Per Skillermark - Academia.edu (original) (raw)

Papers by Per Skillermark

This paper presents a generic radio access network cost assessment and optimisation methodology, ... more This paper presents a generic radio access network cost assessment and optimisation methodology, allowing a performance-vs.-cost assessment of different deployment options considered in beyond-3G networks as, e.g., the WINNER1 system. Cost assessments are based on an identification and classification of relevant cost components of advanced radio access network deployments, including radio access points of different types, like macro and micro

2011 2nd International Conference on Wireless Communication, Vehicular Technology, Information Theory and Aerospace & Electronic Systems Technology (Wireless VITAE), 2011

... BS antenna 3D model from [2], 1 degree down-ltilt Terminal antenna Omni, indoor or outdoor, w... more ... BS antenna 3D model from [2], 1 degree down-ltilt Terminal antenna Omni, indoor or outdoor, with 0dBi gain or direc-tional outdoor with 13dBi gain Modulation and cod-ing schemes QPSK, 16QAM, 64 QAM, Turbo codes with rates according to standard Scheduling Round ...

2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007

In this paper, the impact of transmit antenna separations at the base station on the downlink in ... more In this paper, the impact of transmit antenna separations at the base station on the downlink in a cellular OFDM system with per antenna rate control (PARC) is investigated. For the minimum mean square error (MMSE) with successive interference cancellation (SIC) receiver, the highly correlated interference resulting from closely spaced antennas is more easily suppressed than the independent interference resulting

2008 14th European Wireless Conference, 2008

In this paper, multiple antenna based intercell interference mitigation techniques are studied in... more In this paper, multiple antenna based intercell interference mitigation techniques are studied in the downlink of an OFDM-based cellular radio network. At the base stations, multiple antennas are used for transmit beamforming in order to reduce the intercell interference spatially spread in the network. At the user terminals, multiple receive antennas facilitate implementation of interference rejecting baseband signal processing techniques,

2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007

This paper presents and evaluates different multi-antenna deployments in an OFDM wireless system.... more This paper presents and evaluates different multi-antenna deployments in an OFDM wireless system. Two downlink implementations, higher order sectorization (HOS) and downlink SDMA using fixed beams (FB), are considered. HOS with 3-, 6-, and 12-sector sites are compared with downlink FB SDMA in a 3-sector site where each sector is using up to four antennas. In the uplink we evaluate SDMA using multi-antenna MMSE receiver at base station. The simulation results indicate that in the downlink FB SDMA with four antennas per sector provides a cell throughput improvement of more than 100% compared to a 3-sector site equipped with a single antenna each. The gain can be further improved by using HOS at the expense of additional complexity. The uplink results show that SDMA allows to increase the throughput by up to a factor of two.

VTC Spring 2008 - IEEE Vehicular Technology Conference, 2008

This paper outlines and evaluates a simplified interference model applicable in multi-cell multi-... more This paper outlines and evaluates a simplified interference model applicable in multi-cell multi-antenna radio network simulations. Based on the path-loss, the model classifies interferers as either strong or weak and the channels of strong interferers together with the channel of the desired signal are accurately modeled using a spatial channel model (SCM). The SCM assures that the spatial signature of the signals is accounted for in the evaluations. The channels of weak interferers are simply characterized by the path-loss and interference is modeled as additive white Gaussian noise (AWGN). The model is verified by means of simulations of a 57 sector OFDM/TDMA network and by comparing results achieved using the simplified model to results from simulations with full interference modeling, i.e., to the case when all interferers are accurately modeled. The verification results demonstrate that the simplified model with at least eight links accurately modeled provides a high modeling accuracy and results are comparable to results achieved with full interference modeling. Moreover, in the employed simulation tool this reduces the simulation time by up to a factor of four. The model may hence be used as a means to speed up simulations of multi-cell multi-antenna radio networks.

