Performance of CDMA/PRMA as an Access Technique for Integrated Services in a UMTS High Altitude Platform System

Abstract

High Altitude Platforms (HAPs) have gained a great interest in recent years. HAP systems will be global in nature but national in service provision. They will deliver IMT-2000 mobile and fixed wireless access using the proposed IMT-2000 terrestrial component radio transmission technologies and protocols. Under the above consideration, in this paper the performance of a MAC protocol based on the combination of the well-known Packet Reservation Multiple Access (PRMA) scheme with Code Division Multiple Access (CDMA) technologies in a Frequency Division Duplex (FDD) mode is studied, for a HAP operating at the 2 GHz frequency band at an altitude of 22 km. The impact of acknowledgement delay has been examined through computer simulations, along with the selection of suitable channel access functions (CAFs) to control the access of mobile users. Moreover the protocol performance is investigated in a cellular HAP environment and compared to that of a ground-based system. Finally, different traffic scenarios have been considered in order to investigate the access delay for non-real time traffic and the packet dropping performance for real time traffic.

Cross-Layer Designs of Multicarrier NC-PRMA Systems over Powerlines

“…Speech distortion due to a 1% packet drop is rarely audible and, hence, a packet dropping probability P drop <0.01 is considered to be an acceptable level [6]. The mean access delay is defined as the time interval between a new transmission request and the time when a reservation is obtained [7].…”

“…For delay insensitive services, such as non-real time data packets, there are no severe limits on delay constraints and data packets are never dropped at the MAC, i.e. a negligible dropping probability [7] is assumed.…”

Performance Investigation of CDMA/PRMA with Imperfect Power Control in TDD Cellular Systems

“…Single switching point is adopted; first seven TSs form the downlink subframe and last eight TSs form the uplink subframe. For a single cell with perfect power control in [1,2], the bit error rate, p e , can be simplified as…”

“…Notice that these eight CSs in a TS may not be fully utilized if the interference level is too high. However, in previous studies [1][2][3], it is always assumed that all Q CSs can be fully utilized regardless of the interference variations. Next, since a contention packet only contains the necessary information for slot reservation, contention packets can use a more powerful BCH code, BCH (255, 63, 30).…”

“…The performance of code-division multiple access/packet-reservation multiple access (CDMA/PRMA) protocol has been studied in [1][2][3]. In these studies, each time slot (TS) is divided into a fixed number of code slots (CSs) based on the assumption of perfect power control.…”