You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: Hardware Decoders for Polar Codes: An Overview 
Chapter Title:  C. Approximate Tree Pruning in LLR-Based SCL Decoding 
1. Abstract of Cited Paper (BIB001):  We present an LLR-based implementation of the successive cancellation list (SCL) decoder. To this end, we associate each decoding path with a metric which (i) is a monotone function of the path’s likelihood and (ii) can be computed efﬁciently from the channel LLRs. The LLR-based formulation leads to a more efﬁcient hardware implementation of the decoder compared to the known log-likelihood based implementation. Synthesis results for an SCL decoder with block-length of N = 1024 and list sizes of L = 2 and L = 4 conﬁrm that the LLR-based decoder has considerable area and operating frequency advantages in the orders of 50% and 30%, respectively.

Literature Review:
Since SCL decoding heavily relies on SC decoding for the computation of the path metrics, one may expect that the pruning techniques described in Section III should be applicable to SCL decoding as well. Unfortunately, in order to update the LLR-based path metric of BIB002 , all the LLRs produced by the leaves of the decoder tree are required and these node computations cannot be pruned if one wants to implement exact SCL decoding. Nevertheless, BIB001 describes an approximate SCL decoding algorithm which is based on tree pruning that simply ignores some of the path metric updates corresponding to computation tree leaves. The resulting performance degradation is small and an outline of a hardware architecture is presented which can achieve a throughput of slightly over 1 Gbps for a polar code of length N = 8192 and rate R = 0.5 using SCL decoding with L = 4.