Before revision:  On one hand, they provide the following Quality of Service (QoS) guarantees: Using maximal matchings as crossbar schedules results in at least 50\% switch throughput and order-optimal (i.e., independent of the switch size N) average delay bounds for various traffic arrival processes.
After revision:  On one hand, they provide the following Quality of Service (QoS) guarantees: Using maximal matchings in every time slot results in at least 50\% switch throughput and order-optimal (i.e., independent of the switch size N) average delay bounds for various traffic arrival processes.