2010 IEEE 72nd Vehicular Technology Conference - Fall, 2010

In this paper, we consider the problem of joint adaptive beamforming from multiple Access Points ... more In this paper, we consider the problem of joint adaptive beamforming from multiple Access Points (APs), equipped with array antennas, to multiple single-antenna User Equipments (UEs). We derive an iterative algorithm for Multi-Cell Beam-Forming (MCBF) under per-cell power constraints and the constraint that a UE may receive data transmission from a single AP. The scheme is suitable for coordinated beamforming

2009 IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications, 2009

The test environments for system level evaluations of IMT-A (International Mobile Telecommunicati... more The test environments for system level evaluations of IMT-A (International Mobile Telecommunications-Advanced) candidate technologies are analyzed. Compared to the evaluation criteria for previous IMT standards, the IMT-A test environments provide significantly more realistic settings for evaluating system-level performance. The models include line-ofsight probability in all scenarios, different groups of users in terms of propagation and speed, as well as indoor and outdoor deployments. This contribution scrutinizes the evaluation conditions and presents resulting performance for a basic Long-Term Evolution (LTE) candidate system. Each environment contains challenging characteristics. Examples include a mix of indoor and outdoor users, a mix of line-of-sight and non-line-ofsight conditions, and terminal speeds making accurate tracking of channel quality difficult. Together, these characteristics suggest that a radio transmission technology fulfilling the ITU IMT-A requirements is well suited for meeting a variety of challenges of real deployment scenarios.

Recently, several works have pointed out the negative impact of intercell interference variation ... more Recently, several works have pointed out the negative impact of intercell interference variation on the performance of link adaptation in multi-cell single input single output (SISO) systems. However, the performance of adaptive precoder selection in multiple input multiple output (MIMO) cellular networks in the presence of interference variation is much less understood. In this paper we develop a simulation model for MIMO orthogonal frequency division multiple access (OFDMA) networks that allows us to study the impact of popular scheduling and power control algorithms on the time variation of the uplink interference power. We find that employing a time persistent proportional fair scheduler (which we term proportional fair in frequency, PFF, scheduler) together with an open loop power control scheme significantly reduces intercell interference variation and thereby it provides higher throughput than traditional schedulers that are primarily optimized for a single cell setting without taking into account the variation of the intercell interference power.

VTC Spring 2008 - IEEE Vehicular Technology Conference, 2008

The expected performance improvements of next- generation mobile radio access networks (RANs) can... more The expected performance improvements of next- generation mobile radio access networks (RANs) can be achieved, e.g., by a flexible deployment of different types of radio access points (RAPs), such as intelligent relay nodes (RNs). To facilitate a cost-vs.-performance assessment of different deployment options, this paper presents a classification of different RAN cost components. Then, a method for deployment cost optimization

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference, 2009

Future cellular networks are expected to provide significantly higher capacity than today's syste... more Future cellular networks are expected to provide significantly higher capacity than today's systems. To support this higher capacity a denser deployment might be necessary. An alternative way is to deploy Multiple-Input-Multiple-Output (MIMO) base stations (BSs), called advanced BSs, so that the system capacity is improved without increasing the BSs density. This paper compares Single-Input-Single-Output (SISO) BS deployments with MIMO BS deployments from a cost perspective. We use a deployment methodology starting with a sparse density of BSs. By deploying additional BSs sequentially the number of BSs is increased until the traffic demand in the network area is supported. Providing equal service level, i.e., supporting the same traffic demand, by means of different deployment realizations enables a relevant comparison between the alternative single and multiple antenna systems. With the models and assumptions used here, results show that in order to support the same users' service level, the cost of deploying MIMO BSs is significantly less compared to increasing the density of SISO BSs. The cost gain is due to the reducing of the number of required BSs for the case of MIMO deployment.

