Downlink OFDMA Resource Allocation Under Partial Channel State Information

Abstract

The problem of resource allocation (RA) in a downlink OFDMA system is examined under the realistic assumption of imperfect channel state information (CSI) at the base station. In this case, there is a nonzero outage probability that the assigned rate at a particular subcarrier/user pair will not be supported by the true channel realization, which may lead to a significant waste of the system's available resources. It is therefore necessary to obtain RA algorithms that take into account the effect of imperfect CSI. By exploiting the statistical description of the imperfect CSI, various algorithms are proposed that tradeoff complexity versus performance, aiming at maximizing the system's successfully transmitted rate.

A flexible mid-term frequency domain scheduler for resource allocation in HetNets based on the SINR requested by users

“…There are three categories from this perspective: (a) strategies which allocate resources assuming perfect, instantaneous knowledge of channel state [27]; (b) strategies performing allocation by assuming partial, imperfect knowledge of channel state [28][29][30]; and (c) strategies allocating resources assuming no knowledge about channel state [20].…”

Achievable Net-Rates in Multi-User OFDMA with Partial CSI and Finite Channel Coherence

“…The pdf pγk f,t (·) is given in (2) and pγ fr ,tr (·) is given in (5). Hence, we can show that (see also [17] for a similar derivation) p γ fr ,tr (γ fr,tr ) =…”

“…The scheduler may apply an SNR back-off to reduce the probability for such a scenario and to increase the effective throughput. Similarly, [5] analyzed the probability that an allocated rate is not supported by the actual channel. However, they assumed blockstatic fading and perfect CSI at the receiver.…”

Queue-aware optimal resource allocation for the LTE downlink

“…The optimal power and sub-carrier allocation are then determined using convex duality techniques. While [10] assumed full CQI availability except for an estimation error term, [13] takes imperfect CQI into account by factoring for outages due to erroneous CQI at the base-station. In [14], the authors consider opportunistic resource allocation in OFDM under various fairness constraints, and propose a Hungarian algorithm based solution.…”