Packet Transmission Delay Research Articles

Delay Analysis of ML-MAC Algorithm For Wireless Sensor Networks

The present work is to evaluate energy consumption in wireless sensor networks for multi-layer medium access control (ML-MAC) scheme where the delay times, i.e., packet transmission delay, maximum response time delay, clock-drift delay, sleep delay and queuing delay are considered. Sensor nodes in ML-MAC algorithm have very short listening time than sensor-MAC (S-MAC) which would minimize the energy. The number of collisions where two or more nodes try to send at the same time is reduced in ML-MAC. Simulation results of performance of ML-MAC compared with ML-MAC considering the delay time and S-MAC.

Analytical average throughput and delay estimations for LTE uplink cell edge users

Estimating average throughput and packet transmission delay for worst case scenario (cell edge users) is crucial for LTE cell planners in order to preserve strict QoS for delay sensitive applications. Cell planning techniques emphasize mostly on cell range (coverage) and throughput predictions but not on delay. Cell edge users mostly suffer from throughput reduction due to bad coverage and consequently unexpected uplink transmission delays. To estimate cell edge throughput a common practice on international literature is the use of simulation results. However simulations are never accurate since MAC scheduler is a vendor specific software implementation and not 3GPP explicitly specified. This paper skips simulations and proposes an IP transmission delay and average throughput analytical estimation using mathematical modeling based on probability delay analysis, thus offering to cell planners a useful tool for analytical estimation of uplink average IP transmission.

Asym-MAC: A MAC Protocol for Low-Power Duty-Cycled Wireless Sensor Networks with Asymmetric Links

Duty-cycling is a primary technique significantly improving the energy efficiency of Wireless Sensor Networks (WSNs). Thus, a large number of MAC protocols have been developed for duty-cycled WSNs. Especially, recently proposed receiver-initiated MAC protocols are well suited for extremely low duty-cycled WSNs. However, as it is shown in this paper, they perform poorly when highly asymmetric links are present. In this paper, a hybrid MAC protocol called Asym-MAC is proposed which takes advantage of both receiver-initiated and sender-initiated MAC protocols to combat performance degradation due to asymmetric links. Experimental results demonstrate that Asym-MAC has up to 2.8X higher packet reception ratio and up to 66.7% smaller packet transmission delay compared with A-MAC, the state-of-the-art receiver-initiated MAC protocol.

Optimization of Energy Consumption in Wireless Sensor Networks using Particle Swarm Optimization

ABSTRACT The present work is to optimize energy consumption in wireless sensor networks for multi-layer medium access control (ML-MAC) scheme where the delay times, i.e., maximum response time delay, packet transmission delay, clock-drift delay, sleep delay and queuing delay are considered. Particle swarm optimization (PSO) is a popular multidimensional optimization procedure which is used in this paper to achieve less power consumption in wireless sensor networks. Keywords Energy consumption, Medium access control, Wireless sensor networks, Particle swarm optimization. 1. INTRODUCTION A wireless sensor network (WSN) is a collection of large number of sensor nodes that are deployed in an ad-hoc manner and communicate using a short-range radio channel. Sensor nodes are battery operated and normally they cannot be recharged due to its deployment in harsh and remote environment. Therefore, energy efficiency is a very critical issue to enhance the network lifetime [1,2,3]. ML-MAC is a distributed contention-based MAC algorithm where nodes discover their neighbors based on their radio signal level Step 2:[4-8]. Also, ML-MAC is a self-organizing MAC algorithm that does not require a central node to control the operation of the nodes. ML-MAC saves energy to re-send the falsified packets. ML-MAC is a contention based algorithms, which use an active/sleep routine in frame to save energy consumption. There are four major sources of energy waste [1]: collision, overhearing, control packet overhead and idle listening. The frame length T

