Franz Treml

Performance analysis of temporary removal scheduling applied to mobile WiMax scenarios in tight frequency reuse

WiMax broadband MAN based on the IEEE 802.16d/e standard offers high data rate scenarios for both mobile and fixed wireless access. Different power control and scheduling options are investigated within the context of interference limited WiMax deployments in tight frequency reuse assuming nomadic mobility. A novel, very promising scheduling approach based on a flexible temporary removal strategy is introduced and analyzed in detail. The temporary removal can be easily combined with conventional scheduling techniques providing considerable performance benefits. Detailed system level simulations have been performed over a wide range of system load scenarios demonstrating a significant throughput and capacity gain of approximately 50% compared to the well-known cyclic/round-robin and maximum CIR schedulers

Performance evaluation of IEEE802.16 WiMax with fixed and mobile subscribers in tight reuse

WiMax broadband MAN based on the IEEE 802.16d/e standard supports mobile as well as fixed wireless access services. The underlying subscriber data links are characterised by totally different radio conditions such as propagation, interference rejection capability, terminal antenna gain, pattern and height. This leads to a significant coverage mismatch, different user throughput, system capacity and spectrum efficiency. In this paper, the basic performance of mobile and fixed subscribers has been thoroughly analysed for homogeneous hexagonal 3.5 GHz cellular deployments of an OFDM-based WiMax system depending on cell size, frequency reuse and offered traffic load. Network level simulation results on user FTP-application throughput, channel load, modulation and coding scheme utilisation and packet call blocking have been presented for cell radius of 300, 1000 and 2000 m in tight 1 × 1 and 1 × 3 frequency reuse, respectively. The future performance enhancements from optional features as Block Turbo Coding, downlink Power Control, scheduling schemes, sub-channelling in scalable OFDMA and advanced antenna technology have been evaluated and simulation results provided.

Performance analysis of IEEE802.16 based cellular MAN with OFDM-256 in mobile scenarios

The recent IEEE802.16d/e standardization initiative for wireless metropolitan area networking (MAN) aims at portable and mobile broadband wireless access (BWA) in cellular deployments as well as conventional fixed residential high throughput access (e.g. wireless DSL) and feeding applications such as IEEE802.11 WLAN hotspot backhaul. This paper focuses on the basic IEEE802.16d/e performance presenting end-to-end application throughput, capacity and spectrum efficiency figures for pure mobile scenarios. Detailed link level and system level simulations have been performed in interference limited cellular environment for tight 1x1 and 1x3 frequency reuse showing very promising results on 3.5 MHz OFDM channels (256 sub-carriers) in the 3.5 GHz band. The dependency of the application throughput, channel utilization and coding scheme distribution on the system load has been thoroughly analyzed. It is shown that admission control functionality is mandatory for a system in 1x1 reuse to avoid overload and packet call blocking conditions, whereas 1x3 reuse works properly over the entire system load range.

Performance analysis of dynamic TDM-transport for GSM voice and GPRS/EDGE packet data services

Todays GSM and GPRS mobile networks are based on static 16 kbps terrestrial transport on the Abis interface using E1/T1 lines. For the introduction of the high data rate GPRS coding schemes such as CS4 with up to 20 kbps, EDGE with up to 59.2 kbps and high quality wideband adaptive multirate voice codecs with up to 23.85 kbps the terrestrial Abis capacity per air interface radio channel has to be extended. With FAAS a fully dynamic allocation strategy of n/spl times/16 kbps subslots is proposed on a per site basis for both voice and data to optimally match the capacity requirements of high bandwidth radio channels. The approach includes bringing up and releasing Abis resources out of the Abis resource pool on demand. The interaction with admission control, radio resource management and link adaptation involving upgrade and downgrade procedures is taken into account. To avoid unacceptable voice blocking a new concept for voice protection is included. Detailed simulation results for different cell configurations are presented for voice only and mixed voice and GPRS/EDGE packet data scenarios at varying load, which allow the appropriate dimensioning of the Abis resource pool per site. Depending on the cell load capacity gains up to 70% (typically 30-40% for medium load) can be achieved compared to a static Abis allocation approach promising considerable cost savings for operators.

Contrasting GPRS and EDGE over TCP/IP on BCCH and nonBCCH carriers

The introduction of EDGE in current GSM/GPRS deployments will give operators a significant boost in network capacity and will offer mobile data users high bandwidth packet data services. Intelligent radio resource management allows the allocation of the GPRS/EDGE packet data channels (PDCHs) on the beacon carrier (BCCH) or on nonBCCH carriers. Most key performance indicators (KPIs) such as user data throughput, channel capacity and spectrum efficiency are affected by an appropriate choice of the cell configuration. In this paper detailed simulation results for the end to end performance of GPRS and EDGE over TCP/IP are presented. Todays GPRS 4 timeslot capable mobiles as well as EDGE 2 and 4 multislot mobiles are investigated. The performance of PDCH allocations on the BCCH and nonBCCH carrier has been contrasted for pure GPRS and EDGE services showing the pros and cons for each configuration. Finally mixed scenarios with GPRS and EDGE multiplexing on the same PDCHs are covered.

Quality of service in GPRS/EDGE mobile radio networks

An advanced QoS strategy comprising 3GPP QoS parameters along with operator specific weighting factors is used to define the appropriate QoS priority of each service type and user profile. A deterministic up- and downgrading strategy as well as admission control is applied to ensure both a minimum service level, defined by the operator for low-priority services, and a full bandwidth for delay time sensitive services and premium users. The simulation results show that, especially in highly loaded and even overloaded GSM/GPRS/EDGE networks, the introduction of QoS provides significant benefits for the end user and offers means to increase the service revenues according to the charging policy adopted by the network operator. The introduction of an appropriate QoS strategy is the prerequisite for an overlay deployment strategy of GSM/EDGE and UMTS. The efficiency of QoS management is crucial for all mobile network technologies and has high impact on fulfilling the demands of mobile subscribers with continuously growing expectations.

Different OFDM Link Level Performance Under the Presence of Co-Channel Interference and Noise

OFDM link level performance in terms of raw bit error rate (BER) versus signal-to-noise and interference ratio (SNIR) has been investigated for robust BPSK and QPSK modulation schemes in a WiMax like framework for both noise and interference limited scenarios. A fundamental difference between additive white Gaussian noise (AWGN) and co-channel interference has been observed especially under static/stationary conditions leading to a huge performance gap of several dB. The latter significantly depends on essential properties of the interference such as synchronization, modulation order as well as the received number of simultaneous interferers. Furthermore preamble based real channel estimation behaves completely different under noise and co-channel interference conditions thus considerably affecting the link level results. Real channel estimation proves to be very susceptible against co-channel interference and shows some additional degradation compared to ideal channel estimation with perfect channel state information. Moreover it has been shown that dominant co-channel interference has a strong impact on the results obtained under stationary/static conditions, whereas the statistics of a mobile fading channel significantly flattens those effects and reduces the performance gap to a rather marginal extent