Results 1 - 10 of 61

Bit Rearrangement for MIMO Retransmissions

by Sung Ho Moon, Hyung Ho Park, Andrea Goldsmith, Minseok Oh
"... Abstract — In this paper, we propose a new hybrid automatic repeat request (H-ARQ) scheme in MIMO. The proposed scheme performs bit-level exchanges and modifications every retransmission and covers all combinations of number of antennas and number of retransmissions in M-QAM. In order to obtain a be ..."
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Abstract — In this paper, we propose a new hybrid automatic repeat request (H-ARQ) scheme in MIMO. The proposed scheme performs bit-level exchanges and modifications every retransmission and covers all combinations of number of antennas and number of retransmissions in M-QAM. In order to obtain a

ANTENNA

by Ba L, Rf Saw, Rf Saw, Fr Ac- N, Seq Gen, Freq Det
"... A cellular repeater is a system of duplex reception, amplification, and transmission used to enhance uplink (UL) and downlink (DL) signals in areas of low radio coverage. This enhancement expands the coverage of cellular network base transceiver stations (BTS) at low cost. The signals at the input a ..."
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and output ports of the two transceivers (TRX), each dedicated for the UL or DL direction of signal reception, amplification, and re-transmission, are multiplexed at a directional donor and local area antennas by means of diplexers in FDD systems such as GSM and WCDMA FDD. For the DL path, assuming a fixed

Strategies for ARQ in 2×2 MIMO Systems

by Elisabeth De Carvalho, Petar Popovski
"... Abstract — Packet retransmission strategies are presented for 2x2 MIMO spatial multiplexing systems. Antennas for retransmission are selected to maximize an approximation of the throughput of the system. A sign change or conjugate operation is allowed for retransmitted packets. The proposed scheme p ..."
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Abstract — Packet retransmission strategies are presented for 2x2 MIMO spatial multiplexing systems. Antennas for retransmission are selected to maximize an approximation of the throughput of the system. A sign change or conjugate operation is allowed for retransmitted packets. The proposed scheme

Effect of limited number of retransmissions of RCPT hybrid ARQ for DS-CDMA mobile radio

by Deepshikha Garg, Ryohei Kimura, Fumiyuki Adachi - Proc. WPMC02, pp 971-975 , 2002
"... In this paper, we evaluate by computer simulations the signal energy per information bit (E b/N 0) for rate compatible punctured turbo (RCPT) coded hybrid ARQ for direct sequence code division multiple access (DS-CDMA) with antenna diversity reception and Rake combining in a frequency selective Rayl ..."
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In this paper, we evaluate by computer simulations the signal energy per information bit (E b/N 0) for rate compatible punctured turbo (RCPT) coded hybrid ARQ for direct sequence code division multiple access (DS-CDMA) with antenna diversity reception and Rake combining in a frequency selective

A medium access control protocol with retransmission using NACK and directional antennas for broadcasting in wireless ad-hoc networks", The 5th European Wireless Conference

by Yoriko Utsunomiya, Michito Takahashi, Masaki B, Iwao Sasase , 2004
"... Abstract: To improve the throughput perfor-mance keeping high reliable broadcasting, we pro-pose an efficient Medium Access Control protocol for broadcasting in wireless ad-hoc networks with IEEE 802.11. In the proposed protocol, to reduce the number of retransmissions, a broadcast packet is retrans ..."
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is retransmitted according to NACK instead of ACK. Moreover, the broadcast packet is retrans-mitted only to the area including nodes that re-quest retransmission by using directional anten-nas. By computer simulations, we show that the proposed protocol can improve throughput per-formance keeping high reliable

ARQ strategies for 2×2 spatially multiplexed

by Mimo Systems, Elisabeth De Carvalho, Petar Popovski
"... Abstract — This paper presents packet retransmission strategies for MIMO spatial multiplexing (SM) systems with independent coding and independent ARQ processes per stream. The received signals containing the retransmitted packets are kept in memory and combined. We present two methods to select the ..."
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the retransmission antennas. The first methods is based on CSI: the optimization criterion is the minimization of the SNRs averaged over the outputs of a zero forcing linear equalizer. The second method is blind to CSI. When 2 packets are decoded with errors, retransmission follows a space time block code (STBC

Antenna Sectorization and Macrodiversity in CDPA Wireless Systems

by Flaminio Borgonovo, Michele Zorzi, Luigi Fratta - in Proc , 1995
"... Recently, a new method for achieving spectrum reuse in cellular systems, called Capture-Division Packetized Access (CDPA), has been introduced. The method uses a single frequency in all cells, and uses packet switching and packet retransmission as a means to overcome destructive cochannel interferen ..."
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Recently, a new method for achieving spectrum reuse in cellular systems, called Capture-Division Packetized Access (CDPA), has been introduced. The method uses a single frequency in all cells, and uses packet switching and packet retransmission as a means to overcome destructive cochannel

Smart Antennas, Dumb Scheduling for Medium Access Control

by Vidyut Naware, Lang Tong , 2003
"... We consider the problem of stability of slotted ALOHA for a system consisting of N users communicating with a common receiver, which employs spatial diversity to receive multiple transmissions simultaneously. We introduce a general packet reception model to incorporate multiple packet receptions sin ..."
Abstract - Cited by 6 (4 self) - Add to MetaCart
the phase transition, the best strategy is for both users to transmit with probability one which is an extreme case of slotted ALOHA with retransmission probability one. This significant finding suggests that if the physical layer is even reasonably good there is no need for sophisticated Medium Access

Antenna redundancy for increasing transmission reliability in wireless industrial LANs

by Andreas Willig - Halmstad University, Halmstad, Sweden , 1993
"... Abstract — In this paper we introduce the concept of an-tenna redundancy, which uses different transmitter antennas for performing retransmissions, however, without transmitting in parallel over multiple antennas and therefore without requiring complex space-time processing techniques in receivers. ..."
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Abstract — In this paper we introduce the concept of an-tenna redundancy, which uses different transmitter antennas for performing retransmissions, however, without transmitting in parallel over multiple antennas and therefore without requiring complex space-time processing techniques in receivers

Four Transmit Diversity Schemes for Coded OFDM Systems with Four Transmit Antennas

by C. Yuen, Y. Wu, S. Sun
"... Abstract — We compare four open-loop transmit diversity schemes in a coded Orthogonal Frequency Division Multiplexing (OFDM) system with four transmit antennas, namely cyclic shift diversity (CSD), Space-Time Block Code (STBC, Alamouti code is used) with CSD, Quasi-Orthogonal STBC (QO-STBC) and Mini ..."
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Abstract — We compare four open-loop transmit diversity schemes in a coded Orthogonal Frequency Division Multiplexing (OFDM) system with four transmit antennas, namely cyclic shift diversity (CSD), Space-Time Block Code (STBC, Alamouti code is used) with CSD, Quasi-Orthogonal STBC (QO
Results 1 - 10 of 61