# Adaptive Method for Packet Loss Types in IoT: An Naive Bayes Distinguisher
## 2 Related Work  
At present, scholars have carried out a lot of research work on the hybrid network TCP congestion control strategy. The main schemes include segmentation connection scheme, link layer scheme, cross-layer cooperation scheme and end-to-end scheme. The segmented connection scheme divides the TCP connection into two parts, a wired segment and a wireless segment, each of which is a complete TCP connection. The wired segment is a part of the path from the sender to the base station, using traditional TCP protocols. The wireless segment is a part from the base station to the receiver, using an improvement TCP protocol. However, in this way, the sender can only receive feedback from the base station and cannot know the transmission situation of the wireless segment, which violates the end-to-end semantics of TCP protocol [18; 19; 20; 21; 22], TCP-Split [23] algorithm and TCP-Snoop [24] algorithm used the base station as a TCP agent, which was responsible for retransmission and corresponding control of packet loss on wireless link. They identified the cause of packet loss and dealt with it without sender. However, this method required a large amount of buffering and processing capability of the base station, and was not suitable for the current network with increasing data traffic. The link layer scheme sense packet loss and complete retransmission at the wireless link layer, which is flexible in operation, but has certain repeatability with high-level error control and is easy to compete with each other. Moreover, wireless end users also have the problem of energy limitation and their performance is often not unsatisfactory [25; 26; 27]. There are two typical methods, Forward Error Correction (FEC) and Automatic Repeat Request (ARQ). With FEC technology, the receiver recovered damaged data according to the check sequence of the data packet. However, the cost of bandwidth resources was expense and the network performance was reduced. The ARQ technology has retransmitted wrong packets according to the ACK feedback from the receiver, but the channel usage rate was not high. The cross-layer cooperation scheme is a protocol of cooperation among multiple layers, which improves the congestion control strategy. For example, ELN [28] transferred the status information from the link layer to the transport layer by marking the ELN bit, which has been carried as a TCP option on the ACK. As a result, the sender knew the generation of the wireless packet loss. The end-to-end scheme improves TCP protocols and does not require support from nodes other than the sender and receiver. It is very popular and has many research results (e.g., TCP-Reno, TCP-Vegas, and TCP-Westwood). This type of scheme generally makes improvement depends on a certain parameter, such as round-trip time (RTT), one-way delay, receive packet time interval (RPTI) and retransmission rate. It obtains the threshold value or membership range for distinguishing packet loss types or current network states through statistical analysis. NCPLD [29] measured the RTT value at the sender and compared it with the delay threshold that has been set. If the RTT value was less than the threshold, the category of packet loss was judged as wireless random loss, otherwise, it was congestion packet loss. The simulation of NCPLD showed that the classification accuracy of packet loss was high with high wireless loss rate. However, when the wireless loss rate was low, the network performance was not superior to the traditional TCP protocol. TCP-Biaz [30] constructed a probabilistic packet loss detector mechanism base on the RTT value, but the improved performance was not high. TCP-Casablanca [16] marked packets as different priority levels at the sender in equal intervals. During the transmission process, the router performed different discarding behaviors according to the packet priority level. After received the data packets, the receiver identified the packet loss type by statistically analyzing the loss probability of each priority data packet.