Bijoy, HDSL May Be? 🙂 It is not pure E1. It have line coding differ from one, standardizided for E1.
MKT, E1 is only E1 and nothing more. It have bit rate = 2048 kbit/s from point of view of transmitter and line code HDB3 according to G.703. I.e. you have a “pipe” with throughput 2048 kbit/s.
But you may have a Source (or sources) which generates some bit stream with speed bit rate > 2048 kbit/s and you should negotiate your bit stream with throughput of your bottleneck “pipe”. You do this by means of any well-known methods of sourse coding (or compression) dependently from source characteristics (for example Shennon or Haffman, Lempel-Ziv, JPEG, MPEG or others..)