Multiaccess strategies in an integrated UTRA system

Performance of the access channel in cdma2000 and random access channel in W-CDMA is studied in this paper. In such systems, the accessing user can degrade the performance of existing users by introducing extra interference such as packet collision and blocking. We study how much the random access channel in W-CDMA is superior to an access channel in cdma2000 by employing a more complicated channel structure. In addition, channel occupancy, which is a measure of interference to other channel types in the system, is also investigated. Simulation is carried out to compare the performance of these channels under fixed frame error rates and varying offered load conditions.

Narrowing the 'Digital Divide': The Role of Complementarities between Fixed and Mobile Data in South Africa

The growing demand for mobile and wireless access to Internet services has generated interest in how to use broadband infrastructures to provide such services. In this paper we provide, as a first step, an introductory presentation of alternative architectures for providing wireless Internet access, and in particular, the mobile IP service, when the fixed backbone network, either in the Internet or the public switched telephone network (PSTN) contains ATM entities. All the architectures use an interworking function (IWF) which encapsulates the functions of protocol adaptation, inter-BSC handoff encryption, authentication and packet routing and addressing. The first architecture we consider provides a wireless Internet access service only, without integration with voice services or provision for non-Internet data services (e.g. messaging or fax), and uses a centralized IWF. The second architecture is similar but uses a distributed IWF. We then consider two architectures where voice and data services are integrated. In architecture 3, voice and data services share the radio system only, with switching and other functions being provided separately for each service. architecture 4 not only allows voice and data to share the PSTN switching resources, but also considers the interworking of ATM switches in the PSTN backbones with narrowband PSTN switches as well as Internet ATM transport.

Random access channel is incorporated in IEEE 802.16 WiMAX system to transport contention-based messages in the uplink, such as bandwidth requests generated by best effort applications, from mobile stations (MSs) to the base station(BS). Regarding the packet transmissions in the random access channel, delay, throughput and power consumption are usually considered as major performance metrics. We propose an enhanced power calibration protocol to optimize the system performance in terms of channel access delay, system throughput and MS transmit power consumption. Optimal selection of power levels is formulated in order to maximize the achievable throughput while being subject to power consumption constraint of mobile stations. Our scheme can substitute the random backoff mechanism in the current the WiMAX uplink random access channel, as it can accomplish a significantly improved access delay performance without an increment of design complexity. Simulations are conducted to validate our protocol and confirm its performance superiority as compared to the random channel access method used in the current WiMAX.

The word ‘telematics’ was used for the first time in France in 1978 by Simon Nora and Alain Minc; it is a contraction of the French words ‘tétécommunications’ and ‘informatique’, and defines a marriage between computers and data transmission networks. This paper describes the five systems which will be implemented to provide telematic services via satellite in Europe during the next few years: EUTELSAT, TELECOM 1, UNISAT, DFS and ITALSAT. The main characteristics of the ‘special service’ transponders are presented, showing that, in Europe, (a) 2 to 5 transponders per satellite will be devoted to the special (telematic) services; (b) 4 satellites out of the 5 use the 12.5–12.75 GHz down‐link band for this purpose (only ITALSAT uses the 20 GHz down‐link for the same purpose), and (c) e.i.r.p.s at 12 GHz are in the range 40–49 dBW.The ground and space segments corresponding to this new service are presented. The main peculiarity of the ground segment is the exclusive use of ‘small’ earth‐stations equipped with fixed antennas and SCPC or 25–60 Mb/s TDMA multiple access equipment. Telematic services include videoconference at 2048 kb/s, voice services, computer‐to‐computer transfer of data, data distribution, remote printing, electronic mail, high‐speed facsimile, offshore voice and data services, digital network overflow, transatlantic digital business etc…Customer bit rates start from 2.4, 4.8, 9.6 and 32 kb/s (for TELECOM 1) up to 2048 kb/s by 64 kb/s steps. Bit error rates are maintained below 10−6 (standard) or 10−10 (higher grade) during 99 per cent of the year using FEC. The five networks for telematics via satellite in Europe are independent. A large efficiency improvement of the different services should be obtained through a future interconnection of the various networks via intersatellite links.

