1,386 research outputs found
Energy and Spectral Efficient Inter Base Station Relaying in Cellular Systems
This paper considers a classic relay channel which consists of a source, a relay and a destination node and investigates the energy-spectral efficiency tradeoff under three different relay protocols: amplify-and-forward; decode-and-forward; and compress-and-forward. We focus on a cellular scenario where a neighbour base station can potentially act as the relay node to help on the transmissions of the source base station to its assigned mobile device. We employ a realistic power model and introduce a framework to evaluate the performance of different communication schemes for various deployments in a practical macrocell scenario. The results of this paper demonstrate that the proposed framework can be applied flexibly in practical scenarios to identify the pragmatic energy-spectral efficiency tradeoffs and choose the most appropriate scheme optimising the overall performance of inter base station relaying communications
DMT Optimal Cooperative Protocols with Destination-Based Selection of the Best Relay
We design a cooperative protocol in the context of wireless mesh networks in order to increase the reliability of wireless links. Destination terminals ask for cooperation when they fail in decoding data frames transmitted by source terminals. In that case, each destination terminal D calls a specific relay terminal B with a signaling frame to help its transmission with source terminal S. To select appropriate relays, destination terminals maintain tables of relay terminals, one for each possible source address. These tables are constituted by passively overhearing ongoing transmissions. Hence, when cooperation is needed between S and D, and when a relay B is found by terminal D in the relay table associated with terminal S, the destination terminal sends a negative acknowledgment frame that contains the address of B. When the best relay B has successfully decoded the source message, it sends a copy of the data frame to D using a selective decode-andforward transmission scheme. The on-demand approach allows maximization of the spatial multiplexing gain and the cooperation of the best relay allows maximization of the spatial diversity order. Hence, the proposed protocol achieves optimal diversitymultiplexing trade-off performance. Moreover, this performance is achieved through a collision-free selection process
Generalized Area Spectral Efficiency: An Effective Performance Metric for Green Wireless Communications
Area spectral efficiency (ASE) was introduced as a metric to quantify the
spectral utilization efficiency of cellular systems. Unlike other performance
metrics, ASE takes into account the spatial property of cellular systems. In
this paper, we generalize the concept of ASE to study arbitrary wireless
transmissions. Specifically, we introduce the notion of affected area to
characterize the spatial property of arbitrary wireless transmissions. Based on
the definition of affected area, we define the performance metric, generalized
area spectral efficiency (GASE), to quantify the spatial spectral utilization
efficiency as well as the greenness of wireless transmissions. After
illustrating its evaluation for point-to-point transmission, we analyze the
GASE performance of several different transmission scenarios, including
dual-hop relay transmission, three-node cooperative relay transmission and
underlay cognitive radio transmission. We derive closed-form expressions for
the GASE metric of each transmission scenario under Rayleigh fading environment
whenever possible. Through mathematical analysis and numerical examples, we
show that the GASE metric provides a new perspective on the design and
optimization of wireless transmissions, especially on the transmitting power
selection. We also show that introducing relay nodes can greatly improve the
spatial utilization efficiency of wireless systems. We illustrate that the GASE
metric can help optimize the deployment of underlay cognitive radio systems.Comment: 11 pages, 8 figures, accepted by TCo
Reliable multi-hop routing with cooperative transmissions in energy-constrained networks
We present a novel approach in characterizing the optimal reliable multi-hop virtual multiple-input single-output (vMISO) routing in ad hoc networks. Under a high node density regime, we determine the optimal cardinality of the cooperation
sets at each hop on a path minimizing the total energy cost per transmitted bit. Optimal cooperating set cardinality curves are derived, and they can be used to determine the optimal routing strategy based on the required reliability, transmission power, and path loss coefficient. We design a new greedy geographical
routing algorithm suitable for vMISO transmissions, and demonstrate the applicability of our results for more general networks
Energy-efficiency for MISO-OFDMA based user-relay assisted cellular networks
The concept of improving energy-efficiency (EE) without sacrificing the service quality has become important nowadays. The combination of orthogonal frequency-division multiple-access (OFDMA) multi-antenna transmission technology and relaying is one of the key technologies to deliver the promise of reliable and high-data-rate coverage in the most cost-effective manner. In this paper, EE is studied for the downlink multiple-input single-output (MISO)-OFDMA based user-relay assisted cellular networks. EE maximization is formulated for decode and forward (DF) relaying scheme with the consideration of both transmit and circuit power consumption as well as the data rate requirements for the mobile users. The quality of-service (QoS)-constrained EE maximization, which is defined for multi-carrier, multi-user, multi-relay and multi-antenna networks, is a non-convex and combinatorial problem so it is hard to tackle. To solve this difficult problem, a radio resource management (RRM) algorithm that solves the subcarrier allocation, mode selection and power allocation separately is proposed. The efficiency of the proposed algorithm is demonstrated by numerical results for different system parameter
Spectral-energy efficiency trade-off of relay-aided cellular networks
Wireless communication networks are traditionally designed to operate at high spectral
e ciency with less emphasis on power consumption as it is assumed that endless
power supply is available through the power grid where the cells are connected to. As
new generations of mobile networks exhibit decreasing gains in spectral e ciency, the
mobile industry is forced to consider energy reform policies in order to sustain the
economic growth of itself and other industries relying on it. Consequently, the energy
e ciency of conventional direct transmission cellular networks is being examined
while alternative green network architectures are also explored. The relay-aided cellular
network is being considered as one of the potential network architecture for energy
e cient transmission. However, relaying transmission incurs multiplexing loss due to
its multi-hop protocol. This, in turn, reduces network spectral e ciency. Furthermore,
interference is also expected to increase with the deployment of Relay Stations
(RSs) in the network. This thesis examines the power consumption of the conventional
direct transmission cellular network and contributes to the development of the
relay-aided cellular network.
