The queuing mechanism at the AP dictates the channel bandwidth allocation to clients in the downlink direction. Since the channel conditions at the clients vary, different data transmission rates are often used for different clients. As far as we know, the existing literature on scheduling schemes [20,22,27] does not consider the impact of rate diversity. Thus, the aggregate network throughput when only downlink traffic is present is impacted in the same way as previously explained. We also note that if loss rates experienced by nodes differ and both packet transmissions in uplink and downlink directions use different data rates, the achieved throughputs of competing clients may not be equal or easily predictable, even when all nodes use DCF and the AP employs a fair queuing scheme.