Delay-aware reliable broadcast scheme based on power control for VANETs

In vehicular Ad-hoc network (VANET), many multi-hop broadcast schemes are employed to widely propagate the warning messages among vehicles and the key is to dynamically determine the optimal relay vehicle for retransmission. In order to achieve reliable and fast delivery of warning messages, this paper proposes a delay-aware and reliable broadcast protocol (DR-BP) based on transmit power control technique. First, a comprehensive model is derived to evaluate the transmission in vehicle-to-vehicle communications. This model considers the wireless channel fading, transmission delay and retransmissions characters occurring in the physical layer/medium access control (PHY/MAC) layer. Then, a local optimal relay selection mechanism based on the above model is designed. In DR-BP scheme, only the vehicle selected as the optimal relays can forward warning messages and the transmit power is time-varying. Finally, extensive simulations verify the performance of DR-BP under different traffic scenarios. Simulation results show that DR-BP outperforms the traditional slotted 1-persistence (S1P) and flooding scheme in terms of packets delivery ratio and transmission delay.

Reliability Analysis of Link Stability in Secured Routing Protocols for MANETs

The prime characteristics of Mobile Ad Hoc Network (MANET) are infrastructure free, absence of centralized authority and dynamic nature of nodes which are more vulnerable to security attacks. Reliability and security are prime issues to protect information and nodes in a network during communication which has received more research interest in designing a dynamic secured routing scheme. QoS is set of service requirement that needs to be satisfied by the network during the data transmission in the network. From the perception of QoS best effort protocols ensure optimum network operation in a unpredictable mobile environment. The multimedia applications are intolerable towards delay and reliability which are the features of mobile network, hence the potentials of MANET were not utilized in multimedia applications. These issues of delay and reliability of packet transmission in MANET are contributed by stability of the communication link even during the mobility of the nodes Its a necessity to analyze the performance of various secured routing protocols based on the stability of the communication link in case of mobility of nodes during data transfer. This paper is focused on a comparative study of various secured reactive routing protocols in MANET signifying the connectivity stability during the mobility of the nodes.

Routing Metric of Expected Delay in Multi-Radio Multi-Channel Wireless Mesh Networks

Many routing metrics have been proposed to improve the performance of wireless mesh networks (WMNs). Most of these routing metrics describe intra-flow and inter-flow interference respectively, which brings in adjustable parameters or results in non-isotonicity. However, the adjustable parameters, used to balance the intra-flow and inter-flow interference, are difficult to adapt to the network status, and non-isotonicity makes the design of routing metric complicated. In this paper, we propose an isotonic metric of expected delay (MED) in multi-radio multi-channel (MRMC) WMNs. In particular, MED uses the expected available bandwidth (EAB), which can capture the logical intra-flow and inter-flow interference uniformly, to estimate the delay of the path. In MED, both expected packet transmission delay and expected queuing delay are estimated to capture physical interference, logical interference, load and noise comprehensively. Simulation results show that the proposed metric can improve overall network performance effectively.

도심 교차로에서 효율적 경로 관리를 위한 자동차 통신용 라우팅 알고리즘

본 논문에서는 도심 교차로에서 경로 이탈 확률을 낮추어 줄 수 있는 차량 통신용 라우팅 알고리즘을 제안한다. 차량이 밀집된 도심의 교차로 지역에서는 차량들의 방향 전환으로 잦은 네트워크 단절과 패킷 전송지연 문제를 발생 시킬 수 있다. 본 논문에서는 이러한 문제점을 개선하기 위해 전송 노드 선정 과정에서 같은 진행방향의 노드를 이웃 노드로 선정하여 교차로에서 네트워크 단절의 비율을 낮출 수 있는 VANET (Vehicular Ad-hoc Network)용 라우팅 알고리즘을 제안한다. 시뮬레이션을 통한 성능분석 결과는 제안하는 알고리즘이 기존 라우팅 알고리즘에 비해 도심 교차로에서 경로 이탈 확률을 약 10% 감소시키며 네트워크 단절 비율을 5% 감소시킴을 보인다. This paper proposes a vehicle ad-hoc network (VANET) routing algorithm to reduce the probability of routing path discontinuity in urban intersections. In urban intersections, the vehicles may frequently change their moving directions. It can cause the disconnection of routing path and the increase of a packet transmission delay. In order to resolve this problem, the proposed routing algorithm exploits the information of moving directions in urban intersections. In this way, the proposed algorithm can reduce the probability of the local maximum which causes the increase of the number of routing hops and packet transmission delay. Simulation results show that the proposed algorithm can reduce the local maximum probability by 10% and increase the successful packet transmission ratio by 5% compared to the conventional VANET routing algorithms.

