Cross-layer QoS Analysis of Opportunistic OFDM-TDMA and OFDMA Networks

Abstract

Abstract-Performance analysis of multiuser orthogonal frequency division multiplexing (OFDM-TDMA) and orthogonal frequency division multiple access (OFDMA) networks in support of multimedia transmission is conducted in this work. We take a cross-layer approach and analyze several quality-of-service (QoS) measures that include the bit rate and the bit error rate (BER) in the physical layer, and packet average throughput/delay and packet maximum delay in the link layer. We adopt a cross-layer QoS framework similar to that in IEEE 802.16, where service classification, flow control and opportunistic scheduling with different subcarrier/bit allocation schemes are implemented. In the analysis, the Rayleigh fading channel in the link layer is modeled by a finite-state Markov chain, and the channel state information (CSI) is assumed to be available at the base station. With the M/G/1 queueing model and flow control results, our analysis provides important insights into the performance difference of these two multiaccess systems. The derived analytical results are verified by extensive computer simulation. It is demonstrated by analysis and simulation that OFDMA outperforms OFDM-TDMA in QoS metrics of interest. Thus, OFDMA has higher potential than OFDM-TDMA in supporting multimedia services.Index Terms-quality of services (QoS), multiple access, OFDM, OFDMA, cross-layer analysis, opportunistic scheduling.

QoE Analysis of Media Streaming in Wireless Data Networks

“…The boundary b r is obtained by b r = − 2 3 (ln(5BER))(2 2r − 1) [10].Thus, R r is written as [b r , b r+1 ). In this paper, the BER requirement is taken as 10 −5 .…”

A Coordinated Resource Allocation Algorithm for Infrastructure-Based Relay Networks

“…If the best connection is a single-hop connection, that is, l best ∈ L 1hop , the BS uses all slots which are not required to fulfill the demanded subframe size of the RSs. The subframe size is S 0 = S 0 and given by (10). The subcarrier, bit, and power allocation is found by solving the problem in (9a), (9b), (9c), and (9d).…”

“…A cross-layer design of the allocation of subcarriers at the medium access control layer and a suitable choice of the transmit power and the used modulation scheme on the physical layer improve the performance of an OFDMA system [2]. Hence, various cross-layer methods exist for OFDMA systems dealing with the allocation of resources, for instance, given in [2,[9][10][11][12]. However, these methods are limited to conventional cellular networks in which no RSs are deployed.…”

Flow-level performance of opportunistic OFDM-TDMA and OFDMA networks

“…However, by letting K represent the number of independent subcarriers instead of the total number of subcarriers, G OFDM−TDMA LB (n, K ) provides a close approximation of G OFDM−TDMA (n, K ), and a tight upper bound of G OFDM−TDMA (n, K ) can be derived based on the solution of (16) and (17). Note that the number of independent subcarriers K equals to K/Δk * , where x denotes the largest integer which is less than or equal to x and Δk * is the smallest solution of the equation for frequency correlation function R i F (Δk * ) = 0.…”

“…In [15], OS algorithms in OFDM systems under infinite backlogs and dynamic packet arrivals have been investigated; in [16], a generalized processor sharing (GPS) based scheduler integrated with power and subcarrier allocation is proposed to maximize the system throughput; and in [17], the OS performance of OFDM-TDMA systems has been compared with that of OFDMA systems at the packet level. So far, research on OS for OFDM systems has mainly focused on the packet level.…”