# A Single-Rate Multicast Congestion Control (SRMCC) Mechanism in Information-Centric Networking
## 2 Related Work  
There are many researchers dedicated to the study of multicast congestion control [15; 16; 17; 18]. Most of the mechanisms are based on rate rather than window, because many window-based AIMD algorithms reduce the size of the window by half when they encounter congestion, so that the change in throughput is quite obvious [19]. In contrast, the adjustment of sending rates makes the fluctuation of throughput smoother. Existing rate-based multicast congestion control mechanisms can be divided into two main categories: single-rate congestion control, and multi-rate congestion control [20]. In multi-rate mechanisms, the multicast source maintains multiple layers with different transmission rates, and receivers subscribe to different subsets of layers according to network bandwidth and congestion status [18]. However, these mechanisms are relatively complex and require frequent feedback [15]. Single-rate multicast congestion control approaches are very effective and easily applied [21], and the mechanism proposed in this paper also belongs to this category. We have focused on various mechanisms which employ the single-rate method and a multicast source to control congestion. For the sake of brevity and novelty, the literature reviews of typical mechanisms in this category are as follows. [PERSON]. [22] introduced a new single-rate multicast congestion control scheme called explicit rate multicast congestion control (ERMCC). However, ERMCC achieves TCP friendliness only on the path to the slowest receiver with the proper adjustment of its rate adaptation parameters. Pragmatic general multicast congestion control (PGMCC) [23] is a window-based TCP-like scheme which is based on positive ACKs between the sender and the group representative (the acker). Only the acker is responsible for sending positive ACKs to the multicast source, miming a classic TCP receiver. When packet loss events occur, other receivers send NACKs. In reality, PGMCC does not provide a feedback suppression mechanism. TCP-friendly multicast congestion control (TFMCC) [24] extends the basic mechanisms of TFRC [25] to dynamically adjust the sending rate. To ensure TCP fairness, TFMCC adopts a conservative method to control the sending rate, which estimates the steady-state throughput of the TCP source according to an equation, and simultaneously uses the round trip time (RTT) and packet loss rate of the slowest receiver mentioned as the current limiting receiver (CLR). However, TFMCC responds slowly to varying networks that cause CLR changes. Adaptive smooth multicast protocol (ASMP) [26] is a single-rate multicast transport control mechanism designed for multimedia applications. According to the TCP-friendly rate control (TFRC) specification [25], multicast receivers need to calculate the TCP-friendly bandwidth share. The smoothness is achieved by dynamically estimating protocol parameters and adjusting the \"smoothness factor\". However, ASMP does not consider the buffer status of the router. Generalized multicast congestion control (GMCC) [27] uses a set of independent single-rate sub-sessions (also called layers) as building blocks to provide multi-rate features with low complexity. The receiver is responsible for joining and leaving layers. Compared to other multi-rate schemes, GMCC can vary the number of layers and the transmission rate within the layers. A multicast congestion avoidance scheme named MCA was proposed by [28], which was based on rate and end-to-end. It provides two different schemes based on bit-based and explicit rate-based feedback models. They can avoid the drop-to-zero problem and are fair to unicast congestion avoidance schemes. Additionally, in the field of ICN, [PERSON]. [29] proposed a lightweight enhancement to the content-oriented publish/subscribe system (R-COPSS) not only for reliability but also for flow and congestion control. It selects an ACKer according to the minimum rate that the publisher can support for the particular pub/sub tree, the packet loss rate, and throughput reported by the subscribers.