Optimization of a p-persistent Network Diversity Multiple Access Protocol for a SC-FDE System

This paper presents a Medium Access Control (MAC) protocol solution designed to properly handle collisions when in the presence of a multi-packet detection receiver for Single-Carrier (SC) modulations with Frequency-Domain Equalization (FDE). It is considered an iterative frequency-domain receiver that jointly performs equalization, multi-packet separation and channel decoding operations, for up to Qmax mobile terminals transmitting in one slot. In this work, it is proposed and evaluated a p-persistent Network Diversity Multiple Access (NDMA) random MAC protocol designed to cope with a total number of mobile terminals J, for a maximum decoding capability of Qmax simultaneous packets. An accurate analytical model is presented to optimize two different scenarios: in the first one, a saturated network is considered and it is determined the packet transmission probability that maximizes the uplink throughput; the second represents a non-saturated network and the goal is to compute the optimal transmission probability associated to each mobile terminal that minimizes the packet transmission delay. In the end, analytical results obtained through physical and MAC layer simulations are discussed.

Routing Metrics for Minimizing End-to-End Delay in Multiradio Multichannel Wireless Networks

This paper studies how to select a path with the minimum expected end-to-end delay (EED) in a multiradio multichannel (MR-MC) wireless mesh network. While the existing studies mainly focus on the packet transmission delay due to medium access control (MAC), our new EED metric further takes into account the queuing delay at the MAC layer. In particular, in the MR-MC context, we develop a generic iterative approach to compute the multiradio achievable bandwidth (MRAB) for a path, taking the impact of inter-/intraflow interference and space/channel diversity into consideration. The MRAB is then combined with the EED to form the metric weighted end-to-end delay (WEED). As a byproduct of MRAB, a channel diversity coefficient is defined to quantitatively represent the channel diversity for a given path. Moreover, we design and implement a distributed WEED-based routing protocol for MR-MC wireless networks by extending the well-known AODV protocol. Extensive simulation results are presented to demonstrate the performance of EED/WEED-based routing, with comparison to some existing well-known routing metrics.

Analysis of Packet Transmission Delay in Vehicular DC-ARQ

Considering the DC-ARQ mechanism, this paper discussed the information transmission cycle of between vehicle nodes in the vehicle and road environment, and obtained the analytical expression of delay performance for GBN-ARQ retransmission protocol. The results obtained in the paper provide a way to improve vehicle ad-hoc network transmission capacity.

Beyond OFDM: Best-Effort Dynamic Spectrum Access Using Filterbank Multicarrier

Orthogonal frequency division multiplexing (OFDM), widely recommended for sharing the spectrum among different nodes in a dynamic spectrum access network, imposes tight timing and frequency synchronization requirements. We examine the use of filterbank multicarrier (FBMC), a somewhat lesser known and understood alternative, for dynamic spectrum access. FBMC promises very low out-of-band energy of each subcarrier signal when compared to OFDM. In order to fully understand and evaluate the promise of FBMC, we first examine the use of special pulse-shaping filters of the FBMC PHY layer in reliably transmitting data packets at a very high rate. Next, to understand the impact of FBMC beyond the PHY layer, we devise a distributed and adaptive medium access control (MAC) protocol that coordinates data packet traffic among the different nodes in the network in a best-effort manner. Using extensive simulations, we show that FBMC consistently achieves at least an order of magnitude performance improvement over OFDM in several aspects including packet transmission delays, channel access delays, and effective data transmission rate available to each node in static, indoor settings. Using measurements of power spectral density and high data rate transmissions from a transceiver that we build using our National Instruments hardware platform, we show that while FBMC can decode/distinguish all the received symbols without any errors, OFDM cannot. Finally, we also examine the use of FBMC in a vehicular network setup. We find that FBMC achieves an order of magnitude performance improvement over large distances in this setup as well. Furthermore, in the case of multihop vehicular networks, FBMC can achieve about 20 × smaller end-to-end data packet delivery delays and relatively low packet drop probabilities. In summary, FBMC offers a much higher performing alternative to OFDM for networks that dynamically share the spectrum among multiple nodes.

