A new call admission control (CAC) strategy based on the soft capacity constraint (SCC) concept is proposed for CDMA cellular systems. The use of the SCC concept allows maximizing system capacity while at the same time meeting the quality of service (QoS) requirements in terms of the outage probability. The fractional channel reservation (FCR) scheme is also used in the proposed CAC strategy as a system capacity booster. The proposed CAC strategy is mathematically analyzed by means of a teletraffic analysis considering both soft handoff and users' mobility. Realistic mobility conditions are taken into account by characterizing users' mobility parameters considering a smooth random mobility model. Novel mathematical expressions for the new call blocking, handoff failure, and forced termination probabilities are then derived. Mason's rule is employed for the derivation of the forced termination probability.

A teletraffic analysis for the performance evaluation of the joint use of dynamic resource allocation (DRA), channel de-allocation (DAS), and channel re-allocation (RAS) strategies in GSM/GPRS networks is developed. In addition, an efficient DRA strategy with a link quality awareness policy, channel de-allocation and re-allocation policies as well as user prioritization (called DRA LA DAS RAS) is proposed. To the authors' knowledge, most related works have either studied link adaptation (LA) or dynamic resource allocation (DRA) strategies as independent topics but have failed to address their combined effect on GSM/GPRS systems. DRA LA DAS RAS uses both call degradation and call compensation techniques. Calls with the largest number of channels allocated and the worst link quality are degraded first. Conversely, calls with the lowest number of channels allocated and the best link quality are upgraded first. This allows upgraded calls to release resources more rapidly, making them readily available for new calls. Numerical results show that the proposed DRA LA DAS RAS strategy significantly improves system performance, i.e. up to 82% (74%) {58%} [37%]less blocking probability relative to the DRA (DRA LA with p=0.75) {DRA DAS} [DRA LA DAS with p=0.75]strategy.

In this paper, the performance of three different fair resource allocation strategies for packet data transmission in wireless networks with link adaptation (LA) is mathematically analyzed. The strategies aim at achieving fair access, fair transmission rate or simultaneous fair access and transmission rate. As a case study, the performance of the considered strategies is evaluated in GSM/EGPRS networks in terms of call blocking probability for voice packet data users and system throughput. However, the analysis is valid for any Radio Transmission Technology that uses LA techniques. For the mathematical analysis, packet data traffic (i.e., IP) is modeled as a process showing pseudo-long range dependence. In particular, to capture their bursty nature, packet data arrivals are considered to follow a Modulated Markov Poisson Process (MMPP) process. Numerical results show that voice calls get lower blocking probability than data packet transmissions when a fair access resource allocation strategy is used. Also, a trade off between (access and/or transmission rate) fairness and system utilization is observed. Finally, it is also shown that high grade of burstiness significantly degrades the system performance.

In this paper, a new system level approach for modeling wireless channel unreliability in CDMA cellular systems is proposed. The analysis takes into account call connection types (i.e., soft handoff or single base station) and their respective link reliabilities, which according to some measurements in real cellular networks reported in the literature can adequately be modeled by considering a Poisson call interruption process. This is turn results in significant simplifications of system level analysis. Then, with the proposed interruption modeling, an elegant teletraffic analysis for the performance evaluation of mobile cellular CDMA networks considering both wireless link unreliability and resource insufficiency is developed. Realistic mobility conditions are taken into account by characterizing users' mobility parameters by means of a smooth random mobility model. Novel mathematical expressions for the new call blocking, handoff failure, and forced termination probabilities are then derived. Graph theory and Mason's rule are employed for the derivation of the forced termination probability.

