ISSN:1047-9627    

DOI:10.1002/dac.4510060102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper describes the implementation of a prototype ATM adaptation layer (AAL) within the kernels of two machines running Sun Operating System 4.1.1. The implementation is achieved by using the STREAMS paradigm and an Ethernet link between the two machines as a surrogate optical fibre link. The flexibility of the STREAMS facility for building layered protocols, and the real‐time performance limitations of the STREAMS scheduling system are identified. STREAMS is shown to be no less susceptible to naïve buffer utilization than earlier paradigms. It is necessary to minimize message passing and copying of data to achieve high throughput. This study has clarified several key issues in the functional design of AA

ISSN:1047-9627    

DOI:10.1002/dac.4510060103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe access to a multiservice synchronous TDM network is considered, where hybrid frames are used to carry two basic traffic types (a circuit‐switched isochronous and a packet‐switched asynchronous one), generated by several users. Each user is assigned a portion of the total available bandwidth, in terms of slots/frame, which is dynamically allocated between the two traffic types at the user premises, by means of a local randomized decision rule. The users' bandwidth shares (capacities) are allocated by a centralized agent, whose goal is to minimize a global cost function that accounts for packet delays and call blocking of the entire process. Parametric optimization problems for the central agent are defined and the application of suitable descent techniques is shown, with the cost function extending over a finite and an infinite time horizon, respectively. The specific nature of the optimization problems is discussed, and numerical examples and simulations are presented that illustrate the effectiveness of the met

ISSN:1047-9627    

DOI:10.1002/dac.4510060104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis study represents the sequel and conclusion of a previous one already published in this Journal a few issues ago.1In that article, we tackled the problem of evaluating theoretically the performance of an adaptive MLSE receiver for MSK signals on a frequency‐selective stationary radio propagation channel, and we validated the theoretical findings (in the form of upper and lower bounds to the BER of the receiver) by means of computer simulations. In the present paper, we report on the performance of the very same scheme of channel‐estimator‐plus‐Viterbi‐equalizer receiver for mobile communications in a more realistic operating environment. In particular, we completely encompass here thegroupe spécial mobile(GSM) transmission format, based on the Gaussian minimum shift keying (GMSK) modulation scheme and on narrowband time‐division multiple access (TDMA) transmission. Also, we remove the assumption of a time‐invariant propagation channel, assuming the recommended standard GSM channels as benchmark transmission conditions. Finally, with the aid of extensive computer simulations, we analyse the sensitivity of the MLSE receiver to unwanted co‐channel and adjacent‐channel interference coming from other users of the mobile c

ISSN:1047-9627    

DOI:10.1002/dac.4510060105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe design of a copy network is presented for use in an ATM (asynchronous transfer mode) switch supporting BISDN (broadband integrated services digital network) traffic. Inherent traffic characteristics of BISDN services require ATM switches to handle bursty traffic with multicast connections. In typical ATM switch designs a copy network is used to replicate multicast cells before being forwarded to a point‐to‐point routeing network. In such designs, a single multicast cell enters the switch and is replicated once for each multicast connection. Each copy is forwarded to the routeing network with a unique destination address and is routed to the appropriate output port. Non‐blocking copy networks permit multiple cells to be multicasted at once, up to the number of outputs of the copy network. Another critical feature of ATM switch design is the location of buffers for the temporary storage of transmitted cells. Buffering is required when multiple cells require a common switch resource for transmission. Typically, one cell is granted the resource and is transmitted while the remaining cells are buffered. Current switch designs associate discrete buffers with individual switch resources. Discrete buffering is not efficient for bursty traffic as traffic bursts can overflow individual switch buffers and result in dropped cells, while other buffers are under‐used. A new non‐blocking copy network is presented in this paper with a shared‐memory input buffer. Blocked cells from any switch input are stored in a single shared input buffer. The copy network consists of three banyan networks and shared‐memory queues. The design is scalable for large numbers of inputs due to low hardware complexity, O (Nlog2N), and distributed operation and control. It is shown in a simulation study that a switch incorporating the shared‐memory copy network has increased throughput and lower buffer requirements to maintain low packet loss probability when compared to a switch with a discrete buff

ISSN:1047-9627    

DOI:10.1002/dac.4510060106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this communication we present a novel means of signalling between an out‐of‐service RT and the CO when connected via a passive optical network which contains other RTs in‐service using a TDMA protocol. A simple experiment using a non‐coherent receiver is used to demonstrate the te

ISSN:1047-9627    

DOI:10.1002/dac.4510060107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:1047-9627    

DOI:10.1002/dac.4510060108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:1047-9627    

DOI:10.1002/dac.4510060101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY