This paper presents the dynamic integrated-services MAC (DIS-MAC) protocol designed to enable service differentiation in CDMA-based hybrid wireless mesh networks (WMNs) through an integrated medium access that allows both contention-based and contention-free scheduled access modes. DIS-MAC utilizes dynamic capacity partitioning that adjusts CDMA capacity limits assigned to the two access modes in response to changes in network traffic loading. The contention-based access is made compatible with the IEEE 802.11 standard, while the contention-free scheduled access provides differentiated delay guarantees for real-time traffic over single-hops connecting among mesh routers, clients and gateways. The scheduler enables feedback-enhanced delay target-tracking and delay-bandwidth decoupling. Numerical results show that DIS-MAC provides high resource utilizations and differentiated delay bounds in a WMN environment characterized with heterogeneous real-time and non-real-time traffic sources.

This paper focuses on sharing of open spectrum under a new sharing policy of prioritized dynamic spectrum leasing, where the designated spectrum broker dynamically allocates time-varying unused licensed spectrum resources to secondary networks of various access priorities. The proposed optimal stochastically controlled dynamic guard bandwidth (OSC-DGB) scheme enables the spectrum broker to adapt differentiated capacity limits of open spectrum for prioritized connection accesses by secondary networks in anticipation of their access request rates, which are expected to be opportunistic and non-stationary. The differences in capacity limits determine the amount of guard band reserved for the higher priority secondary networks. This spectrum adaptation problem is formulated as a finite-horizon Markov decision process to minimize service denials of secondary networks according to their spectrum access priorities, which is solved through dynamic programming. Numerical results show that OSC-DGB enables close tracking of connection blocking targets while optimizing resource utilizations.

To enable combined connection-level and application-level QoS support in future multi-class CDMA-based system characterized with highly non-stationary loading at both levels, this paper integrates two adaptive control mechanisms of prioritized admission and rate scheduling. The buffered adjusted multimode dynamic guard bandwidth (BAM-DGB) admission control enables connection-level prioritization via dynamic guard method with differentiated congestion controls that minimizes handoff droppings in non-stationary environment. The adaptive differentiated services medium access control (ADS-MAC) complements the admission control with the target-tracking weighted fair queuing (TT-WFQ) scheduler that adapts allocated transmission rates subject to constraints imposed by the admission control. It enables delay-bandwidth decoupling for maximum resource utilizations, and absolute delay target- tracking for balanced degradations during system congestions. Numerical results indicate that the proposed mechanisms are able to maintain consistent connection dropping probabilities and scheduling delay targets under non-stationary loading and congestion conditions.

To minimize QoS degradations during nonstationary packet loadings, predictive rate schedulers adapt the operation according to anticipated packet arrival rates deduced via specified estimation algorithm. Existing predictive rate schedulers are developed under the assumption of perfect estimation, which may not be possible in future CDMA-based cellular networks characterized with highly nonstationary and bursty traffic. Additional shortcoming of existing rate schedulers is the coupling of delay and bandwidth, that is, close interdependence of delay and bandwidth (rate), whereby controlling one is accomplished solely by changing the other. In order to mitigate for the arrival rate estimation errors and delay-bandwidth coupling, this paper presents the feedback-enhanced target-tracking weighted fair queuing (FT-WFQ) rate scheduler. It is an adaptive rate scheduler over multiclass CDMA systems with predictive adaptation control to adapt to nonstationary loadings; and feedback-enhanced reactive adaptation control to counteract arrival rate estimation errors. When the predictive adaptation control is not able to maintain long-term delay targets, feedback information will trigger reactive adaptation control. The objective of FT-WFQ scheduler is to minimize deviations from delay targets subject to maximum throughput utilization. Analytical and simulation results indicate that FT-WFQ is able to substantially reduce degradations caused by arrival rate estimation errors and to minimize delay degradations during nonstationary loading conditions.

Guard-based call admission control schemes support admission priorities based on resources sharing with differentiated resource capacity limits. To minimize deviation from call blocking/dropping targets due to nonstationary call arrival condition, dynamic guard-based schemes with predictive adaptation control adjust differentiated capacity limits according to predicted future arrival rates based on specified estimation algorithms. Existing dynamic guard admission schemes are developed under the assumption of perfect estimation, which may not be possible in a highly nonstationary environment and, thus resulting in failures to maintain targeted blocking/dropping probabilities. This paper presents the fairly adjusted multimode-dynamic guard bandwidth scheme, which is a dynamic-guard-based scheme over code-division multiple-access systems with predictive adaptation control to adapt interference-based guard loading-limits under nonstationary call arrival condition; and reactive adaptation control to counteract arrival rate estimation errors. When the predictive adaptation control policy mode is not able to maintain long-term call blocking or dropping targets due to estimation error, this will trigger reactive adaptation control policy modes that include temporary blocking (preemption) of one or more lower priority classes subject to fairness constraints to ensure lower priority classes are not preempted at all costs during estimation error recovery. Analytical and simulation results show that proposed scheme is able to provide performance guarantees in terms of dropping probabilities under nonstationary traffic arrival and imperfect arrival rate estimation.

The TDMA-based dynamic guard channel scheme supports prioritized call admission control and adapts new call and handoff request admission priorities in response to nonstationary request arrivals or loading. We present an adjusted multimode dynamic guard bandwidth (AM-DGB) scheme that extends the blocked-calls-dropped dynamic guard bandwidth concept to CDMA-based systems, supporting multiple admission priority classes, based on request types and traffic classes. AM-DGB employs operation modes that temporarily block one or more lower-priority classes completely when pure dynamic guard operation is unable to keep long-term blocking rates under predefined targeted thresholds. Analytical and simulation results show that AM-DGB is able to maintain consistent performance guarantees in terms of dropping probabilities.