In this paper, the performance of three fair resource allocation strategies for packet data transmission in EDGE/GPRS networks are mathematically analyzed. The strategies aim at achieving, respectively, fair access, fair transmission rate and, simultaneous fair access and transmission rate. The differences in terms of QoS and GoS caused by link adaptation (LA) and multi-slot allocation experienced by data users in EGPRS networks is smoothed by these strategies through the use of multiple resource reservation and/or dynamic resource allocation strategies, which, at the same time, compensate users with poor radio channel conditions. Also, the performance of the proposed strategies is evaluated by means of teletraffic analysis tools in terms of packet blocking probabilities and throughput

In this paper, call admission and code allocation schemes are proposed to provide service differentiation in the forward link of wideband code-division multiple-access (WCDMA) systems. In particular, this paper proposes multiple leaf code reservation (MLCR) schemes, where different numbers of orthogonal variable spreading factor (OVSF) leaf codes (i.e., codes of the lowest layer of the OVSF code tree) are reserved to differentiate users with different bandwidth requirements. Leaf codes are only reserved for as long as the call admission process lasts. Once the decision of whether a new request is admitted or not has been made, a Code Dereservation procedure is carried out to increase flexibility in the code assignment phase. The performance of these MLCR strategies with/without code reassignments is then evaluated. Analysis shows that MLCR schemes are also useful in improving fair access among different traffic classes. In addition, perfect fair access among requests with different data rates can be achieved when code reassignments are jointly employed with the proposed OVSF-code reservation schemes.

In this paper, the performance of mobile cellular systems with link adaptation (LA) is analytically evaluated. Half- and full-rate vocoders are considered in the analysis. Mathematical expressions for the new call blocking, handoff failure, and forced termination probabilities are obtained. To our knowledge, no similar analysis considering LA exists in the literature. Also, the link quality-aware dual fractional channel reservation (LQA DFCR) scheme is proposed. In LQA DFCR, user differentiation is implemented in terms of link quality. Preference is given to users with good link quality because they require fewer resources than users with bad link quality. Numerical results show that the proposed LQA DFCR scheme effectively increases system capacity: LQA DFCR achieves more than a 11% capacity gain relative to systems with the non priority scheme (NPS) and with LA, and approximately 3% relative to the fair access prioritisation scheme (FAPS) strategy. Numerical results also show that LA yields an approximately 18% capacity increase relative to a cellular system without LA when no admission control is employed (admission control strategies further increase system capacity.) The synergy between LA and admission control strategies yields more than a 31% capacity gain

In this letter, recursive formulas for the new call blocking and handoff failure probabilities for Fractional Guard Channel (FGC) policies in cellular networks are derived. The effect of users' mobility on the maximum system capacity achieved with the Guard Channel (GC), the Limited Fractional Guard Channel (LFGC), and the Uniform Fractional Guard Channel (UFGC) strategies is then evaluated. Results show that maximum system capacity decreases exponentially as the mean cell dwell time decreases and that the relative capacity gain of each scheme depends on the mean cell dwell time. It was also found that LFGC outperforms GC and UFGC under any mobility condition.

In this paper, the performance of dynamic resource allocation and channel de-allocation in integrated voice/data wireless networks with link adaptation is mathematically analyzed and evaluated. To our knowledge, all previous related works published in the literature have considered only link adaptation (LA) or dynamic resource allocation (DRA) separately. Additionally, a DRA strategy with link quality-aware prioritized channel de-allocation (called DRA LA DAS) is proposed. With the DRA LA DAS scheme that calls with the greatest number of channels and the worst link quality are degraded first. In this way, in DRA LA DAS preference is given to data users with good quality link which, on average, retain resources less time than data users with bad quality link. Numerical results show that the proposed DRA LA DAS strategy significantly improves system performance. The GSM/GPRS system is used as a case study. The GSM voice new call blocking and forced termination probabilities, GPRS packet dropping probability, average GPRS packet transmission time, and channel utilization are analyzed

In this paper, recursive formulas to calculate the new call blocking and handoff failure probabilities for fractional guard channel (FGC) policies in cellular networks are derived. Since the limited fractional guard channel (LFGC), the uniform fractional guard channel (UFGC), the guard channel (GC), and the non-prioritization schemes (NPS) are particular cases of the FGC policies; the recursive formulas for the blocking probabilities of these schemes are implicitly obtained as well. The optimal performance of the GC, LFGC, and UFGC strategies is compared in terms of the maximum system capacity for different mobility conditions. It is observed that as mobility increases the system capacity decreases. Results show that the relative capacity gain of the different schemes depends on the value of the mean cell dwell time relative to the mean service time. It is shown that LFGC overcome the GC, UFGC, and NPS strategies for any mobility condition and can achieve as much as 3% capacity gain relative to GC, 10% relative to UFGC, and 12% relative to NPS.

