Link layer algorithms for efficient multicast service provisioning in 3G cellular systems

Abstract

Abstract-In this work we introduce error control algorithms for multicast delivery in 3G cellular networks. For efficiency reasons, the delivery of multicast flows is usually achieved by allocating a common channel in the forward direction. This enables multiple users to be served by a single physical resource. However, different users are affected by independent channel error processes and new techniques, different from plain ARQ, have to be found to perform error recovery. These new algorithms are needed to deliver the multicast flow in an efficient manner and to enable a reliable, performant and network operator inexpensive multicast service. In the paper different hybrid ARQ algorithms for the error recovery of multicast flows over common channels are proposed and their performance is evaluated both analytically and by simulation. The proposed solutions have been found to be effective and advantageous over plain ARQ techniques. At the end of the paper, results on the achievable video quality are reported for the multicast video streaming case by considering the H.263 video coding format.

SYNAPSE++: Code Dissemination in Wireless Sensor Networks Using Fountain Codes

“…Packets are encoded using arithmetic on the Galois field GF ð2Þ, i.e., by means of bitwise XOR operations. This substantially speeds up the execution time with respect to traditional packet-based Reed Solomon codes [5], [23], which use more complex operations among polynomial coefficients in GF ð2 q Þ, with q > 2. In fact, fast operations over GF ð2 q Þ require the use of lookup tables, which is substantially slower than XORing symbols.…”

“…In addition, the forward channel (transmitter ! receivers) performance (e.g., delay and throughput efficiency) is heavily impacted even for a small number of receivers and low error rates [23]. As a solution, in the literature several HARQ schemes have been proposed, see, e.g., [5], [23].…”

“…HARQ scales considerably better than ARQ as a single redundancy packet can recover different losses at multiple receivers. We advocate the use of fountain codesbased HARQ schemes for programming WSNs as these retain the good performance of previous HARQ schemes [5], [23] while presenting additional advantages:…”

“…Due to the rateless nature of these codes, we do not need to know in advance the error probability p. This simplifies implementation and increases efficiency. In fact, the actual amount of redundancy to use within our dissemination protocol can be decided on the fly, while retaining the good error recovery performance of traditional HARQ schemes that use packet-based Reed Solomon [5], [23] or Tornado [24] codes. .…”

Performance of Parity-Based Loss Recovery for Reliable Multicast in Third-Generation Mobile Networks

“…Only recently have hybrid ARQ techniques for reliable multicast been investigated in the context of video streaming over a third-generation air interface. In [6], [7], [8], the authors investigate the reliable delivery of video content over a third-generation air interface to a group of users. Since delay guarantees are important for video streaming, the authors focus on the delay as the main performance metric.…”