| 1. |
- Anchora, Luca, et al.
(författare)
-
Capacity Gains due to Orthogonal Spectrum Sharing in Multi-Operator LTE Cellular Networks
- 2012
-
Ingår i: Proceedings of the Ninth International Symposium on Wireless Communication Systems (ISWCS). - 9781467307604 - 9781467307611 ; , s. 286-290
-
Konferensbidrag (refereegranskat)abstract
- Static spectrum allocation leads to resource wastage and inter-operator spectrum sharing is a possible way to improve spectrum efficiency. In this work, we assume that two cellular network operators agree upon sharing part of their spectrum, which can then be dynamically accessed by either of them in a mutually exclusive way. Our goal is to numerically assess the gain, in terms of cell capacity, due to such orthogonal spectrum sharing. Hence, we propose a centralized algorithm that performs coordinated scheduling, in order to numerically evaluate an upper bound on the achievable sum capacity. The algorithm is centralized and exploits complete information on both networks to perform the optimum allocation. The simulation results illustrate the impact of the multiuser diversity and the asymmetry in the traffic load among the networks on the overall achievable gain.
|
|
| 2. |
- Anchora, Luca, et al.
(författare)
-
Resource Allocation and Management in Multi-Operator Cellular Networks with Shared Physical Resources
- 2012
-
Ingår i: Proceedings of the Ninth International Symposium on Wireless Communication Systems (ISWCS). - : IEEE. - 9781467307604 - 9781467307611 ; , s. 296-300
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we focus on next-generation cellular networks and discuss physical resources sharing among the operators. This implies cooperative usage of the available radio frequencies and also infrastructure sharing. In particular, we analyze the spectrum sharing gain achievable at different time scales and the main factors impacting on it. Then, we move towards a wider idea of resource sharing and consider a joint spectrum and infrastructure sharing (full sharing). We describe a two-layer resource management architecture that enables operators to reduce costs while still guaranteeing a good service level. The main findings of our investigations are to quantify the effectiveness of resource sharing and open up new perspectives for the operators of next-generation networks.
|
|
| 3. |
- Farhadi, Hamed, 1983-, et al.
(författare)
-
Power Control in Wireless Interference Networks with Limited Feedback
- 2012
-
Ingår i: International Symposium on Wireless Communication Systems (ISWCS), 2012. - : IEEE conference proceedings. - 2154-0217. - 9781467307604 - 9781467307611 ; , s. 671-675
-
Konferensbidrag (refereegranskat)abstract
- This paper addresses a power control problem in a wireless time-varying K-user interference network. Each transmitter intends to communicate to its desired receiver at afixed rate. Quantized channel gains are globally available through limited feedback signals. To eliminate multi-user interference, interference alignment scheme is performed based on the imperfect channel knowledge. The communication quality is affected by the channel quantization errors and interference leakage. We proposea power control algorithm, aiming to guarantee successful transmissions of each user while minimizing the transmission powerof the network. Our results show that even with limited number of feedback bits, by performing power control the considered interference alignment scheme can outperform the conventional time-division-multiple-access scheme.
|
|
| 4. |
- Luo, J., et al.
(författare)
-
Transmit Beamforming for Inter-Operator Spectrum Sharing : From Theory to Practice
- 2012
-
Ingår i: Proceedings of the International Symposium on Wireless Communication Systems. - : IEEE conference proceedings. - 9781467307604 - 9781467307611 ; , s. 291-295
-
Konferensbidrag (refereegranskat)abstract
- In this paper, four transmit beamforming (BF) techniques are selected and compared to realize inter-operator spectrum sharing, which is a promising solution for the spectrum shortage problem. The BF techniques include two game-theoretic (GT) algorithms, zero-forcing (ZF) and minimum mean square error (MMSE). After a brief description of the BF techniques in a multiple-input single-output (MISO) system, their computational complexity is analyzed. The effectiveness of these techniques in real radio frequency (RF) signal transmission is verified by implementation on a flexible hardware-in-the-loop (HIL) testbed. First, several important aspects regarding practical implementation are discussed. Afterwards, the HIL measurement results are shown, where considerable sum rate gain can be observed due to spectrum sharing. Finally, the appropriate BF technique can be chosen based on a tradeoff between complexity and performance.
|
|
| 5. |
- Söderman, Pehr, et al.
(författare)
-
Sub-second transport layer vertical handover using mSCTP in Android mobile devices
- 2012
-
Ingår i: Wireless Communication Systems (ISWCS), 2012 International Symposium on. - : IEEE. - 9781467307604 - 9781467307611 ; , s. 661-665
-
Konferensbidrag (refereegranskat)abstract
- Contemporary mobile devices such as smartphones and tablets are increasingly equipped with multiple network interfaces that enable automatic vertical handover between heterogeneous wireless networks including WiFi and cellular 3G and 4G networks. However, the employed vertical handover schemes are mostly quite simple, and incur non-negligible service disruptions to ongoing sessions, e.g., video streaming and live conferencing sessions. A number of improved mobility management frameworks for these lightweight mobile devices have been proposed in the past recent years. Although these may result in negligible service disruptions, the vast majority of them are network- or integrated network- and link-layer based, and require support in the infrastructure to be successfully deployed. This paper demonstrates the feasibility of using an infrastructure-independent, transport-level vertical handover scheme on a smartphone for an application as demanding as video streaming. In our study, we used a previously developed Android-based mobility framework. The study shows that a standardized mobility solution based on the Stream Control Transmission Protocol (SCTP) and its extension for Dynamic Address Reconfiguration (DAR), incurs a service disruption on par with comparable proposed network- and link-layer solutions.
|
|
| 6. |
- Andersson, Mattias, et al.