This paper presents the optimum random access channel (RACH) structure in terms of the number of control signaling bits accommodated and the transmission bandwidth based on the link budget in order to satisfy the coverage requirement for the single-carrier (SC)-FDMA based E-UTRA uplink. First, we propose grouping of the RACH purposes to reduce the number of control signaling bits to be conveyed by the RACH. By employing the proposed purpose-grouping scheme, only a four-bit random ID and a two-bit purpose grouping index for the non-synchronized RACH are required. Simulation evaluations including a system-level simulation show that the non-synchronized RACH comprising a 0.5-msec preamble signature sequence can convey the aforementioned 6-bit control signal at the cell edge when the inter-site distance (ISD) is 500 m under full channel load conditions with one-cell frequency reuse. It is also shown, however, that a RACH longer than one-sub-frame, e.g., 1.0 msec, is necessary to support the ISD of 1732 m assuming the same conditions. We also show that although there is no distinct difference in the transmission bandwidth from 1.25 to 5 MHz from the viewpoint of the misdetection probability, a 1.25-MHz transmission bandwidth for the RACH is suitable from the viewpoints of flexible resource assignment in the time domain and small number of option in the transmission bandwidth.

We perform a new analysis of the performance of the wideband code-division multiple access (W-CDMA) randomized slotted-offset random access channel (RAC) with Nakagami-m fading and compare it with that of a comparable randomized slotted-ALOHA-based RAC. Previously, it was shown that the W-CDMA RAC is fast, robust and simple to implement (see Esmailzadeh, R. and Gustafsson, M., Proc. 1997 IEEE ICUPC Conf, p.43-7, 1997). However, it was assumed that any random access packet arrival events involving multiple packets from cochannel mobile stations would result in lost packets. Closed-form equations are developed for the collision process of the arriving random access packets in slotted-offset and slotted-ALOHA RACs. An analysis is developed of the signal-to-interference-and-noise ratio of a packet involved in a multipacket DS-CDMA collision with a generalized Nakagami fading channel and diversity reception at the base station. A closed-form equation is developed for the bit error rate and packet throughput of the slotted-offset- and slotted-ALOHA-based RACs. The results of the analysis show that considerable improvement in the RAC performance can be achieved when multiple arrival collisions, on the same timeslot and with the same signature code, are partially resolved. The results also show the RAC's sensitivity to fading severity, packet E/sub b//N/sub 0/, spreading gain and number of base station receive selection diversity antennas. Compared to the randomized slotted-ALOHA designs, W-CDMA RAC performs as well in light fading conditions and slightly worse in severe fading conditions.

A packet aggregation method is proposed in this paper to lower the packet collision rate when the random access channel is used for machine type communications (MTC) uplink channel access in LTE. With the proposed packet aggregation method, a UE triggers random access when the aggregated packets in the buffer reaches the given threshold. However, this method reduces the packet collision rate at the expense of an extra latency which is used to aggregate certain amount of packets. Therefore, the tradeoff should carefully be selected between packet loss rate reduction and extra channel access latency. In this paper, we derive the packet loss rate and channel access latency as functions of amount of aggregated packets using a Semi-Markov chain model. With the derived results, the optimal amount of aggregated packets which satisfies the packet loss requirement and keeps the latency as small as possible can be found, which is verified through simulations.

The Long Range Wide Area Network (LoRaWAN) is one of the fastest growing Internet of Things (IoT) access protocols. It operates in the license free 868 MHz band and gives everyone the possibility to create their own small sensor networks. The drawback of this technology is often unscheduled or random channel access, which leads to message collisions and potential data loss. For that reason, recent literature studies alternative approaches for LoRaWAN channel access. In this work, state-of-the-art random channel access is compared with alternative approaches from the literature by means of collision probability. Furthermore, a time scheduled channel access methodology is presented to completely avoid collisions in LoRaWAN. For this approach, an exhaustive simulation study was conducted and the performance was evaluated with random access cross-traffic. In a general theoretical analysis the limits of the time scheduled approach are discussed to comply with duty cycle regulations in LoRaWAN.

