Guaranteed QoS for UDP and TCP Flows to Measure Throughput in VANETs Abubakar Aminu Mu’azu*, Low Tang Jung, Halabi Hasbullah, Ibrahim A. Lawal, and Peer Azmat Shah Department of Computer & Information Sciences, Universiti Teknologi PETRONAS Bandar Seri Iskandar, 31750 Tronoh, Perak, Malaysia {abuaminu_g01797,ibrahim_g01867}@utp.edu.my, {lowtanjung,halabi}@petronas.com.my,
[email protected]
Abstract. The level of Quality of Service (QoS) guarantees in vehicular ad hoc networks (VANETs) is much more tasking and challenging as result of rapid topology changing and high mobility of mobile hosts. Thus, making multi-hop communication and as well as contention for channel access more difficult. QoS in VANETs is measured in terms of throughput, connection duration and packet loss. In this paper, UDP and TCP protocols are used as traffic to satisfy bandwidth requirement while optimizing network throughput for providing QoS using clustering approach. The results obtained through NCTUns simulator are used for analysis of throughput for both UDP and TCP traffics. Keywords: QoS Guarantee, UDP/TCP traffic classes, throughput, VANETs.
1
Introduction
VANETs are undoubtedly the most favorite network model for Intelligent Transportation Systems (ITS). VANETs are dependent on short-range wireless communication (e.g., IEEE 802.11) among vehicles. The Dedicated Short Range Communication (DSRC) was developed as WLAN standard IEEE802.11p for the wireless access in the vehicular environment (WAVE). The IEEE 802.11p physical layer is comparable to that of IEEE 802.11a standard which is recommended as VANET MAC protocol. This perhaps experiences a huge amount of packet loss rate as a result of collisions as well as access delays viewed as common challenging issues associated with contention-based MAC protocols. Its performance improves by using Time Division Multiple Access (TDMA) scheme [1] to attain restructuring of TDMA slots with no central controls. The bandwidth allocation of 75 MHz supports seven separate channels includes a control channel (CCH) and six other service channels (SCHs) each spanning 10 MHz bandwidth. *
Corresponding author.
H.-Y. Jeong et al. (eds.), Advances in Computer Science and Its Applications, Lecture Notes in Electrical Engineering 279, DOI: 10.1007/978-3-642-41674-3_158, © Springer-Verlag Berlin Heidelberg 2014
1137
1138
A.A. Mu’azu et al.
Ultimately, most of the researches focus on finding quality route and hardly is there any focus on guaranteeing QoS. Therefore our propose design intends to discover and establish the optimal path, as well as guaranteeing QoS. The algorithm for formation as well as maintaining the cluster is not under this research, scope, so we adopt [2] with modifications. Also in our propose scheme, the V2V communication scenario is going to be a clustering-based multi-channel ad hoc network; whereby all the vehicles within the a communication range will self-organized into different clusters each that contains a cluster-head (CH) vehicle chosen as with 3with an extension of CH Link Connectivity Duration. However, such CH is made to have dual transmission powers; that’s, whenever a CH needs to communicate with its cluster member, it chooses a short range transmission power. Otherwise, the CH utilizes a long range transmission power while it must exchange information using its neighboring CHs. The remaining sections of the paper are arranged as follows; Section 2 presents state-of-the-art in guaranteeing QoS over VANETs. Section 3 states related works. Section 4 describes the basic idea of the proposed scheme. Section 5 shows a simulation experiment analysis. Finally, section 6 concludes the paper.
2
State-of-the-Art
Supporting QoS in VANETs is really a challenge because of some certain features that led to intermitted link interruptions. In general, the guaranteed service (GS) guarantees that packets are obtainable within the guaranteed delivery time, and does not be discarded due to buffer over flows. Various kinds of multimedia applications typically have extremely diversified QoS requirements in regards to data transfer rates and delay bounds and many others. The majority of the current MANET routing protocols and QoS designs include difficulties for VANETs in addressing both of these needs due to the next reasons. Several of them fail easily to capture and employ neighbor-availability information. When the route setup fails, re-construction process is needed; and as a result, they can't guarantee a route that may last for an acceptable period of time which results in packets loss. More so, several schemes were suggested [3][4] for QoS guarantees in mobile ad hoc network (MANET). However, there is no proper or appropriate implementation framework to satisfy the QoS needs for the rapid network topology. A distributed cluster-based multi-channel communications scheme in [5] combines the clustering with contention free/- based MAC protocol. 2.1
Clustering
The formation of cluster region by gathering VANETs nodes that falls within a radio range. Vehicles within the same direction into are group into the same clusters, with a cluster-head (CH) vehicle elected and some ordinary members (OMs). The cluster concept has successfully been utilized for MANET to get a better delivery ratio as well as to reduce broadcast issue [11].
Guaranteed QoS for UDP and TCP Flows to Measure Throughput in VANETs
1139
VANET applications are able to use an extended range, Z, to utilize the control channel in order that a cluster-head can easily communicate with nearby cluster-heads for safety message disseminations, as well as a shorter range, z, for a service channel that is utilized for intra-cluster managements as shown in fig. 1 below;
Fig. 1. Neighborhood Relationship
For the reason that nodes exchange their status information through control channel, it will be feasible for node w to identify that x is within 2z distance. Conversely, to improve the stability of the CH in [2], we modified the procedures by adding the CH Link Connectivity Duration (LCD) which is the stability of the link. LCD is computed using the formula, motivated from [11] LCD =
(α 2 + γ 2 )R 2 − (αδ − βγ )2 − (αβ + γδ) α
2
+γ
2
α = v i cos θ i − v j cos θ
Where
j
β = ai − a j γ = v i sin θ i − v j sin θ j δ = bi − b j
( ai , bi ), ( a j , b j ), is the neighboring VANET nodes (vehicles i and j ) Cartesian coordinates with the inclination of
θ i , respectively
(0 < θ i , θ j < 2 ∏ ) depending upon
the x-axis and moving at vi, speed. R is the IEEE 802.11p wireless transmission range. We assume that the CH and source vehicle are adjacent, otherwise LCD is the minimum of LCDi (1
