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Multibeam antennas (MBAs) are capable of supporting concurrent communications with multiple neighboring users in wireless networks and, thus, can improve the throughput over omnidirectional antennas and switched-beam directional antennas. The throughput performance, however, may degrade in the absence of a proper access scheme for user scheduling, and thus, collisions occur. The probability of having such collisions further increases in a multipath propagation environment, which is commonly encountered in a wireless network. Furthermore, there is an increased demand to deliver various types of data with differentiated quality and latency requirements. Thus, it is desirable to incorporate user/packet priority in the medium access control (MAC) protocol. In this paper, priority-based access schemes are proposed for wireless networks exploiting MBAs, respectively, in single-path and multipath environments. An analytical framework is then developed to analyze the node throughput performance when the proposed access scheme is used. The analytical and simulated results clearly show that, in contrast to a random-access scheme, where significant throughput degradation occurs in a multipath propagation environment, when the proposed access scheme is applied, the node throughput becomes a nondecreasing function of the offered load, and the degradation due to multipath is significantly mitigated.

In forthcoming personal communication systems (PCSs), small cells are deployed to achieve high spectral efficiency. This has significant impacts on location tracking of mobile users. The increase in location update (LU) load leads to more contention on the reverse control channel. Thus, many algorithms are designed to distribute the LU load to a larger number of cells. This avoids the inefficiency of random accessing due to high offered load. In an alternative approach (Wong 1995), a contention-free LU algorithm is proposed. Two or more mobile units are permitted to register with a base station simultaneously without contention. A probabilistic paging mechanism called Bloom filtering is used to select cells to be paged. Since there is no contention in LU, inefficiencies due to random accessing are bypassed. In this paper, we present another contention-free LU algorithm. It is hybrid in the sense that LUs are temporally or geographically triggered. The use of hybrid LU alleviates inefficiencies inherent to temporal triggered LU in Wong. Three selective paging schemes are considered in this paper. Tradeoff between paging delay and paging bandwidth is addressed. The performance of this algorithm is compared to Wong and other conventional strategies. Numerical results show that the new algorithm compares favorably with previous proposed strategies.

Some new performance measures and channel reservation for handoff calls for maximizing the service provider's revenue in a personal communications service (PCS) network, with general cell residence time and general requested call holding time, are investigated. Here, each cell within the PCS network consists M channels, but only when at least m+1 (0/spl les/m

Location management cost in a wireless network is expressed in this work as the sum of signaling cost due to paging and signaling cost due to registration. We introduce and compare a heuristic method and an asymptotic method for selecting a disjoint partition of a one-dimensional service area to minimize location management costs. In special cases for which the best design is known, the asymptotic design rule outperforms the heuristic rule, including cases for which the number of location areas is small. With offered load /spl lambda/, per-event paging cost P, per-event registration cost R, and fixed traffic patterns, optimal location area edges depend on /spl radic//spl lambda/P/R and location management costs are proportional to /spl radic//spl lambda/PR.

The capacity gains from the transition from analog-to-digital time-division multiple-access (TDMA) air-interface technology depend on the number of base-station radios (transceivers) changed from analog to digital. It is possible to have no capacity gains, and even losses, if too many radios are changed over. This paper addresses the problem of finding the optimal radio mix. An analytical model is developed to compute the blocking rate experienced by subscribers in a cell, given the cell's offered load, the mix of analog and dual-mode subscriber units, and the analog-to-digital split of the radio frequency (RF) channels available to the cell.

A new personal communications services (PCS) hand-off scheme is proposed. This scheme provides for hand-off to radio ports on which there is no free channel by "sub-rating" an existing connection. With sub-rating, an occupied full-rate channel is temporarily divided into two half-rate channels: one to serve the existing call and the other to serve the hand-off request. The blocking probabilities (combined forced terminations of existing calls and blocking of new call attempts) of this new scheme compare favorably with the standard scheme (nonprioritizing) and the previously proposed prioritizing schemes. The costs for this scheme are presented and discussed, as well as the additional procedural complexity of implementing on-the-fly sub-rating and the impact of continuing the conversation on a lower rate channel (which may lower speech quality of increase battery drain). Analytical models and simulations investigating the traffic impacts are presented, as are the results that show that even in the highest offered load considered a 3-min conversation in the busy hour experiences less than half a second of sub-rated conversation on average and only about 3% of the calls experience more than 5.12 s of sub-rated conversation. This scheme can increase capacity by 8-35% for systems with 1% call incompletion probability.

We propose a random multiple access scheme named S-ISMA/CD (slotted idle signal multiple access with collision detection) for a centralized wireless communication network where upstream and downstream traffic are transmitted over separate channels. Two versions of the scheme, S-ISMA/CD1 and S-ISMA/CD2, are studied in this paper. The S-G (throughput versus offered load) performance of both schemes are evaluated. We also study the dynamic behavior of the system with finite population of terminals on the upward channel. By using EPA (equilibrium point analysis), a fluid approximation method, the throughput and delay performance is evaluated. As a result, it is shown that both schemes have high channel efficiency although S-ISMA/CD1 has a little better performance on the downward channel while S-ISMA/CD2, is easier in implementation and more reliable in operation. >

Idle signal multiple access (ISMA) was proposed to solve the problem of hidden terminals in CSMA (carrier sense multiple access) systems. Its extensions, I-ISMA (ISMA for integrated services) and S-ISMA/CD (slotted ISMA with collision detection), were shown to be effective in personal communication networking. In this paper, we introduce a reservation technique to the ISMA scheme and propose the so-called reserved ISMA (R-ISMA) scheme to improve the channel efficiency. S-G (throughput versus offered load) performance of R-ISMA is evaluated. We also present the dynamic analysis to evaluate the throughput and delay performance of the system. Two methods for the dynamic analysis are proposed. One is the traditional Markov analysis, which provides the exact numerical results, and the other is TFA (transient fluid approximation) analysis, which simplifies the computation complexity. Numerical examples and discussions are given. >