigations we show the performance of the proposed scheme in terms of achieved fairness to the receivers and efficient allocation of downlink to uplink ratios based on the TCP traffic.

On the Study of Half-Duplex Asymmetric Two-Way Relay Transmission Using an Amplify-and-Forward Relay

This paper studies the information-theoretic metric of outage probability for a half-duplex asymmetric two-way amplify-and-forward (AF) relaying. Unlike current research activities, our main purpose is to examine the impact of traffic asymmetry on system outage probability. First, an exact but two-integral-form outage probability is derived over Rayleigh fading channels. To provide more insight, a closed-form asymptotic outage probability is then obtained. It is shown that the outage probability in the system is determined only by the one-way channel or related to the two-way links, depending on the asymmetric level of the two senders' target rates and the terminals' average transmission powers. Following this analysis, optimum power allocation and opportunistic relay selection are studied to optimize the overall performance of the considered AF scenario. Next, with the aid of traffic knowledge, novel power allocation and relay selection criteria are proposed, followed by an analysis of the outage probability with the relay selection. Simulation experiments are performed to validate the proposed studies in this paper. The results show that the proposed power allocation and relay selection methods can achieve significant performance gains in terms of outage probability, regardless of symmetric or asymmetric traffic and channels.

From Switches to Packets: The New World of Interconnection

Abstract As the telecommunications market transitions from POTS to VoIP, interconnection plays a key role. How will migration from a termination regime to a peering regime impact carriers and subscribers? Cunningham and Alexander model the potential results under conditions of both traffic symmetry and asymmetry. Competition for subscribers, they find, is the key factor in holding interconnection costs down, although possibly increasing prices for subscribers. Under symmetry, this may ultimately increase firms' profits. Under asymmetry, some firms will lose profits. The consequences of this may be somewhat offset by public policies. This has implications for universal service, antitrust law, and network neutrality.

Outage performance of amplify-and-forward two-way relaying with asymmetric traffics

This letter conducts the outage analysis for an amplify-and-forward (AF) based two-way relaying by jointly considering outage events at the two senders with asymmetric traffics. Unlike the current research activities, our goal is to explore the impact of traffic asymmetry on the system outage probability. We first derive the exact expressions of outage probability for the AF scenario over Rayleigh fading channels. To gain more insight, approximated expressions are developed at high signal-to-noise ratio (SNR) region. After that we interestingly find that the asymmetry of system traffics has significant impact on the system outage probability and the outage probability in the system is determined only by the one-way channel or related simultaneously to the two-way links, depending on the level of asymmetry between the two senders’ information rates. Simulation experiments are done. The simulation results verify our propositions and validate the accuracy of our derived expressions.

Design and Performance Analysis of Mobility Management Schemes Based on Pointer Forwarding for Wireless Mesh Networks

We propose efficient mobility management schemes based on pointer forwarding for wireless mesh networks (WMNs) with the objective to reduce the overall network traffic incurred by mobility management and packet delivery. The proposed schemes are per-user-based, i.e., the optimal threshold of the forwarding chain length that minimizes the overall network traffic is dynamically determined for each individual mobile user, based on the user's specific mobility and service patterns. We develop analytical models based on stochastic Petri nets to evaluate the performance of the proposed schemes. We demonstrate that there exists an optimal threshold of the forwarding chain length, given a set of parameters characterizing the specific mobility and service patterns of a mobile user. We also demonstrate that our schemes yield significantly better performance than schemes that apply a static threshold to all mobile users. A comparative analysis shows that our pointer forwarding schemes outperform routing-based mobility management protocols for WMNs, especially for mobile Internet applications characterized by large traffic asymmetry for which the downlink packet arrival rate is much higher than the uplink packet arrival rate.

A heuristic approach for designing hybrid PONs employing WDM and OCDMA with asymmetric traffic distribution

In this paper we examine the resource provisioning aspects in a passive optical network (PON) employing wavelength-division multiplexing (WDM) and optical code-division multiple access (OCDMA) techniques. A judicious resource allocation scheme is proposed for a given set of optical codes and wavelengths with due consideration to the traffic asymmetry between upstream and downstream transmissions. The proposed scheme employs some initial heuristic estimates, followed by a subsequent open search mode towards reaching an optimal solution. The search mechanism in the provisioning scheme is carried out by employing some network performance metrics and evaluated using the appropriate analytical models.