Development of Unstructured Architecture for Voice and Data Services in Mobile Communication

A relatively new area of development is integrated voice and data systems. With its advent come challenges for both the engineering and behavoural scientists. Because integrated voice and data systems provide an opportunity to rely on human social interactions and communication, the user interface for such an integrated system is greatly simplified. Below we describe the behavioural issues which have guided the development of an integrated voice-data system.

The increasing need for service providers makes the performance of network management must also be improved. In this study, the author builds a clustering controller using the Open Network Operating System (ONOS) controller on an Software Defined Network (SDN) network. ONOS has a cluster feature that allows it to distribute traffic loads to other controllers to increase performance. The performance of clustering controller is compared with single controller and multi controller without clustering by measuring Quality of Service (QoS) on delay, jitter, and throughput parameters for data, voice, and video services. The test is done by adding background traffic. After being tested and analyzed, the performance of the clustering controller has the most superior QoS with an average delay in data services of 0.047026667 ms, jitter of 0.015414943 ms, throughput of 37.56360736 kbit/s. In the voice service, the delay value is 0.03909 ms, the jitter is 0.01828 ms, the throughput is 72.79049 kbit/s. In the video service, the delay value is 0,12072 ms, the jitter is 0,042013 ms, and the throughput is 5314,059 kbit/s. While in single and multi controller the average value obtained is not much different from the clustering controller. This is due to the single controller architecture, the network control center is only centered on 1 controller, as well as multi controllers, so that it affects the performance of service distribution.

Random access channel (RACH) procedures in modern wireless communications are generally based on multi-channel slotted-ALOHA, which can be optimized by flexibly organizing devices' transmission and retransmission. However, due to the lack of information about the traffic generation statistics and the occurrence of random collision, optimizing RACH in an exact manner is generally challenging. In this article, we first summarize the general structure of optimization for different RACH schemes, and then review existing RACH optimization methods based on machine learning (ML) and non-ML techniques. We demonstrate that the ML-based methods can better optimize RACH schemes compared to non-ML-based methods due to their capability in solving high-complexity long-term optimization problems. To further improve the RACH performance, we introduce a decoupled learning strategy (DLS) for access control optimization, which individually executes two sub-tasks: traffic prediction and access control configuration. In detail, the traffic prediction relies on an online supervised learning method adopting recurrent neural networks that can accurately capture traffic statistics over consecutive frames, while the access control configuration uses either a non-ML-based controller or a cooperatively trained deep reinforcement learning (DRL)-based controller selected depending on the complexity of different random access schemes. Numerical results show that the DLS optimizer considerably outperforms conventional DRL optimizers in terms of higher training efficiency and better access performance.

The telecommunications industry (TI) is challenged by a significant increase in the complexity of information transfer due to a recent proliferation of data mining technologies, techniques and applications. As the result, TI is facing a fundamental paradigm shift, with the convergence of voice and data services as well as ever expanding technologies to its users. This technological movement towards a convergence of telephony and computer technologies, web-based networks, and wired and wireless services is creating areas of tremendous opportunities. These areas of opportunity are for continuous quality improvements and applications of the voice and data convergence mining techniques and their implementations. The TI’s implementation of the data mining algorithms reduces information overload, increases data integrity and accuracy, and effectively manages its global networks.

This paper addresses self-optimization of the random access channel (RACH) in the Third-Generation Partnership Project (3GPP) Long-Term Evolution (LTE). Ensuring satisfactory random access (RA) performance in terms of access delay (AD) is crucial for reducing the delays associated with initial access and handovers. The feasibility of self-optimization is investigated by means of simulations, where the coupling between several parameters and the RACH performance in terms of AD is provided. We present two candidate feedback control algorithms that automatically adjust key RACH parameters to meet specified AD targets.