ing and receiving signals) is a challenge for Ethernet transport. Two techniques are emerging in the packet world to ensure the availability of carrier-grade synchronization signals namely: Synchronous Ethernet IEEE 1588 version 2. Next Generation Mobile Communications Ecosystem The term Synchronous Ethernet (ITU-T G.8262 and G.8264) applies to the network clock, which is the clock that is controlling the bit rate leaving the Ethernet interface. Synchronous Ethernet reproduces in the Ethernet world the same synchronous mechanisms at the physical level of the traditional TDM world. It has not gain much attention because of two reasons: It requires every node of the transmission network to be capable of it, meaning a considerable investment is required. It only supports FDD cellular systems. It does not provide timing information, required by TDD systems. IEEE 1588 version 2 [22] is a packet-based synchronization mechanism where timing packets trans- mitted over dedicated data sessions are used to propagate the clock signal from a primary reference source (master) to destination (slave) nodes. Since they are based on IP packets, the accuracy of the clock recovered at the client side depends on the type of network transport used and loading conditions. For this reason, the deployment of IEEE 1588v2 requires careful planning to ensure the accuracy needed by cellular networks is delivered. Each timing packet contains a timestamp, which can be used to retrieve the time of day. For this reason, IEEE 1588v2 can deliver frequency and timing stabilities, the latter required by TDD cellular networks. 7.4.2.2.2 Pseudowire (PWE3) A PWE3 (the 3 standing for the third power of E, i.e., EEE) emulates a point-to-point link, and provides a single service which is perceived by its user as an unshared link or circuit of the chosen service. It is not intended that an emulated service be indistinguishable from the service that is being emulated and the emulation only needs to be sufficient for the satisfactory operation of the service