GEN05-4: Carrier Offset and Channel Estimation for Cooperative MIMO Sensor Networks

Iltis, R.A.; Mirzaei, Shahnam; Kastner, Ryan; Cagley, R.E.; Weals, B.T.

doi:10.1109/glocom.2006.170

Cited by 10 publications

(1 citation statement)

References 9 publications

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“…Since relay networks are virtual MIMO systems [6], many existing MIMO channel-estimation algorithms, e.g., those proposed in [19]- [22], can also be adapted. Frequency offset estimation and channel estimation for cooperative MIMO sensor networks are discussed in [23], where the complexity is reduced by using a generalized successive interference cancellation (GSIC) algorithm. Per-subcarrier channel estimation for AF OFDM without frequency offset is studied in [24].…”

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Cooperative OFDM Channel Estimation in the Presence of Frequency Offsets

Zhang

Tellambura

2009

IEEE Trans. Veh. Technol.

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Abstract-Channel estimation in the presence of frequency offsets is developed for cooperative orthogonal frequency-division multiplexing (OFDM) systems. A two-time-slot cooperative channel estimation protocol is proposed. The source broadcasts the training sequence to the relays and the destination (first time slot), and the relays retransmit the training sequence (second time slot). Pilot designs for amplify-and-forward (AF) and decode-andforward (DF) relays are derived. These designs eliminate interrelay interference (IRI), which occurs due to the simultaneous relay retransmissions, and minimize the mean square error (MSE). Consequently, the number of AF and DF relays is constrained to be less than N/(2L − 1) and N/L , respectively, where N is the total number of subcarriers, L is the channel order, and a is the maximum integer part of a. The pairwise error probability (PEP) of orthogonal space-time coding in cooperative OFDM due to both frequency offset and channel-estimation errors is also evaluated. The optimal power allocation ratio between the source and the relays to minimize the PEP is derived for AF and DF relays. When L < 16, DF relays outperform AF relays in terms of PEP. With L = 4 and 16 active relays, the gap is 9 dB for a frequency offset error variance of 10 −3 , and this gap increases to about 11.3 dB when the variance increases to 10 −2 .

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Cooperative OFDM Channel Estimation in the Presence of Frequency Offsets

Zhang

Tellambura

2009

IEEE Trans. Veh. Technol.

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Asynchronous cooperative communication systems: A survey on signal designs

Wang

Xia

2011

Sci. China Inf. Sci.

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Cooperative communications is a promising technique for future high speed wireless communications. These systems may be formulated as virtual multi-input multi-output (MIMO) systems where spatial/cooperetive diversity is a key advantage. However, different from MIMO systems, one of the major challenges for cooperative communications systems is that the cooperative transmissions in cooperative systems may be neither time nor frequency synchronized, since the transmissions are from multiple cooperative nodes at different locations. The existing signal designs for co-located MIMO systems may not be able to collect the cooperative diversity in cooperative communications systems. This paper gives an overview of recent research efforts on combating the time and frequency asynchronism of the cooperative communication network. We focus on the signal designs (or space-time codings/modulations) to achieve full cooperative diversity, and summarize some of the resent distributed space-timing coding and space-frequency coding techniques to combat timing errors and frequency offsets, and in the meantime to achieve full cooperative diversity, in both one-way and two-way cooperative networks.

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