A mobility-aware call admission strategy for wireless communication systems, called regulated call dropping (RCD) with fractional channel reservation (FCR) (RCD-FCR), is proposed. RCD-FCR combines a RCD scheme with the FCR strategy to increase fairness among all classes of mobile users and channel utilization efficiency. Users are classified according to their mobility characteristics int slow and fast moving users (i.e., pedestrians and vehicles). Calls by slow moving users are intentionally dropped in a controlled manner (through the use of a call dropping authorization probability). The FCR strategy', on the other hand, is used to improve the protection of ongoing calls against new calls. Numerical results show that RCD-FCR achieves 23.3% capacity gain relative to the nonpriority scheme and 5.56% relative the FCR strategy.

In mobile cellular systems with link adaptation (LA), different quality/.ones, in terms of the Signal-to-interference Ratio (SIR), are distinguished. In this paper, the quality zone residence time distribution in mobile cellular systems with link adaptation is addressed. The cell residence time distribution has been widely studied in the literature. However, a literature survey shows that relatively few in-depth papers have addressed the quality zone residence time. In this work, comprehensive simulation results for a generalised mobility model are shown. Results show that as the mobility randomness increases, the probability density function of the quality zone residence time tends to a negative exponential one.

In this paper, a new adaptive resource allocation strategy called equal resource sharing allocation with differentiated QoS (ERSAQoS) is presented. This strategy is suitable for operation in environments with integrated service types (i.e.: voice, video, videophone) with different bandwidth requirements and priorities each. Our strategy allows soft-controlled differentiated QoS provisioning. Results show that ERSAQoS meets the upper capacity bound for flexible resource allocation strategies while improving the QoS of the prioritised service types.

In this paper, the multiple fractional channel reservation (MFCR) strategy for service differentiation is proposed. Contrary to the rest of the channel reservation schemes proposed in the literature, these strategy reserves, on average, real numbers of channels to prioritise different call types (new or handoff) in multiple service environments. Determining the right number of reserved channels for each call type to satisfy all QoS constraints is a difficult task. Also, selecting the right prioritisation order is not an easy process, as it depends on QoS constraints and system characteristics. Thus, an algorithm to determine the optimum numbers of reserved channels to achieve maximum system capacity when using the MFCR is also proposed. To our knowledge, the capacity optimisation problem considering individual QoS constraints for each call type had only been addressed in single service environments.

In this paper, the performance of wireless mobile communication systems with link adaptation is evaluated by means of a teletraffic analysis. To our knowledge, no similar analysis considering link adaptation exists in the literature. In particular, mathematical expressions for the handoff call arrival rate, the intra-cell handoff failure and the forced termination probabilities are derived. Half- and full-rate vocoders are considered and a link quality-aware dual channel reservation (LQA DCR) scheme is proposed. In LQA DCR, preference is given to users with good link quality because they require fewer resources than users with bad link quality. Numerical results show that the proposed LQA DCR scheme effectively increases system capacity.

A mobility-aware handoff prioritisation strategy for wireless communication systems with heterogeneous platform types, called regulated call dropping (RCD) with channel reservation (CR) (RCD-CR), is proposed. RCD-CR combines a RCD scheme with the CR strategy to increase fairness among all classes of mobile users and channel utilisation efficiency. Call dropping (pre-emptive) strategies have almost exclusively been used to prioritise real time traffic over non-real time data traffic (delay tolerant traffic classes) in the literature. In this paper, call dropping is used to prioritise calls carrying real time traffic over other calls carrying the same class of traffic. RCD-CR takes into account the different speeds of slow and fast mobile users to equalise the QoS provided to all of them. With the aim of releasing resources to attend handoff calls by fast moving users, calls by slow moving users are intentionally dropped in a controlled manner (through the use of a call dropping authorisation probability). The CR strategy, on the other hand, is used to improve the protection of ongoing calls against new calls.

In this paper, the transmission delay in adaptive resource allocation strategies with uniform quality of service (QoS) provisioning is addressed. The accuracy of a mathematical analysis approach is corroborated by semi-analytical results. The analytical approach is based on the fact that in flexible resource allocation (FRA) strategies with uniform QoS provisioning all active sessions of each service type equally share their resources and tend to utilise an average bandwidth. The fact that the probability density function of the normalized transmission delay is almost a symmetrical function is also considered.

