Pub Date : 2015-12-03DOI: 10.1109/PIMRC.2015.7343326
L. Mohjazi, Diana W. Dawoud, P. Sofotasios, S. Muhaidat, M. Dianati, M. Valkama, G. Karagiannidis
The present work is devoted to the analytic performance evaluation of cooperative spectrum sensing (CSS) over generalized fading channels. The proposed analysis is based on the efficient Gaussian-Finite-Mixture (GFM) that allows the derivation of a simple and accurate closed-form expression for the average probability of energy detection (ED) under different fading environments. Capitalizing on this, we derive generalized closed-form expressions for the global probabilities of detection for the CSS with two main hard centralized fusion rules, namely, the AND and the OR rules. The efficiency and usefulness of the proposed expressions is justified by comparing the corresponding complementary receiver operating characteristic (ROC) curves for both multipath and composite multipath/shadowing fading channels, which are otherwise particularly difficult to obtain. The offered analytic results are corroborated by respective results from computer simulations and it is shown that the corresponding performance depends significantly on both the severity of fading and the involved number of users in the collaborative network.
{"title":"Unified analysis of cooperative spectrum sensing over generalized multipath fading channels","authors":"L. Mohjazi, Diana W. Dawoud, P. Sofotasios, S. Muhaidat, M. Dianati, M. Valkama, G. Karagiannidis","doi":"10.1109/PIMRC.2015.7343326","DOIUrl":"https://doi.org/10.1109/PIMRC.2015.7343326","url":null,"abstract":"The present work is devoted to the analytic performance evaluation of cooperative spectrum sensing (CSS) over generalized fading channels. The proposed analysis is based on the efficient Gaussian-Finite-Mixture (GFM) that allows the derivation of a simple and accurate closed-form expression for the average probability of energy detection (ED) under different fading environments. Capitalizing on this, we derive generalized closed-form expressions for the global probabilities of detection for the CSS with two main hard centralized fusion rules, namely, the AND and the OR rules. The efficiency and usefulness of the proposed expressions is justified by comparing the corresponding complementary receiver operating characteristic (ROC) curves for both multipath and composite multipath/shadowing fading channels, which are otherwise particularly difficult to obtain. The offered analytic results are corroborated by respective results from computer simulations and it is shown that the corresponding performance depends significantly on both the severity of fading and the involved number of users in the collaborative network.","PeriodicalId":274734,"journal":{"name":"2015 IEEE 26th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123818408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-03DOI: 10.1109/PIMRC.2015.7343602
Atoosa Dalili Shoaei, Mahsa Derakhshani, S. Parsaeefard, T. Le-Ngoc
This paper presents an adaptive hybrid TDMA-CSMA MAC protocol to improve network performance and isolation among service providers (SPs) in a virtualized 802.11 network. Aiming to increase network efficiency, wireless virtual-ization provides the means to slice available resources among different SPs, with an urge to keep different slices isolated. Hybrid TDMA-CSMA can be a proper MAC candidate in such scenario benefiting from both the TDMA isolation power and the CSMA opportunistic nature. In this paper, we propose a dynamic MAC that schedules high-traffic users in the TDMA phase with variable size to be determined. Then, the rest of active users compete to access the channel through CSMA. The objective is to search for a scheduling that maximizes the expected sum throughput subject to SP reservations. In the absence of arrival traffic statistics, this scheduling is modeled as a multi-armed bandit (MAB) problem, in which each arm corresponds to a possible scheduling. Due to the dependency between the arms, existing policies are not directly applicable in this problem. Thus, we present an index-based policy where we update and decide based on learning indexes assigned to each user instead of each arm. To update the indexes, in addition to TDMA information, observations from CSMA phase are used, which adds a new exploration phase for the proposed MAB problem. Throughput and isolation performance of the proposed self-exploration-aided index-based policy (SIP) are evaluated by numerical results.