(författare)
-
Polar codes for bidirectional broadcast channels with common and confidential messages
- 2012
-
Ingår i: International Symposium on Wireless Communication Systems (ISWCS), 2012. - : IEEE conference proceedings. - 9781467307604 ; , s. 1014-1018
-
Konferensbidrag (refereegranskat)abstract
- We consider the bidirectional broadcast channel with common and confidential messages. We show that polar codes achieve the capacity of binary input symmetrical bidirectional broadcast channels with confidential messages, if one node's channel is a degraded version of the other node's channel. We also find a new bound on the cardinality of the auxiliary random variable in this setup.
|
|
| 7. |
- De Nardis, L., et al.
(författare)
-
Impact of mobility in cooperative spectrum sensing : Theory vs. simulation
- 2012
-
Ingår i: Wireless Communication Systems (ISWCS), 2012 International Symposium on. - : IEEE. - 9781467307604 ; , s. 416-420
-
Konferensbidrag (refereegranskat)abstract
- This work addresses the problem of cooperative spectrum sensing in cognitive radio networks, focusing on the impact of mobility on performance of cooperative sensing. First, a review of the most recent results on cooperative spectrum sensing is provided, resulting in the identification of measurement correlation and frame error rate in the reporting channel as the main parameters influencing the performance of cooperative sensing schemes. Next, the paper discusses the extension of the analysis to the case of mobile sensors, and determines the set of assumptions made in existing literature when taking into account mobility in sensing. The paper moves then to remove some of such assumptions, by presenting simulation results obtained in presence of realistic models for propagation in the considered area, as well as of a realistic mobility model. A comparison between theoretical derivation and simulation results shows that correlation among measurements taken by different sensors and the selected mobility model may significantly affect the sensing performance.
|
|
| 8. |
- Lv, Jing, et al.
(författare)
-
Linear Precoding in MISO Cognitive Channels with Causal Primary Message
- 2012
-
Ingår i: 2012 International Symposium on Wireless Communication Systems (ISWCS). - : IEEE conference proceedings. - 9781467307604 ; , s. 406-410
-
Konferensbidrag (refereegranskat)abstract
- The coexistence of a single-input single-output (SISO) primary link and a multiple-input single-output (MISO) secondary link is considered in an extended cognitive radio channel setup, where the secondary transmitter has to obtain (“learn”) the primary message in a first phase rather than having non-causal knowledge of it. An achievable rate region is derived that combines decode-and-forward relaying with linear precoding in the second phase. The optimal transmission strategy is found that maximizes the secondary rate with the primary rate requirement. The performance of the proposed strategy is compared with that in [1], where dirty-paper coding (DPC) is deployed in the second phase, in terms of average secondary rate. The performance degradation is negligible at certain SNR and primary link load, and the implementation is of lower complexity. The comparison with the underlay strategy in [2] is also performed, where the secondary transmitter has no knowledge of the primary message.
|
|
| 9. |
- Nasiri Khormuji, Majid, et al.
(författare)
-
Input-distribution optimization for estimate-and-forward relaying
- 2012
-
Ingår i: Wireless Communication Systems (ISWCS), 2012 International Symposium on. - : IEEE. - 9781467307604 ; , s. 201-205
-
Konferensbidrag (refereegranskat)abstract
- We investigate the design of optimized input distributions for the two-hop Gaussian relay channel under an average power constraint. In our study, the relay is confined to implement an estimate-and-forward strategy. We demonstrate that the rate achievable by an optimized discrete input distribution can significantly outperform that achievable by a Gaussian codebook. The lower bound obtained by the optimized EF scheme is also used to establish an improved lower bound on the rates achievable by compress-and-forward.
|
|
| 10. |
- Salimi, Somayeh, et al.
(författare)
-
Pairwise secret key agreement using the source common randomness
- 2012
-
Ingår i: Wireless Communication Systems (ISWCS), 2012 International Symposium on. - : IEEE. - 9781467307604 ; , s. 751-755
-
Konferensbidrag (refereegranskat)abstract
- A secret key agreement setup between three users is considered in which each pair of them wishes to agree on a secret key hidden from the remaining user. The three users observe i.i.d. outputs of correlated sources and there is a noiseless public channel from each user for communication to the others. In this setup, inner and outer bounds of the secret key capacity region is derived. Moreover, some special cases are obtained in which the inner bound coincides the explicit outer bound. Also a binary-erasure example is presented through which the results are examined.
|
|