In this paper, a novel approach to mathematically analyse the performance of adaptive resource allocation strategies with uniform quality of service (QoS) provisioning, when session service time depends on the allocated bandwidth, is proposed. Our proposed approach is based on the fact that in adaptive resource allocation strategies with uniform QoS provisioning all active sessions of each service type tend to utilise a bandwidth close to the average. The transmission delay experienced by sessions, compared to an optimal transmission operating at the maximum bandwidth requested is a characteristic related performance measurement that is also addressed in this work.

The performance of a flexible resource allocation strategy (FRA) combined with a dynamic channel allocation strategy (DCA) is assessed. Special attention is given to the upper capacity limits. Hence, the maximum packing (MP) is selected as the DCA strategy whereas the resource sharing for data services (RSDS) is selected as the FRA strategy. MP and RSDS represent, respectively, the upper limit in terms of capacity in DCA and FRA strategies. The assessment is performed in a Manhattan-like environment. Results show that the combination of DCA and FRA can produce an increase in terms of capacity of about 18% with respect to the use of FRA only.

A new flexible resource allocation (FRA) scheme called flexible resource allocation strategy with prioritised levels (FRASPL) is proposed. FRASPL meets the upper capacity bound for FRA strategies while providing acceptable quality to the admitted request by using degradation and compensation of all active calls. FRASPL can trade-off capacity and QoS. FRASPL is deliberately designed to cope with several service types defining also prioritisation rules that makes it different to the rest of the strategies previously proposed in the literature.

A comprehensive study of flexible resource allocation (FRA) strategies is presented and a new strategy called Flexible Resource Allocation Strategy with Differentiated Priorities and QoS (FRAQoS) is proposed. FRAQoS copes with scenarios where multiple types of service coexist with different priorities and QoS requirement each, offering service integration and differentiation required by 2.5G and 3G systems. Also, a fair comparison of FRAQoS with almost all the previously proposed strategies is performed through the use of an analytical model (validated by computer simulations).

We present a new flexible resource allocation (FRA) strategy, called resource sharing for data services (RSDS), that dynamically averages the allocated resources to the call requests based on the number of calls in a cell. RSDS accommodates the maximum number of requests while providing acceptable quality to the admitted request through the use of. degradation and compensation techniques. An analytical model (validated by computer simulations) is developed to model RSDS in a scenario with multiple types of service, each of them with different priorities. Preliminary results indicate that the RSDS strategy outperforms some strategies already reported in the literature.

A complete traffic model and analysis for microcellular mobile systems with handoff using fixed channel allocation (FCA) is described. Only the new call arrival rate is supposed to be known and a method of assessing the hand-off arrival rate in each cell for any kind of traffic is derived. The analytical method is validated with a real non-uniform traffic distribution and is verified by simulations. An extension to the nonuniform compact pattern allocation algorithm is presented as an application of this analysis. Based on this extended concept, we propose a modified version of a dynamic channel allocation (DCA) strategy called compact pattern with maximised channel borrowing (CPMCB). It is shown that CPMCB is now a self-adaptive prioritised hand-off DCA strategy with enhanced performance that can be exploited in a PCS environment. The effect of user mobility on the grade of service is also considered by CPMCB.

The compact pattern with maximized channel borrowing (CPMCB), a new dynamic channel assignment strategy (DCA), is proposed. This new DCA algorithm takes advantage of the compact patterns to decrease the blocking probability by always assigning a channel to a pattern that improves the system performance. Channel borrowing and channel reallocation strategies are also used to minimize the blocking probability of each cell of the system. In the case of nonuniform traffic the new strategy is shown to have an 8% more traffic carrying capacity than the borrowing with directional channel locking (BDCL) scheme at a blocking rate of 2%, and better performance than CP based DCA under heavy loads of nonuniform traffic. This without violating the interference constraints as the latter strategy does. The maximum number of channel reallocations is at most one, being this therefore another advantage over BDCL. Also, a new interference limited environment with real traffic conditions is used. Results for this scenario with the standards AMPS and IS-54 are included, which validate the better performance of CPMCB as well.