{"title":"Learning-based hybrid TDMA-CSMA MAC protocol for virtualized 802.11 WLANs","authors":"Atoosa Dalili Shoaei, Mahsa Derakhshani, S. Parsaeefard, T. Le-Ngoc","doi":"10.1109/PIMRC.2015.7343602","DOIUrl":"https://doi.org/10.1109/PIMRC.2015.7343602","url":null,"abstract":"This paper presents an adaptive hybrid TDMA-CSMA MAC protocol to improve network performance and isolation among service providers (SPs) in a virtualized 802.11 network. Aiming to increase network efficiency, wireless virtual-ization provides the means to slice available resources among different SPs, with an urge to keep different slices isolated. Hybrid TDMA-CSMA can be a proper MAC candidate in such scenario benefiting from both the TDMA isolation power and the CSMA opportunistic nature. In this paper, we propose a dynamic MAC that schedules high-traffic users in the TDMA phase with variable size to be determined. Then, the rest of active users compete to access the channel through CSMA. The objective is to search for a scheduling that maximizes the expected sum throughput subject to SP reservations. In the absence of arrival traffic statistics, this scheduling is modeled as a multi-armed bandit (MAB) problem, in which each arm corresponds to a possible scheduling. Due to the dependency between the arms, existing policies are not directly applicable in this problem. Thus, we present an index-based policy where we update and decide based on learning indexes assigned to each user instead of each arm. To update the indexes, in addition to TDMA information, observations from CSMA phase are used, which adds a new exploration phase for the proposed MAB problem. Throughput and isolation performance of the proposed self-exploration-aided index-based policy (SIP) are evaluated by numerical results.","PeriodicalId":274734,"journal":{"name":"2015 IEEE 26th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122907226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-03DOI: 10.1109/PIMRC.2015.7343500
M. I. Hossain, Andres Laya, Francesco Militano, S. Iraji, J. Markendahl
The increasing adoption of Machine-Type Communication (MTC) applications on existing Long Term Evolution (LTE) brings new challenges for traditional signaling mechanism and system capacity. MTC is related to high number of devices; which represents a challenge when performing control and signaling procedures required for getting resource grant, since these processes are inefficient compared to the actual resource usage for small data transmissions. Solutions based on device grouping propose a static grouping approach, which does not perform well in low load scenario. This paper introduces the notion of a flexible admission/connection that can give granular group device control to Core network. With the proposed approach devices can be grouped for a certain period of time under supervision and control of a gateway and they can be ungrouped when there is no need for grouping them together. In this way, a finer control can be achieved on prioritizing certain services and load balancing. Our simulation results demonstrate significant signaling reduction by using this simple scheme compared to conventional connection procedure.
{"title":"Reducing signaling overload: Flexible capillary admission control for dense MTC over LTE networks","authors":"M. I. Hossain, Andres Laya, Francesco Militano, S. Iraji, J. Markendahl","doi":"10.1109/PIMRC.2015.7343500","DOIUrl":"https://doi.org/10.1109/PIMRC.2015.7343500","url":null,"abstract":"The increasing adoption of Machine-Type Communication (MTC) applications on existing Long Term Evolution (LTE) brings new challenges for traditional signaling mechanism and system capacity. MTC is related to high number of devices; which represents a challenge when performing control and signaling procedures required for getting resource grant, since these processes are inefficient compared to the actual resource usage for small data transmissions. Solutions based on device grouping propose a static grouping approach, which does not perform well in low load scenario. This paper introduces the notion of a flexible admission/connection that can give granular group device control to Core network. With the proposed approach devices can be grouped for a certain period of time under supervision and control of a gateway and they can be ungrouped when there is no need for grouping them together. In this way, a finer control can be achieved on prioritizing certain services and load balancing. Our simulation results demonstrate significant signaling reduction by using this simple scheme compared to conventional connection procedure.","PeriodicalId":274734,"journal":{"name":"2015 IEEE 26th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127756376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-03DOI: 10.1109/PIMRC.2015.7343565
Kun Yang, Pingyang Wang, Xuefen Hong, Xing Zhang
One of the main purposes for heterogeneous wireless networks is to promote the network energy efficiency. Cell Range Expansion (CRE), as a promising solution to offload macro BS traffic and improve the network capacity, will help to improve the network energy efficiency. Users that offloaded to micro Base Stations (BSs) will always have much lower downlink (DL) signal-to-interference-and-noise ratio (SINR) but higher uplink (UL) SINR. Therefore, introducing CRE can improve UL transmission performance while decrease DL performance slightly. In this paper, exploiting stochastic geometry, we focus on the performance of downlink and uplink joint transmission in two-tier heterogeneous network where micro BS employs CRE. We derive the expression of whole network transmission success probability (TSP) and energy efficiency (EE) which considering joint transmission of DL and UL. Both theoretical and simulation results show that there is an optimal CRE bias and an optimal transmit power of macro BS to maximize TSP and EE. When the optimal value of CRE bias is selected, the increase of micro BS density has little influence on EE but can improve TSP considerably.