Distributed timeslot allocation with crossed slots in CDMA‐TDD systems

AbstractCode division multiple access system with time division duplex (CDMA‐TDD) is a promising solution to cope with traffic asymmetry of downlink (DL) and uplink (UL) in multimedia services. When a rate of asymmetry is different in each cell, CDMA‐TDD system may employ crossed slots, where a timeslot is used for different links in cells. However, it may suffer from base station (BS)‐to‐BS and mobile station (MS)‐to‐MS interference problem. Zone division scheme is an efficient way to tackle the crossed slot interference by dividing a cell into inner and outer zones and restricting communication in crossed slots only to inner zone. In this paper, we propose distributed crossed slot resource allocation with zone division in multi‐cell CDMA‐TDD system. Two conditions for crossed slot resource allocation are defined and the bound on the size of inner zone is analyzed mathematically based on the conditions. Relationship between the capacity of crossed slot and the size of inner zone is also analyzed. Then, numerical results of the mathematical analysis are presented; showing that the proposed crossed slot allocation is effective for traffic asymmetry problem. Copyright © 2009 John Wiley & Sons, Ltd.

Channel Asymmetry in Cellular OFDMA-TDD Networks

This paper studies time division duplex- (TDD-) specific interference issues in orthogonal frequency division multiple access- (OFDMA-) TDD cellular networks arising from various uplink (UL)/downlink (DL) traffic asymmetries, considering both line-of-sight (LOS) and non-LOS (NLOS) conditions among base stations (BSs). The study explores aspects both of channel allocation and user scheduling. In particular, a comparison is drawn between the fixed slot allocation (FSA) technique and a dynamic channel allocation (DCA) technique for different UL/DL loads. For the latter, random time slot opposing (RTSO) is assumed due to its simplicity and its low signaling overhead. Both channel allocation techniques do not obviate the need for user scheduling algorithms, therefore, a greedy and a fair scheduling approach are applied to both the RTSO and the FSA. The systems are evaluated based on spectral efficiency, subcarrier utilization, and user outage. The results show that RTSO networks with DL-favored traffic asymmetries outperform FSA networks for all considered metrics and are robust to LOS between BSs. In addition, it is demonstrated that the greedy scheduling algorithm only offers a marginal increase in spectral efficiency as compared to the fair scheduling algorithm, while the latter exhibits up to 20% lower outage.

Downlink Capacity Analysis of Collaborative Crossed Timeslots in CDMA TDD Systems

Traffic asymmetry between uplink and downlink is expected to be a remarkable 3G characteristic in cellular mobile multimedia communications. CDMA system with TDD is a good solution to this traffic asymmetry. However, the level of traffic asymmetry may be significantly different from a cell to another cell. To tackle this problem and to support the traffic hot spot, crossed slots are examined. The use of crossed slots is restricted within a certain range of a cell by investigating the inter-cell interference and the maximum planned load factor. We examine the radius of inner zone and discuss the capacity of downlink crossed slots for various neighbor cell environments. Computational results show that the capacity increase in the target cell is outstanding by reducing the service range of neighbor cells. When all six neighbors reduce their service range by 20%, the capacity at target cell crossed slot is increased by 35%. Monte Carlo simulation is performed with large scale fading to verify the numerical analysis.

Balancing Uplink and Downlink under Asymmetric Traffic Environments Using Distributed Receive Antennas

Recently, multimedia services are increasing with the widespread use of various wireless applications such as web browsers, real-time video, and interactive games, which results in traffic asymmetry between the uplink and downlink. Hence, time division duplex (TDD) systems which provide advantages in efficient bandwidth utilization under asymmetric traffic environments have become one of the most important issues in future mobile cellular systems. It is known that two types of intercell interference, referred to as crossed-slot interference, additionally arise in TDD systems; the performances of the uplink and downlink transmissions are degraded by BS-to-BS crossed-slot interference and MS-to-MS crossed-slot interference, respectively. The resulting performance unbalance between the uplink and downlink makes network deployment severely inefficient. Previous works have proposed intelligent time slot allocation algorithms to mitigate the crossed-slot interference problem. However, they require centralized control, which causes large signaling overhead in the network. In this paper, we propose to change the shape of the cellular structure itself. The conventional cellular structure is easily transformed into the proposed cellular structure with distributed receive antennas (DRAs). We set up statistical Markov chain traffic model and analyze the bit error performances of the conventional cellular structure and proposed cellular structure under asymmetric traffic environments. Numerical results show that the uplink and downlink performances of the proposed cellular structure become balanced with the proper number of DRAs and thus the proposed cellular structure is notably cost-effective in network deployment compared to the conventional cellular structure. As a result, extending the conventional cellular structure into the proposed cellular structure with DRAs is a remarkably cost-effective solution to support asymmetric traffic environments in future mobile cellular systems.

