With the availability of large bandwidth and high data rates the transmission of data, voice and video over the Internet is gaining popularity. Voice-over-IP (VoIP) uses packetized transmission of speech over the Internet (IP network).However, at the receiving end; packets are missing due to network delay, network congestion (jitter) and network errors. This packet loss degrades the quality of speech at the receiving end of a voice transmission system in an IP network. Since the voice transmission is a real-time process, the receiver cannot request for retransmission of the missing packets. This causes a need for reconstruction of the lost packet. Concealment algorithms, either transmitter or receiver based, are used to replace these lost packets. The goal of this paper is to review the different PLC algorithm on the receiver side.

The transmission of voice over packet switched networks, such as an Internet Protocol (IP), is an area of active research. The speech packets when transmitted over unreliable IP networks, such as the internet, may encounter losses due to dropped packets or late arrivals. This packet loss may change the meaning of senders message as well degrades the quality of speech at the receiving end of a voice transmission system over network. Since the voice transmission is a real-time process, request of retransmission of the missing packets is unpredictable. Concealment of Packet Loss algorithms, either transmitter or receiver based, are used to replace these lost packets. This paper is to study (reviews) the error-concealment schemes for speech packet transmission over the internet. The existing techniques can be classified into source coder-dependent schemes that exploit coder-specific characteristics to perform reconstruction and source coder-independent schemes .These techniques are use to solve the problem of loss of speech packets over IP to improve the perceived speech quality.