LTE application and congestion performance

The complexity of today's wireless networks and the new applications from smartphones call for an in-depth understanding of the mutual impact of networks and applications. We have created a unique Long Term Evolution (LTE) end-to-end network and application performance platform which fulfills several pre-identified needs: 1) to model an actual market so that when traffic models change one can quickly assess the overall impact to customers, 2) optimize products to achieve the best end user experience, 3) develop guidelines for network deployment and capacity analysis, and 4) understand and extend application performance results from the field and lab testing. In this paper we analyze and report the impact of thin traffic applications on the LTE network. In particular, we analyze the performance of underlying packet transmission protocols and the impact of machine-to-machine telemetry on the LTE control plane. We further propose a protocol enhancement to reduce the signaling load and packet transmission delays over a LTE network.

Reliable Key Management and Data Delivery Method in Multicast Over Wireless IPv6 Networks

Multicast is an efficient way to reduce the required bandwidth of transmitting data simultaneously to a group of users in wireless IPv6 networks. Nevertheless, multicast suffers from two main drawbacks which can be looked from two perspectives, namely security and QoS. With regard to security, the main challenge is to provide security protection to multicast data, which can be achieved by using a secure key management process. Considering a highly dense environment where connection of users to the network is changing frequently due to join or leave operations, key updating approach may burden a network devices with a huge amount of complex encryption/decryption processes. From the QoS perspective, multicast transmission over WLAN offers a tradeoff between the transmission rate and the coverage. The transmission rate of multicast is confined by the user with the lowest data rate in the group which is called fixed base rate problem. To address the above mentioned problems, we propose and implement a lightweight key management and data delivery scheme for multicast over wireless IPv6 networks. The proposed solution is envisaged to reduce the complexity of key updating, while at the same time is able to address the fixed base rate problem. The performance evaluation (by means of analytical and test-bed implementation) of the proposed key management method indicates its efficiency in reducing communication, computation, and storage costs, while maintaining both forward and backward securities. Moreover, the proposed data delivery method is able to improve the throughput and QoS, with low packet loss and transmission delay.

R-MAC: Risk-Aware Dynamic MAC Protocol for Vehicular Cooperative Collision Avoidance System

The key for cooperative collision avoidance (CCA) systems is the real-time and reliable delivery of safety-related messages among vehicles, which include periodical beacons and risk-triggered warning messages. In this paper, we first design a risk-aware dynamic medium-access control (R-MAC) protocol tailored for vehicular CCA applications. In this protocol, each frame is divided into two parts: TDMA segment for transferring beacons and CSMA segment for delivering warning messages. Then, we propose a stochastic model to predict the average total number of potential collisions in a platoon of vehicles, which determines the size of CSMA segment in the R-MAC protocol meticulously. Monte Carlo simulations validate that our model is reliable and practical. The performance of the R-MAC protocol is verified through theoretical analysis and extensive simulations under different traffic scenes. Simulation results show that R-MAC outperforms the traditional IEEE 802.11p protocol in terms of packets delivery rate and transmission delay, as well as the Jain's fairness index of the medium access between beacons and warning messages.

Robust Takagi–Sugeno fuzzy control design for non‐linear networked control systems with asynchronous premise variables

This study is devoted to controlling a class of non-linear systems in the presence of packet transmission delays, packet losses and sampling-related phenomena over a communication network. To increase the applicability of the Takagi–Sugeno (T–S) fuzzy approach for non-linear networked control systems, this study sets the premise variables in T–S fuzzy plant and control to be asynchronous and then introduces a useful relaxation technique in a better position to handle the asynchronous problem. Moreover, this study provides a method capable of exploiting fully the induced delay term d (t) from the derivation of robust stabilisation condition.

