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In view of the new feature after introducing the relay nodes (RNs) into the conventional cellular networks, a novel soft frequency reuse (SFR)-based inter-cell interference coordination (ICIC) scheme is proposed in the relay enhanced cellular networks. On the basis of original ICIC scheme for conventional cellular network, RNs in the proposed SFR scheme reuses part of neighboring cell-edge bands to...
In this paper, we investigate carrier frequency synchronization in the downlink of 3GPP Long Term Evolution (LTE). A complete carrier frequency offset estimation and compensation scheme based on standardized synchronization signals and reference symbols is presented. The estimation performance in terms of mean square error is derived analytically and compared to simulation results. The impact of estimation...
The capacity and coverage area of a cell may vary due to changed environment, insertion or deletion of base stations, or malfunctioning base stations, and wrong parameter selection in the network planning phase. Suboptimal capacity and coverage area leads to the waste of network resources and the lower quality. Reacting on the changed situation manually is very expensive and time consuming. Therefore,...
We develop a general model based on random coding bounds to explain and predict the coding performance of various type-I and type-II hybrid automatic repeat request (HARQ) schemes based on the bit-interleaved coded modulation (BICM) in 3GPP HSPA. We explore how the intrinsic properties of BICM interact with various transmitter-side (e.g., whether to use the same bit mapping for retransmission) and...
Interference problems in cochannel femtocell networks may cause significant performance degradation for certain femtocell/macrocell users. These problems and potential solutions are recently being investigated within the 3GPP. The goal of the present paper is to review the simulation framework for femtocell networks in 3GPP and briefly summarize some of the important inter-cell interference coordination...
Space-frequency block codes (SFBC) combined with frequency switched transmit diversity (FSTD) is used in the downlink of 3GPP LTE system, where all transmit antennas are collocated at eNodeBs. However, all transmit antennas serving a cell are distributed at the cell edge in edge-excited distributed antenna systems. The performance of SFBC is greatly affected by the different large scale fading from...
With the ever-increasing proliferation of air interfaces that coexist in the same operating area, advanced Radio Resource Management is crucial to take advantage of the available system resources. In this paper, we consider a downlink multi-class heterogeneous network where cells include two co-localized Radio Access Technologies (RAT): WiMAX [1] and UMTS [2]. We propose a Centralised Access Control...
In this paper, we present a review of automatic repeat request (ARQ) and hybrid ARQ (HARQ) mechanisms implemented or proposed in beyond 3rd generation (B3G) wireless systems based on OFDMA. In particular, we will focus on part of the IEEE 802.16 standard family (IEEE 802.16-2005, IEEE 802.16m) and on 3GPP Long Term Evolution (LTE). In the second part of this overview, some performance curves show...
In this paper, we analyze the interference distribution and gain of beamforming in closed access femtocells in downlink of a two-tier HSDPA cellular network. We show through simulations that indoor femtocell deployment leads to a dominant interferer scenario. According to results even simple null steering method based on the scarce codebook of HSDPA transmit diversity mode 1 can be beneficially applied...
In GERAN networks, Multiple Users Reusing One Single timeslot (MUROS) promises to enhance the cell capacity through pairing of two or more users onto a single timeslot. So far no work has been done on the basis on which the different users would be paired. The criteria used for the pairing decision to pair two or more users is critical for MUROS as this will eventually decide the actual gains due...
Current cellular systems suffer from co-channel interference, when simultaneous transmissions in other cells use the same physical resources. Schemes involving cooperation between Base Stations (BS) are currently discussed for further releases of the 3GPP Long Term Evolution (LTE) system as a promising method to mitigate co-channel interference for users located at cell-edge. The BS cooperation approach...
The 3GPP (Third Generation Partnership Project) LTE (Long Term Evolution) and LTE-Advanced activities work toward the evolved UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access (E-UTRA), and the solution of IMT-Advanced (International Mobile Telecommunications) and systems beyond. The combination of OFDM (orthogonal frequency division multiplexing) and MIMO (multiple-input...
In current wireless standards like 3GPP LTE or IEEE 802.16 / WiMAX multiple access is based on orthogonal signalling using single-carrier frequency-division multiple access (SC-FDMA) or orthogonal frequency-division multiple access (OFDMA). Links between a base station and different terminals use mutually orthogonal radio resources. This paper studies potential gains in average cell throughput by...
In a downlink transmission, users can benefit from the high capacity gain achieved by transmitting independent data streams from multiple antennas to multiple users sharing the same physical time-frequency resources. This technique is known as multiuser MIMO (MU-MIMO). However, performance of MU-MIMO is sensitive towards propagation imperfections, such as time dispersion and inter-stream interference...
Power control has been extensively studied as an important way of mitigating interference and providing minimum signal to interference plus noise ratio (SINR) guarantees. Such formulation of power control is well-motivated in cellular PCS and UMTS, as both voice and streaming media require guaranteed short-term rates. A key difficulty is that the problem can easily become infeasible, implying that...
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