异构无线网络的主要目的之一是提高网络的能量效率。小区范围扩展(Cell Range Expansion, CRE)是一种很有前途的解决方案，可以减轻宏观BS业务的负担，提高网络容量，有助于提高网络的能源效率。卸载到微型基站(BSs)的用户总是具有更低的下行链路(DL)信噪比(SINR)，但更高的上行链路(UL) SINR。因此，引入CRE可以提高UL传输性能，同时略微降低DL传输性能。本文利用随机几何理论，研究了微基站采用CRE的两层异构网络中下行和上行联合传输的性能。推导了考虑DL和UL联合传输的全网传输成功率(TSP)和能量效率(EE)的表达式。理论和仿真结果均表明，为了使TSP和EE最大化，宏观BS存在最优CRE偏置和最优发射功率。当CRE偏置的最优值选定时，微BS密度的增加对EE影响不大，但能显著提高TSP。
{"title":"Joint downlink and uplink network performance analysis with CRE in heterogeneous wireless network","authors":"Kun Yang, Pingyang Wang, Xuefen Hong, Xing Zhang","doi":"10.1109/PIMRC.2015.7343565","DOIUrl":"https://doi.org/10.1109/PIMRC.2015.7343565","url":null,"abstract":"One of the main purposes for heterogeneous wireless networks is to promote the network energy efficiency. Cell Range Expansion (CRE), as a promising solution to offload macro BS traffic and improve the network capacity, will help to improve the network energy efficiency. Users that offloaded to micro Base Stations (BSs) will always have much lower downlink (DL) signal-to-interference-and-noise ratio (SINR) but higher uplink (UL) SINR. Therefore, introducing CRE can improve UL transmission performance while decrease DL performance slightly. In this paper, exploiting stochastic geometry, we focus on the performance of downlink and uplink joint transmission in two-tier heterogeneous network where micro BS employs CRE. We derive the expression of whole network transmission success probability (TSP) and energy efficiency (EE) which considering joint transmission of DL and UL. Both theoretical and simulation results show that there is an optimal CRE bias and an optimal transmit power of macro BS to maximize TSP and EE. When the optimal value of CRE bias is selected, the increase of micro BS density has little influence on EE but can improve TSP considerably.","PeriodicalId":274734,"journal":{"name":"2015 IEEE 26th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133920641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-03DOI: 10.1109/PIMRC.2015.7343464
Liang Chen, Lin Ma, Yubin Xu
Advanced interference coordination and resource management schemes are important in heterogeneous wireless networks in order to achieve a high network capacity and good user experience. In this paper, we present a joint consideration of the sub-channel allocation and power distribution in MIMO two-tier networks where the femtocells form clusters of equal size. All of the BSs have a multi-antenna configuration utilizing zero-forcing beamforming. The optimization objective maximizes the long-term system throughput and guarantees the fairness among Femto users (FUEs) in different tiers at the same time. After that, a modified genetic algorithm (GA) is addressed to resolve the mixed-integer nonlinear programming problem involved. Each chromosome in the proposed GA is divided into an integer string for sub-channel allocation, and a real number strings for power distribution. In addition, new initialization, crossover and mutation operations are employed for this new type of chromosomes. Conducted simulations show that the proposed GA can increase the throughput of the system and guarantee the fairness among the FUEs.
