| 1. |
- Balador, Ali, et al.
(författare)
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A Reliable Token-Based MAC Protocol for V2V Communication in Urban VANET
- 2016
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Ingår i: 2016 IEEE 27TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC). - Piscataway : IEEE. - 9781509032549 - 9781509032556 ; , s. 1586-1591
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Konferensbidrag (refereegranskat)abstract
- Safety applications developed for vehicular environments require every vehicle to periodically broadcast its status information (beacon) to all other vehicles, thereby avoiding the risk of car accidents in the road. Due to the high requirements on timing and reliability posed by traffic safety applications, the current IEEE 802.11p standard, which uses a random access Medium Access Control (MAC) protocol, faces difficulties to support timely and reliable data dissemination in vehicular environments where no acknowledgement or RTS/CTS (Request-to-Send/Clear-to-Send) mechanisms are adopted. In this paper, we propose the Dynamic Token-Based MAC (DTB-MAC) protocol. It implements a token passing approach on top of a random access MAC protocol to prevent channel contention as much as possible, thereby improving the reliability of safety message transmissions. Our proposed protocol selects one of the neighbouring nodes as the next transmitter; this selection accounts for the need to avoid beacon lifetime expiration. Therefore, it automatically offers retransmission opportunities to allow vehicles to successfully transmit their beacons before the next beacon is generated whenever time and bandwidth are available. Based on simulation experiments, we show that the DTB-MAC protocol can achieve better performance than IEEE 802.11p in terms of channel utilization and beacon delivery ratio for urban scenarios.
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| 2. |
- Bin Redhwan, Sakib, et al.
(författare)
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Evaluation of the effect of base station antenna polarization on the performance of CoMP transmission techniques based on synchronous multi-link measurements
- 2016
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Ingår i: 2016 IEEE 27th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications - (PIMRC). - 9781509032549 - 9781509032556
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Konferensbidrag (refereegranskat)abstract
- In this paper, the effect of polarization on the downlink achievable sum-rate of multi-user Cooperative Multi-Point (CoMP) systems is studied using synchronous multi-link channel measurements with two different antenna arrangements. In the first setup, four dual-polarized antenna patches with inter-patch distance varied from half wavelength to 8 m are considered at the base station (BS). In the second setup, two BSs located 60 m apart are used, each is provided with dual-polarized antennas spaced half a wavelength apart. Based on the BS antenna element selection, scenarios with different antenna polarizations at the BSs are considered. We consider four virtual users each is equipped with two antennas (V and H-polarized) with half-wavelength inter-element distance. The users are equally spaced with inter-user distance of about 0.5 m and moving in different routes. For each setup, the 8 × 4 MIMO multi-user channels are used to evaluate the achievable sum-rate of the system, where the minimum mean square error (MMSE) beamforming at both the BS and the mobile station (MS) is used. It is found that the performance improvement gained from using dual-polarized antennas at the BS vanishes if the BS antenna elements are distributed over large distance (i.e., having a large antenna array aperture). However, in the measured environment, for the case of having two BSs each of which is provided with co-located antennas, using dual-polarized antennas provide about 40% improvement in the ergodic sum-rate compared to using single-polarized antennas.
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| 3. |
- Eklund, Johan, 1966-, et al.
(författare)
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Efficient Scheduling to Reduce Latency for Signaling Traffic using CMT-SCTP
- 2016
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Ingår i: 27th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), September 4-7, Valencia, Spain. - : IEEE. - 9781509032549 ; , s. 2127-2132
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Konferensbidrag (refereegranskat)abstract
- To mitigate delay spikes during transmission of bursty signaling traffic, concurrent multipath transmission (CMT) over several paths in parallel could be an option. Still, unordered delivery is a well known problem when concurrently transmitting data over asymmetric network paths, leading to extra delay due to Head-of-Line Blocking (HoLB). The Stream Control Transmission Protocol (SCTP), designed as a carrier for signaling traffic over IP, is currently being extended with support for CMT (CMT-SCTP). To reduce the impact of HoLB, SCTP has support for transmission of separate data flows, called SCTP streams. In this paper, we address sender scheduling to optimize latency for signaling traffic using CMT-SCTP. We present dynamic stream-aware (DS) scheduling, which utilizes the SCTP stream concept, and continuously considers the current network status as well as the data load to make scheduling decisions. We implement a DS scheduler and compare it against some existing schedulers. Our investigation suggests that DS scheduling could significantly reduce latency compared to dynamic path scheduling that does not consider streams. Moreover, we show that naive round-robin scheduling may provide low latency over symmetric network paths, but may transmit data on non-beneficial asymmetric network paths leading to increased latency. Finally, our results show that a static stream based approach, found beneficial for bulk traffic, is not appropriate for bursty signaling traffic.