모바일 플랫폼을 위한 네트워크 환경 측정 시스템 설계 및 구현

모바일 네트워크 사용량이 급증함에 따라 트래픽 수요 문제를 해결하기 위한 많은 연구가 이뤄지고 있다. 특히 네트워크 환경 측정 분야는 정확한 분석을 통해 네트워크상에 발생되는 문제들의 원인을 찾아냄으로써 트래픽 수요 문제를 해결할 수 있는 기반을 제공한다. 특히 최근 스마트폰의 수요가 늘어남에 따라 모바일 플랫폼 특성이 네트워크에 미치는 영향을 고려한 측정시스템이 필요하다. 이에 본 논문에서는 모바일 플랫폼을 위한 네트워크 환경 측정 시스템을 설계하였다. 설계된 시스템은 클라이언트를 통하여 얻은 패킷의 정보를 통하여 패킷 전송간의 지연시간과 throughput을 실시간으로 계산한다. 그리고 측정시 클라이언트인 모바일 단말기에 요구되는 계산량을 줄임으로써 모바일 단말기에 걸리는 부하를 최소화하였다. 설계한 시스템을 통하여 네트워크 자원을 최대로 사용하였을 시 Wi-Fi 망이 3G 망보다 짧은 전송지연시간, 높은 최대 throughput, 낮은 손실률을 가지고, Android가 iOS보다 짧은 전송지연시간과 높은 최대 throughput을 가지며, UDP가 TCP보다 긴 전송지연시간, 높은 최대 throughput을 가진다는 것을 확인하였다.

Multicast-Unicast Data Delivery Method in Wireless IPv6 Networks

Multicast IPv6 is an efficient way of transmitting data simultaneously to a group of IPv6 users. It has the advantage of reducing the required bandwidth of IPv6 data delivery compared to unicast transmission. The data rate of multicast transmission over WLAN is confined by the user with the lowest rate in the multicast group, which is called the fixed base rate problem. This paper proposes a delivery method that incorporates both multicast and unicast transmissions to solve the fixed base rate problem. The proposed method divides the IPv6 network into two levels: multicast mode for the upper level of the network [IPv6 server to Access Point (AP)], and unicast mode for the lower level (AP to mobile nodes). To maintain the end-to-end multicast transmission, the AP is responsible for converting multicast packets to unicast packets. Such a combination enables the proposed method to inherit the advantages of both multicast and unicast transmissions. The performance of our proposed method is evaluated in a test-bed environment that considers the transmission of real-time video application. The proposed multicast-unicast is able to improve the throughput and video quality experienced by the end user, with low packet loss and transmission delay.

T–S fuzzy control design for a class of nonlinear networked control systems

This paper is devoted to controlling a class of nonlinear systems over a communication network in the presence of packet transmission delays, packet losses, quantization errors, and sampling-related phenomena. Specifically, based on the Takagi–Sugeno (T–S) fuzzy approach, this paper presents a way of designing a quantized controller that allows all the states of nonlinear NCSs to converge exponentially to a bounded ellipsoid. In particular, this paper provides a method capable of exploiting fully the time-varying delay term d(t), induced by Jensen inequality, for nonlinear NCSs.

A novel LIPA scheme for LTE VoIP services with home eNBs

The need for wireless multimedia communication motivates the development of the 4G cellular wireless networks. To this end, the 4G standard, Long Term Evolution (LTE), is specified by the 3GPP. Especially, the local IP access (LIPA) function has been defined for a home base station (HeNB) to offload traffic from the core network as otherwise packets are always routed through the packet data network gateway which is located at the back-end side. Without the LIPA function, the packet routing in an LTE network is in a detour way, even if in the communication between two user equipments (UEs) attaching to the same HeNB. To implement the LIPA function, two solutions have been proposed in the literature. However, they still suffer from a few shortcomings. In this paper, we propose a novel solution, in which an additional bearer is responsible for local data packet detection and, once detected, is transformed into a data bearer for local data packet delivery. Qualitative analysis distinguishes our solution from the two previous solutions in several aspects. Simulation results show that our method outperforms the two solutions in terms of packet transmission delay and mean opinion score (MOS). An extension is proposed to provide local IP access for UEs attaching to different serving HeNBs which are yet in the same domain. Analytical results shows that applying the extension, the domain edge router can provide hundreds of VoIP connections with the local IP access service, which is ten times more than the two solutions in the literature can do.