{"title":"Fairness awared joint sub-channel and power allocation via genetic algorithm in MIMO two-tier networks","authors":"Liang Chen, Lin Ma, Yubin Xu","doi":"10.1109/PIMRC.2015.7343464","DOIUrl":"https://doi.org/10.1109/PIMRC.2015.7343464","url":null,"abstract":"Advanced interference coordination and resource management schemes are important in heterogeneous wireless networks in order to achieve a high network capacity and good user experience. In this paper, we present a joint consideration of the sub-channel allocation and power distribution in MIMO two-tier networks where the femtocells form clusters of equal size. All of the BSs have a multi-antenna configuration utilizing zero-forcing beamforming. The optimization objective maximizes the long-term system throughput and guarantees the fairness among Femto users (FUEs) in different tiers at the same time. After that, a modified genetic algorithm (GA) is addressed to resolve the mixed-integer nonlinear programming problem involved. Each chromosome in the proposed GA is divided into an integer string for sub-channel allocation, and a real number strings for power distribution. In addition, new initialization, crossover and mutation operations are employed for this new type of chromosomes. Conducted simulations show that the proposed GA can increase the throughput of the system and guarantee the fairness among the FUEs.","PeriodicalId":274734,"journal":{"name":"2015 IEEE 26th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134233127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-03DOI: 10.1109/PIMRC.2015.7343313
Xiongwen Zhao, Qingdong Han, Bin Li, Jianwu Dou, W. Hong
Based on a ring, a disk and an elliptical scattering models, the power spectrum densities (PSDs) are derived and investigated for fixed-to-fixed (F2F) propagation scenarios where a local scatterer is moving in any direction with random velocity at the predefined geometries of the models. The velocity distributions of the scatterers are assumed to follow uniform, exponential and mixed Gaussian, and the transceiver vehicles are moving either with low- and high-speed. The results show that the one-ring, disk scattering model and the model in [15] are very close in describing the PSDs for the F2F radio channels. Moreover, different shape factors have little effect on the PSDs in the disk model. As the shape factor is large enough, the disk model tends to be the same as the one-ring model. The PSDs derived from the elliptical model are different from the one-ring and disk models because the scatterers are distributed not only close to the transceiver ends, but also between the transceiver.
{"title":"Doppler power spectrum densities for fixed-to-fixed radio channels with moving scatterers in millimeter-wave band","authors":"Xiongwen Zhao, Qingdong Han, Bin Li, Jianwu Dou, W. Hong","doi":"10.1109/PIMRC.2015.7343313","DOIUrl":"https://doi.org/10.1109/PIMRC.2015.7343313","url":null,"abstract":"Based on a ring, a disk and an elliptical scattering models, the power spectrum densities (PSDs) are derived and investigated for fixed-to-fixed (F2F) propagation scenarios where a local scatterer is moving in any direction with random velocity at the predefined geometries of the models. The velocity distributions of the scatterers are assumed to follow uniform, exponential and mixed Gaussian, and the transceiver vehicles are moving either with low- and high-speed. The results show that the one-ring, disk scattering model and the model in [15] are very close in describing the PSDs for the F2F radio channels. Moreover, different shape factors have little effect on the PSDs in the disk model. As the shape factor is large enough, the disk model tends to be the same as the one-ring model. The PSDs derived from the elliptical model are different from the one-ring and disk models because the scatterers are distributed not only close to the transceiver ends, but also between the transceiver.","PeriodicalId":274734,"journal":{"name":"2015 IEEE 26th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134346887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-03DOI: 10.1109/PIMRC.2015.7343352
Kyeongyeon Kim, Y. Yun, Chanhong Kim, Z. Ho, Yong-Ho Cho, J. Seol
As a promising candidate to replace cyclic prefixed orthogonal frequency division multiplexing (CP-OFDM), a new quadrature amplitude modulation filter-bank multi-carrier (QAM-FBMC) has been proposed for enabling spectral efficiency increase and spectrum confinement while keeping near orthogonality. QAM transmission can combat intrinsic interference of conventional offset-QAM (OQAM)-FBMC, which is main bottleneck in channel estimator and multiple antenna transceiver design. Compared to existing single filter based QAM-FBMC, the new QAM-FBMC has more optimization freedom in multiple prototype filters to increase self signal-to-interference ratio (SIR). In this paper, the possibility of per-tone multiple input multiple output (MIMO) reception in the new QAM-FBMC system is exploited. Our MIMO receiver is constructed with per-tone MIMO equalization in oversampled signal domain and its soft-demapper in symbol domain. Not only the separate log likelihood ratio (LLR) calculation per stream but also joint LLR calculation (i.e., soft maximum likelihood (ML) detection) is implemented with pre-processing. Simulation results show that the per-tone MIMO reception in QAM-FBMC is comparable to that of CP-OFDM.