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| 4. |
- Flordelis, Jose, et al.
(författare)
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Exploiting antenna correlation in measured massive MIMO channels
- 2016
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Ingår i: 2016 IEEE 27th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications, PIMRC 2016. - 9781509032549
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Konferensbidrag (refereegranskat)abstract
- We investigate antenna correlation of an M-antenna massive multiple-input multiple-output (MIMO) setup with the purpose of obtaining a low-rank representation of the instantaneous massive MIMO channel. Low-rank representation bases using short-term and long-term antenna correlation statistics are defined, and their performance is evaluated with data sets obtained from channel measurements in both indoor and outdoor environments at 2.6 GHz. Our results indicate that the short-term bases can capture a larger amount of the channel energy compared to the long-term ones, but they have a limited timespan, one coherence time or less. On the other hand, the long-term bases are stable over time-spans of a few seconds. Hence, they can be obtained relatively easily. We also investigate a rank-p vector-scalar LMMSE channel estimator that exploits antenna correlation. Our results show that the investigated estimator can achieve a performance similar to that of full-rank LMMSE at a (2p + 1)/M times lower cost. The investigated estimator may be used in conjunction with estimators that exploit correlation in the frequency and time domains or, alternatively, in situations in which these estimators cannot be used, e.g., when pilot separation is larger than the channel coherence bandwidth or time.
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| 5. |
- Garcia, Johan, 1970-, et al.
(författare)
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Estimating data transfer capacity for intermittent connectivity: A transport aware model
- 2016
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Ingår i: 2016 IEEE 27th Annual International Symposium On Personal, Indoor, And Mobile Radio Communications (PIMRC). - New York : IEEE. - 9781509032549 - 9781509032556 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Communication performed with mobile devices will experience varying levels of connectivity as the communication device moves in and out of coverage. A subset of mobile communication devices operate under conditions where the connectivity is characterized by relatively short contact periods occurring intermittently. In this paper we propose a model to predict the amount of data that can be transferred during such short contact periods. The model includes aspects of the transport layer slow-start behavior and is validated using data from a long-running measurement campaign in the networks of four Swedish cellular networks. Further validation of the modeling assumptions is performed by employing a numerical optimization technique based on non-linear least squares regression using the iterative Levenberg-Marquardt approach. The model is then used to explore the relevant parameter space.
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| 6. |
- Ghanbari, Amirhossein, 1984-, et al.
(författare)
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Value Creation and Coopetition in M2M Ecosystem : - The Case of Smart City
- 2016
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Ingår i: 2016 IEEE 27TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC). - : IEEE. - 9781509032549 ; , s. 330-335
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Konferensbidrag (refereegranskat)abstract
- Wireless ICT as a subcategory of the ICT industry has long been serving end users as its direct customers. The value for end users, i.e. connectivity as the end product of this industry, has been created in a linear chain where two major group of actors have been cooperating with each other: Telecom Equipment Vendors (TEV) and Mobile Network Operators (MNO). By the demand of other industries for connecting devices/machines in order to enable various services, Machine to Machine (M2M) communications and Internet of Things have emerged as new concepts where Wireless ICT could serve other industries. As a result “connectivity” became an enabler (service) and not the final product.In this paper we argue that linear telecom value chains are incapable of serving this new demand, since wireless ICT requires to co-create value with other industries. This causes the formation of telecom value networks in which traditional telecom actors have to form new (different) business relationships with each other; Cooperation with competitors and Competition with cooperators.