International Journal of Communication Systems, 2009

The current 3GPP working assumption on the Evolved Universal Terrestrial Radio Access (E-UTRA) ph... more The current 3GPP working assumption on the Evolved Universal Terrestrial Radio Access (E-UTRA) physical layer is that it will be based on single carrier frequency division multiple access (SC-FDMA) for the uplink and orthogonal frequency division multiple access (OFDMA) for the downlink. According to the concept specification, inter-cell interference mitigation techniques applicable to SC-FDMA and OFDMA systems are expected to be the key radio resource management techniques for E-UTRA. In this paper we propose and analyze a simple reuse partitioning technique (assuming coordinated subcarrier allocation in the cells) that is able to minimize intercell interference. We propose a model that is able to take into account that sessions dynamically enter and leave the system. Rigid sessions require a class-specific fixed number of subcarriers, while elastic sessions can enter the system if a minimum number of sub-carriers is allocated to them. In this rather general setting we analyze the system performance in terms of the expected number of sub-carrier collisions, the session blocking probabilities and the signal-to-noise-and-interference ratio performance. We present numerical results on the various trade-offs between these measures that provide insight into the behavior of OFDM based cellular systems and help dimension the parameters of a reuse partitioned system.

IEEE Journal on Selected Areas in Communications, 2000

This paper discusses the requirements on future radio access and, based on the requirements, prop... more This paper discusses the requirements on future radio access and, based on the requirements, proposes a framework for such a system. The proposed system based on orthogonal frequency-division multiplexing supports very low latencies and data rates up to 100 Mb/s with wide area coverage and 1 Gb/s with local area coverage. Spectrum flexibility is identified as one main requirement for future systems, and the proposed framework can be deployed in a wide range of spectrum allocations with bandwidths ranging from 2.5 to 100 MHz. Multihop relaying, useful to extend the range for the high data rates, and multiple-antenna configurations are integral parts of the framework. A packet-centric approach is taken for the dataflow processing, implying that the scheduling mechanism and the retransmission protocol operate on complete packets rather than segments thereof, thus allowing for cross-layer optimization. Finally, numerical evaluations are provided, illustrating the feasibility of future very wideband radio access.

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 2007

Future cellular networks are expected to provide significantly higher capacity than today's ... more Future cellular networks are expected to provide significantly higher capacity than today's systems. This might require a denser access point deployment, with a potential increase in network deployment cost as a consequence. A promising way to reduce cost is a multi-hop deployment where wireless relay nodes (RN) are introduced to enhance capacity and coverage. In this paper, a deployment procedure

IEEE WIRELESS COMMUNICATIONS, 2011

The global mobile communication industry is growing rapidly. Today there are already more than 4 ... more The global mobile communication industry is growing rapidly. Today there are already more than 4 billion mobile phone subscribers worldwide [1], more than half the entire population of the planet. Obviously, this growth is accompanied by an increased energy consumption of mobile networks. Global warming and heightened concerns for the environment of the planet require a special focus on the energy efficiency of these systems . The EARTH 1 project [3] is a concerted effort to achieve this goal and as part of its objectives, a holistic framework is developed to evaluate and compare the energy efficiency of several design approaches of wireless cellular communication networks.

2011 IEEE 73rd Vehicular Technology Conference (VTC Spring), 2011

In order to quantify the energy savings in wireless networks, the power consumption of the entire... more In order to quantify the energy savings in wireless networks, the power consumption of the entire system needs to be captured and an appropriate energy efficiency evaluation framework must be defined. In this paper, the necessary enhancements over existing performance evaluation frameworks are discussed, such that the energy efficiency of the entire network comprising component, node and network level contributions can be quantified. The most important addendums over existing frameworks include a sophisticated power model for various base station (BS) types, which maps the RF output power radiated at the antenna elements to the total supply power of a BS site. We also consider an approach to quantify the energy efficiency of large geographical areas by using the existing small scale deployment models along with long term traffic models. Finally, the proposed evaluation framework is applied to quantify the energy efficiency of the downlink of a 3GPP LTE radio access network.

