26-04-2014, 12:11 PM
Wireless ATM
Wireless ATM[.ppt (Size: 904.5 KB / Downloads: 945)
Background
Information Super Highway
Access to all types of information and media
Based on ATM/B-ISDN Technology
Rapid increase of mobile telecom. service
Full capacity of the second generation mobile systems
New solution with more capacity and better performance
Compatibility with the fixed telecom. infra structure
Cost-effectiveness
ATM - basic principle
favored by the telecommunication industry for advanced high-performance networks, e.g., B-ISDN, as transport mechanism
statistical (asynchronous, on demand) TDM (ATDM, STDM)
cell header determines the connection the user data belongs to
mixing of different cell-rates is possible
different bit-rates, constant or variable, feasible
interesting for data sources with varying bit-rate:
e.g., guaranteed minimum bit-rate
additionally bursty traffic if allowed by the network
System Design Goal of WATM
Flexible multiservice capability including voice, data and multimedia
Compatibility with ATM & B-ISDN
Guaranteed QoS for various service types
Low terminal cost, power consumption and complexity
Radio bandwidth efficiency
Efficient, scalable and cost-effective network architecture
Compliance with regulatory constraints
Description of the Protocols
APCP: Access Point Control Protocol
used between the access point and the switch.
foreseen only in the case of the need of the communication of information related to the status of the radio resources from the access point to the switch.
foreseen that the Access Point does not perform ATM switching functions.
B-ICI’: B-ICI with supplemental signaling information to support the transport of the mobility information
B-ICI+M: B-ICI with supplemental signaling information to support mobility
+M could represent more than one protocol operating on the interface
P-NNI’: P-NNI with supplemental signaling information to support the transport of the mobility information
P-NNI+M: PNNI with supplemental signaling information to support mobility
UNI’: UNI with supplemental signaling information to support the transport of the mobility information
UNI+M: UNI with supplemental signaling information to support mobility
WAL: Wireless Access Layer. The WAL is the wireless segment for end-to-end ATM connection. It includes the wireless MAC, LLC, and PHY layers.
FDD-Based MAC Proposals
Idea : have two channels per BS coverage area, one for the uplink (UL) and the other for the downlink (DL)
UL : used by the MTs for sending request and information packets, according to some reservation and contention algorithm,
DL : used by the BS in a scheduled mode, for sending acknowledgments (ACKs) and information packets.
Possible to have an almost immediate feedback from the BS in order to know (at the MT) if a request was successful or if a collision occurred.
The MAC protocol proposals
DQRUMA (Distributed Queuing Request Update Multiple Access)
PRMA/DA (Packet Reservation Multiple Access with Dynamic Allocation)
DSA++ (Dynamic Slot Assignment Protocol)
DTDMA/PR (Dynamic TDMA with Piggybacked Reservation)