Firstly, the power consumption of the direct transmission cellular network is investigated.
While most work considered transmitter side strategies, the impact of the
receiver on the Base Station (BS) total power consumption is investigated here. Both
the zero-forcing and minimum mean square error weight optimisation approaches are
considered for both the conventional linear and successive interference cancellation
receivers. The power consumption model which includes both the radio frequency
transmit power and circuit power is described. The in
uence of the receiver interference
cancellation techniques, the number of transceiver antennas, circuit power
consumption and inter-cell interference on the BS total power consumption is investigated.
Secondly, the spectral-energy e ciency trade-o in the relay-aided cellular network is
investigated. The signal forwarding and interference forwarding relaying paradigms
are considered with the direct transmission cellular network taken as the baseline.
This investigation serves to understand the dynamics in the performance trade-o .
To select a suitable balance point in the trade-o , the economic e ciency metric is
proposed whereby the spectral-energy e ciency pair which maximises the economic
pro tability is found. Thus, the economic e ciency metric can be utilised as an alternative
means to optimise the relay-aided cellular network while taking into account
the inherent spectral-energy e ciency trade-o .
Finally, the method of mitigating interference in the relay-aided cellular network is
demonstrated by means of the proposed relay cooperation scheme. In the proposed
scheme, both joint RS decoding and independent RS decoding approaches are considered
during the broadcast phase while joint relay transmission is employed in the
relay phase. Two user selection schemes requiring global Channel State Information
(CSI) are considered. The partial semi-orthogonal user selection method with reduced
CSI requirement is then proposed. As the cooperative cost limits the practicality of
cooperative schemes, the cost incurred at the cooperative links between the RSs is
investigated for varying degrees of RS cooperation. The performance of the relay
cooperation scheme with di erent relay frequency reuse patterns is considered as well.
In a nutshell, the research presented in this thesis reveals the impact of the receiver on
the BS total power consumption in direct transmission cellular networks. The relayaided
cellular network is then presented as an alternative architecture for energy
e cient transmission. The economic e ciency metric is proposed to maximise the
economic pro tability of the relay network while taking into account the existing
spectral-energy e ciency trade-o . To mitigate the interference from the RSs, the
relay cooperation scheme for advanced relay-aided cellular networks is proposed
Enabling non-linear energy harvesting in power domain based multiple access in relaying networks: Outage and ergodic capacity performance analysis
The Power Domain-based Multiple Access (PDMA) scheme is considered as one kind of Non-Orthogonal Multiple Access (NOMA) in green communications and can support energy-limited devices by employing wireless power transfer. Such a technique is known as a lifetime-expanding solution for operations in future access policy, especially in the deployment of power-constrained relays for a three-node dual-hop system. In particular, PDMA and energy harvesting are considered as two communication concepts, which are jointly investigated in this paper. However, the dual-hop relaying network system is a popular model assuming an ideal linear energy harvesting circuit, as in recent works, while the practical system situation motivates us to concentrate on another protocol, namely non-linear energy harvesting. As important results, a closed-form formula of outage probability and ergodic capacity is studied under a practical non-linear energy harvesting model. To explore the optimal system performance in terms of outage probability and ergodic capacity, several main parameters including the energy harvesting coefficients, position allocation of each node, power allocation factors, and transmit signal-to-noise ratio (SNR) are jointly considered. To provide insights into the performance, the approximate expressions for the ergodic capacity are given. By matching analytical and Monte Carlo simulations, the correctness of this framework can be examined. With the observation of the simulation results, the figures also show that the performance of energy harvesting-aware PDMA systems under the proposed model can satisfy the requirements in real PDMA applications.Web of Science87art. no. 81
Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey
This paper provides a comprehensive review of the domain of physical layer
security in multiuser wireless networks. The essential premise of
physical-layer security is to enable the exchange of confidential messages over
a wireless medium in the presence of unauthorized eavesdroppers without relying
on higher-layer encryption. This can be achieved primarily in two ways: without
the need for a secret key by intelligently designing transmit coding
strategies, or by exploiting the wireless communication medium to develop
secret keys over public channels. The survey begins with an overview of the
foundations dating back to the pioneering work of Shannon and Wyner on
information-theoretic security. We then describe the evolution of secure
transmission strategies from point-to-point channels to multiple-antenna
systems, followed by generalizations to multiuser broadcast, multiple-access,
interference, and relay networks. Secret-key generation and establishment
protocols based on physical layer mechanisms are subsequently covered.
Approaches for secrecy based on channel coding design are then examined, along
with a description of inter-disciplinary approaches based on game theory and
stochastic geometry. The associated problem of physical-layer message
authentication is also introduced briefly. The survey concludes with
observations on potential research directions in this area.Comment: 23 pages, 10 figures, 303 refs. arXiv admin note: text overlap with
arXiv:1303.1609 by other authors. IEEE Communications Surveys and Tutorials,
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