This paper presents a generic radio access network cost assessment and optimisation methodology, ... more This paper presents a generic radio access network cost assessment and optimisation methodology, allowing a performance-vs.-cost assessment of different deployment options considered in beyond-3G networks as, e.g., the WINNER1 system. Cost assessments are based on an identification and classification of relevant cost components of advanced radio access network deployments, including radio access points of different types, like macro and micro

2011 2nd International Conference on Wireless Communication, Vehicular Technology, Information Theory and Aerospace & Electronic Systems Technology (Wireless VITAE), 2011

... BS antenna 3D model from [2], 1 degree down-ltilt Terminal antenna Omni, indoor or outdoor, w... more ... BS antenna 3D model from [2], 1 degree down-ltilt Terminal antenna Omni, indoor or outdoor, with 0dBi gain or direc-tional outdoor with 13dBi gain Modulation and cod-ing schemes QPSK, 16QAM, 64 QAM, Turbo codes with rates according to standard Scheduling Round ...

2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007

In this paper, the impact of transmit antenna separations at the base station on the downlink in ... more In this paper, the impact of transmit antenna separations at the base station on the downlink in a cellular OFDM system with per antenna rate control (PARC) is investigated. For the minimum mean square error (MMSE) with successive interference cancellation (SIC) receiver, the highly correlated interference resulting from closely spaced antennas is more easily suppressed than the independent interference resulting

2008 14th European Wireless Conference, 2008

In this paper, multiple antenna based intercell interference mitigation techniques are studied in... more In this paper, multiple antenna based intercell interference mitigation techniques are studied in the downlink of an OFDM-based cellular radio network. At the base stations, multiple antennas are used for transmit beamforming in order to reduce the intercell interference spatially spread in the network. At the user terminals, multiple receive antennas facilitate implementation of interference rejecting baseband signal processing techniques,

2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007

This paper presents and evaluates different multi-antenna deployments in an OFDM wireless system.... more This paper presents and evaluates different multi-antenna deployments in an OFDM wireless system. Two downlink implementations, higher order sectorization (HOS) and downlink SDMA using fixed beams (FB), are considered. HOS with 3-, 6-, and 12-sector sites are compared with downlink FB SDMA in a 3-sector site where each sector is using up to four antennas. In the uplink we evaluate SDMA using multi-antenna MMSE receiver at base station. The simulation results indicate that in the downlink FB SDMA with four antennas per sector provides a cell throughput improvement of more than 100% compared to a 3-sector site equipped with a single antenna each. The gain can be further improved by using HOS at the expense of additional complexity. The uplink results show that SDMA allows to increase the throughput by up to a factor of two.

VTC Spring 2008 - IEEE Vehicular Technology Conference, 2008

This paper outlines and evaluates a simplified interference model applicable in multi-cell multi-... more This paper outlines and evaluates a simplified interference model applicable in multi-cell multi-antenna radio network simulations. Based on the path-loss, the model classifies interferers as either strong or weak and the channels of strong interferers together with the channel of the desired signal are accurately modeled using a spatial channel model (SCM). The SCM assures that the spatial signature of the signals is accounted for in the evaluations. The channels of weak interferers are simply characterized by the path-loss and interference is modeled as additive white Gaussian noise (AWGN). The model is verified by means of simulations of a 57 sector OFDM/TDMA network and by comparing results achieved using the simplified model to results from simulations with full interference modeling, i.e., to the case when all interferers are accurately modeled. The verification results demonstrate that the simplified model with at least eight links accurately modeled provides a high modeling accuracy and results are comparable to results achieved with full interference modeling. Moreover, in the employed simulation tool this reduces the simulation time by up to a factor of four. The model may hence be used as a means to speed up simulations of multi-cell multi-antenna radio networks.

