| 1. |
- Bilstrup, Katrin, et al.
(författare)
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Evaluation of the IEEE 802.11p MAC method for vehicle-to-vehicle communication
- 2008
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Ingår i: 68th IEEE Vehicular Technology Conference, 2008. VTC 2008-Fall. - Piscataway, N.J. : IEEE Press. - 9781424417216 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- In this paper the medium access control (MAC) method of the upcoming vehicular communication standard IEEE 802.11p has been simulated in a highway scenario with periodic broadcast of time-critical packets (so-called heartbeat messages) in a vehicle-to-vehicle situation. The 802.11p MAC method is based on carrier sense multiple access (CSMA) where nodes listen to the wireless channel before sending. If the channel is busy, the node must defer its access and during high utilization periods this could lead to unbounded delays. This well-known property of CSMA is undesirable for time critical communications. The simulation results reveal that a specific node/vehicle is forced to drop over 80% of its heartbeat messages because no channel access was possible before the next message was generated. To overcome this problem, we propose to use self-organizing time division multiple access (STDMA) for real-time data traffic between vehicles. This MAC method is already successfully applied in commercial surveillance applications for ships (AIS) and airplanes (VDL mode 4). Our initial results indicate that STDMA outperforms CSMA for time-critical traffic safety applications in ad hoc vehicular networks.
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| 2. |
- Gunnarsson, Fredrik, et al.
(författare)
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Downtilted Base Station Antennas - A Simulation Model Proposal and Impact on HSPA and LTE Performance
- 2008
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Ingår i: Proceedings of the 68th IEEE Vehicular Technology Conference. - 9781424417223 - 9781424417216 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a low-complexity model for vertical antenna radiation patterns, e.g. for inclusion in system- level simulations. They can be seen as extensions to the horizontal radiation pattern model used in 3GPP simulation scenarios. The model is verified against and compared to predicted and measured data from real networks. The impact on system-level performance is also investigated. It is seen that using the proposed model, simulated geometry distributions and soft handover statistics closely matching those of real networks may be achieved. The analysis also concludes that many real networks have better cell isolation than what is modeled by the 3GPP antenna model. As a consequence, the horizontal radiation pattern model significantly under-estimates the system level performance in such networks. Furthermore, the proposed model is used to assess the LTE and HSPA system-level performance for realistic scenarios.
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| 3. |
- Sternad, Mikael, et al.
(författare)
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Resource allocation and control signaling in the WINNER flexible MAC concept
- 2008
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Ingår i: 68TH IEEE VEHICULAR TECHNOLOGY CONFERENCE, FALL 2008. - 9781424417216 ; , s. 1553-1557, s. Art. no. 4657161-
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Konferensbidrag (refereegranskat)abstract
- The EU WINNER projects have studied OFDM-based packet data systems beyond 3G that use adaptivity on all time-scales to obtain high flexibility and performance. The adaptive transmission in both downlink and uplink is scheduled and controlled at base stations and relay nodes and requires frequent transmission of control information over the downlink. The use of scheduling, adaptive modulation and coding, with fine granularity in both time and space, could potentially result in unrealistic bandwidth demands for such downlink control signaling. The present paper describes how this problem has been handled within WINNER in two cases: Frequency-adaptive transmission, which allows individual link adaptation within time-frequency resource units and non-frequency adaptive transmission, which averages over the channel variations in the frequency domain. An important tool for limiting the associated control information is to broadcast only a small essential set of control data to all user terminals, using a safe but therefore bandwidth-demanding code rate. The remaining control information is multicast to groups of users with different signal to interference and noise ratios (SINRs). The modulation and code rates of these transmissions are adjusted to the SINRs of these groups. The over-all coded data rate of the control transmission can thereby be reduced to acceptable levels.
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| 4. |
- Beckman, Claes, 1962-, et al.
