Multicast device-to-device (D2D) transmission is important for applications like local file transfer in commercial networks and is also a required feature in public safety networks. In this paper we propose a tractable baseline multicast D2D model, and use it to analyze important multicast metrics like the coverage probability, mean number of covered receivers and throughput. In addition, we examine how the multicast performance would be affected by certain factors like dynamics (due to e.g., mobility) and network assistance. Take the mean number of covered receivers as an example. We find that simple repetitive transmissions help but the gain quickly diminishes as the number of repetitions increases. Meanwhile, dynamics and network assistance (i.e., allowing the network to relay the multicast signals) can help cover more receivers. We also explore how to optimize multicasting, e.g. by choosing the optimal multicast rate and the optimal number of retransmission times.
In parallel with the academic studies, standardization effort in addressing multicast services has been is being undertaken and mainly focuses on single-rate multicast. For example, multicast services were addressed in GSM WCDMA and are being addressed in LTE by 3GPP; the 3GPP work item is known as multimedia broadcast and multicast service (MBMS) @cite_15 . Similarly, 3GPP2 addressed multicast services in CDMA2000 with the work item known as broadcast and multicast service (BCMCS) @cite_10 .
@cite_15 @cite_10
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TV is regarded as a key service for mobile devices. In the past, Mobile TV was often associated with broadcast transmission. However, unicast technology is sufficient in many cases, especially since mobile users prefer to access content on-demand, rather than following a fixed schedule. In this paper we will focus on 3G mobile networks, which have been primarily optimized for unicast services. Based on a traffic model we will discuss the capacity limits of 3G networks for unicast distribution of Mobile TV. From the results it can be concluded that the capacity is sufficient for many scenarios. In order to address scenarios in which broadcast is a more appropriate technology, 3GPP has defined a broadcast extension, called Multimedia Broadcast Multicast Service (MBMS). MBMS introduces shared radio broadcast bearers and has thus the capabilities of a real broadcasting technology. We will give a short overview about MBMS including a discussion on MBMS capacity. Since MBMS is primarily a new transport technology, additional application and service layer technologies are required, like electronic service guide and service protection. These mechanisms are standardized by the Open Mobile Alliance (OMA) and are favorably combined with MBMS or 3G unicast distribution in order to create complete end-to-end solutions. In order to optimize a system for delivery of broadcast services over 3G networks, the advantages of broadcast and unicast should be combined. We argue that hybrid unicast-broadcast delivery offers the best system resource usage and also the best user experience, and is thus favorable not only for broadcast delivery in 3G networks, but actually also for non-cellular broadcast systems like DVB-H or DMB Video service delivery over 3GPP Long Term Evolution-Advanced (LTE-A) networks is gaining momentum with the adoption of the evolved Multimedia Broadcast Multicast Service (eMBMS). In this paper, we address the challenge of optimizing the radio resource allocation process so that heterogeneous groups of users, according to their propagation conditions, can receive layered video streams at predefined and progressively decreasing service levels matched to respective user groups. A key aspect of the proposed system model is that video streams are delivered as eMBMS flows that utilize the random linear network coding (NC) principle. Furthermore, the transmission rate and NC scheme of each eMBMS flow are jointly optimized. The simulation results show that the proposed strategy can exploit user heterogeneity to optimize the allocated radio resources while achieving desired service levels for different user groups. In this paper, we present an experiment- and simulation-based study to evaluate the use of full duplex (FD) as a potential mode in practical IEEE 802.11 networks. To enable the study, we designed a 20-MHz multiantenna orthogonal frequency-division-multiplexing (OFDM) FD physical layer and an FD media access control (MAC) protocol, which is backward compatible with current 802.11. Our extensive over-the-air experiments, simulations, and analysis demonstrate the following two results. First, the use of multiple antennas at the physical layer leads to a higher ergodic throughput than its hardware-equivalent multiantenna half-duplex (HD) counterparts for SNRs above the median SNR encountered in practical WiFi deployments. Second, the proposed MAC translates the physical layer rate gain into near doubling of throughput for multinode single-AP networks. The two results allow us to conclude that there are potentially significant benefits gained from including an FD mode in future WiFi standards. Multicasting is emerging as an enabling technology for multimedia transmissions over wireless networks to support several groups of users with flexible quality of service (QoS) requirements. Although multicast has huge potential to push the limits of next generation communication systems; it is however one of the most challenging issues currently being addressed. In this survey, we explain multicast group formation and various forms of group rate determination approaches. We also provide a systematic review of recent channel-aware multicast scheduling and resource allocation (MSRA) techniques proposed for downlink multicast services in OFDMA based systems. We study these enabling algorithms, evaluate their core characteristics, limitations and classify them using multidimensional matrix. We cohesively review the algorithms in terms of their throughput maximization, fairness considerations, performance complexities, multi-antenna support, optimality and simplifying assumptions. We discuss existing standards employing multicasting and further highlight some potential research opportunities in multicast systems.