{"title":"Pre-processing based soft-demapper for per-tone MIMO operation in QAM-FBMC systems","authors":"Kyeongyeon Kim, Y. Yun, Chanhong Kim, Z. Ho, Yong-Ho Cho, J. Seol","doi":"10.1109/PIMRC.2015.7343352","DOIUrl":"https://doi.org/10.1109/PIMRC.2015.7343352","url":null,"abstract":"As a promising candidate to replace cyclic prefixed orthogonal frequency division multiplexing (CP-OFDM), a new quadrature amplitude modulation filter-bank multi-carrier (QAM-FBMC) has been proposed for enabling spectral efficiency increase and spectrum confinement while keeping near orthogonality. QAM transmission can combat intrinsic interference of conventional offset-QAM (OQAM)-FBMC, which is main bottleneck in channel estimator and multiple antenna transceiver design. Compared to existing single filter based QAM-FBMC, the new QAM-FBMC has more optimization freedom in multiple prototype filters to increase self signal-to-interference ratio (SIR). In this paper, the possibility of per-tone multiple input multiple output (MIMO) reception in the new QAM-FBMC system is exploited. Our MIMO receiver is constructed with per-tone MIMO equalization in oversampled signal domain and its soft-demapper in symbol domain. Not only the separate log likelihood ratio (LLR) calculation per stream but also joint LLR calculation (i.e., soft maximum likelihood (ML) detection) is implemented with pre-processing. Simulation results show that the per-tone MIMO reception in QAM-FBMC is comparable to that of CP-OFDM.","PeriodicalId":274734,"journal":{"name":"2015 IEEE 26th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115322179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-03DOI: 10.1109/PIMRC.2015.7343394
I-Wei Lai, Chia-han Lee, G. Ascheid, H. Meyr, T. Chiueh
We propose an efficient iterative multiple-input multiple-output (MIMO) detection algorithm based on the local search. Specifically, since the MIMO channel matrix twists the lattice structure of the received symbols, the proposed channel-aware local search (CA-LS) defines its search neighborhood according to the instantaneous channel realization. Such channel-dependent neighborhood can be efficiently identified by using the sphere decoder in a set that comprises the differences between pairs of QAM vectors, which is termed as delta vectors. The delta vectors with small quadratic norms with respect to the channel matrix are identified and then used as the search directions of the CA-LS. Features like sparsity and non-uniformity of delta vectors are exploited to reduce the SD complexity. Furthermore, by reformulating the detection criterion, the log-likelihood ratio (LLR) computations and searches of the CA-LS are greatly simplified. Numerical simulations demonstrate that compared with other practical iterative MIMO detectors, e.g., the list sphere decoder, the CA-LS achieves superior performance in both error rate and complexity aspects.