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| 7. |
- Haghifam, Mahdi R., et al.
(författare)
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On joint energy and information transfer in relay networks with an imperfect power amplifier
- 2016
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Ingår i: 27th IEEE Annual International Symposium on Personal, Indoor, and Mobile Radio Communications, PIMRC 2016; Valencia; Spain; 4-8 September, 2016. - 9781509032549 ; , s. Art no 7794872-
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Konferensbidrag (refereegranskat)abstract
- This paper investigates the outage probability and the throughput of relay networks with joint information and energy transfer where the relay harvests energy from transmitted radio-frequency (RF) signal of the source. Considering different power consumption models, we derive the outage probability of the systems for both adaptive and non-adaptive power allocations at the relay. With a total energy consumption constraint at the source, we provide closed-form expressions for the optimal time sharing and power allocation between the source energy and information transfer signals. The analytical and simulation results demonstrate the efficiency of joint energy and information transfer systems in different conditions
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| 8. |
- Hu, Sha, et al.
(författare)
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Channel shortening algorithms for multiple intersymbol interference channels
- 2016
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Ingår i: 2016 IEEE 27th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications, PIMRC 2016. - 9781509032549
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Konferensbidrag (refereegranskat)abstract
- We consider channel shortening (CS) algorithms for communication systems where multiple single antenna nodes are transmitting single carrier signals to a single antenna receiver over known intersymbol interference channels. We discuss seven methods to shorten the intersymbol interference (ISI) channels, and the parameters are optimized from a generalized mutual information (GMI) perspective. The motivation for dealing with seven methods is that each one may come across as the 'natural' CS receiver, and we therefore consider them all in order to compare their performances. A favorable outcome is that the strongest method is also the one that is easiest to optimize.
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| 9. |
- Papaioannou, Panagiotis, et al.
(författare)
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Performance evaluation of CoMP transmission schemes using measurements versus the COST 2100 channel model
- 2016
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Ingår i: 2016 IEEE 27th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications, PIMRC 2016. - 9781509032549
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Konferensbidrag (refereegranskat)abstract
- Coordinated Multi Point (CoMP) transmission and reception techniques are used in order to improve the performance of single or multiple cells in wireless systems. A system using CoMP techniques is capable of jointly optimizing its transmission and/or reception and, hence, achieving higher performance. In this work, performance evaluation of three CoMP techniques are performed based on simulations using the COST 2100 channel model and also based on measured channels collected from a synchronous multi-link measurement campaign at Lund University. The contribution of this work is twofold. First, the performance evaluation of different CoMP transmission techniques, namely, the Joint Processing, the Partial Joint Processing and the Coordinated Beamforming, are presented. Second, the capability of the COST 2100 model in predicting the relative performance of different CoMP techniques is assessed. It was found that the COST 2100 model is capable of estimating the relative performance of the studied CoMP schemes well. Moreover, detailed comparison highlighting the agreements and discrepancies between the performance results based on the measured channels and those based on the COST 2100 model are reported.
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| 10. |
- Rondón, Raúl, et al.
(författare)
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An Analytical Model of the Effective Delay Performance for Bluetooth Low Energy
- 2016
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Ingår i: IEEE 27th International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'17), Valencia, Spain, Sept. 2016.. - : IEEE. - 9781509032549 ; , s. 6-11
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Konferensbidrag (refereegranskat)abstract
- With the uprising trend of the integration of wireless sensing systems in fields such as health care and industrial processes, where information exchange between power-limited devices is required, lower energy consumption and Quality of Service demands are becoming more stringent. Bluetooth LowEnergy is a promising technology that provides, besides ultra-low energy properties, compatibility with most mobile units. However,apart from power efficiency, opportune and reliable information delivery is mandatory in time-critical applications. In this paper we propose an analytical model of the delay performance of Bluetooth Low Energy for connection-oriented applications under different bit error conditions. In addition to the physical over-the-air latency, we also analyze the effect of the occurrence time of an Application Layer event on the effective transmission delay. We highlight the impact of the device’s processing speed and the timing configuration of the connectionon the final measured latency. Simulation results validate the accuracy of the model for all the analyzed cases.
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