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In this paper, we propose a joint relay selection and power allocation algorithm for a multi-user, multi relay cellular network using decode-and-forward cooperation strategy with imperfect knowledge of channels. The objective is to minimize the total uplink power of the network taking each user's target data rate as the quality of service constraint under imperfect channel state information (CSI),...
Exploitation of the spatial dimension in MIMO systems enables co-channel concurrent transmissions between the nodes, thus increases the capacity of the network. A major challenge in the implementation of concurrent transmissions is the mitigation of the interference without causing excessive communication overhead in the network. In this paper, we present a low overhead Concurrent Communications scheme...
This paper presents a SC-FDE/OFDM MMSE equalizer for 60GHz wireless communications in 65nm CMOS process. By applying a 4-parallel signal processing architecture, the 512pt FFT/IFFT processor, the Golay channel estimator, and the MMSE equalizer are all clocked at 1/4 input symbol sampling rate. Occupying a core area of 1.12mm2, the symbol sampling rate at 1V supply is 1.46GS/s. With 16QAM modulation,...
This paper presents low power hardware generation, based on a CAL actor language dataflow implementation. The CAL language gives a higher level of abstraction and generate both hardware and software description. The original CAL flow is targeted for hardware-software co-design of complex systems on FPGA. Modifications are done to the original CAL flow to facilitate low power ASIC implementations....
In this paper, we focus upon the effect of MUI on the channel estimation stage, through a non-parametric approach, in open-loop and closed-loop SpU-MIMO systems. The corresponding BER is integrated within a general framework for MAC-layer performance evaluation of ad-hoc networks. This framework is used to derive the throughput-related network performance and to provide corresponding numerical examples...
In this paper, we analyze and evaluate throughput performance of open-loop and closed-loop MIMO slotted ALOHA ad hoc networks with multiple receivers. We employ two slotted ALOHA variants with realistic modelling considerations; interaction(s) between the link and the MAC-layer are explicitly accounted for via a probabilistic approach using the output SINR of the receiver's MIMO processing stage....
In this paper we investigate limitations facing high rate transmission in the downlink of UMTS systems. A solution is proposed based on space-time filtering to allow parallel channel transmission and spreading code reuse. The optimum receiver is derived taking into consideration non-ideality in space-time filtering caused by channel estimation errors. Comparisons with ordinary CDMA receivers, based...
This paper proposes a joint transmit-receive spectrum sharing method based on space division multiplexing (SDM) in cognitive radio networks (CRN). By exploiting spatial correlation features between cognitive transmission and interference from cognitive base station (CBS) to primary user (PU) as well as interference from primary base station (PBS) to cognitive user (CU), appropriate primary system...
A cooperative Medium Access Control (MAC) protocol employing auction-style relay selection combined with superposition coding is designed. In our proposed scheme, the source achieves its target throughput with the aid of cooperation. The potential candidate relays carry out autonomous decisions concerning whether to contend for a transmission opportunity to convey their traffic in the light of their...
We address multi-cell reference signal design in support of coordinated multi-point transmission techniques in LTE-Advanced downlink. We start our discussion from theoretical considerations on MSE-optimum multi-cell reference signal design, giving motivation to orthogonalization of the reference signals between cooperating cells. Furthermore, design aspects such as choice of multiplexing schemes,...
Local area deployments in general and femtocells in particular have proved to be an effective solution for providing ubiquitous coverage in a cost-efficient manner, satisfying the high data rate and QoS requirements for LTE-Advanced systems. In this paper, we investigate inter-cell interference management schemes for dense local area deployments. We propose a distributed capacity based channel allocation...
While femtocell network enhances throughput and coverage, it also introduces cross-tier interference. In the uplink, to protect existing macrocell users (MUs), the interference accumulated at the macrocell base station (MBS) by femtocell users (FUs) should be limited. Due to variable distances between a femtocell base station (FBS) and the MBS, FU associated with the FBS closer to the MBS will impose...
Cognitive radios (CR) are an efficient approach to deploy a secondary network in the vacant portions of the spectrum licensed to primary networks. However, when primary users return to a channel used by a CR, the later should vacate the channel and start a restoration process by searching and sensing other channels. The restoration process objective is to find the best channel in the shortest time...
This paper focuses on the performance of LTE in rural areas which is based on a channel measurement campaign conducted with the Eurecom OpenAirInterface LTE testbed at 800MHz. This testbed is based on LTE release 8 PHY layer and implements transmission modes 1 (single antenna - SISO), 2 (transmit diversity), and 6 (single-user MIMO - closed loop rank-1 precoding) in real time. In addition to the throughput...
Opportunistic access of licensed spectrum using a cognitive radio network (CRN) is getting research attraction due to its ability to improve utilisation of this scarce resource without affecting the primary users (PUs). To improve wide acceptability of CRN, it must be equipped with efficient protocols to deal with multiple primary networks to provision QoS guarantee for demand-driven applications...
The work described in this paper proposes two Smart Hybrid-Automatic Repeat Request (SHARQ) schemes with incremental redundancy, that are developed for a dual-hop network of two relays implementing cooperative communication. In a dual-hop network consisting of multiple relays, one of the most challenging tasks is to determine an appropriate trade-off point between the end-to-end block-error rate (BLER)...
In this paper, we propose to reduce the effect of rate-independent MAC overheads in random access protocols by partitioning the transmission channel spectrum into a narrow channel and a wide channel. The narrow channel is used for transmitting the short packets (approximately 100 bytes long) and the wide channel is used for transmitting the longer packets. We intend to use multiple radios, one each...
Prior work in implementing spectrum sharing scenarios for cognitive radio networks has relied on the unlikely assumption of full cross-channel knowledge made available to the cognitive transmitter (CT) and/or the target primary receiver (PR). However, estimation of this cross-channel knowledge is not only important from a practical stand-point, but also in limiting the real interference power felt...
This paper utilizes a general superimposed training based transmission scheme that includes superimposed training and pilot symbol assisted modulation (PSAM) as special cases. The channel estimator of the scheme is the linear minimum mean square error (LMMSE) estimator. By taking into account errors of this method, we derive the closed-form lower bound of the data throughput under the constraint of...
In LTE-Advanced, multiuser MIMO has been identified as a key technique for increasing system spectral efficiency in closed-loop MIMO. Transmission parameters like precoding and transmission rate are adapted based on finite rate feedback from the users. Switching between single user and multiuser transmission modes is possible without higher layer signaling, which means that the feedback should be...
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