2010 IEEE 72nd Vehicular Technology Conference - Fall, 2010

In this paper, we consider the problem of joint adaptive beamforming from multiple Access Points ... more In this paper, we consider the problem of joint adaptive beamforming from multiple Access Points (APs), equipped with array antennas, to multiple single-antenna User Equipments (UEs). We derive an iterative algorithm for Multi-Cell Beam-Forming (MCBF) under per-cell power constraints and the constraint that a UE may receive data transmission from a single AP. The scheme is suitable for coordinated beamforming

2009 IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications, 2009

The test environments for system level evaluations of IMT-A (International Mobile Telecommunicati... more The test environments for system level evaluations of IMT-A (International Mobile Telecommunications-Advanced) candidate technologies are analyzed. Compared to the evaluation criteria for previous IMT standards, the IMT-A test environments provide significantly more realistic settings for evaluating system-level performance. The models include line-ofsight probability in all scenarios, different groups of users in terms of propagation and speed, as well as indoor and outdoor deployments. This contribution scrutinizes the evaluation conditions and presents resulting performance for a basic Long-Term Evolution (LTE) candidate system. Each environment contains challenging characteristics. Examples include a mix of indoor and outdoor users, a mix of line-of-sight and non-line-ofsight conditions, and terminal speeds making accurate tracking of channel quality difficult. Together, these characteristics suggest that a radio transmission technology fulfilling the ITU IMT-A requirements is well suited for meeting a variety of challenges of real deployment scenarios.

Recently, several works have pointed out the negative impact of intercell interference variation ... more Recently, several works have pointed out the negative impact of intercell interference variation on the performance of link adaptation in multi-cell single input single output (SISO) systems. However, the performance of adaptive precoder selection in multiple input multiple output (MIMO) cellular networks in the presence of interference variation is much less understood. In this paper we develop a simulation model for MIMO orthogonal frequency division multiple access (OFDMA) networks that allows us to study the impact of popular scheduling and power control algorithms on the time variation of the uplink interference power. We find that employing a time persistent proportional fair scheduler (which we term proportional fair in frequency, PFF, scheduler) together with an open loop power control scheme significantly reduces intercell interference variation and thereby it provides higher throughput than traditional schedulers that are primarily optimized for a single cell setting without taking into account the variation of the intercell interference power.

VTC Spring 2008 - IEEE Vehicular Technology Conference, 2008

The expected performance improvements of next- generation mobile radio access networks (RANs) can... more The expected performance improvements of next- generation mobile radio access networks (RANs) can be achieved, e.g., by a flexible deployment of different types of radio access points (RAPs), such as intelligent relay nodes (RNs). To facilitate a cost-vs.-performance assessment of different deployment options, this paper presents a classification of different RAN cost components. Then, a method for deployment cost optimization

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference, 2009

Future cellular networks are expected to provide significantly higher capacity than today's syste... more Future cellular networks are expected to provide significantly higher capacity than today's systems. To support this higher capacity a denser deployment might be necessary. An alternative way is to deploy Multiple-Input-Multiple-Output (MIMO) base stations (BSs), called advanced BSs, so that the system capacity is improved without increasing the BSs density. This paper compares Single-Input-Single-Output (SISO) BS deployments with MIMO BS deployments from a cost perspective. We use a deployment methodology starting with a sparse density of BSs. By deploying additional BSs sequentially the number of BSs is increased until the traffic demand in the network area is supported. Providing equal service level, i.e., supporting the same traffic demand, by means of different deployment realizations enables a relevant comparison between the alternative single and multiple antenna systems. With the models and assumptions used here, results show that in order to support the same users' service level, the cost of deploying MIMO BSs is significantly less compared to increasing the density of SISO BSs. The cost gain is due to the reducing of the number of required BSs for the case of MIMO deployment.

