Rosnes E.,Ceragon Networks
IEEE Transactions on Information Theory | Year: 2012
An interleaver is a critical component for the channel coding performance of turbo codes. Algebraic constructions are of particular interest because they admit analytical designs and simple, practical hardware implementations. Also, the recently proposed quadratic permutation polynomial (QPP)-based interleavers by Sun and Takeshita have provided excellent performance for short-to-medium block lengths, and have been selected for the 3GPP LTE standard. In this paper, we derive some upper bounds on the best achievable minimum distance d min of QPP-based conventional binary turbo codes (with tailbiting termination, or dual termination when the interleaver length N is sufficiently large) that are tight for larger block sizes. In particular, we show that the minimum distance is at most 2(2 ν+1+9), independent of the interleaver length, when there exists an inverse polynomial of degree two, where ν is the degree of the primitive feedback and monic feedforward polynomials. However, allowing the QPP to have no inverse polynomials of degree two may give strictly larger minimum distances (and lower multiplicities). In particular, we provide several QPPs with no quadratic inverse for some of the 3GPP LTE interleaver lengths giving a d min with the 3GPP LTE constituent encoders which is strictly larger than 50. For instance, we have found a QPP for N=6016 which gives an estimated d min of 57. Furthermore, we provide the exact minimum distances and the corresponding multiplicities for all 3GPP LTE turbo codes (with dual termination) which shows that the best minimum distance is 51. Finally, we compute the best achievable minimum distances with QPP interleavers for all 3GPP LTE interleaver lengths N = 4096, and compare these minimum distances with the ones we get when using the 3GPP LTE polynomials. © 2012 IEEE. Source
Ceragon Networks | Date: 2011-09-27
A method of allocating wireless communication capacity in a wireless point-to-point link including obtaining a channel having a bandwidth for use in the wireless point-to-point link, allocating a first portion of the bandwidth for use for transmitting from a first point to a second point of the wireless point-to-point link, and allocating a second portion of the bandwidth for use for transmitting from the second point to the first point of the wireless point-to-point link, in which the bandwidth is asymmetrically assigned between the first portion and the second portion. Related apparatus and methods are also described.
Ceragon Networks | Date: 2011-05-12
A method for managing traffic in a communication network which includes a protected path including a first path and a second path, including refraining from sending redundant data along the second path, and using freed up communication capacity obtained by refraining from sending redundant data along the second path for sending other data along the second path. The above-described method and further comprising measuring path integrity, in which the refraining from sending and the using freed up communication capacity depend, at least partly, on meeting a stability criterion applied to the measured path integrity. A network management unit configured to functionally connect to a communication node configured to provide path protection by sending redundant data along a first path and a second path, configured to cause the communication node to refrain from sending redundant data along the second path, and use freed up communication capacity, obtained by causing the communication node to refrain from sending redundant data along the second path, for sending other data along the second path. Related apparatus and methods are also described.
Ceragon Networks | Date: 2010-09-28
A method for managing protection of a plurality of defined paths in a communication system including listing the defined paths, each item in the list including a defined path identifier, a defined path ingress node, a defined path egress node, and a defined path protection period, wherein some of the defined paths share an ingress node and an egress node, managing a sending of Continuity Check Messages (CCMs) along at least some of the defined paths, such that a CCM is sent every protection period, and for at least a plurality of the defined paths which share an ingress node and an egress node, managing a sharing of the protection of the plurality of the defined paths, the sharing including sending one set of CCMs, shared by the plurality of the defined paths, at a frequency based, at least in part, on a shortest one of the protection periods of the plurality of the defined paths. A method for protecting a plurality of paths which share at least one leg in a communication network, including sharing, between the paths, Continuity Check Messages (CCMs) for at least the shared leg. Related apparatus and methods are also described.
Ceragon Networks | Date: 2010-12-07
A method for interference reduction in transmission of at least two single carrier frequency continuous communication beams including producing a first communication signal for a first digital communication link, producing a second communication signal for a second digital communication link, transmitting the first communication signal over a first continuous communication beam at a first frequency, transmitting the second communication signal over a second continuous communication beam at the first frequency, characterized by modifying the first communication signal using transmitter interference cancellation. A method for interference reduction in reception of at least two single carrier frequency continuous communication beams including receiving a first received signal from a first digital communication link, receiving a second received signal from a second digital communication link, modifying the first received signal, adding the modified first received signal to the second received signal, thereby producing a reduced-interference second received signal, characterized by the modifying of the first received signal being based, at least in part, on reducing an error rate of the reduced-interference second received signal. Related apparatus and methods are also described.