In this paper, we design a new single‐input multiple‐output context‐aware cognitive transceiver (CTR) that is able to switch to the best performing modem in terms of link‐level throughput. On the top of conventional adaptive modulation and coding, we allow the proposed CTR to make best selection between three different pilot‐utilization modes: conventional data‐aided (DA) or pilot‐assisted, non‐DA (NDA) or blind, and NDA with pilots, which is a newly proposed hybrid version between the DA and NDA modes. We also enable the CTR to make best selection between two different channel identification schemes: conventional least‐squares (LS) and newly developed maximum‐likelihood estimators. Depending on whether pilot symbols can be exploited or not at the receiver, we further enable the CTR to make the best selection among two data detection modes: coherent or differential. Owing to exhaustive link‐level simulations on the downlink of a long‐term evolution system, we draw out the optimal decision rules in terms of the best combination triplet of pilot‐use, channel‐identification, and data‐detection modes that yield the best link‐level throughput as function of channel type, mobile speed, signal‐to‐noise ratio, and channel quality indicator. The proposed CTR offers a link‐level throughput gains improvement as high as 700% compared with DA LS for VehB channel type at a mobile speed of 100 km/h in the low signal‐to‐noise ratio region. For VehA channels, its throughput gain improvements can reach 114%. For PedA and PedB channels, the proposed CTR provides throughput enhancements of about 66% and 330%, respectively. Moreover, realistic simulations at the system‐level of the long‐term evolution‐HetNet network suggest that the new context‐aware CTR outperforms the conventional transceiver (i.e., pilot‐assisted LS‐type channel estimation with coherent detection) by as much as 50% and 60% gains in average and cell‐edge (i.e., five percentile) throughputs, respectively, in the high‐clustering case with type‐B channels. In the low clustering scenario, the average and cell‐edge throughput gain improvements offered by the proposed CTR exceed 80% and 90% for type‐B channels. Copyright © 2016 John Wiley & Sons, Ltd.

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Coherent detection requires accurate channel estimation to provide the high data rates promised by the LTE standard. However, for high-speed wireless data transmission services, channel estimation becomes a challenging task when the pilot insertion rate becomes insufficient to allow proper tracking of the channel variation. In this paper, we design a new singleinput multiple-output (SIMO) context-aware cognitive transceiver (CTR) that is able to switch to the best performing modem (modulation-demodulation) in terms of link-level throughput. For that purpose, on the top of conventional adaptive modulation and coding, we allow the context-aware CTR to make best selection among three different pilot-utilization modes: Conventional DataAided (DA) or pilot-assisted, Non-Data-Aided (NDA) or blind and Non-Data-Aided with pilot (NDA w. pilot) which is a newly proposed hybrid version between the DA and NDA modes. We also enable the CTR to make best selection between two different channel identification schemes: conventional Least Squares (LS)-type and newly developed Maximum Likelihood (ML) estimators. Depending on whether pilot symbols are used or not, we further enable the CTR to make best selection among two data detection modes: coherent or differential. Owing to extensive and exhaustive LTE-downlink link-level simulations, we are able to draw out the decision rules of the new CTR that identify the best combination triplet of pilot-use, channel-identification, and datadetection modes. The latter is able to achieve the best link-level performance against any given operating conditions in terms of channel type, mobile speed, SNR, and Channel Quality Indicator (CQI). Significant link-level throughput gains of the new proposed CTR against the conventional one (i.e., pilot-assisted LS-type channel estimation with coherent detection) can be achieved in most operating conditions and could reach as much as 700% at low SNR and high mobility!

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