{"title":"Channel-aware local search (CA-LS) for iterative MIMO detection","authors":"I-Wei Lai, Chia-han Lee, G. Ascheid, H. Meyr, T. Chiueh","doi":"10.1109/PIMRC.2015.7343394","DOIUrl":"https://doi.org/10.1109/PIMRC.2015.7343394","url":null,"abstract":"We propose an efficient iterative multiple-input multiple-output (MIMO) detection algorithm based on the local search. Specifically, since the MIMO channel matrix twists the lattice structure of the received symbols, the proposed channel-aware local search (CA-LS) defines its search neighborhood according to the instantaneous channel realization. Such channel-dependent neighborhood can be efficiently identified by using the sphere decoder in a set that comprises the differences between pairs of QAM vectors, which is termed as delta vectors. The delta vectors with small quadratic norms with respect to the channel matrix are identified and then used as the search directions of the CA-LS. Features like sparsity and non-uniformity of delta vectors are exploited to reduce the SD complexity. Furthermore, by reformulating the detection criterion, the log-likelihood ratio (LLR) computations and searches of the CA-LS are greatly simplified. Numerical simulations demonstrate that compared with other practical iterative MIMO detectors, e.g., the list sphere decoder, the CA-LS achieves superior performance in both error rate and complexity aspects.","PeriodicalId":274734,"journal":{"name":"2015 IEEE 26th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114185023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-03DOI: 10.1109/PIMRC.2015.7343548
Rahul Thakur, Vijeth J. Kotagi, C. Murthy
Use of femtocells for indoor and office environment has proved to be an effective solution to handle ever increasing mobile data demands. Femtocell helps improving network capacity in an energy efficient manner without significantly burdening the operator with huge capital and operational expenditure. Since extremely dense femtocell deployments are expected in near future, it is of interest to look into their energy efficiency measures. In this paper, we analyse the energy efficiency aspect of cell selection scheme for femtocell networks. Cell selection scheme defines the criteria on which mobile users associate themselves with base stations. Hence, it plays a crucial role in system load balancing and total energy consumption. We suggest a unique cell selection scheme that assigns mobile users to femtocell base stations considering the capacity improvement obtained per unit increase in transmit power. Our proposed scheme shows an improvement in network performance in terms of both system capacity and energy efficiency. Additionally, we suggest the use of power spreading over subchannels to keep overall interference minimum while maximizing spectrum utilization.
{"title":"An energy efficient cell selection scheme for femtocell network with spreading","authors":"Rahul Thakur, Vijeth J. Kotagi, C. Murthy","doi":"10.1109/PIMRC.2015.7343548","DOIUrl":"https://doi.org/10.1109/PIMRC.2015.7343548","url":null,"abstract":"Use of femtocells for indoor and office environment has proved to be an effective solution to handle ever increasing mobile data demands. Femtocell helps improving network capacity in an energy efficient manner without significantly burdening the operator with huge capital and operational expenditure. Since extremely dense femtocell deployments are expected in near future, it is of interest to look into their energy efficiency measures. In this paper, we analyse the energy efficiency aspect of cell selection scheme for femtocell networks. Cell selection scheme defines the criteria on which mobile users associate themselves with base stations. Hence, it plays a crucial role in system load balancing and total energy consumption. We suggest a unique cell selection scheme that assigns mobile users to femtocell base stations considering the capacity improvement obtained per unit increase in transmit power. Our proposed scheme shows an improvement in network performance in terms of both system capacity and energy efficiency. Additionally, we suggest the use of power spreading over subchannels to keep overall interference minimum while maximizing spectrum utilization.","PeriodicalId":274734,"journal":{"name":"2015 IEEE 26th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)","volume":"170 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114305331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-03DOI: 10.1109/PIMRC.2015.7343283
Reham Almesaeed, N. Abdullah, A. Doufexi, A. Nix
In order to alleviate the mobile data explosion problem, a Wi-Fi offloading strategy has been proposed. Given the recent deployment of Wi-Fi like systems in the TVWS (TV White Space), the mobile offloading to White-Fi networks is an attractive solution to mobile operators to provide full broadband coverage in dense urban environments. To quantify the amount of throughput and coverage gain achieved from users offloading, this paper conducts a simulation-based analysis for a range of carrier class access points (AP) densities considering practical deployment of the IEEE 802.11af and 802.11g networks. The study takes into account a realistic modelling of the TV channels availability and wireless channel propagation. The interference from co-channel operation and DVB-T systems are also considered. The paper shows that the opportunistic deployment of White-Fi networks generally results in high throughput gain and coverage probability at various AP densities as compared to Wi-Fi only networks. It also grants a higher fraction of users with high throughput capability as compared to 802.11g only networks. In addition, the study provides the mobile operators with a range of performance statistics that can help them to select the suitable range of AP deployment to meet certain performance thresholds.
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