International Journal of Communication Systems, 2009

The current 3GPP working assumption on the Evolved Universal Terrestrial Radio Access (E-UTRA) ph... more The current 3GPP working assumption on the Evolved Universal Terrestrial Radio Access (E-UTRA) physical layer is that it will be based on single carrier frequency division multiple access (SC-FDMA) for the uplink and orthogonal frequency division multiple access (OFDMA) for the downlink. According to the concept specification, inter-cell interference mitigation techniques applicable to SC-FDMA and OFDMA systems are expected to be the key radio resource management techniques for E-UTRA. In this paper we propose and analyze a simple reuse partitioning technique (assuming coordinated subcarrier allocation in the cells) that is able to minimize intercell interference. We propose a model that is able to take into account that sessions dynamically enter and leave the system. Rigid sessions require a class-specific fixed number of subcarriers, while elastic sessions can enter the system if a minimum number of sub-carriers is allocated to them. In this rather general setting we analyze the system performance in terms of the expected number of sub-carrier collisions, the session blocking probabilities and the signal-to-noise-and-interference ratio performance. We present numerical results on the various trade-offs between these measures that provide insight into the behavior of OFDM based cellular systems and help dimension the parameters of a reuse partitioned system.

IEEE Journal on Selected Areas in Communications, 2000

This paper discusses the requirements on future radio access and, based on the requirements, prop... more This paper discusses the requirements on future radio access and, based on the requirements, proposes a framework for such a system. The proposed system based on orthogonal frequency-division multiplexing supports very low latencies and data rates up to 100 Mb/s with wide area coverage and 1 Gb/s with local area coverage. Spectrum flexibility is identified as one main requirement for future systems, and the proposed framework can be deployed in a wide range of spectrum allocations with bandwidths ranging from 2.5 to 100 MHz. Multihop relaying, useful to extend the range for the high data rates, and multiple-antenna configurations are integral parts of the framework. A packet-centric approach is taken for the dataflow processing, implying that the scheduling mechanism and the retransmission protocol operate on complete packets rather than segments thereof, thus allowing for cross-layer optimization. Finally, numerical evaluations are provided, illustrating the feasibility of future very wideband radio access.

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 2007

Future cellular networks are expected to provide significantly higher capacity than today's ... more Future cellular networks are expected to provide significantly higher capacity than today's systems. This might require a denser access point deployment, with a potential increase in network deployment cost as a consequence. A promising way to reduce cost is a multi-hop deployment where wireless relay nodes (RN) are introduced to enhance capacity and coverage. In this paper, a deployment procedure

IEEE WIRELESS COMMUNICATIONS, 2011

The global mobile communication industry is growing rapidly. Today there are already more than 4 ... more The global mobile communication industry is growing rapidly. Today there are already more than 4 billion mobile phone subscribers worldwide [1], more than half the entire population of the planet. Obviously, this growth is accompanied by an increased energy consumption of mobile networks. Global warming and heightened concerns for the environment of the planet require a special focus on the energy efficiency of these systems . The EARTH 1 project [3] is a concerted effort to achieve this goal and as part of its objectives, a holistic framework is developed to evaluate and compare the energy efficiency of several design approaches of wireless cellular communication networks.

2011 IEEE 73rd Vehicular Technology Conference (VTC Spring), 2011

In order to quantify the energy savings in wireless networks, the power consumption of the entire... more In order to quantify the energy savings in wireless networks, the power consumption of the entire system needs to be captured and an appropriate energy efficiency evaluation framework must be defined. In this paper, the necessary enhancements over existing performance evaluation frameworks are discussed, such that the energy efficiency of the entire network comprising component, node and network level contributions can be quantified. The most important addendums over existing frameworks include a sophisticated power model for various base station (BS) types, which maps the RF output power radiated at the antenna elements to the total supply power of a BS site. We also consider an approach to quantify the energy efficiency of large geographical areas by using the existing small scale deployment models along with long term traffic models. Finally, the proposed evaluation framework is applied to quantify the energy efficiency of the downlink of a 3GPP LTE radio access network.