Traffic asymmetry balancing in OFDMA-TDD cellular networks

This paper proposes a novel approach to interference avoidance via intercell relaying in cellular OFDMA-TDD (orthogonal frequency division multiple access — time division duplex) systems. The proposed scheme, termed asymmetry balancing, is targeted towards next-generation cellular wireless systems which are envisaged to have ad hoc and multi-hop capabilities. Asymmetry balancing resolves the detrimental base station (BS)-to-BS interference problem inherent to TDD networks by synchronizing the TDD switching points (SPs) across cells. In order to maintain the flexibility of TDD in serving the asymmetry demands of individual cells, intercell relaying is employed. Mobile stations (MSs) in a cell which has a shortage of uplink (UL) resources and spare downlink (DL) resources use free DL resources to off-load UL traffic to cooperating MSs in a neighboring cell using ad hoc communication. In an analogous fashion DL traffic can be balanced. The purpose of this paper is to introduce the asymmetry balancing concept by considering a seven-cell cluster and a single overloaded cell in the center. A mathematical model is developed to quantify the envisaged gains in using asymmetry balancing and is verified via Monte Carlo simulations. It is demonstrated that asymmetry balancing offers great flexibility in UL-DL resource allocation. In addition, results show that a spectral efficiency improvement of more than 100% can be obtained with respect to a case where the TDD SPs are adapted to the cell-specific demands.

Resource Allocations for TDD OFDMA Cellular Systems Considering Traffic Asymmetries

The time division duplex cellular system can support various downlink and uplink traffic ratios by setting the downlink and uplink transmission periods appropriately. However, it causes severe co-channel interference problem when some cells are active in the downlink while the others are in the uplink [2]. To mitigate this problem, a resource allocation scheme combined with sectorization is proposed for orthogonal frequency division multiple access. Simulations demonstrate that the proposed scheme improves both spectral efficiency and outage performance compared to the conventional allocation schemes.

Hybrid Division Duplex System for Next-Generation Cellular Services

The paper proposes a new duplexing scheme, which is called the hybrid division duplex (HDD), that is suitable for fourth-generation mobile communication systems. The proposed mobile communication system is much more flexible and efficient in providing asymmetric data service and managing intercell interference by exploiting the advantages of both time division duplex (TDD) and frequency division duplex (FDD) schemes. The HDD scheme has a pair of frequency bands such as the FDD, performing a TDD operation using one of the bands in such a manner that allows for simultaneous FDD and TDD operations. Considering the properties of the HDD system architecture, frequency hopping orthogonal frequency division multiple (OFDM) access is adopted in one band for the TDD operation and code division multiple access (CDMA) in the other band for the FDD uplink operation. The important advantage of the HDD scheme is the robustness against cross time slot interference that is inherent to the TDD system, which is caused by the asynchronous downlink/uplink switching boundaries among all neighbor cells. From the simulation results, the proposed system can achieve approximately 7% and 30% improvement with regard to the downlink and uplink throughput, respectively, as compared to the conventional TDD system under cell-independent downlink/uplink traffic asymmetries. It demonstrates that the HDD scheme is a viable solution for future communication systems that are projected to have a cell-independent asymmetric-traffic-supported hierarchical cell structure.

Adaptive TDD Synchronisation for WIMAX Access Networks

In adaptive time division duplex (ATDD) wireless systems, severe co-channel interference conditions can occur if the movable downlink/uplink (UL) TDD boundary is not synchronised among all frames in base stations. To reduce interference outage and to improve a system's spectral efficiency, a new single frequency cell (SFC) network architecture is proposed, which allows for distributed boundary synchronisation (DBS) via inter-sector signalling. SFC-DBS dynamically synchronises TDD boundaries among neighbouring sectors for each frame, thus avoiding sector-to-sector interference, while preserving the ATDD radio resource assignment efficiency. Analysis shows that SFC-DBS achieves an additional 6–11 dB in the average UL signal-to-interference ratio, compared with existing channel assignment schemes, which corresponds to 25–50 % capacity gain subject to traffic asymmetry in different sectors. More importantly, the proposed SFC scheme does not incur any further cost in the frequency planning, whereas the DBS scheme requires only minor system modifications. Compared with interference cancellation via antenna arrays and beamforming, SFC-DBS achieves similar performance, albeit without the cost for complex radio transceivers and multiple antenna elements.

An efficient demand-assign medium access control protocol for high-speed wireless networks

With the convergence of mobile and fixed communication networks, mobile users are increasingly demanding applications offering the same quality of service (QoS) as provided by wired access. High-speed time division duplex access mode is typical of high-speed mobile communication systems in order to simultaneously handle real-time, interactive, and best effort traffic classes. This paper proposes a medium access control (MAC) protocol that makes efficient use of radio resources for access. The proposed protocol, named dynamic-time division duplexing (D-TDD), is based on a multiple-access TDD air interface capable of supporting uplink and downlink traffic asymmetries. Validation of the D-TDD good performance was achieved by comparison with an ideal scheme and a different MAC protocol recently proposed in the literature on this subject.