1. An adaptive quality control loop for a rate adaptation based on modulation and coding scheme (MCS) levels and multiple spreading codes, comprising: adjusting a first channel condition threshold in a transmitter based on a first error detection result from a receiver for a first data packet transmission between the transmitter and receiver using a first variable size step for the adjusting, wherein the first channel condition threshold is based on a first modulation and coding scheme (MCS) level used in the first data packet transmission, and the first variable size step is determined by the transmitter using a desired MCS error rate for the first MCS level, comprising; determining the first variable size step using a block or bit error rate target criterion and a first data rate associated with the first MCS level; wherein the desired MCS error rate for the first MCS level is based on a block error rate target criterion, MCS probabilities for the first MCS level and for other MCS levels, and MCS error rates for the other MCS levels.