(författare)
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Verifying 3G License Requirements : some Preliminary Swedish Results
- 2008
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Ingår i: The 68th IEEE Vehicular Technology Conference. - : IEEE. - 9781424417216 ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- In the year 2000, the Swedish Telecom regulator “Post&Telestyrelsen” (PTS) granted in a “beauty contest” four licenses for operation of 3G mobile networks. Through this process, the licensees committed themselves to cover 8.860.000 inhabitants of the Swedish population. In order to verify the coverage and confirm compliance with the license requirements, PTS, developed a test procedure in close collaboration with the licensees. The present paper gives an overview of the considerations behind the design of the test method and presents some preliminary results. Today all Swedish 3G operators comply with the licence requirement and it is concluded that a method for verifying the requirement accepted by the licensees is an important tool for successful licensing of spectrum and fulfilment of licensing obligations.
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| 5. |
- Nilsson, Dennis, 1980, et al.
(författare)
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Efficient In-Vehicle Delayed Data Authentication Based on Compound Message Authentication Codes
- 2008
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Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 9781424417223
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Konferensbidrag (refereegranskat)abstract
- Modern vehicles contain an in-vehicle network consisting of a number of electronic control units (ECUs). These ECUs are responsible for most of the functionality in the vehicle, including vehicle control and maneuverability. To date, no security features exist in this network since it has been isolated. However, an upcoming trend among automobile manufacturers is to establish a wireless connection to the vehicle to provide remote diagnostics and software updates. As a consequence, the in-vehicle network is exposed to external communication, and a potential entry point for attackers is introduced. Messages sent on the in-vehicle network lack integrity protection and data authentication; thus, the network is vulnerable to injection and modification attacks. Due to the real-time constraints and the limited resources in the ECUs, achieving data authentication is a challenge. In this paper, we propose an efficient delayed data authentication using compound message authentication codes. A message authentication code is calculated on a compound of successive messages and sent together with the subsequent messages, resulting in a delayed authentication. This data authentication could be used to detect and possibly recover from injection and modification attacks in the in-vehicle network.
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| 6. |
- Verendel, Vilhelm, 1980, et al.
(författare)
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An Approach to using Honeypots in In-Vehicle Networks
- 2008
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Ingår i: 68th Semi-Annual IEEE Vehicular Technology, VTC 2008-Fall, Conference; Calgary, AB; Canada; 21 September 2008 through 24 September 2008. - 1550-2252. - 9781424417223
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Konferensbidrag (refereegranskat)abstract
- An emerging trend among automobile manufacturers is to introduce wireless technology in the vehicles. By allowing wireless communication, real-time information exchange between vehicles as well as between infrastructure and vehicles becomes a reality. This communication allows for road condition reporting, decision making, and remote diagnostics and firmware updates over-the-air, creating a complex critical infrastructure involving vehicles, road-side equipment, and firmware issuers. Allowing external parties wireless access to the vehicle creates a potential entry-point for cyber attacks. Since the safety of the driver depends on correct vehicle operation it is of utmost importance that the in-vehicle network is sufficiently protected against attacks. If we can learn the attackers' preferences, techniques, and weaknesses in existing systems, we can use this information to design security solutions for the in-vehicle network. In this paper, we present and discuss the use of honeypots as a means of collecting such attacker information. We show how to design a vehicle honeypot, how to gather data from attackers, and discuss how to process and analyze the gathered data. Furthermore, we provide a discussion where we highlight important issues related to using honeypots in vehicles.
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| 7. |
- Xiaoyu, Wei, et al.
(författare)
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A Joint Power and Rate Control Algorithm and Fairness Enhancement for Multiuser OFDM System
- 2008
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Ingår i: 68TH IEEE VEHICULAR TECHNOLOGY CONFERENCE, FALL 2008. - 9781424417223 ; , s. 1872-1876
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Konferensbidrag (refereegranskat)abstract
- A joint adaptive power and adaptive rate (APAR) control algorithm for OFDM systems that aims at sum-rate maximization, subject to certain power and rate constraints, is presented in this paper. In the basic optimization framework, the overall system throughput is the main objective, but as such it lacks user fairness consideration. Two scheduling schemes that allow adjusting the trade-off between fairness and throughput are proposed and combined with the APAR scheme for fairness enhancement. Simulation results show that enhanced system performance and balanced efficiency-fairness trade-off can be achieved by the proposed schemes in downlink.
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